Obsidian hydration dating of naturally worked sediments in the Yellowstone region, Montana and
Wyoming
by Kenneth Donald Adams
A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in
Earth Sciences
Montana State University
© Copyright by Kenneth Donald Adams (1990)
Abstract:
The purpose of this study was to develop an obsidian hydration dating technique that could be applied
to naturally worked sediments. Two field settings were chosen. The first setting is a group of five
post-glacial fluvial terraces cut into an obsidian-rich outwash plain near West Yellowstone, MT. The
second field setting is a group of five raised and deformed Holocene lakeshores near Breeze Point on
Yellowstone Lake, WY. Results from the terraces imply that grains are only partially reworked, so that
each grain can potentialIy record several events. The dominant reworking mechanism in the fluvial
environment is fracturing as opposed to abrasion. All of the terraces were cut in a shorter period of time
than the technique can discern. Using the calibration curve from Pierce and others (1976) and a
hydration value of 6.5 ±0.5 microns, an age of 20±3 ka is obtained for the terraces. An alternate method
using hydration rate constants for the Obsidian Cliff flow (Michels, 1985), an effective hydration
temperature (EHT) of 1.4 °C and a rind value of 6.5 ± 0.5 microns yields an age of 15,520 + 2480
-2300 yrs. Both of these ages are older than those calculated by Nash (1984) for the same terraces.
However, if the calibration I^C date of 7,100 ± 50 yrs B.P. used by Nash (1984) is too young, his
calculated terrace ages are also too young.
Results from the Holocene lakeshores imply coastal processes do not serve as an effective mechanism
to fracture obsidian gravel. All of the shorelines possess a dominant rind signal at about 5.5 ± 0.5
microns. Hydration rate constants for the Obsidian Cliff flow (Michels, 1985) were used instead of
constants calculated for the Aster Creek flow (Michels, 1988), which forms the local bedrock in the
area, because the latter are thought to be in error. Using Obsidian Cliff constants, an EHT of 1.0 °C and
a rind value of 5.5 ± 0.5 microns, the shorelines yield an age of 12,270 +2330 -2130 yrs. Considering
that all dated postglacial shorelines in the Yellowstone Lake basin are younger than about 9 ka, it is
concluded that the rind signal associated with the shorelines probably dates from latest Pinedale time.
All of the terraces and shorelines have rinds that are thicker than those used to date these features. It is
hypothesized that these older peaks may date from reworking by Eowisconsin glaciers, Bull Lake
glaciers and hydration dating from original cooling cracks, in order of increasing thickness and age.
Hydration rate is dependent on temperature and the chemistry of the glass. Because chemistry varies
within and between flows, rate would also be expected to vary. Much of the observed spread in rind
thicknesses is probably due to natural variation in hydration rate. Therefore, it is not appropriate to use
a single set of hydration rate constants determined from a single sample to calculate ages for artifacts
and geological samples without recognizing this limitation.
OBSIDIAN HYDRATION DATING OF NATURALLY
WORKED SEDIMENTS IN THE YELLOWSTONE
REGION, MONTANA AND WYOMING
by
K e n n e th D o n ald Adams
A t h e s i s s u b m i t te d i n p a r t i a l f u l f i l l m e n t
o f t h e r e q u i r e m e n ts f o r t h e d e g re e
of
M a s te r o f S c ie n c e
in
E a r th S c ie n c e s
MONTANA STATE UNIVERSITY
Bozem an, M ontana
M arch 1990
/
1/5 92
Adi !99ii
APPROVAL
o f a t h e s i s s u b m itte d by
K e n n e th D o n ald Adams
T h is t h e s i s h a s b e e n r e a d b y e a c h member o f t h e t h e s i s c o m m itte e
a n d h a s b e e n fo u n d t o b e s a t i s f a c t o r y r e g a r d in g c o n t e n t , E n g l is h u s a g e ,
f o r m a t, c i t a t i o n s , b i b l i o g r a p h i c s t y l e , and c o n s i s t e n c y , and i s r e a d y
f o r s u b m is s io n t o t h e C o lle g e o f G r a d u a te S t u d i e s .
fyOuy'ic/^Le^r
D a te
C h a i r p e r s o n , G ra
r a d uuaatite C om m ittee
A pproved f o r t h e M a jo r D e p a rtm e n t
D a te
H ead, M pjor D e p a rtm e n t
A pproved f o r t h e C o lle g e o f G ra d u a te S t u d ie s
D at
y
G ra d u a te Dean
iii
STATEMENT OF PERMISSION TO USE
In
m e n ts
th e
p re s e n tin g
fo r
th is
a m a s t e r 's
L ib ra ry
s h a ll
th e s is
d e g re e
make i t
in
p a rtia l
fu lfillm e n t
of
a t M ontana S t a t e U n i v e r s i t y ,
a v a ila b le
to
b o r ro w e r s
under
th e
re q u ire ­
I a g re e t h a t
r u le s
of
th e
L i b r a r y . B r i e f q u o t a t i o n s from t h i s t h e s i s a r e a l l o w a b l e w i t h o u t s p e c i a l
p e r m i s s i o n , p r o v id e d t h a t a c c u r a t e a ck n o w led g em en t o f s o u r c e i s m ade.
P e r m is s io n
fo r
e x te n s iv e
q u o ta tio n
from
t h e s i s may be g r a n t e d by my m a jo r p r o f e s s o r ,
Dean o f L i b r a r i e s w hen,
th e
m a te ria l
is
m a te ria l in t h i s
fo r
in
th e
Any
re p ro d u c tio n
h is
absence,
of
th is
by t h e
t h e p r o p o s e d u se o f
c o p y in g
or
use
of
th e
t h e s i s f o r f i n a n c i a l g a in s h a l l n o t b e a llo w e d w i t h o u t
S i g n a tu r e
A id rc k
or in
o p i n io n o f e i t h e r ,
s c h o la rly ' p u rp o se s.
my w r i t t e n p e r m i s s i o n .
D a te
or
_2 % /
/fTO
iv
ACKNOWLEDGEMENTS
The a u t h o r w is h e s t o
fo r
s u g g e s tin g
th e
id e a
t h a n k W illia m W. L ocke
and c r i t i c a l
(C o m m ittee
C hairm an)
g u id a n c e t h r o u g h o u t t h e p r o j e c t .
Jam es G. S c h m itt an d J o h n M ontagne p r o v id e d h e l p f u l r e v ie w s and d i s c u s ­
s io n .
Wayne L .
te c h n ic a l
R o s s i,
H a m ilto n ,
a s s is ta n c e
and
N a t io n a l
P ark
s tim u la tin g
D e p a rtm e n t o f M a th e m a tic a l
S e rv ic e ,
d is c u s s io n
s u p p lie d
an d
much n e e d e d
re v ie w s .
R ic h a rd
S c i e n c e s , p r o v id e d e x p e r t a d v ic e and
a n a ly s e s o f d a ta .
T hanks a r e a l s o d u e t o t h e N a t i o n a l S c ie n c e F o u n d a tio n f o r f u n d in g
t h e p r o j e c t an d Ken P i e r c e
o f th e
U .S .
G e o lo g ic a l
S u rv e y
fo r h e lp fu l
d i s c u s s i o n s . My a p p r e c i a t i o n i s a l s o e x p r e s s e d t o M ary, f o r my i n s p i r a ­
tio n
and
to
my p a r e n t s
who n e v e r
e n c o u ra g e d me t o go f a r t h e r .
s to p p e d
b e lie v in g
in
me and
a lw a y s
V
TABLE OF CONTENTS
Page
LIST OF TABLES
............................................, . . ........................ ....
v ii
LIST OF FIGURES . . . . . . . . . . . . . . . . . . . . . . . . . . .
ABSTRACT
. . . . . . . . . . . . . . . . . .
........................
. . . . .
METHODS . . . . .
..................................................... ; ....................
Sampl i n g ............................
O b s id ia n Sand P l a i n . . .
.................................. .
Y e llo w s to n e L ake ......................................
H y d r a tio n R in d M easu rem en t . . . . . . . . . . .
G r a in S iz e S e l e c t i o n . . . . . . . . . . . . . .
Z e ro T h ic k n e s s H y d r a tio n R in d s . . .................... . .
S t a t i s t i c a l M ethods and D a ta P r e s e n t a t i o n
. . .
x
I
I
OnW
INTRODUCTION . ...........................................
The P ro b lem
................................................
P r e v io u s W o r k ........................
Q u a te r n a r y G eo logy o f F i e l d S i t e s
W est Y e llo w s to n e B a s in ...........................................
Y e llo w s to n e L ake B a s in . . . . . . . . .
....................
v iii
. . .
.
.
.
.
19
.1 9
19
21
21
27
29
32
RESULTS . . . . . . . . .
........................................... . . . . . . . . . . .
O b s id ia n Sand P l a i n
. . ....................................... . . . . . . . . . .
Y e llo w s to n e L ake . . . . . . . . . . . . . . . . . . . . . . .
35
35
47
DISCUSSION .................... . . . . . . . . . . . .
.................................
O b s id ia n Sand P l a i n
. . . . . . . . . . . . . . . . . . . . .
S o la r I n s o l a ti o n
............................................ . . . . . . . . . .
R ew orking P r o c e s s e s .................................. . . . . . . . . . . .
D ep th o f R ew orking . . . . . . . . . . . . . . . . . . .
Age o f T e r r a c e s . . . . . . . . . . . . . . . . . . . . .
Y e llo w s to n e L ake . . . . . . . . . . . . . . . . . . . . . . .
■ R ew orking P r o c e s s e s . . . . . . .
................... . . . . . . .
Age o f S h o r e l i n e s . . . . . . . . . . . . . . . . . . . .
I n t e r p r e t a t i o n o f O ld e r E v e n t s ............................
The O b s id ia n H y d r a tio n T e c h n iq u e . . . . . . . .
.............................
53
53
53
54
56
58
63
63
65
72
75
CONCLUSIONS......................................................................................
81
REFERENCES CITED
APPENDICES
. . . . .
...................
....................................................
. . . . . . . .
. . . . . . .
6
11
. . . . . . .
. . .
. . .
. . .
. . .
.
.
.
.
.
.
.
.
.
.
.
.
.............................
84
90
vi
TABLE OF CONTENTS-Continued
Page
A -Sam ple P r e p a r a t i o n Flow C h a r t. . . . . . . . . . . . . . . .
B - H y d r a tio n R in d M easu rem en t Flow C h a r t .....................................................
C -C h em ical A n a ly s e s o f O b s id ia n G r a in s ................................................ .
D -R ind M easu rem en t D a ta f,or I n d i v i d u a l S a m p lin g L e v e ls
f o r T e r r a c e TO . ............................. .... ...................................................................
E -R in d M easu rem en t D a ta f o r T e r r a c e s T l T h ro u g h T4 a n d .
t h e M odern S tre a m . . . . . . . . . . . . . . . . . . . . . .
F -R in d M easu rem en t D a ta f o r S h o r e l i n e s ............................. . . . . .
91
94
97
99
101
104
Vii
LIST OF TABLES
T a b le
P age
1 . D a ta a r r a y a n d a n a l y s e s o f m e a su re m e n t e r r o r e x p e r im e n t . „ . .
26
2 . D a ta a r r a y a n d a n a l y s e s o f h y d r a t i o n r i n d t h i c k n e s s e s f o r
d i f f e r e n t g r a i n s i z e c l a s s e s fro m T e r r a c e TO (8 0 -1 0 0 c m ). . . .
28
3 . C h i s q u a r e t e s t t o d e te r m in e i f a l l t e r r a c e s h a v e t h e sam e
num ber o f z e r o t h i c k n e s s r i n d s . . . . . . . . . . . . . . . . .
31
A. C h i s q u a r e t e s t t o d e te r m in e i f t h e m odern s tr e a m h a s t h e same
num ber o f z e r o t h i c k n e s s r i n d s a s t h e t e r r a c e s .......................... . . .
31
5 . H y d r a tio n r a t e s a n d n u m e r ic a l a g e s f o r a 5 .5 m ic ro n r i n d and
e f f e c t i v e h y d r a t i o n t e m p e r a t u r e s r a n g i n g fro m - I t o 11 0C f o r
A s t e r C re e k o b s i d i a n ................................................................... .................................
68
6 . H y d r a tio n r a t e s a n d c o r r e s p o n d in g a g e s c a l c u l a t e d f o r a 6 .5
m ic ro n r i n d a f t e r F rie d m a n a n d Long (1 9 7 6 ) a n d M ic h e ls (1985)
f o r o b s i d i a n C l i f f o b s i d i a n u s i n g t h e sam e t e m p e r a t u r e s . . . .
77
7 . C h e m ic a l a n a l y s e s o f d e t r i t a l b e a c h p e b b le s fro m t h e B re e z e
P o in t a r e a . . . . . .
............................. . . . . . . . . .
....................
98
8 . C h e m ic a l a n a l y s e s o f O b s id ia n C l i f f o b s i d i a n .
98
. . . . . . . . .
9 . R in d m ea su rem e n t d a t a f r o i n d i v i d u a l s a m p lin g l e v e l s f o r
..................................
T e r r a c e TO. . . . . . . . . . . . . . . . . .
.
100
1 0 . R in d m e a su re m e n t d a t a f o r T e r r a c e s T l th r o u g h TA a n d t h e
m odern s tr e a m . . .................... . . . . . .
.................... . . . . . . .
102
1 1 . R in d m ea su rem e n t d a t a f o r S h o r e l i n e s SI t h r o u g h S5 a t
Y e llo w s to n e L a k e . . . . . . . . .
.................................................
105
v iii
LIST OF FIGURES
F ig u r e
Page
1. Map sh o w in g s tu d y a r e a i n r e l a t i o n t o P i n e d a l e i c e m a rg in . . .
2 . R e g io n a l map o f Y e llo w s to n e N a t io n a l P a rk and v i c i n i t y sh ow ing
r h y o l i t e l a v a flo w s a n d l o c a t i o n o f s tu d y s i t e s ............................. .
3.
7
13
C om puter g e n e r a te d d ia g ra m o f s tu d y s i t e I sh o w in g l o c a t i o n
o f sa m p le p i t s ...............................................................................................
20
4 . S u rv e y e d p r o f i l e o f b e a c h berm s a t B re e z e P o i n t sh o w in g
l o c a t i o n s o f sa m p le p i t s ..........................................................................................
22
5 . R in d m e a su re m e n t d a t a f o r T e r r a c e TO a t 0 - 20 cm d e p th . . . .
36
6 . R in d
m e a su re m e n t d a t a
f o r T e r r a c e TO a t
20 - 40
cm d e p th . . . .
37
7 . R ind
m e a su re m e n t d a t a
f o r T e r r a c e TO a t
40 - 60
cm d e p th . . . .
38
8 . R in d
m ea su rem e n t d a t a
f o r T e r r a c e TO a t
60 - 80
cm d e p th . . . .
39
9 . R in d
m e a su re m e n t d a t a
f o r T e r r a c e TO a t
80 - 100 cm d e p th
. . .
40
1 0 . A g g re g a te r i n d m ea su rem e n t d a t a f o r T e r r a c e TO. ..................................
41
1 1 . R in d
m e a su re m e n t d a t a
f o r T e r r a c e T l . ...........................................................
42
1 2 . R in d
m ea su rem e n t d a t a
f o r T e r r a c e T 2................................................................
43
1 3 . R in d
m e a su re m e n t d a t a
f o r T e r r a c e T 3 ................................................................
44
1 4 . R ind
m ea su rem e n t d a t a
f o r T e r r a c e T 4................................................................
45
1 5 . R in d m e a su re m e n t d a t a f o r m odern s t r e a m ...........................................
16. R in d
m ea su rem e n t d a t a
. .
46
f o r S h o r e l i n e S I .........................
48
1 7 . R in d m e a su re m e n t d a t a
f o r S h o r e li n e S 2...........................................................
49
1 8 . R in d m e a su re m e n t d a t a
f o r S h o r e li n e S3. . . . ........................................
50
1 9 . R in d m e a su re m e n t d a t a
f o r S h o r e l i n e S 4 .........................
51
2 0 . R in d m e a su re m e n t d a t a
f o r s h o r e l i n e S5...................................
52
ix
L IST OF FIGURES— C o n tin u e d
F ig u r e
Page
2 1 . H y d r a tio n c a l i b r a t i o n c u rv e sh o w in g a g e s o f M ad iso n R iv e r
t e r r a c e s and a n i n t e r p r e t e d o l d e r e v e n t i n r e l a t i o n t o g l a c i a l
d e p o s i t s i n t h e W est Y e llo w s to n e a r e a . . . . . . .
........................
22.
C o r r e l a t i o n c h a r t sh o w in g a g e s o f s e l e c t e d s u r f i c i a l g e o lo g ic
f e a t u r e s i n t h e W est Y e llo w s to n e a r e a . . . . . . . . . . . . .
60
61
2 3 . H i s to g r a p h o f 233 r i n d m e a s u re m e n ts from an a r c h a e o l o g i c a l s i t e
i n M exico . . . . . . . . . . . . . . . . . . . . . . . . . . .
79
2 4 . Flow c h a r t f o r sam p le p r e p a r a t i o n p r o c e d u r e s . . . . .
...................
92
........................
95
2 5 . Flow c h a r t f o r h y d r a t i o n r i n d m e a su re m e n t
X
ABSTRACT
The p u r p o s e o f t h i s s tu d y w as t o d e v e lo p an o b s i d i a n h y d r a t i o n
d a t i n g te c h n i q u e t h a t c o u ld be a p p l i e d t o n a t u r a l l y w o rk ed s e d im e n ts .
Two f i e l d s e t t i n g s w e re c h o s e n . The f i r s t s e t t i n g i s a g ro u p o f f i v e
p o s t - g l a c i a l f l u v i a l t e r r a c e s c u t i n t o an o b s id i a n - r i c h
o u tw a sh p l a i n
n e a r W est Y e llo w s to n e , MT. The s e c o n d f i e l d s e t t i n g i s a g ro u p o f f i v e
r a i s e d an d d e fo rm e d H o lo c e n e l a k e s h o r e s n e a r B re e z e P o i n t on Y e llo w s to n e
L a k e , WY„ R e s u l t s fro m t h e t e r r a c e s im p ly t h a t g r a i n s a r e ,only p a r t i a l l y
re w o rk e d , s o t h a t e a c h g r a i n c a n p o t e n t i a l I y r e c o r d s e v e r a l e v e n t s . The
d o m in a n t r e w o r k in g m echanism i n t h e f l u v i a l e n v iro n m e n t i s f r a c t u r i n g a s
o p p o se d t o a b r a s i o n . A ll o f t h e t e r r a c e s w e re c u t i n a s h o r t e r p e r i o d o f
tim e th a n t h e te c h n i q u e can d i s c e r n . U s in g t h e c a l i b r a t i o n c u rv e fro m
P i e r c e and o t h e r s (1976) an d a h y d r a t i o n v a l u e o f 6 .5 + 0 . 5 m ic r o n s , an
ag e o f 20 + 3 k a i s o b t a i n e d f o r t h e t e r r a c e s . An a l t e r n a t e m ethod u s in g
h y d r a t i o n r a t e c o n s t a n t s f o r t h e O b s id ia n C l i f f flo w ( M ic h e ls , 1 9 8 5 ) , an
e f f e c t i v e h y d r a t i o n te m p e r a t u r e (EHT) o f 1 .4 ° c and a r i n d v a l u e o f 6 .5
+ 0 .5 m ic r o n s y i e l d s a n age o f 1 5 ,5 2 0 + 2480 -2 3 0 0 y r s . B o th o f t h e s e
a g e s a r e o l d e r t h a n t h o s e c a l c u l a t e d by N ash (1 9 8 4 ) f o r t h e same
t e r r a c e s . H ow ever, i f t h e c a l i b r a t i o n
d a t e o f 7 ,1 0 0 + 50 y r s B .P .
u se d by N ash (1 9 8 4 ) i s t o o y o u n g , h i s c a l c u l a t e d t e r r a c e a g e s a r e a l s o
to o young.
R e s u l t s from t h e H o lo c e n e l a k e s h o r e s im p ly c o a s t a l p r o c e s s e s do n o t
s e r v e a s an e f f e c t i v e m echanism t o f r a c t u r e o b s i d i a n g r a v e l . A ll o f t h e
s h o r e l i n e s p o s s e s s a d o m in a n t r i n d s i g n a l a t a b o u t 5 .5 + 0 .5 m ic r o n s .
H y d r a tio n r a t e c o n s t a n t s f o r t h e O b s id ia n C l i f f flo w ( M ic h e ls , 1985)
w e r e u s e d i n s t e a d o f c o n s t a n t s c a l c u l a t e d f o r t h e A s t e r C reek flo w
( M ic h e ls , 1 9 8 8 ) , w h ic h fo rm s t h e l o c a l b e d ro c k i n t h e a r e a , b e c a u s e t h e
l a t t e r a r e th o u g h t t o be i n e r r o r . U s in g O b s id ia n C l i f f c o n s t a n t s , an
EHT o f 1 .0 °C and a r i n d v a l u e o f 5 .5 + 0 .5 m ic r o n s , t h e s h o r e l i n e s
y i e l d an a g e o f 1 2 ,2 7 0 +2330 -2 1 3 0 y r s . C o n s id e r in g t h a t a l l d a te d p o s t ­
g l a c i a l s h o r e l i n e s i n t h e Y e llo w s to n e L ake b a s i n a r e y o u n g e r th a n a b o u t
9 k a , i t i s c o n c lu d e d t h a t t h e r i n d s i g n a l a s s o c i a t e d w i t h th e s h o r e ­
l i n e s p r o b a b ly d a t e s from l a t e s t P i n e d a l e tim e .
A ll o f t h e t e r r a c e s and s h o r e l i n e s h a v e r i n d s t h a t a r e t h i c k e r t h a n
t h o s e u s e d t o d a te t h e s e f e a t u r e s . I t i s h y p o t h e s i z e d t h a t t h e s e o l d e r
p e a k s may d a te from re w o rk in g by E o w is c o n s in g l a c i e r s . B u ll L ake g l a ­
c i e r s an d h y d r a t i o n d a t i n g from o r i g i n a l c o o li n g c r a c k s , i n o r d e r o f
i n c r e a s i n g t h i c k n e s s and a g e .
H y d r a tio n r a t e i s d e p e n d e n t on t e m p e r a t u r e and t h e c h e m is tr y o f t h e
g l a s s . B e c a u se c h e m is tr y v a r i e s . w i t h i n a n d b e tw e e n f lo w s , r a t e w o u ld
a l s o be e x p e c te d t o v a r y . Much o f t h e o b s e rv e d s p r e a d i n r i n d t h i c k ­
n e s s e s i s p r o b a b ly due t o n a t u r a l v a r i a t i o n i n h y d r a t i o n r a t e .
T h ere­
f o r e , i t i s n o t a p p ro p r ia te to use a s in g le s e t o f h y d ra tio n r a t e
c o n s t a n t s d e te r m in e d from a s i n g l e sa m p le t o c a l c u l a t e a g e s f o r a r t i ­
f a c t s and g e o l o g i c a l s a m p le s w i t h o u t r e c o g n i z i n g t h i s l i m i t a t i o n .
I
INTRODUCTION
The P ro b lem
Num erous m eth o d s h a v e b e e n d e v e lo p e d and u s e d
d e p o s i t s and e v e n t s , i n c l u d i n g
o lo g y
(P a rk e r
am ino
a c id
o th e rs ,
ra c e m iz a tio n
1979; H a ll
o th e rs ,
and
a n d H e in y ,
1976;
1 9 8 4 ),
s o il
(W e h m ille r,
and
d a te
Q u a te r n a r y
d a t i n g (T e ra s m a e , 1 9 8 4 ) , d e n d ro c h ro n ­
d e v e lo p m e n t
1 9 8 4 ),
1 9 8 3 ). and o b s i d i a n
F rie d m a n
to
(B irk e la n d ,
h o r n b le n d e
h y d ra tio n
O b ra d o v ic h ,
1 9 8 1 ).
e tc h in g
d a tin g
A ll
1 9 8 4 ),
of
(L o c k e ,
(P ie rc e
th e s e
and
m eth o d s
a t t e m p t t o m e a s u re a c e r t a i n p r o p e r t y o r c o n d i t i o n t h a t c h a n g e s p r o g r e s ­
s iv e ly
w ith
s itu a tio n s
in
any
tim e .
H ow ever,
g iv e n
th e v a r ie ty
f a c e d by Q u a te r n a r y r e s e a r c h e r s ,
g iv e n
lo c a tio n .
T h erefo re,
In
la v a
th e
flo w s
tu n itie s
n a ry
Y e llo w s to n e
(C h ris tia n s e n
to u t i l i z e
s tu d ie s .
h y d ra tio n
re g io n
an d B la n k ,
s t o n e , MT. I n t h i s
fie ld
can be a p p l i e d
te c h n iq u e s
chosen
by
th e
c o n s tra in ts .
a re
abundant
1972)
w h ic h
rh y o litic
p r o v id e
o b s id ia n
many
P ie rc e
te c h n iq u e s
to
re g io n ,
and i n
and
d a te
o th e rs
g la c ia l
(1 9 7 6 )
e v e n ts
u sed
o p p o r­
1968;
F rie d m a n and O b r a d o v ic h ,
1986)
in
tio n s
(F rie d m a n
to
and
o t h e r a r e a s w h e re o b s i d i a n i s
1981)
and
f lu v ia l
t h e m ore common u s a g e
S m ith ,
1960;
o b s id ia n
n e a r W est Y e llo w ­
o b s i d i a n h y d r a t i o n h a s a l s o b e e n u s e d t o d a te v o l c a n i c e v e n ts
a d d itio n
of
t h e o b s i d i a n h y d r a t i o n d a t i n g t e c h n i q u e f o r Q u a te r ­
F o r. e x a m p le .
d a tin g
th e re
c o m p le x ity
few m eth o d s
d a tin g
r e s e a r c h e r a r e d i c t a t e d l a r g e l y by f i e l d
and
d a rk ,
fo r
1964;
te rra c e s
(F rie d m a n ,
(L u n d s tro m ,
a rc h e o lo g ic a l
M e ig h a n ,
fo u n d ,
a p p lic a ­
1983) .
T h is
2
t e c h n i q u e h a s t h e a d v a n ta g e o f b e in g low c o s t and r e l a t i v e l y
s tra ig h t­
f o rw a r d t o p e rf o r m . H ow ever, t h e t e c h n i q u e i s l i m i t e d t o t h e e x t e n t t h a t
t h e r e m u st b e o b s i d i a n
p ria te
fie ld
p rese n t in
s itu a tio n s .
The
s u f f ic ie n t q u a n titie s
p u rp o se
m e th o d o lo g y t h a t c a n b e u s e d t o
of
th is
s tu d y
an d i n
is
to
a p p ro ­
d e v e lo p
d a t e Q u a te r n a r y la n d f o r m s t h a t
a
c o n ta in
n a t u r a l l y w o rk ed o b s i d i a n .
T h is
s tu d y
fo cu ses
tio n a l s e ttin g s ,
on o b s i d i a n
n a tu ra lly
t h e f i r s t o f w h ic h i s
re w o rk e d i n
two d e p o s i -
a f lig h t of f lu v ia l te rra c e s n e a r
W est Y e llo w s to n e , MT. T h e se t e r r a c e s w e re fo rm ed by p r o g r e s s i v e dow ncut­
tin g
of
th e
M adison
R iv e r
th r o u g h
an
o b s id ia n -ric h
o u tw a sh
p o s t - P i n e d a l e tim e (N ash , 1 9 8 4 ) . T h is i s an i d e a l s i t e
p la in
in
a t w h ic h t o a p p ly
o b s i d i a n h y d r a t i o n d a t i n g t o f l u v i a l t e r r a c e s b e c a u s e t h e same t e r r a c e s
w e re d a te d by
and t h e
sc arp
d e g r a d a t i o n m ethod
(N a sh ,
1 9 8 4 ),
th u s
a ll o w i n g a n in d e p e n d e n t c h e c k a g a i n s t t h e a g e s o b t a i n e d i n t h i s s tu d y .
The s e c o n d
n e a r B re e z e
P o in t
p o s t-P in e d a le
le v e l
an d
s e ttin g
in
at
is
a
g ro u p
of
Y e llo w s to n e L a k e ,
age
and
d e fo rm ed by
a
have
p r o b a b ly
com plex
ra is e d
WY.
and
T h ese
been
in te ra c tio n
of
d e v e lo p m e n t
s h o u ld p r o v id e a m eans t o
of
a m e th o d o lo g y
s h o re lin e s
s h o re lin e s
ra is e d
d o w n c u ttin g a t t h e o u t l e t o f Y e llo w s to n e L ake
The s u c c e s s f u l
d e fo rm e d
a re
a ls o
tc
la k e
re la tiv e
v o lc a n o -te c to n ic s
and
(M eyer and L o c k e , 1 9 8 6 ) .
to
d e te r m in e r e c e n t r a t e s
d a te
th e s e
s h o re lin e s
o f d e f o r m a tio n i n t h e
Y e llo w s to n e C a ld e r a .
The
f lu v ia l
te rra c e s
su rfa c e s
p r o v id e
an
te rra c e
b e in g
a llo w e d f o r t h e
th e
w e re
unam biguous
o ld e s t
d e lib e ra te ly
event
chosen
s tra tig ra p h y
(Thompson and J o n e s ,
d e v e lo p m e n t o f t h e
firs t
w ith
1986) .
because
th e
T h is
su c h
u p p e rm o s t
a s s u m p tio n
t e c h n i q u e and i n t e r p r e t a t i o n
of th e
3
re s u lts
w ith o u t
ta k in g
in to
account
th e
p o s s ib ility
th a t
th e
h ig h e s t
s u r f a c e may n o t b e t h e o l d e s t .
C o n te m p o ra ry u p l i f t d a t a r e p o r t e d b y D z u r i s i n a n d x a m a s h ita
f o r t h e Y e llo w s to n e L ake a r e a
rev e rsed
have
to
s u b s id e n c e .
d o c u m e n ted
lin e s
In a d d itio n ,
su b m e rg e d
B o th o f t h e s e l i n e s
in d ic a te
s h o re lin e s
th a t
B a ily
(1984)
w h ic h
a ls o
o f e v id e n c e l e a d t o
a ro u n d Y e llo w s to n e
some a r e a s
(1 9 8 7 )
of u p lift
a n d H a m ilto n
in d ic a te
have
(1 9 8 5 )
s u b s id e n c e .
th e c o n c lu s io n t h a t th e s h o re ­
L ake c a n n o t b e
assum ed
to
be
in
a
re la tiv e
s e q u e n c e w i t h t h e u p p e rm o s t s h o r e l i n e b e i n g t h e o l d e s t .
a
P r e v io u s Work
R oss
o b s id ia n
tio n .
and
S m ith
(1955)
firs t
n o te d
th a t
su rfa c e s
on
w e a th e re d
h ad u n d e rg o n e a c h e m ic a l a n d p h y s i c a l c h a n g e known a s h y d r a ­
H y d r a tio n
is
th e
d e n s ity and r e f r a c t i v e
in ta k e
of
w a te r,
w h ic h
in d e x i n a d d i t i o n t o
t o becom e m e c h a n ic a l ly s t r a i n e d
cau ses
an
in c re a s e
in
c a u s in g th e h y d ra te d l a y e r
(R o ss an d S m ith , 1 9 5 5 ) .
The d i f f e r e n c e
b e tw e e n t h e r e f r a c t i v e i n d i c e s o f t h e h y d r a t e d an d n o n h y d r a t e d p o r t i o n s
o f t h e o b s i d i a n a n d t h e i n c r e a s e d b i r e f r i n g e n c e d u e t o m e c h a n ic a l s t r a i n
m ak e
th e
h y d ra te d
la y e r
e a s ily
v is ib le
w ith
a
s ta n d a rd
p e tro g ra p h ic
m ic r o s c o p e (F rie d m a n a n d S m ith , 1 9 6 0 ) .
F u r t h e r s t u d y b y F rie d m a n an d S m ith (19 6 0 ) d e te r m in e d t h a t h y d r a /
t i o n o c c u r s u n d e r n o rm a l a tm o s p h e r ic c o n d i t i o n s an d t h a t r a t e i s l a r g e l y
dependent
upon
T h erefo re,
it
h y d ra tio n
te m p e ra tu re
is
o c c u rre d
n e c essa ry
and
th e
and
to
c h e m ic a l
know
b o th
c o m p o s itio n
c u r a t e l y d e te r m i n e tim e e l a p s e d s i n c e
of
c o m p o s itio n
of
th e
te m p e ra tu re
th e
g la s s
h y d ra tio n b eg an .
in
th e
at
g la s s .
w h ic h
o rd e r to
ac­
The c o m p o s itio n
4
o f a g iv e n
sam p le c a n be d e te r m in e d by s t a n d a r d a n a l y t i c a l
but
th e
e ffe c tiv e
has
span n ed
a
h y d r a t i o n te m p e r a t u r e m u st b e e s t i m a t e d
c o n s id e ra b le
am ount
of
t im e ,
g iv e n
th e
te c h n iq u e s ^
if
h y d ra tio n
e v id e n c e
fo r
Q u a te r n a r y c l i m a t i c c h a n g e ( S h a c k le to n a n d Opd y k e , 1 9 7 3 ) .
F rie d m a n
o b s id ia n
an d
Long
(1 9 7 6 )
h e ld a t v a r i o u s
e x p e rim e n te d
te m p e ra tu re s
w ith
se v era l
ty p e s
fo r d if f e r e n t le n g th s
of
o f tim e t o
d e te r m in e t h e A r r h e n iu s e q u a ti o n r e l a t i n g h y d r a t i o n r a t e t o t e m p e r a t u r e .
T h is e q u a t i o n t a k e s t h e f o l l o w i n g fo rm :
k = Ab- e Zrt
w h e re k i s
c o n s ta n t,
th e
h y d ra tio n r a te
E is
t h e a c t i v a t i o n e n e rg y o f t h e h y d r a t i o n p r o c e s s
p e r m o le ) , R i s
is
per
th e gas c o n s ta n t
a b s o l u t e te m p e r a t u r e
IO^ y e a r s
lo g a rith m ic
tio n s h ip s
T h u s,
and i t s
because
c u rv e .
th e
h y d ra tio n
p lo tte d
F rie d m a n an d Long
c o n te n t,
te m p e r a t u r e
A is
a
(c a lo rie s
( c a l o r i e s p e r d e g r e e p e r m o le ) , and T
( K e l v i n s ) . R a te i s
b e tw e e n s i l i c a
if
(m ic ro n s s q u a r e d p e r IO^ y e a r s ) ,
e x p r e s s e d a s m ic r o n s s q u a r e d
a g a in s t
(1 9 7 6 )
te m p e ra tu re
a ls o
re fra c tiv e
d e te r m in e d
f o ll o w s
ttie
a
re la ­
in d e x a n d h y d r a t i o n r a t e .
t o w h ic h an o b s i d i a n
sa m p le h a s
been exposed
c h e m ic a l c o m p o s itio n o r r e f r a c t i v e in d e x a r e know n, t h e r a t e o f
h y d r a t i o n c a n be c a l c u l a t e d .
F rie d m a n a n d Long (1 9 7 6 )
c o n c lu d e d t h a t i f
I)
te m p e ra tu re
is
th e
e ffe c tiv e
h y d ra tio n
of
a
sa m p le
d e te r m in e d
by
d i r e c t m e a su re m e n t o r by e s t i m a t i o n th r o u g h c l i m a t i c r e c o r d s and 2) t h e
h y d ra tio n
c o n te n t,
ra te
is
d e te r m i n e d
r e f r a c t i v e in d e x ,
10 % a c c u r a c y i s
p o s s ib le .
e m p iric a lly
or
c a lc u la te d
from
s ilic a
o r c h e m ic a l in d e x t h e n n u m e r ic a l d a t i n g t o +
T h is p r i n c i p l e h a s b e e n a p p l i e d t o n a t u r a l l y
re w o rk e d o b s i d i a n i n s e v e r a l s t u d i e s i n t h e Y e llo w s to n e r e g i o n .
P ie rc e
and o t h e r s
(1976)
re la te d
th e
th ic k n e ss
of h y d ratio n rin d s
5
on p e b b le s
in
till
m e a s u re d r i n d s
e s t)
rin d s
(o ld e r)
to
g la c ia l
f e l l in to
e v e n ts
w ith
Y e llo w s to n e ,
MT,
f i v e d i s t i n c t g ro u p s w i t h t h e t h i n n e s t
a s s o c ia te d w ith P in e d a le
rin d s
n e a r W est
P in e d a le
d e g la c ia l
te rm in a l
d e p o s its
an d th e
m o r a in e s , . c o o l i n g
The
(y o u n g ­
th ic k e r
c ra c k s
on t h e
W est Y e llo w s to n e f lo w . B u l l L ake t e r m i n a l m o ra in e s an d c o o l i n g c r a c k s on
th e
O b s id ia n
C liff
flo w ,
in
o rd er
of
in c re a s in g
th ic k n e s s .
The
two
g ro u p s o f r i n d s a s s o c i a t e d w i t h o r i g i n a l c o o li n g c r a c k s w e re c a l i b r a t e d
a g a i n s t K-Ar a g e s f o r t h e W est Y e llo w s to n e and O b s id ia n C l i f f flo w s t o
y i e l d a p p ro x im a te a g e s f o r th e g l a c i a l e v e n ts by i n t e r p o l a t i o n .
F rie d m a n
lo c a litie s
n iq u e s .
and
in
O b ra d o v ic h
th e w e s te rn
(1981)
U .S .
d a te d v o l c a n i c
u s in g
o b s id ia n
e v e n ts
h y d ra tio n
at
se v era l
d a tin g
te c h ­
The a g e s f o r t h e s e e v e n ts ra n g e from 12 k a t o o v e r I Ma and t h e
h y d ra tio n
d a t e s w e re
com pared w i t h
ages
o b ta in e d
th r o u g h
I ^ c and K -A r
m e th o d s . I n m o st c a s e s t h e a g re e m e n t b e tw e e n t h e two a g e s w as "g o o d " (+
20 % ),
th u s
e s ta b lis h in g
th e
re lia b ility
of
th e
o b s id ia n
h y d ra tio n
d a t i n g m eth o d f o r v o l c a n i c e v e n t s .
More s p e c i f i c a l l y , F rie d m a n and O b ra d o v ic h (1 9 8 1 ) c o n d u c te d p a r t o f
th e ir
re se a rc h
h y d ra tio n
C liff
in
Y e llo w s to n e
d a t i n g w as
s im ila r
P a rk ,
in
WY. A l l
c h e m ic a l
of
th e
o b s id ia n
c o m p o s itio n
to
th e
s a m p le s u s e d f o r e x p e r i m e n t a l d e t e r m i n a t i o n o f h y d r a t i o n
te m p e ra tu re of - 1 °
C w as u se d f o r
th e
g la c ia l
used
fo r
O b s id ia n
ra te .
A
t e m p e r a t u r e b e c a u s e m o st
o f t h e s i t e s w e re c o v e re d by a l a r g e te m p e r a te i c e s h e e t ( P i e r c e , 1 9 7 9 ).
P r e s e n t day t e m p e r a t u r e s w e re d e te r m in e d u s in g t h e P a llm a n n te c h n iq u e o f
te m p e ra tu re i n t e g r a t i o n
(F rie d m a n a n d N orm an, 1 9 8 1 ). H y d r a tio n r i n d a g e s
w e re p l o t t e d w i t h + 20 % u n c e r t a i n t y o f t h e age w h i l e t h e K-Ar a g e s w e re
p lo tte d w ith
t h e i r p u b l is h e d u n c e r t a i n t i e s .
As i n o t h e r r e g i o n s o f t h e
6
p l o t t e d w ith t h e i r p u b lis h e d u n c e r t a i n t i e s .
w e s te rn
U .S .
re se a rc h ,
th e
w h e re
F r ie d m a n
and
As i n o t h e r r e g i o n s o f t h e
O b r a d o v ic h
a g re e m e n t b e tw e e n t h e
(1 9 8 1 )
ag es o b ta in e d
c o n d u c te d
th e ir
t h r o u g h K -A r d a t i n g
a n d o b s i d i a n h y d r a t i o n d a t i n g w as g o o d .
L u n d stro m
(19 8 6 )
g ro u p o f f l u v i a l
re la te d
te rra c e s
th e
a lo n g
th ic k n e s s
of
h y d ra tio n
to
a
t h e M ad iso n R iv e r b e lo w Q uake L ake i n
s o u th w e s t M o n tan a. The m e th o d o lo g y w as n o t c l e a r l y
d a ta l i s t e d
rin d s
fro m w h ic h t h e r e s u l t s w e re d e r i v e d .
p r e t a t i o n p o s t u l a t e d b y L u n d s tro m
(1 9 8 6 )
s ta te d
n o r w e re t h e
T h e re fo re , th e i n t e r ­
cannot be o b je c tiv e ly
e v a lu a ­
te d .
Q u a te r n a r y G e o lo g y o f F i e l d S i t e s
W est Y e llo w s to n e B a s in
The
la te
C e n o z o ic ,
e x te n s io n a l.
W est Y e llo w s to n e
B a s in
c o n ta in s
a b u n d a n t, e v id e n c e f o r a t l e a s t tw o m a jo r g l a c i a t i o n s i n t h e P l e i s t o c e n e
t h a t have been c o r r e la te d
P in e d a le
1953;
g la c ia tio n s
R ichm ond,
in
1964;
w ith th e
th e
W ind
W itk in d ,
t y p e s e c t i o n s o f t h e B u l l L ake a n d
R iv e r
1969;
M o u n ta in s
P ie rc e
of
Wyoming
and o t h e r s ,
1 976;
(A ld e n ,
P ie rc e ,
1 9 7 9 ) . The f l o o r o f t h e b a s i n i s c o v e r e d b y up t o 30 m e t e r s o f o b s i d i a n r i c h g r a v e l t h a t l i e s b e tw e e n t h e m ore e x t e n s i v e B u l l L ak e m o ra in e s a n d
th e
s m a lle r
o rig in
of
P in e d a le
th is
g rav e l
m o ra in e s
d e p o s it
(F ig .
I)
(R ichm ond,
1 9 6 4 ).
has b e e n a m a tte r o f
The a g e
d e b a te
and
amongr t h e
s e v e r a l a u t h o r s who h a v e w o rk ed i n t h i s a r e a .
A ld e n
p o s td a tin g
(1 9 5 3 )
th e
d e s c rib e d
th e
B u l l L ake m o ra in e s
g rav e l
d e p o s it
a t H o rse B u t t e .
as
a
T h is
la rg e
te rra c e
in te r p re ta tio n
w as b a s e d on t h e o b s e r v a t i o n t h a t t h e d e p o s i t d o e s n o t a p p e a r t o h a v e
7
nns'
1 I TOO'
I 1CT45'
;
^
U
WYOMING
44 ‘ 45 '
-
44 - 30 '
F i g u r e I - Map sh o w in g s tu d y a r e a i n
M a jo r e l e m e n t s o f g l a c i a l o u t b u r s t
( a f t e r P i e r c e , 1 9 7 9 ).
r e l a t i o n t o P i n e d a l e i c e m a r g in .
f l o o d h y p o t h e s i s a r e a l s o shown
8
been
o v e rrid d e n
by
a
g la c ie r.
Al d e n
(1 9 5 3 )
h y p o th e s iz e d
th a t
th e
W is c o n s in - a g e m o ra in e s o f B e a v e r C re e k , d o w n stream from Hebgen L a k e , may
h a v e dammed th e n a rro w M adison Canyon, t h e r e b y c r e a t i n g a l a r g e l a k e i n
t h e W est Y e llo w s to n e B a s in i n t o w h ic h t h e o b s i d i a n g r a v e l was d e p o s i t e d .
Richmond
(1 9 6 4 )
re p o rte d
th a t
th e
O b s id ia n
Sand
P la in
(OSP)
was
d e p o s it e d i n t h e B u l l L a k e - P in e d a le i n t e r g l a c i a t i o n . T h is i n t e r p r e t a t i o n
was b a s e d on s i m i l a r s o i l c h a r a c t e r i s t i c s d e v e lo p e d on a l o e s s cap fo u n d
on b o th t h e
sa n d p l a i n
and t h e B u l l Lake m o ra in e s a t H o rse B u t t e .
Thus
th e sa n d p l a i n was d e p o s i t e d a f t e r r e c e s s i o n o f B u l l L ake i c e b u t b e f o r e
th e
s o il
fo rm in g
(R ichm ond,
1 9 6 4 ).
e s p e c ia lly
th e
p e rio d
He
of
a ls o
lith o lo g y
th e
B u ll
Ia k e -P in e d a le
s ta te d
th a t
th e
of
th e
o b s id ia n
in te rg la c ia tio n
s tru c tu re ,
g rav el
te x tu re
su g g est
th a t
it
and
is
u n r e la te d to g l a c i a t i o n .
Richmond (1964) s u g g e s te d t h a t b e c a u s e t h e g r a v e l o c c u r s i n b e d s 10
to
30
cm t h i c k
tu re s ,
it
and
w as
d is p la y s
d e p o s it e d
s e d im e n t may h a v e b e e n
f lo w s
w ith in
m a te ria l,
or
th e
p a rk
c r o s s b e d d in g
by
s h a llo w
d e riv e d
w h ic h
a lte rn a tiv e ly
c o n ta in
W itk in d
(19 6 9 )
d e s c rib e d
r e la tio n s h ip s
th e
o u tw ash .
and
o th ers
E v id e n c e
(1976)
in clu d es
have
OSP a s
a t H o rse B u t t e
b a s i n w h e re t h e g r a v e l o v e r l i e s t i l l
P ierce
th e
Much
su rfa c e s
sa n d
been
and
s tru c ­
of
th is
o f o b s id i a n
g rav el
s iz e
d e riv e d
th ro u g h
th e
been
d e p o s ite d
(R ichm ond, 1 9 6 4 ) .
m e ltw a te r from r e c e d in g B u l l L ake i c e .
g r a p h ic
from
s tr e a m s .
abundant
a ls o
f l u v i a l r e w o rk in g o f l a r g e r c l a s t s
c h a n n e l-a n d -fill
a g g r a d in g
d ire c tly
c o u ld
an d
h a v in g
E v id e n c e f o r t h i s
and
a lo n g
th e
is
n o rth
by
th e s t r a t i ­
ed g e
of
th e
o f B u l l L ake a g e .
su g g ested
h y d ratio n
th a t
rin d s
th e
from
OSP i s
one
P in e d a le-age
lo c a lity
on
th e
9
d e p o s i t , w h ic h do n o t
P i n e d a l e m o ra in e s
th is
e v id e n c e
d iffe r
s ig n ific a n tly
( P ie r c e and o t h e r s ,
d o es n o t r u l e
in
th ic k n e s s
from
th o s e
in
1 9 7 6 ) . I t m u st be e m p h a s iz e d t h a t
o u t th e
h y p o th e s is
o f a c o m p o s ite
ag e f o r
th e OSP.
P ie rc e
fu rth e r
(1979)
m a in ta in e d
p o s tu la te d m u ltip le
t h e sa n d p l a i n
th a t
t h e OSP i s
g la c ia l
o u tb u rs t
P in e d a le -a g e
f lo o d s
fo r
o u tw a sh and
th e
o rig in
of
( F ig u r e I ) . G e o th e rm al h e a t c o u ld h a v e form ed a l a k e 100
km^ i n a r e a and 100 m d eep i n t h e U p p e r, Midway and L ow er G e y s e r B a s in s
( P i e r c e , 1 9 7 9 ). R e le a s e o f t h i s l a k e by g l a c i a l dam f a i l u r e a t N a tio n a l
P a rk
M o u n ta in w o u ld
Y e llo w s to n e B a s in .
have
re le a s e d
P o n d in g
of
c a ta s tr o p h ic
th e
flo o d s
flo o d w a te rs
in to
by m o ra in e
th e
W est
damming a t
B e a v e r C re e k , 1 .5 km w e s t o f H ebgen dam, may h a v e c a u s e d a low g r a d i e n t
f lo o d d e l t a t o a c c u m u la te i n t h e B a s in ( P i e r c e , 1 9 7 9 ).
In s e v e r a l a r e a s ,
t h e g r a v e l d e p o s i t c o n s i s t s o f s h e e t l i k e b e d s 15
t o 60 cm t h i c k w i t h p l a n a r c r o s s s t r a t i f i c a t i o n
h ig h
a n g le s
to
t h e b e d d in g
c ro s s b e d d e d
la y e rs
d e v e lo p e d .
The
a re
( P ie r c e ,
1 9 7 9 ).
common and
c ro ssb e d s
of
fin e
i n c l i n e d a t b o th low and
S ilt-ric h
c u t-a n d -fill
g rav e l
in te rs titia l
s tru c tu re s
g e n e ra lly
f i n e s . T h ese s e d im e n ta r y
c h a ra c ­
te ris tic s
s u g g e s t r a p i d d e p o s i t i o n by s h e e t f lo o d
The s t r o n g e s t e v id e n c e t h a t P i e r c e
fo r
th e
O b s id ia n
Sand P l a i n
is
( P i e r c e , 1 9 7 9 ).
(1979) p r e s e n t e d f o r a P in e d a le
th e
d o c u m e n ta tio n
of
a
o u tw a sh c h a n n e ls e m a n a tin g from a P in e d a le t e r m i n a l m o ra in e
th e
m o u th
of
M a d is o n
C anyon
o n to
p o o r ly
boxw ork
and v e ry l i t t l e
have
a re
open
s tru c tu re
age
i n t e r b e d s b e tw e en
th e
OSP.
T h u s,
th e
s e rie s
of
com plex a t
m o ra in e s
a re
from
OSP
p h y s i c a l l y t i e d t o t h e sa n d p l a i n .
P ie rc e
(197 9)
a ls o
sta te d
th a t
h y d ratio n
rin d s
th e
I
10
c o l l e c t e d a t d e p th s fro m two t o tw e lv e m e te r s a r e t h e same t h i c k n e s s a s
th o s e
fro m
th e
P in e d a le
te rm in a l
n e ith e r p re s e n te d n o r c ite d ,
d a ta from P i e r c e an d o t h e r s
P ie rc e
on
th e
so i t
m o r a in e s .
H ow ever,
th is
d a ta
was
i s n o t known w h e th e r i t w as t h e same
(1976) o r r e s u l t e d fro m a d d i t i o n a l s t u d i e s .
(1 9 7 9 ) d i s a g r e e d w i t h Richmond (1964) i n a s s i g n i n g t h e s o i l s
OSP
to
th e
B u ll
L a k e - P in e d a le
in te rg la c ia l.
In s te a d ,
(1 9 7 9 ) d e s c r i b e d t h e s o i l s a s w eak and s i m i l a r t o p r o f i l e s
o th e r P in e d a le -a g e
sa n d y
d e p o s its .
The s i l t
in
th e
P ie rc e
d e v e lo p e d on
u p p e r 50 cm o f t h e
p r o f i l e s i s a t t r i b u t e d t o e o lia n i n f l u x and su b se q u e n t t r a n s l o c a t i o n .
From t h e ab o v e d i s c u s s i o n , i t i s e v i d e n t t h a t t h e age and o r i g i n o f
t h e OSP i s
a m a tte r
of q u ite
some d e b a t e .
It
is
lik e ly
th a t
t h e m o st
r e c e n t p e r i o d o f d e p o s i t i o n o c c u r r e d d u r in g t h e P i n e d a l e g l a c i a t i o n , b u t
it
is
a ls o
p o s s ib le
th a t
e a rlie r
p e rio d s
of
d e p o s itio n
c o n trib u te d
to
t h e b u lk o f t h e d e p o s i t .
The OSP w as d i s s e c t e d
by
th e M adison R iv e r i n
l e a v i n g f i v e w e l l d e v e lo p e d , n o r t h f a c i n g ,
o th e rs
(1976)
n esses
as
P in e d a le
B ecause th e
th a n t h i s
re p o rte d
th a t
th e
te rra c e s
a re
flu v ia l te rra c e s .
OSP h a s
t e r m i n a l m o ra in e s
in s e t in to
p o s t-P in e d a le
n e a rly
id e n tic a l
d a te d fro m 2 8 ,0 0 0
th is
d e p o s it,
age r a n g e . N ash (1984) d a te d t h e t e r r a c e s
P i e r c e an d
rin d
to
tim e
th ic k ­
4 0 ,0 0 0 y r s .
th e y m u st be y o u n g e r
u s in g 1^C and s c a r p
d e g r a d a t i o n m eth o d s and a s s i g n e d a g e s o f 1 1 ,6 0 0 + 6 ,4 0 0 ,
9 ,6 0 0 + 5 ,6 0 0
and 7 ,1 0 0 + 50 y e a r s t o T e r r a c e s T2 th r o u g h T4, r e s p e c t i v e l y . T hese a g e s
se rv e
as
an
in d e p e n d e n t
check
a g a in s t
th e . d a t e s
fo r
th e
te rra c e s
o b t a i n e d i n t h i s s tu d y .
P a r t one o f t h i s
th a t can be a p p lie d to
s tu d y d e v i s e s an o b s i d i a n h y d r a t i o n d a t i n g m eth o d
flu v ia l
d e p o s its
to
o b t a i n n u m e r ic a l d a t e s .
The
11
I
t h r e e m ain h y p o th e s e s t h a t w i l l be t e s t e d a r e ;
s o le ly
in
P in e d a le
tim e
and t h a t
th e
I)
h y d ra tio n
t h e OSP w as d e p o s i t e d
rin d s
fro m t h e d e p o s i t
r e f l e c t t h i s a g e , 2) f l u v i a l p r o c e s s e s o f t r a c t i o n t r a n s p o r t e f f e c t i v e l y
re w o rk
o b s id ia n
c h a ra c te ris tic
th is
p e b b le s
so
h y d ra tio n r in d
s tu d y a r e d i r e c t l y
th a t
each
th ic k n e s s ,
te rra c e
and 3 )
possesses
th e
d a te s
an
u n iq u e ,
d e riv e d
fro m
c o m p a ra b le t o t h o s e o b t a i n e d by N ash (1984) f o r
t h e same t e r r a c e s .
Y e llo w s to n e L ak e B a s in
Y e llo w s to n e L ak e o c c u p ie s an i r r e g u l a r l y s h a p e d b a s i n a p p r o x im a te ly
30 km by 25 km t h a t w as fo rm ed a s a r e s u l t o f t h e
co m p lex i n t e r a c t i o n
b e tw e e n c a l d e r a c o l l a p s e and p o s t c o l l a p s e v o lc a n is m , i c e - c a p g l a c i a t i o n ,
and l a c u s t r i n e
p ro ce sse s.
The Q u a te r n a r y h i s t o r y
o f th e
b a s in
in v o lv e s
th e sequence o f th e s e e v e n ts .
T h re e
m a jo r
c a ld e ra -fo rm in g
Y e llo w s to n e r e g i o n i n
la te
e ru p tiv e
P l io c e n e
c y c le s
an d Q u a te r n a r y
o c c u rre d
tim e
in
th e
( C h r is tia n s e n ,
1 9 8 4 ) . E ach o f t h e s e c y c l e s c u lm in a te d i n a m a jo r e r u p t i o n o f e x p l o s i v e ­
ly
e je c te d m a te ria l
te riz e d
at
rh y o litic
w ith
th e
th a t
b e g in n in g
and b a s a l t i c
s m a ll
fo rm e d v o lu m in o u s a s h
e ru p tio n s
and
end
e ru p tio n s .
of
by
lo n g
The f i r s t
rh y o lite
and
f lo w s ,
p e rio d s
c y c le
b a s a lt
and
b u t w as
of
began
c h a ra c ­
in te rm itte n t
a b o u t 2 .2
c u lm in a te d w i t h
Ma
th e
e r u p t i o n o f t h e H u c k le b e r r y R id g e T u f f a t 2 .0 Ma, T h is e r u p t i o n w as t h e
la rg e s t
m a te ria l
of th e
th re e
g re a te r
c a ld e ra -fo rm in g e r u p tio n s
th a n
2500 km3 .
H u c k le b e r r y
R id g e
T u f f fo rm e d a
e ru p te d
h o u rs
or
in
fo rm e d by t h i s
days
e ru p tio n ,
and
C h ristia n s e n
s in g le
not
w h ic h i s
c o o li n g
decades
m o s tly
or
and e j e c t e d
a volum e o f
(1984)
s ta te d
u n it
an d w as
c e n tu rie s .
The
th a t
th e
p r o b a b ly
c a ld e ra
o b s c u re d by m ore r e c e n t
la v a
12
f l e w s , m e a s u re d a p p r o x im a te ly 100 km by 60 km.
The s e c o n d c a l d e r a
fo rm in g e r u p t i o n
o c c u rre d a t
a b o u t 1 .3
Ma and
w as t h e s m a l l e s t of. t h e t h r e e . The c a l d e r a fo rm e d by t h e e r u p t i o n o f t h e
M esa
F a lls - T u ff
is
lo c a te d
in
th e
Is la n d
P a rk
a re a
and. i s
w h o lly
c o n ta i n e d w i t h i n t h e H u c k le b e r r y R id g e . C a ld e ra ( C h r i s t i a n s e n i 1 9 8 4 ). The
vo lu m e o f m a t e r i a l e j e c t e d fro m t h e Mesa F a l l s
C a ld e r a w as a t l e a s t 280
; "
The t h i r d
rec e n t
c y c le ,
rh y o litic
tu re s
le ft
th e
c y c le
m o st
began a t
c o m p le te
l a v a w as i n t e r m i t t e n t l y
th a t
tia n s e n ,
v o lc a n ic
w o u ld
1984) .
e v e n tu a lly
A t 630 k a ,
th e
a b o u t 1 .2
rec o rd .
e ru p te d
o u tlin e
y
th e
;
Ma a n d ,
For
th e
as
firs t
fro m
a set
of
L av a
C re e k
C a ld e ra
c lim a c tic
e ru p tio n
of
t h e m o st
6.00
a rc u a te
th e
fra c ­
(C h ris ­
th ird
c y c le
c a l d e r a o c c u r r e d e m p la c in g m ore t h a n 1000 km^ o f L a v a C reek T u f f .
c a ld e ra i s
a b o u t 75 kin l o n g an d 45 km a c r o s s .
In
t h e l a s t 630 k a ,
c a ld e r a has been f i l l i n g w ith
s e d im e n ts and r h y o l i t i c
o f w h ic h h a v e b e e n e r u p t e d i n
th e l a s t
150 k a
(F ig .
ka
T h is
th e
l a v a f lo w s , many
2)
(C h ris tia n s e n ,
1 9 8 4 ).
The
re s u lt
of
p ro p o se d
p resen t
shape
p o s t-c o lla p s e
a
su b c a ld e ra
of
th e
Y e llo w s to n e
y o lc a n is m .
c o lla p s e
L ake , B a s in
C h ris tia n s e n
a s s o c ia te d
w ith
is
and
th e
l a r g e l y ■t h e
B la n k
e ru p tio n
(1 9 7 2 )
of
th e '
S h o sh o n e L ake T u f f a t a b o u t 162 k a ( l a t e r i n f o r m a l l y ren a m ed th e t u f f o f
B lu ff P o in t in
t h e W est Thumb a r e a ;
C h ristia n s e n ,
1974)
f o r t h e . fo rm a ­
t i o n o f t h e W est. Thumb em baym ent. . The r e m a in d e r o f t h e w e s t e r n s h o r e o f ■
13
I
L
oc
W1 1 I o| ^
,V elloW B toiH
North
F ig u r e 2 - R e g io n a l map o f Y e llo w s to n e N a t i o n a l P a r k a n d v i c i n i t y
sh e w in g r h y o l i t e l a v a flo w s an d l o c a t i o n o f s tu d y s i t e s . Ages of flo w s
( I y e a r s ) i n p a r e n t h e s e s ( A f t e r R ichm ond, 1 9 8 6 ) .
AC BL BP BR CC CF CS DC EB GP -
A s t e r C reek flo w (174)
GR - G ib b o n R i v e r flo w (90)
B u f f a l o L ake flo w (16 0 )
HV - H ayden v a l l e y flo w (102)
T u ff o f B l u f f P o in t (1 6 2 )
ML - Mary L ak e f lo w (1 6 5 )
B e c h l e r R i v e r flo w (1 1 7 )
NP - Nez P e r c e flo w (160)
C ougar C reek flo w (3 9 9 )
0C - O b s id ia n Q i f f flo w (18 3 )
Canyon flo w (61 3 )
PP - P i t c h s t o n e P l a t e a u flo w (70)
C r y s t a l S p r in g s flo w (8 0 )
SC - S p r in g C re e k flo w (? )
Dry C reek f lo w (162)
SL - Summit L a k e flo w (113)
E le p h a n t B ack flo w (153)
SO - S o l f a t a r a P l a t e a u flo w (H O )
G r a n ts P a s s flo w (77)
WT - W est Thumb f lo w (1 4 8 )
WY - W est Y e llo w s to n e flo w (1 1 7 )
14
Y e llo w s to n e
L ak e
is
b o rd ered
by
rh y o litic
c o n t r i b u t e d t o t h e im poundm ent o f t h e l a k e
la v a
( F ig . 2)
The W est Thumb flo w e r u p t e d e a s tw a r d a c r o s s
dammed t h e
on
th e
B rid g e ,
f lo w s
th a t
p ro b a b ly
(R ichm ond, 1 9 7 6 ) .
th e
c a l d e r a b a s i n an d
S o u t h e a s t Arm p a le o c a n y o n a t a b o u t 148 + 12 k a by im p in g in g
fla n k
of
c a u s in g
Sour
th e
C reek
Dome a
f o r m a tio n o f
few
k ilo m e te rs
an a n c e s tr a l
n o rth
of
F is h in g
Y e llo w s to n e L ake
(R ic h ­
mond, 1 9 7 6 ; R ichm ond, 1 9 8 6 ) . The E le p h a n t B ack flo w K -A r d a te d a t 153 +
2 ka o v e r lie s th e s l i g h t l y
o l d e r W est Thumb flo w a n d i s
c u t by a s e r i e s
o f n o r t h e a s t - t r e n d i n g f a u l t s t h a t form a com plex g r a b e n s t r u c t u r e
(USGS,
1 9 7 2 ).
O th e r
rh y o litic
h a v e p la y e d a r o l e
w e re l i k e l y
la v a
in
flo w s
( F ig . 2 )
th e
t h e f o r m a ti o n
of
th ird
th e
v o lc a n ic
c y c le
th a t
may
Y e llo w s to n e L ake B a s in
and
t o h a v e c o n t r i b u t e d s e d im e n t t o . t h e . b a s i n a r e t h e Dry C re e k
f lo w , K -A r d a te d a t 162 + 2 k a ,
174 + 4
of
and t h e A s t e r C reek flo w K-Ar d a te d a t
k a and w h ic h fo rm s t h e l o c a l b e d ro c k i n
th e B reeze P o in t a re a
(R ichm ond, 1 9 8 6 ) .
The Y e llo w s to n e P l a t e a u ,
on w h ic h Y e llo w s to n e L ake i s l o c a t e d ,
has
s e r v e d a s t h e l o c u s f o r a t l e a s t t h r e e i c e c a p g l a c i a t i o n s and p o s s i b l y
a s many a s
tw e lv e
(R ichm ond,
1 9 8 6 ).
G la c ia tio n
p r o b a b ly b e g a n i n
la te .
P l io c e n e tim e b u t t h e o l d e s t , w e l l - d a t e d g l a c i a l d e p o s i t s d a te from t h e
e a r ly . P le is to c e n e .
p e r i o d s a r e known t o
G la c ie rs
d a tin g
have f i l l e d
fro m
th e
Illin o ia ri
a n d o v e rf lo w e d
th e
and W is c o n s in
c a ld e ra
form ed by
t h e e r u p t i o n o f t h e L a v a C reek T u f f . G l a c i e r s t h a t a c c u m u la te d a t a b o u t
150
to
140 k a
have
tra d itio n a lly
been
c o rre la te d
to
th e
B u ll
L ake
G l a c i a t i o n w h i l e g l a c i a l a d v a n c e s o c c u r r i n g from . 117 t o a b o u t 80 k a h a v e
been
re a s s ig n e d
to
th e
E o w is c o n s in
p e rio d
(R ichm ond,
1 9 8 6 ).
Ice
th a t.
15
a c c u m u la te d fro m >45 t o a b o u t 10 k a h a s b e e n c o r r e l a t e d t o t h e P i n e d a l e
G la c ia tio n
P in e d a le
( P i e r c e an d o t h e r s , 1 9 7 6 ) . The d e s i g n a t i o n s o f B u ll L ake and
G la c ia tio n s
f o ll o w
th e
te r m in o lo g y
o f B la c k w e ld e r
(1915)
fo r
t h e Wind R iv e r M o u n ta in s o f Wyoming ( P i e r c e and o t h e r s , 1976; R ichm ond,
1 9 7 6 ; P i e r c e , 1979) w h e re a s g l a c i e r s d a t i n g fro m t h e E o w is c o n s in f o ll o w
t h e te r m in o l o g y o f Richm ond ( 1 9 8 6 ).
The
fo rm a tio n
of
th e
p rese n t
Y e llo w s to n e
L ake b e g a n w i t h
th e
d o w n w a stin g o f P i n e d a l e i c e i n t h e l a k e b a s i n a t a b o u t 1 4 .5 k a when i c e
m a rg in a l
la k e s
fo rm e d
a ro u n d
th e
s ta g n a n t
ic e
(R ichm ond,
1 9 7 6 a ).
Richm ond (1 9 7 6 a ) d e s c r i b e d b r o a d , d i s c o n t i n u o u s t e r r a c e s a t up t o 143 m
a b o v e t h e p r e s e n t Y e llo w s to n e L ake a n d c o n c lu d e d t h a t a l l s u r f a c e s a b o v e
33 m w e re kame t e r r a c e s .
A s h o r e l i n e a t 33 m a b o v e p r e s e n t l a k e
le v e l
show s b o t h i c e - c o n t a c t and w a v e - c u t f e a t u r e s w h ic h m ig h t b e .e x p e c t e d t o
fo rm i n a s s o c i a t i o n w i t h a n i c e - m a r g i n a l l a k e .
S u r f a c e s a t 27 and 2 4 -2 3
m a r e g e n e r a l l y d i s c o n t i n u o u s an d p o o r l y fo rm ed b u t a r e b e l i e v e d t o h a v e
b e e n fo rm e d d u r in g m in o r p a u s e s i n t h e e r o s i o n o f t h e Y e llo w s to n e L ake
o u t l e t (R ichm ond, 1 9 7 6 a ) .
Richm ond
(1 9 7 4 , 1977) m apped p o s t - g l a c i a l s h o r e l i n e s a t 1 8 - 2 0 , 1 7 ,
1 2 - 1 4 , 9 - 1 0 .6 , 7 . 6 , 4 . 5 , an d 3 m a b o v e p r e s e n t l a k e l e v e l . D e l t a i c s a n d s
g rad e d
to
a n 1 8 -2 0 m s h o r e l i n e
at
th e
s o u th end o f t h e
S o u th e a s t Arm
o v e r l i e l a k e s i l t s c o n t a i n i n g o r g a n i c m a t t e r r a d i o c a r b o n d a te d a t 9060 +_
300 y r B .P .
to be th e
(R ichm ond, 1 9 7 4 ) . Richm ond (1 9 7 6 a ) c o n s i d e r e d t h i s s h o r e l i n e
firs t
because th e re
to
fo rm a f t e r c o m p le te d e g l a c i a t i o n o f t h e l a k e b a s i n
a r e num ero u s l a r g e
s p its ,
b a rs
and la g o o n a l d e p re s s io n s
a s s o c i a t e d w i t h t h i s s h o r e l i n e t h a t a r e n o t n o te d a t h i g h e r l e v e l s .
fe a tu re s
a re
in d ic a tiv e
o f s tro n g
lo n g sh o re c u r r e n ts
th a t
a re
Such
u s u a lly
16
a s s o c ia te d w ith l a r g e b o d ie s of open w a te r .
Richm ond
(1974)
o b t a i n e d a minimum r a d i o c a r b o n d a t e o f 5590 + 250
y r B .P . from a la g o o n a l d e p o s i t f o r a 12 m s h o r e l i n e a t t h e s o u th e n d o f
t h e S o u t h e a s t Arm ( B a k e r 8 1 9 7 6 ) . O r g a n i c - r i c h c la y o v e r l y i n g d e p o s i t s o f
th e
Squaw L ake
h y d r o th e r m a l
e x p lo s i o n
have
been
ra d io c a rb o n
d a te d
at
3500 + 250 y r B .P . The 7 .6 m s h o r e l i n e i s c u t i n t o t h e e x p l o s i o n d e p o s i t
in
a b l u f f o f Y e llo w s to n e L ake s o u t h e a s t o f Squaw L a k e .
b e tw e e n b e a c h
g rav e l
an d o v e r l y i n g
c o llu v iu m
r a d i o c a r b o n d a te d a t 620 + 250 y r . B .P .
fo r th is su rfa c e
M eyer
on
C h a rc o a l fo u n d
a 3m
s h o re lin e
w as
t h e r e b y p r o v i d i n g a minimum ag e
(R ichm ond, 1 9 7 6 a ) .
(19 8 6 )
o b ta in e d
d a te s
from
la g o o n a l
d e p o s its
fo r
two
s h o r e l i n e s i n t h e n o r th w e s t p a r t o f t h e l a k e b a s i n . An ag e o f 2495 + 135
y rs
B .P . w as
about
18 m ab o v e
a s s ig n e d to
la k e
d e te r m in e d f o r
S h o re lin e
d a tu m .
a c c u m u la te d
la k e
T he
s in c e
datum
S5
d a te s
th e
S h o re lin e
and
an
(S h o re lin e
w e re
(S h o re lin e
ag e
of
S 4 -th is
d e riv e d
aban d o n m en t
S6
of
fro m
th e
S S '- th is
s tu d y )
1410 + 160 y r s
s tu d y )
at
b asal
was
ab o u t 8 m above
o rg a n ic
s h o re lin e
B .P .
at
m a tte r
th a t
a n d may h a v e
been
c o n ta m in a te d by r o o t l e t i n t r u s i o n . T h e r e f o r e , t h e s e d a t e s may b e s e v e r a l
th o u s a n d y e a r s
1 9 8 6 ) . L ocke
t o o y o u n g and m u st b e c o n s id e r e d minimum d a te s
(1989)
re p o rte d ,
in
a p o s te r,
(M eyer,
two a d d i t i o n a l minimum -^C
d a t e s o f a b o u t 6 k a f o r S h o r e li n e S6 ( S h o r e l i n e S 5 - t h i s s t u d y ) .
From t h e
ab o v e d i s c u s s i o n ,
it
c a n b e c o n c lu d e d
th a t
th e
s h o r e l i n e s a ro u n d Y e llo w s to n e L a k e .w e r e form ed d u r in g t h e l a s t
in d ic a te d
assum ed
by
th a t
minimum
th e
and maximum
s h o re lin e s
w e re
ra d io c a rb o n
d a te s .
h o r iz o n ta l, and
Richm ond
c o rre la te d
e le v a te d
9 ka as
(1 9 7 6 a )
th e m
by
h e i g h t ab o v e p r e s e n t l a k e l e v e l . F u r t h e r w ork by M eyer ( 1 9 8 6 ) , M eyer and
17
L ocke
(1 9 8 6 )
an d Locke- (1 9 8 9 )
s ig n ific a n tly
d e fo rm e d .
shew ed
th a t
th e
ra is e d
T h is w as done by p r e c i s e
la k e s h o re s
le v e lin g
su rv e y s
a re
and
c o r r e l a t i o n o f s h o r e l i n e s b e tw e e n l e v e l i n g l i n e s . E s t i m a t i o n o f v e r t i c a l
d e f o r m a tio n r a n g e u p . t o 4 m m /yr f o r s h o r e l i n e S6 on t h e n o r t h e a s t s h o r e ,
com pared t o t h e h i s t o r i c r a t e
o f 7 .5 m m /yr f o r t h a t a r e a
(M eyer, 1 9 8 6 ;
F e l t o n and S m ith , 1 9 8 2 ) . S h o r e li n e e l e v a t i o n d a t a from M eyer (19 8 6 ) a l s o
i n d i c a t e t h a t some s h o r e l i n e s a r e t i l t e d by a s much a s 6 m/km. G iv e n t h e
e v id e n c e
fo r
v e rtic a l
d e f o r m a t io n ,
r e e v a lu a tio n
of
s h o re lin e
c o rre la ­
t i o n s r e p o r t e d by Richm ond (1976) i s w a r r a n t e d .
The r a d i o c a r b o n d a t e s g iv e n a b o v e i n d i c a t e t h a t l a k e l e v e l h a s b e e n
d e c l i n i n g a t a r o u g h ly c o n s t a n t r a t e
v a rio u s
lin e s
of
g e o m o rp h ic e v id e n c e
has been in te r r u p te d ,
le v e l.
B a ile y
s h o re lin e s
in d ic a te
th a t
la k e
le v e l
d e c lin e
p e rh a p s s e v e r a l t im e s , by e p i s o d e s o f r i s i n g l a k e
(1 9 8 4 )
w h ic h
f o r a b o u t t h e p a s t 9 k a . H ow ever,
and
in d ic a te
H a m ilto n
(1985)
t h a t w a te r
le v e l
h a v e - d o cu m en ted
has
ris e n
to
su b m erg ed
th e
p rese n t
l e v e l a f t e r f o rm in g t h e now su b m erg ed s h o r e l i n e s . M eyer (1986) s u g g e s t e d
th a t
c a ld e ra
cau se
in fla tio n
d iffe re n tia l
le v e l
ris e
as
d o cum ented by P e l tp n
u p lift
of
th e
la k e
th r o u g h o u t t h e l a k e b a s i n .
t h e l a k e o u t l e t w o u ld d epend l a r g e l y
o u tle t
m a te ria l.
dow nw arping
o u tle t
as
L o w e rin g l a k e
in d ic a te d
and
a c co m p a n y in g w a t e r
O p p o sin g r a t e s
on t h e r e l a t i v e
le v e l
may
s h o re lin e s
a ls o
be
tiltin g
(1982) w o u ld
o f d o w n c u ttin g a t
e ro d ib ility
c o n tro lle d
down to w a rd s
o f th e
by
lo c a l
th e
la k e
(M eyer, 1 9 8 6 ).
C o n s id e rin g
d u r in g
by
o u tle t
a n d S m ith
p e rio d s
of
th e
above
s ta b le
to
fa c to rs ,
la k e s h o re s
r i s i n g w a te r l e v e l s ,
a re
p r o b a b ly
form ed
w hen w a v e - c u t c l i f f s
c a n be e f f e c t i v e l y u n d e r c u t (M eyer, 1 9 8 6 ) . P e r io d s o f r i s i n g w a t e r l e v e l
18
h a v e b e e n r o u g h ly
e q u a te d
to
e p is o d e s
of
u p lift
at
th e
o u tle t.
D u rin g
p e r i o d s o f f a l l i n g w a t e r l e v e l t h e w ave e n e rg y i s
p re s u m a b ly d i s s i p a t e d
on
le a s t
th e
w a v e -cu t
p la tfo rm .
The
e x is te n c e
of
at
te n
d is c re te
H o lo c e n e s h o r e l i n e s i m p l i e s a t l e a s t a s many e p is o d e s o f d e f o r m a t io n .
The
s tu d ie s
of
L ocke
and M eyer
( 1 9 8 5 ),
M eyer
(1 9 8 6 )»
M eyer
an d
L ocke (1986) an d L o ck e (1 9 8 9 , p e r s o n a l comm.) h a v e done much t o d e c ip h e r
th e
com plex v o l c a n o - t e c t o n i c
d e f o r m a t io n a l s i g n a l
th a t
is
d is p la y e d
in
t h e Y e llo w s to n e l a k e s h o r e s . H ow ever, t h e s t u d i e s h a v e b e e n r e s t r i c t e d by
t h e l a c k o f a m eans t o n u m e r i c a l ly
f ir m
c o rre la tio n s
g e s te d
th e
d a tin g
an d
use
d a te th e s h o r e l i n e se g m e n ts a n d make
b e tw e e n w id e ly
of
o b s id ia n
c o rre la tio n
spaced
h y d ra tio n
p ro b le m
lo c a tio n s .
d a tin g
because
of
M eyer
te c h n iq u e s
th e
(1986)
to
abundance
su g ­
s o lv e
of
th e
o b s id ia n
g r a v e l on t h e r a i s e d s h o r e l i n e s .
T he
p u rp o se
d e v is e a m e th o d ,
c a lly
th a t
d a te
and
of
th e
second
p a rt
of
th is
s tu d y
th e re fo re ,
is
to
u s in g o b s i d i a n h y d r a t i o n d a t i n g t e c h n i q u e s , t o n u m e ri­
c o rre la te
w ill
be
te s te d
p ro c e sse s
of
s to rm
in
d is c re te
th is
sw ash
p a rt
and
s h o re lin e
of
th e
lo n g s h o re
s e g m e n ts .
s tu d y
is
c u rre n ts
The
th a t
h y p o th e s is
la c u s trin e
e ffe c tiv e ly
re w o rk
o b s i d i a n p e b b le s so t h a t e a c h s h o r e l i n e p o s s e s s e s a u n iq u e , c h a r a c t e r i s ­
t i c h y d ra tio n r in d th ic k n e s s .
19
METHODS
Sam plin g
O b s id ia n Sand P l a i n
S a m p lin g p i t l o c a t i o n s f o r s tu d y s i t e I w e re s e l e c t e d from a s k e t c h
map o f f l u v i a l t e r r a c e s a lo n g t h e M a d iso n R iv e r by N ash (1 9 8 4 )
(F ig . 3 ) .
S a m p lin g
th a t
p its
w e re
lo c a te d
b e tw e e n
d a te d
te rra c e
sc arp s
so
ag e
d a t i n g r e s u l t s fro m t h i s s tu d y s h o u ld b e d i r e c t l y c o m p a ra b le t o t h o s e o f
N ash
(1 9 8 4 ).
T h is
is
because
t a n e o u s l y a c t e d upon by th e
s tr e a m
p o s itio n
is
te rra c e s
s tr e a m
re fle c te d
in
and
te rra c e
sc arp s
a re
s im u l­
a n d t h e ab an d o n m en t o f a p a r t i c u l a r
th e
ages
o f b o th
th e s e
ty p e s
of
su r­
fac e s.
S a m p lin g
p its
w e re
dug
by
th e
a u th o r
on
each
t e r r a c e s t o a d e p th o f one m e te r a n d sa m p le s c o l l e c t e d
m e n ts .
T h e re w as no v i s i b l e
m e n t. S o i l p r o f i l e s
a th ic k e r
s tra tig ra p h y
and v e r y
g e n e ra lly c o n s is te d o f a th in
(20 cm) Bw
h o riz o n .
of
th e
flu v ia l
a t 20 cm i n c r e ­
little
s o il
d e v e lo p ­
(5 cm) A h o r iz o n w i t h
C are w as t a k e n t o d i g t h e p i t s away from
t h e t o e o f t h e a d j a c e n t s lo p e so t h a t t h e r e w as l i t t l e
m a t e r i a l from t h e n e x t h i g h e r t e r r a c e .
c h a n c e o f m ix in g
M odern r i v e r g r a v e l s a m p le s w e r e
c o l l e c t e d from t h e a c t i v e r i v e r c h a n n e l a n d .f r o m an e x p o s e d g r a v e l b a r .
The m odern
g rav e l
s a m p le s w e re
b e c au se of th e d i f f i c u l t y
c o lle c te d
at
a
d e p th
of
about
20
cm
o f d i g g in g a p i t i n t h e a c t i v e c h a n n e l a n d t h e
p r o x im ity o f t h e w a t e r t a b l e t o t h e s u r f a c e o f t h e g r a v e l b a r .
20
Pit T l
Pit T2
Pit T3
Pit TO
Pit T4
*0 1 #
*000
■
L_____ 1? 0 m e te rs
vertical exaggeration
IDAHO
WYOMING
North
MAP LOCATION
F ig u r e 3 - C om puter g e n e r a te d (G o ld en G r a p h ic s . 1984) d ia g ra m o f s tu d y
s i t e I s h e w in g l o c a t i o n o f sam p le p i t s . S k e tc h map a f t e r N ash ( 1 9 8 4 ) .
21
Y e llo w s to n e L ake
S a m p lin g
p its
w e re
dug
by
th e
a u th o r
and W illia m
L ocke
on
a
s e q u e n c e o f b e a c h b a r s a lo n g a low g r a d i e n t d e p o s i t i o n a l c o a s t l i n e n e a r
B re e z e P o i n t f o r
w as
chosen
s tu d y
because
s ite
th e
2 (F ig s .
m a te ria l
2 an d 4 ) .
th a t
T h is
c o m p rise s
ty p e o f c o a s t l i n e
th e
b a rs
m u st
have
t r a v e l e d a l o n g e r d i s t a n c e t h a n b e a c h m a t e r i a l fo u n d i n s t e e p , e r o s i o n a l
c o a s tlin e s
la rg e ly
(K om ar, 1 9 7 6 ) . On a low g r a d i e n t c o a s t l i n e ,
c o n s tru c tio n a l
a n o th e r l o c a t io n w h ile
d e riv e d
fro m
th e
and
th e m a te ria l
was
p r o b a b ly
t h e b e a c h m a t e r i a l on a s t e e p
a d ja c e n t
c liff.
T h is
th e b e a c h m a t e r i a l i s m ore l i k e l y
d iffe re n c e
is
t o b e re w o rk e d i f
th e f e a tu r e s a re
tra n s p o rte d
from
c o a s t l i n e may b e
i m p o r ta n t b e c a u s e
it
is
tra n s p o rte d a
g re a te r d is ta n c e .
Sam ple p i t s
d e p th
of
w e re dug on t h e
o n e m e te r
and
sa m p le s
d e v e lo p m e n t was g e n e r a l l y
p o o r,
c re s ts
o f b e a c h berm s
c o lle c te d
but
at
20
( F ig .
4)
cm i n c r e m e n t s .
t h e r e was a s i g n i f i c a n t
to
a
S o il
am ount o f
o r g a n i c m a t t e r a c c u m u la te d i n t h e A h o r iz o n s o f some o f t h e p i t s .
H y d r a tio n R in d M easurem ent
L a b o r a to r y
from M ic h e ls
p ro ced u res
and B e b r ic h
u sed
(1971)
fo r
sa m p le
p re p a ra tio n
(A p p e n d ix A ).
The m ain
w e re m o d i f i e d
d iffe re n c e
is
t h a t s i x o b s i d i a n g r a i n s i n s t e a d o f a s i n g l e w edge c u t fro m an a n th r o p o ­
l o g i c a l a r t i f a c t a r e m ounted d i r e c t l y t o a s l i d e .
A ll
s a m p le s w e re m e a s u re d b l i n d ,
re la b e le d
id e n tity
by
of
W illia m
th e
L ocke
s a m p le s w as
b e fo re
r e v e a le d
in
th e
sen se
p re p a ra tio n
o n ly
a fte r
th a t
s a m p le s w e re
a n d m e a s u re m e n t.
m e a s u re m e n ts
The
w e re
c o m p le te d . T h is b l i n d i n g p r o c e d u r e s h o u ld d e c r e a s e t h e s u b j e c t i v i t y o f
Elevation (meters) above Bridge Bay datum
22
A—Modern beach berm
I
I
l
Horizontal distance (meters) from present coastline
F i g u r e 4 - S u rv e y e d p r o f i l e o f b e a c h berm s a t B re e z e
l o c a t i o n s o f s a m p le p i t s . V e r t i c a l e x a g g e r a t i o n i s x 2 0 .
P o in t
s h o w in g
23
th e o b s i d i a n h y d r a t i o n d a t i n g te c h n i q u e a s u s e d i n t h i s
s tu d y t o i n s i g ­
n ific a n t le v e ls .
The o p t i c a l
c o n s is ts
s y s te m
u s e d t o m e a s u re h y d r a t i o n
rin d s
in
th is
s tu d y
o f a n A m e ric an O p t i c a l p o l a r i z i n g m ic r o s c o p e o u t f i t t e d w i t h
a
V ic k e r s i m a g e - s p l i t t i n g m e a s u r in g e y e p i e c e . A IOx d ry l e n s w as u s e d f o r
m ea su rem e n t
c o u p le d w i t h
m a g n ific a tio n
of
150x.
a
15x
e y e p ie c e ,
A d m itte d ly ,
th is
th e re b y
p ro v id in g
m a g n ific a tio n
is
a
to ta l
c o n s id e ra b ly
l e s s t h a n w h a t i s recom m ended by M ic h e ls an d B e b r ic h ( 1 9 7 1 ) , b u t b e c a u s e
s ta tis tic a lly
v a lid
sa m p le s i z e s w e re u s e d ,
l e n s w o u ld b e m ore e f f i c i e n t i n
im m e rs io n l e n s .
lim ite d
F u r th e r m o r e ,
it
w as
th o u g h t t h a t a d ry
te r m s o f tim e t h a n a h i g h e r pow er o i l
u s e o f t h e recom m ended o p t i c a l
by w h a t w as a v a i l a b l e
in
th e
D e p a rtm e n t
of
E a rth
s y s te m was
S c ie n c e s
at
M ontana S t a t e U n i v e r s i t y .
W hen , v i e w i n g
in d iv id u a l
g ra in s
under
th e
m ic r o s c o p e
each
rin d
m e a s u re d m u st f i r s t m e e t a s e t o f c r i t e r i a w h ic h w e re c h o s e n i n o r d e r t o
o b ta in
th e
m o st
c o n s is te n t
and
a c c u ra te
m e a su re m e n ts
b e tw e e n
g ra in s ^
T h ese c r i t e r i a i n c l u d e : I ) sm ooth ed g e o f g r a i n a t l e a s t 0 .1 5 mm l o n g 2)
ed g e o f g r a i n p e r p e n d i c u l a r t o m ic r o s c o p e s t a g e
and 3) h y d r a t i o n f r o n t
p a r a l l e l t o ed g e o f g r a i n a n d p e r p e n d i c u l a r t o m ic r o s c o p e s t a g e .
m e a s u r in g l o c a t i o n
p re s e n t,
m e e ts
th e n a z e r o
th e
th ic k n e s s
firs t
tw o
rin d i s
c rite ria
but
th e re
is
rec o rd e d . A d e ta ile d
If
th e
no r i n d
flo w
c h a rt
f o r h y d r a t i o n r i n d m e a su re m e n t p r o c e d u r e s i s l o c a t e d i n - a p p e n d ix B.
The e r r o r
te c h n i q u e
th a t
is
a s s o c ia te d w ith
th e
o b s id ia n
h y d ra tio n
d a tin g
s te m s from tw o m ain s o u r c e s , w h ic h a r e t h e r e s o l u t i o n o f t h e
o p t i c a l s y s te m a n d m e a su re m e n t e r r o r . T h e se s o u r c e s o f e r r o r do n o t v a r y
s ig n ific a n tly
fro m
one
age
d e te rm in a tio n
to
a n o th e r
(M ic h e ls
and
24
B e b r ic h 6 1971) „ B e c a u s e
th e
a ffe c t
a
a ll
s a m p le s
in
com bined
g iv e n
o p e ra to r
s tu d y
and
e q u a lly ,
it
in s tru m e n t
is
e rro r
recom m ended
by
M ic h e ls an d B e b r ic h (1 9 7 1 ) t h a t e a c h l a b o r a t o r y com pute a s t a n d a r d e r r o r
t h a t a p p l i e s t o a l l h y d r a t i o n m e a s u re m e n ts by. t h a t l a b o r a t o r y .
The r e s o l u t i o n o f an o p t i c a l s y s te m i s g iv e n b y :
R = 0 .6 1 0 y /N A
w h e re R i s
lig h t
th e
b e in g
lim it
used
o b je c tiv e le n s
of re s o lu tio n
(m ic ro n s )
(m ic ro n s ) 0 y i s
an d NA i s
( L e a c h , 1 9 7 7 ) . The l i g h t
th e
t h e w a v e le n g th
n u m e r ic a l
so u rc e used in
a p e rtu re
th is
of
of
th e
s tu d y i s
a
t u n g s t e n h a lo g e n b u lb w h ic h e m its t h e f u l l s p e c tru m o f v i s i b l e l i g h t and
c o rre sp o n d s
to
a w a v e le n g th
ra n g in g
fro m
0 .4
to
0 .7 5
m ic r o n s .
T h e se
lo w e r and u p p e r l i m i t s a r e d e s ig n a t e d y ^ and y g , r e s p e c t i v e l y .
F o r t h e MSU/NPS s y s te m t h e l i m i t s o f r e s o l u t i o n a r e g iv e n b y :
R1 = 0 . 6 1 0 ( 0 . 4 ) / 0 . 2 5
R1 = 0 .9 7 6 m ic ro n s ( v i o l e t l i g h t )
and
R2 = 0 . 6 1 0 ( 0 . 7 5 ) / 0 . 2 5
R2 = 1 .8 3 m ic r o n s ( r e d l i g h t )
H ow ever, by u s i n g a n i m a g e - s p l i t t i n g m e a s u r in g e y e p i e c e ,
th e r e s o lu tio n
o f an o p t i c a l s y s te m c a n be i n c r e a s e d by a f a c t o r o f t e n o r m ore (D yson,
I9 6 0 ).
The f i n a l
e r r o r o f th e o p t i c a l
s y s te m
u s in g t h e
im a g e -s p littin g
e y e p ie c e i s g iv e n b y :
E = cR
w h e re E i s
th e e r r o r
(m ic ro n s ),
c is
a c o n s ta n t r e l a t e d to th e c o n tr a s t
from t h e c e n t e r t o t h e ed g e o f an im age and R i s t h e o p t i c a l r e s o l u t i o n
of
t h e m ic r o s c o p e a s
g iv e n ab o v e
(L each ,
1 9 7 7 ),
V a lu e s
o f c g e n e ra lly
v a ry
fro m a b o u t 0 .0 9 6
to
0 .0 6 8
d e p e n d in g on th e
g e n e ra l
c o n d itio n s
of
o b s e r v a t i o n and c o r r e s p o n d t o . a n im p ro v em en t o f from 1 0 .4 t o 1 4 .7 tim e s
th e t h e o r e t i c a l r e s o l v i n g pow er o f t h e m ic r o s c o p e (D y so n , I 9 6 0 ) .
The
fin a l
th e o re tic a l
e rro r
ran g e
of
th e
o p tic a l
s y s te m
e rro r
of + 0 . 1
u se d . in
t h i s s tu d y i s g iv e n by t h e f o l l o w i n g ;
E1 = 0 .0 9 6 ( 0 .9 7 6 )
E1 = 0 .0 9 4 m ic ro n s
and
E2 = 0 .0 9 6 ( 1 .8 3 )
E2 = 0 .1 7 6 m ic ro n s
T h is
ran g e
c o m p a res f a v o r a b l y w i t h
th e
s ta n d a rd
m ic ro n
a c c e p t e d by M ic h e ls an d B e b r ic h (1971) f o r t h e i r l a b o r a t o r y .
An
e x p e rim e n t
w as
done
to
d e te r m in e
th e
e rro r
a s s o c ia te d
w ith
m easurem ent, o f t h e h y d r a t i o n r i n d s . . Two r i n d s w e re m e a s u re d i n th e same
p la c e t h i r t y
tim e s e a c h and t h e mean and s t a n d a r d d e v i a t i o n com puted f o r
e a c h g ro u p o f m e a s u re m e n ts (T a b le I ) . The f i r s t g ro u p h a s a mean o f 5 .7 6
m ic r o n s and s t a n d a r d d e v i a t i o n . o f 0 .3 m ic ro n s w h i l e t h e s e c o n d g ro u p h a s
a mean o f 1 9 .4 3 m ic ro n s , and s t a n d a r d
c o n c lu d e d
f ro m
th is
e x p e rim e n t
d e v ia tio n
th a t
o f 0 .4 4 m ic r o n s .
s m a l le r ,
m e a su re m e n t e r r o r a s s o c i a t e d w i t h th em . T h is i s
rin d s
have
a
It
is
s m a lle r
c o n s is te n t w ith o b se rv a ­
t i o n s i n t h a t t h i c k e r r i n d s , g e n e r a l l y h a v e an i n d i s t i n c t h y d r a t i o n f r o n t
a n d so m e a s u r in g p r e c i s i o n , w o u ld b e .e x p e c te d t o be som ew hat lo w e r .
A s t a n d a r d e r r o r o f +/ 0 .3 m ic r o n s w as a c c e p te d b e c a u s e t h e h y d r a ­
tio n
rin d s
a s s o c ia te d w ith th e f l u v i a l
s tu d y a r e c l o s e r t o t h e f i r s t
t e r r a c e s , and l a k e s h o r e s
in
th is
g ro u p o f e r r o r d e t e r m i n a t i o n m e a s u re m e n ts
t h a n t h e s e c o n d (T a b le I ) . The s t a n d a r d e r r o r o f + 0 .3 m ic r o n s a l s o
26
T a b le I .
Sam ple
D a ta a r r a y and a n a l y s i s o f m ea su rem e n t e r r o r e x p e r i m e n t . • Two
i n d i v i d u a l h y d r a t i o n ;r i n d s , w e re m e a su re d t h i r t y tim e s e a c h t o
d e te r m in e e r r o r a s s o c i a t e d w i t h m e a su re m e n t t e c h n i q u e .
5 - 5 -1 „ g r a i n 5
L l-7 -3 » g ra in 3
5 .2 6 m ic ro n s
5 .6 0
5 .7 1
5 .6 6
5 .4 9 .
5 .8 9
5 .8 9
5 .3 7
5 .7 1
5 .7 1
5 .6 6
6 .0 0
5 .7 7
5 .6 0
5 .8 3
5 .4 3
6 .0 6
5 .6 6
6 .0 6
5 .8 3
6 .1 7
6 .1 1
6 .2 9
5 .0 9
6 .1 7
6 .2 9
S i 83
5 .6 0
5 .7 7
5 .2 6
1 8 .8 6 m ic ro n s
1 9 .8 3
2 0 .5 1
2 0 .0 6
1 9 .0 9
1 9 .5 4
2 0 .0 0
2 0 .0 0 .
1 9 .0 3
1 9 .7 7
1 9 .6 6
1 9 .4 3
1 8 .9 1
1 9 .3 1
1 9 .6 0
1 9 .8 3
1 9 .6 0
1 9 .4 3
1 9 .3 7
1 9 .1 4
1 9 .4 3
1 9 ,2 0
1 9 .3 7
1 9 .0 3
1 8 .6 3
1 8 .4 6
1 9 .8 9
1 9 .4 3
1 9 .4 3
1 9 .0 9
Mean
5 .7 6
1 9 .4 3
S td Dev
0 .3 0
0 .4 4
.
27
i n c l u d e s t h e e r r o r a s s o c i a t e d w i t h t h e o p t i c a l s y s te m .
G r a in S iz e S e l e c t i o n
A ll
o f. th e
s a m p le s from
flu v ia l
g ra v e l.
T h e r e f o r e ,, a n e x p e r im e n t w as p e rfo rm e d t o
t o w ork w i t h
m e a s u re m e n ts
ta k e n
p r e p a ra tio n .
The
in
per
th is
g iv e n
sa m p le
c la s s e s
s tu d y ,
num ber
chosen
from
te rra c e s
c o n ta in
s iz e
s iz e
th e
sh o re s
g ra in
s e d im e n t
b o th
fo r
fin e
sand
and
th e
th r o u g h
la k e c o a rse
d e te r m in e t h e o p tim a l .
b o t h i n te r m s o f t h e num ber o f
of
g ra in s
th is
and
e x p e rim e n t
ease
of
s a m p le
(K D A -88-TO ,. 8 0 -1 0 0
cm) w as o b t a i n e d fro m t h e OSP. The 80 t o 100 cm l e v e l w as c h o s e n b e c a u s e
it
is
th e l e a s t l ik e ly
in s o la tio n .
p a rtic le s
Sam ple
( 0 .0 6 2 5
t o h a v e b e e n a f f e c t e d by b i o t u r b a t i o n and s o l a r
g ra in
to
s iz e s
ran g e
from
16 mm), b u t n o t a l l
c o a rse
s ilt
of th e s e
f o r m e a su re m e n t b e c a u s e of. l a b o r a t o r y l i m i t a t i o n s .
p rep a re d a re
a s f o l l o w s s 0 .5
t o I mm, I
to
p e b b le
s iz e
s i z e s w e re p r e p a r e d
The s i z e s
t h a t w e re
t o 2 mm, 2 t o 4 mm and 4 t o 8
mm. S l i d e s w e re p r e p a r e d , w i t h .a t l e a s t 3 0 g r a i n s f o r e a c h s i z e c l a s s a n d
e x a m in ed u n d e r, t h e . : p e t r o g r a p h i c ,m ic ro sc o p e
th ic k n e s s e s
The
c a lly
( T a b le 2 ) .
sa m p le m eans
in d is tin g u is h a b le
a d d itio n ,
th ic k n e s s e s ,
each
s iz e
t o d e te r m in e h y d r a t i o n r i n d
'
of
th e
fo r
c la s s
h y d ra tio n
th e
rin d
sa m p le
ex am in ed
s iz e s
has
a
th ic k n e s s e s
a re
e x a m in ed
( T a b le
c o m p a ra b le
ran g e
t h e r e f o r e i t w a s .a s s u m e d , t h a t t h e s i z e
c la s s
s ta tis ti­
2 ).
of
In
rin d
th a t o ffe re d
t h e g r e a t e s t num ber o f m e a su re m e n ts p e r g iv e n num ber o f g r a i n s w o u ld be
t h e m o st e f f i c i e n t t o w o rk w i t h f o r t h e r e m a in d e r o f t h e s t u d y .
From T a b le 2 i t i s c o n c lu d e d t h a t t h e optim um g r a i n s i z e t o p r e p a r e
f o r h y d r a t i o n r i n d m e a s u re m e n ts i s
t h e 2 t o 4. mm c l a s s
because
of
th e
)
28
T a b le 2 . D a ta a r r a y a n d a n a l y s i s o f h y d r a t i o n r i n d t h i c k n e s s e s f o r
d i f f e r e n t g r a i n s i z e c l a s s e s from T e r r a c e TO (8 0 -1 0 0 c m )=
S iz e C la s s e s
0 .5 — I mm
1 -2
mm
2 - 4 mm
4 — 8 mm
4 .0 6
5 .2 8
7 .3 9
1 0 .7 8
1 4 .6 1
1 6 .8 9
1 9 .0 6
1 9 .1 7
2 1 .8 9
2 3 .5 6
4 .4 4
5 .3 3
7 .0 6
7 .8 3
8 .7 8
9 .0 0
9 .7 2
1 0 .5 6
1 2 .0 0
1 2 .3 9
1 2 .5 0
1 3 .7 2
1 4 .6 1
1 7 .0 6
1 7 .2 2
1 8 .9 4
2 0 .7 8
2 2 .6 7
2 4 .3 3
2 4 .6 1
2 .8 3
5 .5 0
6 .1 7
6 .3 9
' 7 .7 2
8 .4 4
9 .9 4
1 0 .1 1
1 1 .8 9
.1 2 .2 2
1 2 .4 4
1 3 .5 0
1 4 .0 0
1 4 .1 1
1 4 .5 6
1 5 .0 0
1 9 .6 7
2 0 .2 8
2 0 .3 9
2 0 .6 1
2 1 .2 2
2 1 .5 0
2 2 .3 9
2 3 .1 7
2 5 .3 3
2 5 .8 9
2 7 .9 4
5 .2 8
6 .7 2
7 .7 2
9 .2 8
9 .4 4
9 .5 6
1 0 .6 7
1 1 .3 3
1 1 .6 1
1 2 .7 2
1 3 .7 2
1 3 .7 8
1 4 .2 8
1 4 .4 4
1 4 .5 0
1 6 .0 6
1 6 .1 1
1 6 ,1 7
1 7 .4 4
1 7 .7 2
1 8 .1 1
2 0 .1 7
2 2 .8 3
2 3 .1 7
n=10
n=20
n=27
n= 24
1 4 .2 7
1 3 .6 8
1 5 .3 0
1 3 .8 7
S td Dev
7 .0 1
6 .1 9
6 .9 8
4 .7 2
S td E r r o r
2 .2 2
1 .3 8
1 .3 4
0 .9 6
N
Mean
29
num ber o f m e a s u re m e n ts ta k e n p e r num ber o f g r a i n s .
th e , s m a l l e s t
mm c l a s s
show ed
d iffic u lty
o f p r e p a r a t i o n o f t h e l a r g e r g r a i n s d i c t a t e d t h e c h o ic e o f
t h e 2 t o 4 mm c l a s s .
s ta n d a rd
e rro r
of
A lth o u g h t h e 4 t o
T h is s m a l l e r c l a s s s i z e i s
th e
mean
8
(SEM)1 t h e
th o u g h t.to re p re s e n t a
b a la n c e b e tw e e n h ig h e n e rg y d e p o s i t i o n a l e n y ir p n m e n ts arid e a s e o f sa m p le
p r e p a r a t i o n . G r a in s l a r g e r t h a n t h i s a r e m ore . d i f f i c u l t . to . w o rk w i t h and
ta k e
lo n g e r
e n e rg y
to
p rep a re ,
d e p o s itio n a l
som ew hat e a s i e r t o
fo r
a g iv e n
is
not
as
e ffe c t
of
a w a te r
p re s u m a b ly
e n v ir o n m e n ts
p rep a re ,
num ber o f
g ra in s
but
as
(C h u rc h ,
r e p re s e n ta tiv e
1 9 7 2 ).
S m a lle r
of
h ig h e r
g ra in s
d i d n o t h a v e a s many m e a s u r a b le
g ra in s .
g rea t
film
but
a re
The l i k l i h o o d
w ith
la rg e r
s u r r o u n d in g
of
g ra in s
each
g ra in
r e w o rk in g f o r
due
to
th e
(Z ie g le r,
a re
r i r id s
s m a lle r
c u s h io n i n g
1911;
T h ie l,
1 9 4 0 ). S m a lle r g r a i n s a r e a l s o m ore l i k e l y t o t r a v e l i n s u s p e n s i o n w h ic h
i s n o t an e f f e c t i v e r e w o rk in g m echanism (D o b k in s and F o lk , 1 9 7 0 ) .
In
h in d s ig h t,
th e
u n fo rtu n a te in t h a t i t
th is
rin d
s tu d y
c h o ic e
of
on
K D A -8 8 -T 0 ,
8 0 -1 0 0
cm w a s
i s one o f t h e few b im o d a l s a m p le s e n c o u n te r e d i n
( s e e RESULTS). ,Thus t h e
d e v e lo p m e n t
s a m p le
d iffe re n t
te n ta tiv e
s iz e d
c o n c lu s i o n
g ra in s
te s te d .
has
not
of
c o m p a ra b le
been
a d e q u a t e ly
'
Z e ro T h ic k n e s s H y d r a ti o n R inds
To d e te r m in e
flu v ia l
th e
th a t
s y s te m
a n c e s tra l
each
th ic k n e s s .
if
o b s id ia n
g r a v e l w as
e ffe c tiv e ly
an e x p e rim e n t w as p e rfo rm e d t o t e s t
M adison
te rra c e
I t w as
R iv e r
s u ffic ie n tly
possesses
assu m ed f o r
a
u n iq u e ,
th is
re w o rk e d
re w o rk e d
th e h y p o th e s is
o b s id ia n
c h a ra c te ris tic
e x p e r im e n t
th a t
in
th e
th e
th a t
g ra in s
h y d ra tio n
so
r in d
m cderri s tr e a m
30
se rv e s
as
an a p p r o p r ia te
c u t th e t e r r a c e s .
a n a lo g f o r
th e
a n c e s tra l
M ad iso n R iv e r w h ic h
The e x p e r im e n t c o n s i s t e d o f e x a m in in g o b s i d i a n g r a i n s
fro m T e r r a c e s T l t o T4 a n d t h e m odern s tr e a m a n d s p e c i f i c a l l y n o t i n g t h e
p rese n c e
of z e ro
th ic k n e s s
rin d s
fo u n d on e a c h g r a i n .
Many g r a i n s h ad
m ore th a n o n e l o c a t i o n w h e re a z e r o t h i c k n e s s r i n d c o u ld be o b s e r v e d , a s
o u t l i n e d by t h e m ea su rem e n t s i t e
s e le c tio n
c rite ria ,
b u t n o t m ore t h a n
o n e z e r o t h i c k n e s s r i n d w as r e c o r d e d f o r e a c h g r a i n . By c l a s s i f y i n g e a c h
g ra in
as
p o s s e s s in g
s ta tis tic a l
te s ts
a re
z e ro
m ore
rin d s
or
not
s ig n ific a n t
p o s s e s s in g
( R ic h a r d
z e ro
R o s s i,
rin d s ,
1989,
th e
p e rso n a l
comm.)
The
d a t a w e re a n a ly z e d
u s in g a s e r i e s
( w ith a 5 % r e j e c t i o n l e v e l )
to
of 2 x 2 c h i sq u a re
te s ts
t e s t w h e th e r t h e r e w as a d i f f e r e n c e
in
t h e num ber o f z e r o s fo u n d on e a c h o f t h e u p p e r t e r r a c e s com pared t o t h e
m odern s tr e a m
of z e ro
( T a b le s 3 an d 4 ) . The f i r s t h y p o t h e s i s i s
th ic k n e s s
rin d s
on a l l
su rfa c e s
r e j e c t e d w i t h a P - v a lu e = 0 .0 1 3 5
of th is
o b se rv e d d if f e r e n c e
is
e q u a l.
( T a b le 3 ) :
in z e ro v a lu e s
t h a t th e num ber
T h is h y p o t h e s i s w as
th e re i s
o n ly
h a v in g a r i s e n
a I % chance
from s a m p lin g
o f s i m i l a r p o p u l a t i o n s . The r e j e c t i o n o f t h i s h y p o t h e s i s i n d i c a t e s
th a t
t h e r e i s a d i f f e r e n c e b e tw e e n s a m p le s .
The s e c o n d h y p o t h e s i s i s
t h a t t h e m odern s tr e a m i s
s im ila r to
th e
f o u r o t h e r s u r f a c e s w i t h r e s p e c t t o t h e num ber o f z e r o t h i c k n e s s r i n d s .
T h is
h y p o t h e s i s w as r e j e c t e d w i t h
in d ic a te s
th a t
th e re
is
a
a d iffe re n c e
P - v a lu e
= 0 .0 0 3 2
( T a b le
4)
b e tw e e n t h e m odern s tr e a m
w h ic h
sa m p le
a n d T e r r a c e s T l th r o u g h T4.
The
re s u lts
of
th e s e
two s t a t i s t i c a l
te s ts
im p ly
th a t
re w o rk in g
d o e s t a k e p l a c e i n t h e m odern s tr e a m . H ow ever, r e w o r k in g i s n o t c o m p le te
31
T a b le 3 .
Chi s q u a r e t e s t t o d e te r m in e i f
of z e ro th ic k n e s s r in d s .
a ll
t e r r a c e s h a v e same num ber
R ind T h ic k n e s s
z e ro
T e rra c e
Tl
Tl
T3
T4
M odern s tr e a m
n o n -ze ro
15
11
. 14.
20
25 -
20
24
22
17
11
Hg: T l = T2 = T3 = T4 = M odern s tr e a m
P - v a lu e = 0 .0 1 3 5
T h e r e f o r e r e j e c t Ho0 t h e r e i s a d i f f e r e n c e b e tw e e n s a m p le s .
N o te : 35 t o 37 g r a i n s w e re m e a s u re d fro m e a c h s u r f a c e w i t h e a c h
h a v in g o n ly one m e a s u re m e n t.
'
T a b le 4 .
g ra in
C hi s q u a r e t e s t t o d e te r m in e i f t h e m odern s tr e a m h a s t h e same
num ber o f z e r o t h i c k n e s s r i n d s a s t h e t e r r a c e s .
R in d T h ic k n e s s
z e ro
T e r r a c e s T l t o T4
M odern s tr e a m
60
25
n o n -ze ro
83
11
H : T l + T2 + T3 + T4 = M odern s tr e a m
P - v a lu e = 0 .0 0 3 2
T h e r e f o r e r e j e c t Hq0 t h e r e i s a d i f f e r e n c e b e tw e e n t h e t e r r a c e s and t h e
m odern s tr e a m .
32
a s i n d i c a t e d by th e
p re se n c e of h y d ra tio n
r i n d s on g r a v e l sa m p le d fro m
t h e m odern s tr e a m . T h is i s c o n s i s t e n t w ith , t h e o b s e r v a t i o n o f P i e r c e and
o th e rs
(1 9 7 6 )
th a t
th e
g ra in s
th e y
e x a m in ed
fo r
e v id e n c e
of
g la c ia l
r e w o rk in g a l s o p o s s e s s e d p r e e x i s t i n g r i n d s t h a t d a te d fro m e a r l i e r
e v e n t s . T h e r e f o r e * e a c h r e w o rk in g e v e n t d o e s n o t c o m p le te ly e r a s e t h e
rec o rd
of
p re v io u s
re w o rk in g
e v e n ts ,
p o te n tia lly
e n a b lin g
se v era l
e v e n ts t o be d a te d fro m a s i n g l e g r a i n .
S t a t i s t i c a l M ethods an d D a ta P r e s e n t a t i o n
H y d r a tio n r i n d s on o b s i d i a n a r t i f a c t s
p resen t l i t t l e
a rtifa c t
a re c le a rly
id e n tifia b le
a m b ig u ity i n c o r r e l a t i n g a r i n d w i t h t h e c r e a t i o n o f t h e
(F rie d m a n an d S m ith , 1 9 6 0 ). H ow ever, when e x a m in in g r i n d s
n a tu ra lly
w o rk e d
o b s id ia n ,
th e
rin d s
th a t
d a te from
th e
th a t
(1 9 7 6 ),
b o th
in
ra d ia l
stem m ed fro m
th e ir
s tu d y
p ressu re
g la c ia l
of
c ra c k s
g la c ia lly
and
shear
re a so n e d
on o b s i d i a n
p r o c e s s e s and so c o u ld c o n c e n t r a t e
of
P ie rC e a n d
w orked o b s i d i a n ,
c ra c k s
fro m
event
i n t e r e s t m u st be s e l e c t e d from a num ber o f r i n d t h i c k n e s s e s .
o th e rs
and
g rav el
t h e i r m e a s u re ­
m ent e f f o r t s on r i n d s t h a t fo rm ed a lo n g t h e s e c r a c k s .
The l a c k o f c l e a r l y
m e a s u re i n
i d e n t i f i a b l e e v e n t- s p e c if ic h y d ra tio n rin d s
to
t h e c a s e o f f l u v i a l a n d l a c u s t r i n e w o rk ed s e d im e n t? d i c t a t e s
a s ta tis tic a l
As m e n tio n e d a b o v e ,
on a g iv e n
g r a i n t h e r e may be s e v e r a l r i n d t h i c k n e s s e s and t h e r e f o r e i t
is lo g ic a l
to
assum e t h a t
th a t
th e
p ro g re s s iv e ly
because
s p a ll
a p p ro a c h
to
th e
th in n e s t
th ic k e r
p ro b le m .
rin d s
r in d s
d a te
from t h e m o st r e c e n t
e v e n t and
d a te
f ro m o l d e r e v e n t s .
H o w e v e r,
t h e h y d r a t i o n phenom ena c a u s e s m e c h a n ic a l s t r a i n ,
p a ra lle l
to
th e
g ra in
ed g e
(M ic h e ls
an d B e b r ic h ,
r i n d s te n d t o
1971)
an d t h u s
33
may c a u s e
s iz e s
a n o m o lo u s ly
m u st be
th in
rin d s
to
be
p re s e n t.
s u ffic ie n tly
la rg e
to
be
a b le
C o n s e q u e n tly ,
to
d iffe re n tia te
sa m p le
b e tw e e n
r i n d s t h a t d a te from t h e e v e n t o f i n t e r e s t . a n d t h o s e t h a t a r e c r e a t e d by
o th e r p ro c e sse s
( i.e .
s p a l l i n g an d f r o s t f r a c t u r e ) .
A f u r th e r re a so n s t a t i s t i c a l l y v a lid
n a t u r a l l y - w o rk ed : s p e c im e n s
is
th a t
v a r ie s w ith in in d iv id u a l r h y o lite
h y d ra tio n
it
sam p le s i z e s m u st be u s e d f o r
is
lik e ly
flo w s a n d i s
r a t e v a r i e s b etw een , flo w s
th a t
h y d ra tio n
ra te
a c c e p te d
th a t
g e n e ra lly
(F rie d m a n and L o n g , ; 1 9 7 6 ; M ic h e ls ,
1 9 8 5 ; M ic h e ls , 1988) . F rie d m a n and i,o h g (197,6) p o s t u l a t e d r e l a t i o n s h i p s
b e tw e e n s i l i c a
c o n t e n t and h y d r a t i o n r a t e
a n d .h y d r a tio n r a t e .
a rid , b e tw e e n r e f r a c t i v e
They a l s o fo u n d t h a t i n c r e a s e d
in d e x
CaO ( c a lc iu m o x id e )
and MgO (m agnesium o x id e ) re d u c e t h e h y d r a t i o n r a t e . A n a ly s e s o f s i n g l e ­
so u rc e
( A s te r C reek a n d O b s id ia n
am ong
th e
c h e m ic a l
C liff
c o n s titu e n ts
of
f lo w s )
o b s id ia n
in d iv id u a l
show s v a r i a t i o n
s a m p le s
(F rie d m a n a n d L o n g , 1 9 7 6 ; M ic h e ls , 1 9 8 8 ). I n p a r t i c u l a r ,
CaO and MgO i n
and 2 .0 ,
r e s p e c tiv e ly .
The a n a l y s e s i n d i c a t e
r e p re s e n ta tiv e
g ra in s
may p o s s e s s
h y d ra tio n
d iffe re n t
ra te .
rin d
th a t th e s e
but th a t ra te s
T h e refo re,
th ic k n e s s e s
flo w s
o f 1 .4
p r o b a b ly
a r e v a r i a b l e a ro u n d
s in g le -s o u rc e
th a t
C) .
t h e am ounts o f
t h e A s t e r C reek flo w , v a r y by a s much a s f a c t o r s
do n o t h a v e a u n iq u e h y d r a t i o n r a t e
some
(A p p en d ix
d a te
from
o b s id ia n
th e
same
e v e n t.
F u rth e rm o re ,
h y d ra tio n
so u rc e
sam e
o b s id ia n
(F rie d m a n ^nd L ong,
a r e a may a l s o
from , t h e
f lu v ia l
ra te
because, each
e v e n t.
te rra c e s
possess
If
a
rin d s
g iv e n
1 9 7 6 ),
of
set
f lo w
a
re p re s e n ta tiv e
d e p o s i t s w i t h m ore th a n o p e
d iffe re n t
of
has
th ic k n e s s e s
s e q u e n tia l- d e p o s its
c o n t a i n t h e same, m ix t u r e o f s o u r c e m a t e r i a l ,
th a t
d a te
such
as.
s ta tis t!-
34
ca lly v a lid
of
sa m p le s i z e s fro m e a c h t e r r a c e s h o u ld a l l e v i a t e
d iffe rin g
h y d ra tio n
ra te ? ,
a s su m in g t h a t e a c h
th e p ro b le m
te rra c e
c o n ta in s
th e
same m ix t u r e o f s o u r c e m a t e r i a l .
N o n p a r a m e tr ic
u se d t o
d is p la y
flu v ia l
te rra c e s
p o in t
a
d e n s ity
e s tim a tio n
(T a rte r
t h e r i n d m ea su rem e n t d a t a
and I a k e s h o r e s .
s ta n d a rd
d is trib u tio n
from
and K ro n m al,
th e
sa m p le p i t s
D e n s ity . e s t i m a t i o n
an d
th e
sum t o t a l
1976)
of
a s sig n s
a ll
w as
on t h e
each d a ta
d a ta
p o in ts
d e f i n e s t h e s h a p e o f t h e o v e r a l l d e n s i t y e s t i m a t i o n c u r v e . H ow ever, t h e
shape
of
th e
c u rv e
can
s m o o th in g p a r a m e t e r s .
trie
be
s lig h tly
in te rv a l
ta k e n
fro m
e s tim a tio n
a
and
th e
n o r m a lly
w as
u sed
by
c h o o s in g
d iffe re n t.
The a d v a n ta g e s o f d e n s i t y e s t i m a t i o n o v e r 'p a r a m e - .
fre q u e n c y h isto g ra m s i s
c la s s
a lte re d
th a t b ia s
t e c h n iq u e
d is trib u te d
b ecause
th e
is
does
n o t i n t r o d u c e d by c h o o s in g a
not
assum e t h a t
p o p u la tio n .
d a ta
th e
sam p le w as
F u rth e rm o re ,
d is trib u tio n
fo r
d e n s ity
each
of
th e
s a m p le s a p p e a r s t o b e a m ix tu r e o f s e v e r a l n o r m a lly d i s t r i b u t e d p o p u la ­
tio n s
( R ic h a r d R o s s i ,
1 9 8 9 , . p e r s o n a l com m .). T h is i s
a s i t u a t i o n w h ic h
d o e s n o t e a s i l y l e n d i t s e l f t o p a r a m e t r i c s t a t i s t i c a l a n a l y s i s . H ow ever,
c u rv e
fittin g
p a ra m e tric
p ro ce d u re s
e s tim a te s
p e r s o n a l comm.) .
a re
o f. t h e
c u rre n tly
d a ta
in . p ro g re ss
d is trib u tio n s
th a t
( R ic h a r d
w ill
a llo w
R o s s i,
1990,
35
RESULTS
d
O b s id ia n Sand P l a i n
R in d
s a m p lin g
m ea su rem e n t
d a ta ,
le v e ls
T e rra c e
fo r
e x c lu s iv e
TO
v a rie d
w ith
d e p th
in
an d
o rd e r to
to
d e fin e
z e ro
(A p p e n d ix
e s t i m a t i o n d ia g ra m s i n F i g u r e s 5 - 9 .
d e p th w e re m e a s u re d
of
D)
a re
H y d r a tio n r i n d s
d e te r m in e
an
rin d s ,
if
fo r
show n b y
d e n s ity
fro m e a c h s a m p lin g
h y d ra tio n
a p p ro p ria te
in d iv id u a l
d e p th
rin d
th ic k n e s s
fro m w h ic h
to
m e a s u re r i n d s i n t h e r e m a in d e r o f t h e s a m p lin g p i t s . The 20 t o 40 cm an d
40 t o 60 cm l e v e l s f o r T e r r a c e TO ( F i g s . 6 and 7 ) show t h e m o st r e g u l a r
p e a k i n t h e 0 t o 10 m ic r o n r a n g e a n d t h e r e f o r e t h i s r a n g e o f l e v e l s w as
u s e d i n a l l s u b s e q u e n t sa m p le m e a s u re m e n ts .
I t s h o u ld b e n o t e d t h a t a l l o f t h e d i f f e r e n t p i t l e v e l s e x c e p t t h e
80 t o 100 cm l e v e l show a s i m i l a r p a t t e r n o f d a t a d i s t r i b u t i o n
9 ).
(F ig s . 5 -
The d a t a f o r t h e u p p e r 80 cm o f t h e p i t s u g g e s t t h a t t h e h y d r a t i o n
r i n d s r e c o r d a t l e a s t t h r e e e v e n ts w i t h t h e y o u n g e s t c e n t e r e d a ro u n d 6 .5
m ic r o n s .
The d o m in a n t p e a k a t a b o u t 6 .5
m ic ro n s
f o r th e
80 t o
100 cm
d e p th i s much su b d u e d a n d t h e d i s t r i b u t i o n i n s t e a d d i s p l a y s s t r o n g p e a k s
a t a b o u t 14 a n d 22 m ic r o n s
(F ig .
9 ) . The a g g r e g a te d a t a f o r T e r r a c e TO
c l e a r l y show s a l l t h r e e p e a k s ( F i g . 1 0 ) .
R in d m e a su re m e n t d a t a ,
e x c l u s i v e o f z e r o r i n d s , fro m t h e 20 t o 60
cm d e p th f o r T e r r a c e s T l t o T4 a n d s u r f a c e s a m p le s f o r t h e m odern s tr e a m
(A p p e n d ix E) a r e show n b y d e n s i t y e s t i m a t i o n d ia g ra m s i n F i g u r e s 1 1 - 1 5 .
T h e se d e n s i t y d ia g r a m s show a s t r o n g p e a k c e n t e r e d a ro u n d 6 .5 m ic r o n s .
36
Terrace TO, O - 20 cm (n=32)
Q 0.05
Thickness of Rind (microns)
F i g u r e 5 - R in d m e a s u r e m e n t d a t a f o r T e r r a c e TO a t 0 - 20 cm d e p t h .
37
Terrace TO, 20 - 40 cm (n=31)
Thickness of Rind (microns)
F i g u r e 6 - R ind m e a s u r e m e n t d a t a f o r T e r r a c e TO a t 20 - 40 cm d e p t h .
38
Terrace TO, 40 - 60 cm (n=35)
O 0.05
Thickness of Rind (microns)
F i g u r e 7 - R ind m e a s u r e m e n t d a t a f o r T e r r a c e TO a t 40 - 6 0 cm d e p t h .
39
Terrace TO, 60 - 80 cm (n=33)
Thickness of Rind (microns)
F i g u r e 8 - R in d m e a s u re m e n t d a t a f o r T e r r a c e TO a t 60 - 80 cm d e p t h .
40
Terrace TO, 8 0 - 100 cm (n=27)
Thickness of Rind (microns)
F i g u r e 9 - R in d m e a s u r e m e n t d a t a f o r T e r r a c e TO a t 80 - 100 cm d e p t h .
41
Terrace TO, O - 1 0O cm (n=158)
Thickness of Rind (microns)
F i g u r e 10 - A g g r e g a t e r i n d m e a s u re m e n t d a t a f o r T e r r a c e TO.
42
TerraceH (n=78)
Thickness of Rind (microns)
F i g u r e 11 - R in d m e a s u r e m e n t d a t a f o r T e r r a c e T l .
43
Terrace T2 (n=76)
Thickness of Rind (microns)
F i g u r e 12 - R in d m e a s u r e m e n t d a t a f o r T e r r a c e T2.
44
Terrace T3 (n=60)
Thickness of Rind (microns)
F i g u r e 13 - R ind m e a s u re m e n t d a t a f o r T e r r a c e T 3 .
45
Density of Data
Terrace T4 (n=91)
Thickness of Rind (microns)
F i g u r e 14 - R in d m e a s u r e m e n t d a t a f o r T e r r a c e T4.
46
Modern Stream (n=58)
Q 0.05
Thickness of Rind (microns)
F i g u r e 15 - R ind m e a s u re m e n t d a t a f o r m odern s t r e a m .
47
H ow ever, t h e d i s t r i b u t i o n o f r i n d s t h i c k e r t h a n 6 ,5 m ic r o n s f o r T e r r a c e s
T l t o T4 a n d t h e m odern s tr e a m do n o t a p p e a r t o c o n s i s t e n t l y c l u s t e r .
Y e llo w s to n e L ake
R in d m e a su re m e n t d a t a , e x c l u s i v e o f z e r o r i n d s , f o r t h e f i v e r a i s e d
s h o re lin e s
(A p p e n d ix
F ig u re s 1 6 -2 0 .
6 .2
m ic r o n s .
common p o i n t s
F)
a re
shown b y
d e n s ity
e s tim a tio n
d ia g ra m s
in
E a c h o f t h e d ia g ra m s h a s a p r o m in e n t p e a k b e tw e e n 5 an d
R in d s
th ic k e r
fo r a ll
th a n
th is
do n o t a p p e a r t o
s h o re lin e s b u t a re d i s tr ib u te d
c lu s te r
a ro u n d
b e tw e e n a b o u t
10
a n d 30 m ic r o n s . B o th S h o r e l i n e s S3 a n d S4 ( F i g s . 18 a n d 19) a l s o show a
f a i r l y p r o m in e n t p e a k a t a b o u t 16 m ic r o n s . The u p p e rm o s t s h o r e l i n e ,
S5,
d i s p l a y s a p e a k a t a b o u t 21 m ic ro n s t h a t i s a s p r o m in e n t a s t h e p e a k a t
5 . 2 m ic r o n s ( F i g . 2 0 ) .
48
Shoreline SI (n=63)
Thickness of Rind (microns)
F i g u r e 16 - R in d m e a s u r e m e n t d a t a f o r S h o r e l i n e S I .
49
Shoreline S2 (n=84)
Q 0.05
Thickness of Rind (microns)
F i g u r e 17 - R in d m e a s u r e m e n t d a t a f o r S h o r e l i n e S2.
50
Shoreline S3 (n=80)
O 0.05
Thickness of Rind (microns)
F i g u r e 18 - R ind m e a s u re m e n t d a t a f o r S h o r e l i n e S3.
51
Shoreline S4 (n=62)
Thickness of Rind (microns)
F i g u r e 19 - R ind m e a s u r e m e n t d a t a f o r S h o r e l i n e S4.
52
Shoreline S5 (n=51)
Q 0.05 -
Thickness of Rind (microns)
F i g u r e 20 - R ind m e a s u re m e n t d a t a f o r s h o r e l i n e S5.
53
DISCUSSION
The o r i g i n a l p u r p o s e o f
th is
s tu d y w as t o
o b s id ia n h y d ra tio n d a tin g te c h n iq u e s ,
s h o re lin e s -
D u rin g th e
d e v is e
t o d a te f l u v i a l
c o u rse of t h i s
a m eth o d ,
te rra c e s
u s in g
and l a k e
s t u d y , much i n f o r m a t i o n h a s b e e n
r e v e a l e d a b o u t t h e o b s i d i a n h y d r a t i o n d a t i n g t e c h n i q u e i n g e n e r a l . T h is
in fo rm a tio n
g is ts
has
e m p l o y in g
i m p o r ta n t
th e
ra m ific a tio n s
te c h n iq u e
s e c tio n ,
th e
te c h n i q u e w i l l
te rra c e s
an d l a k e s h o r e s
firs t
in
fo r
th e ir
be
g e o lo g is ts
s tu d ie s .
d is c u s s e d
and t h e n a g e n e r a l
as
and
In
th e
a p p lie d
d is c u s s io n
a rc h a e o lo ­
of
fo llo w in g
to
th e
flu v ia l
o b s id ia n
h y d r a t i o n d a t i n g te c h n i q u e w i l l f o l l o w .
O b s id ia n Sand P l a i n
S o la r I n s o l a ti o n
F rie d m a n
w ill
and L ong
(1976)
h y d r a t e much m ore r a p i d l y
fo u n d
th a t
th a n b u r ie d
o b s id ia n
ex p osed
o b s id ia n .
In
to
th e ir
th e
sun
e x p e ri­
m en ts n e a r W est Y e llo w s to n e , MT, th e y d e te r m in e d t h a t o b s i d i a n from t h e
O b s id ia n C l i f f flo w r e a c h e d a t e m p e r a t u r e o f 1 9 .7 °C i n d i r e c t s u n l i g h t
w h ic h c o r r e s p o n d s
to
a h y d ra tio n
ra te
o f 1 6 .0 m ic r o n s 2/ 1000 y r s .
S o il
t e m p e r a t u r e a t a d e p th o f 0 .9 m a v e r a g e d 6 .9 °C, w h ic h c o r r e s p o n d s t o a
h y d r a t i o n r a t e o f 3 . 4 m ic r o n s 2/1 0 0 0 y r s . The d i s p a r i t y b e tw e e n t h e s e tw o .
r a t e s i s v e r y s i g n i f i c a n t w i t h r e g a r d t o s a m p lin g d e p th .
I t w ould a p p e a r
from t h e s tu d y o f F rie d m a n and Long (1 9 7 6 ) t h a t t o e s c a p e t h e e f f e c t s o f
s o la r h e a tin g ,
su rfa c e .
s a m p le s s h o u ld o n ly b e c o l l e c t e d a t some d e p th below t h e
54
The d a t a from T e r r a c e TO ( F i g s . 5 - 9 ) show t h a t t h e r e i s no a p p a r e n t
in c re a s e
th a t
in
r in d
e ffe c ts
th ic k n e s s
of
e x p e c te d t h a t
s o la r
in
th e
h e a tin g
u p p e r few
a re
d e c im e t e r s w h ic h
n e g lig ib le
t h e r e w o u ld b e an i n c r e a s e
in
at
rin d
th is
im p lie s
s ite .
th ic k n e s s
It
w as
to w a rd
th e
s u r f a c e , b u t t h i s i s n o t p o r t r a y e d by t h e d a t a . One p o s s i b l e e x p l a n a t i o n
is
th a t b io tu rb a tio n
th e re b y
fo rm
n u llify in g
of ro o t
th a t,
th ro w
because
th is
c o u ld h av e t h e
th e
e f f e c t o f m ix in g t h e s u r f a c e l a y e r
s o la r h e a tin g
or
g ro u n d
s ite
is
s ig n a l.
s q u irre l
c o v e re d
B i o t u r b a t i o n may t a k e
b u r ro w in g .
by
snow
fo r
It
is
a ls o
a la rg e
th e
p o s s ib le
p a r t of
each
y e a r , s o l a r h e a t i n g d o e s n o t h a v e a n e f f e c t on t h e h y d r a t i o n r a t e .
R ew orking P r o c e s s e s
R e w o r k in g
in
th e
flu v ia l
e n v iro n m e n t
is
p r o b a b ly
d o m in a te d
by
f r a c t u r i n g a s o p p o s e d t o a b r a s i o n . T b e n h o fe l ( 1 9 4 5 ), i n h i s s tu d y o f t h e
ro u n d in g
of
sand
g r a v e l and s a n d ,
sand g ra in s
th ro u g h
th e
re p o rte d
th a t
s ta te d
th a t
th e sand p a r t i c l e s
a re re p e a te d ly
u n r e a s o n a b le t o
tra n s p o rt.
g ra in s ,
fra c tu re d
p ro ce sse s
s tr e a m
T h is
g ra v e ls
im p lie s
th a t
of
s e d im e n t
by im p a c t and g r i n d i n g .
s iz e
p a rtic le s
re w o rk in g .
re ta in
if
s tr e a m
c o n ta in s
do n o t becom e r o u n d e d . I n s t e a d ,
su g g e st th a t g rav el
sam e
when
much o f
r e w o rk in g
a ls o
D o b k in s
th e ir
d o es
th e
I t is not
re m a in a n g u l a r
and
F o lk
a n g u la rity
occur
in
th e
(1970)
d u rin g
f lu v ia l
e n v ir o n m e n t, t h e n t h e d o m in a n t p r o c e s s i s p r o b a b ly f r a c t u r i n g a s o p p o s e d
to
a b ra s io n ,
c la s ts
w h ic h w o u ld te n d
to
th e
ro u n d n ess
of
in d iv id u a l
(D o b k in s an d F o lk , 1 9 7 0 ).
When e x a m in in g h a n d s p e c im e n s
p e b b le s
in c re a s e
have
a b ra s io n ,
s lig h tly
but
fro s te d
g e n e ra lly
th e
from
c o rn e rs,
o b s id ia n
t h e OSP,
w h ic h
some o f
p r o b a b ly
g ra in s
a re
th e
o b s id ia n
re s u lte d
v e ry
a n g u la r
from
and
55
i r r e g u l a r i n s h a p e . When e x a m in in g t h e s e p e b b le s w i t h a m ic r o s c o p e , some
o f t h e c o r n e r s a p p e a r a b r a d e d , b u t o v e r a l l t h e e d g e s o f t h e p e b b le s a r e
g e n e ra lly
a b ra d e d
sm o o th .
No r i n d s
because
th e
w e re
rin d s
in
m ea su red
th e s e
t h i c k n e s s e s a lo n g t h e a b r a d e d e d g e .
on
a re a s
In s te a d ,
c o rn e rs
d id
not
th a t
a p p e are d
have
c o n s is te n t
a l l r i n d s w e re m e a s u re d on
sm ooth e d g e s . A sm o o th edge w o u ld b e e x p e c te d t o be c r e a t e d th r o u g h t h e
c o n c h o id a l
o b s id ia n
fra c tu re
of
p e b b le s w e a r
o b s id ia n .
in
th e
The ab o v e
flu v ia l
o b s e rv a tio n s
in d ic a te
e n v iro n m e n t m a in ly by
th a t
f ra c tu rin g
and h y d r a t i o n r i n d s w e re m e a s u re d o n ly on f r a c t u r e s u r f a c e s .
The m odern s tr e a m
th a n
th e
h ig h e r
r e w o rk in g i s
c o n t a i n s s i g n i f i c a n t l y m ore z e r o t h i c k n e s s r i n d s
te rra c e s
(T a b le s
an e f f e c ti v e
3
agent in
and
th e
o th e r
su rfa c e s
(T a b le
w h ic h
r e s e ttin g
The m odern s tr e a m p o s s e s s e s a b o u t 20 t o
th a n
4)
im p lie s
rin d s
th a t
flu v ia l
on o b s i d i a n g r a i n s .
60 % m ore z e r o t h i c k n e s s
3)
w h ic h
in d ic a te s
th a t
rin d s
re w o rk in g
p r o c e s s e s a r e e f f e c t i v e on a b o u t 20 t o 60 % o f th e g r a i n s . The p r o c e s s e s
th a t
p ro d u c e z e r o
p ro b a b ly
th ic k n e s s
re fle c t
in
s itu
rin d s
on T e r r a c e s T l t o T4 (T a b le 3 ) m o st
fra c tu rin g ,
s a m p lin g
te c h n iq u e
and
sa m p le
p re p a ra tio n .
G r a in s a r e o n ly p a r t i a l l y
re w o rk e d i n t h e f l u v i a l e n v iro n m e n t w h ic h
i m p l i e s t h a t e a c h g r a i n can p o t e n t i a l l y
r e c o r d m u l t i p l e e v e n t s . T h is i s
e v id e n c e d by m u l t i p l e
fo r
and m u l t i p l e
s tu d y
and
in c lu d e s
v a rio u s
rin d
fac t
th ic k n e s s
th ic k n e s s e s
t h i c k n e s s e s on i n d i v i d u a l
re p o rte d
th e
rin d
by
P ie rc e
and
th a t
g ra in s
in
in
a d d itio n
c o m p le te r e w o rk in g o c c u r s i n
o th e rs
th e
to z e ro
th e
each p i t
(F ig s .
5 -9 )
g r a in s a s o b se rv e d in
th is
( 1 9 7 6 ).
m odern
A d d itio n a l
s tr e a m
th ic k n e s s
le v e l
rin d s
f l u v i a l e n v ir o n m e n t,
possess
e v id e n c e
rin d s
of
(A p p en d ix E ) . I f
th e re
s h o u ld n o t
56
be
any
m e a s u r a b le
fere n c e ,
g rav e l
rin d s
from
an
p rese n t
on m odern
in d iv id u a l
s tr e a m
g rav e l
s h o u ld
o n ly
te rra c e
and
by
possess
in ­
rin d s
t h a t d a t e fro m a s i n g l e e v e n t. B o th o f t h e s e s i t u a t i o n s a r e c l e a r l y n o t
th e c a se .
D ep th o f R ew o rk in g
T h e re w as no v i s i b l e s t r a t i g r a p h y
th e d a t a fro m t h e 80 t o 100 cm d e p th
a b o u t 6 .5
m ic r o n s and i n s t e a d
22 m ic r o n s , r e s p e c t i v e l y .
ag e f o r
firs t
th is
m a te ria l
h y p o th e s is
re w o rk in g by
is
i n t h e p i t on T e r r a c e TO6 h o w ev er
( F ig .
9) l a c k t h e d o m in a n t p e a k a t
show two p ro m in e n t p e a k s a t a b o u t 13 and
T h e se d a t a a r e n o t c o m p a tib le w i t h a P i n e d a l e
and c a n be i n t e r p r e t e d i n a t l e a s t two w a y s. The
th a t
a P in e d a le
th e
ag e
80 cm d e p th
s tr e a m .
re p re s e n ts
T h is i m p l i e s
maximum d e p th , o f
t h a t t h e b u lk o f
th e
d e p o s i t d a t e s fro m an e a r l i e r d e p o s i t i o n a l e v e n t a n d P i n e d a l e r e w o r k in g
o n ly a f f e c t e d th e . u p p e r 80 cm o f t h e OSP a t t h i s l o c a t i o n .
The s e c o n d h y p o t h e s i s i s
th a t
t h e am ount o f m a t e r i a l ab o v e t h e
80
cm d e p th r e p r e s e n t s P i n e d a l e a g g r a d a t i o n . T h is h y p o t h e s i s i s g e n e t i c a l l y
s im ila r to
a s p e c t.
th e f i r s t
B o th
h y p o th e s is
h y p o th e s e s
c a ll
but
fo r
d iffe rs
in
a t le a s t
o n e i m p o r ta n t
some P in e d a l e - a g e m echanism
g r a i n s i n t h e u p p e r 80 cm o f t h e d e p o s i t , how ever one c a l l s
re w o rk in g w h e re
w i t h P i e r c e 's
th e
second c a l l s
fo r
a g g ra d a tio n ,
to
re se t
fo r flu v ia l
w h ic h i s
c o m p a tib le
(1 9 7 9 ) o u t b u r s t f l o o d h y p o t h e s i s .
The a u th o r p r o p o s e s t h a t t h e OSP d o e s n o t d a te from one p a r t i c u l a r
e p is o d e
of
d e p o s itio n ,
u n d e rg o n e a t l e a s t
but
in s te a d
tw o p e r i o d s
is
a
c o m p o s ite
of d e p o s itio n .
d e p o s it
1953;
W itk in d ,
1 9 6 9 ).
H y d r a tio n
rin d s
has
The e a r l i e r m a jo r p e r i o d
o f d e p o s i t i o n p o s t d a t e s t h e r e c e s s i o n o f B u l l L ake i c e fro m
(A ld e n ,
th a t
from
th e
H o rse B u t t e
80
to
100
cm
57
d e p th
( F ig .
in d ic a te s
9)
d is p la y
th a t th is
th e
y o ungest
le v e l la rg e ly
peak
at
about
13 m ic r o n s
w h ic h
d a t e s from B u l l L ake tim e ( F ig . 2 1 ) .
H ow ever, h y d r a t i o n r i n d s on g r a v e l c o l l e c t e d a t
d e p th s
fro m 2 t o
12 m
b e lo w t h e s u r f a c e o f t h e OSP i n o t h e r l o c a t i o n s d a t e from P i n e d a l e tim e
(P ie rc e ,
.1 9 7 9 ).
T h is
in d ic a te s
h i s t o r y o f t h e OSP i s
in
th e
th a t
th e
d e p o s itio n a l
and
e ro s io n a l
com plex a n d t h a t t h e r e may b e l a r g e p a l e o - c h a n n e l s
OSP t h a t w e re
e ro d e d
in
p re -P in e d a le
tim e
and
fille d
d u rin g
P in e d a le a g g ra d a tio n .
O n ly
lo c a tio n
about
of
80
cm
of
s a m p lin g p i t
d e p o s itio n
c o u ld
have
(R ichm ond,
1964)
o r fro m
s e d im e n t was
TO d u r in g
been
in
th e
g la c ia l
a g g ra d e d
or
P in e d a le
tim e .
form
s h a llo w
of
o u tb u rs t
flo o d s
re w o rk e d
at
th e
As m e n tio n e d a b o v e ,
a g g r a d in g
(P ie rc e ,
s tr e a m s
1 9 7 9 ).
From
e v id e n c e p r e s e n t e d b e lo w , a d v a n c in g an d f u l l P i n e d a l e i c e c o n d i t i o n s a r e
c h a r a c t e r i z e d by a g g r a d a t i o n w h e re a s P i n e d a l e r e c e s s i o n i s
c h a ra c te riz e d
by e r o s i o n and t e r r a c e f o r m a ti o n . I t m u st be e m p h a s iz e d t h a t t h i s m u l t i ­
a g e OSP i n t e r p r e t a t i o n i s b a s e d on one s i t e
o n ly b u t i s
c o m p a tib le w i t h
e v id e n c e p r e s e n t e d by A ld e n ( 1 9 5 3 ), Richm ond ( 1 9 6 4 ) , W itk in d (1969) an d
P i e r c e ( 1 9 7 9 ).
It
is
d iffic u lt
to
re c o n c ile
th e
d is p a rity
b e tw e e n
a g g ra d a tio n
d u r in g B u l l L ake r e c e s s i o n a s p o s t u l a t e d by W itk in d (1 9 6 9 ) b u t dow ncut­
t i n g d u r in g P i n e d a l e r e c e s s i o n . H ow ever,
t h e g l a c i a l re g im e o f e a c h i c e
m ass w as v e r y
g la c ie r
d iffe re n t.
W est Y e llo w s to n e B a s in t o
The B u l l L ake
th e p o s i t i o n
e x te n d e d
out
in to
th e
o f H o rse B u t t e w h e re a s P i n e d a l e
i c e j u s t e x i t e d t h e m outh o f M adison Canyon ( F ig .
I).
The g r a d i e n t fro m
t h e m outh o f M a d iso n Canyon t o H o rse B u t t e b e g in s a t a b o u t 1 ° b u t so o n
le s s e n s
to
about
0 .1 °
(P ie rc e ,
1 9 7 9 ).
The g r a d i e n t
of
th e
su rfa c e
is
58
v e r y lo w , b u t p r o b a b l y d o e s n o t
B u l l L ake
ic e
moved a c r o s s .
re fle c t
Richm ond
th e
(19 6 4 )
r a n g e s i n d e p th fro m 12 t o 30 m a n d r e s t s
pounded by
th e
B u l l L ake m o r a i n e s .
la c u s trin e
d e p o s its ,
th e
g ra d ie n t
o rig in a l
re p o rte d
th a t
on l a c u s t r i n e
D e p e n d in g
of
su rfa c e
th e
on t h e
su rfa c e
th a t
th e
th e
g rav e l
s e d im e n ts
th ic k n e s s
im­
o f th e
may h a v e b e e n
much
s te e p e r.
The g l a c i e r
d y n a m ic s
o f B u l l L ak e i c e
a re
fu rth e r d iffe re n tia te d
fro m P i n e d a l e g l a c i e r d y n a m ic s b e c a u s e t h e W est Y e llo w s to n e flo w w as n o t
e m p la c e d u n t i l a t l e a s t l a t e
B u l l L ak e tim e
( P ie r c e and o t h e r s , 1 9 7 6 ).
P ie rc e
B u ll
moved
(1 9 7 6 )
lo w s to n e
re p o rte d
B a s in
fro m
th a t
th e
L ake
s o u th e a s t
o c c u p ie d b y t h e W est Y e llo w s to n e
ic e
th r o u g h
f lo w .
a
in to
th e
15 km gap
P in e d a le
ic e
W est
th a t
Y e l­
is
now
advanced in to
th e
b a s i n fro m t h e n o r t h e a s t an d o r i g i n a t e d a t t h e i c e d i v i d e l o c a t e d i n t h e
v ic in ity
w h ile
o f O b s id ia n C l i f f .
B u ll
L ake
ic e
If
t h e W est Y e llo w s to n e
w as p r e s e n t ,
it
is
lik e ly
th a t
f lo w was e m p la c e d
th e re
w e re
la rg e
j o k u l h l a u p s i n t h e b a s i n d u r in g t h i s t i m e . The W est Y e llo w s to n e f lo w h a s
b e e n K -A r d a t e d
th a t
1975;
it
w as
at
e ru p te d
P ie rc e ,
1975;
117 +_ 8 k a a n d h a s c o n c a v e em baym ents t h a t s u g g e s t
a g a in s t
P ie rc e
ic e
(W a ld ro p ,
and o t h e r s ,
1976;
1975;
W a ld ro p
R ichm ond,
and
P ie rc e ,
19 7 6 b ;
P ie rc e ,
1 9 7 9 ) . The e r u p t i o n o f l a v a i n c o n t a c t w i t h t h e i c e c o u ld h a v e p r o v id e d
a m echanism f o r m e l t i n g a n d f l o o d s
i n t h e W est Y e llo w s to n e B a s in w h ic h
may h a v e c o n t r i b u t e d t o t h e d e p o s i t i o n o f t h e OSP d u r i n g l a t e B u ll L ake
tim e .
Age o f T e r r a c e s
T h e re i s no a p p a r e n t d i f f e r e n c e b e tw e e n t h e p o s i t i o n o f t h e y o u n g ­
e s t p e a k fro m T e r r a c e s TO t h r o u g h T4 ( F i g s . 1 0 - 1 4 ) , i n d i c a t i n g t h a t t h e
59
t e r r a c e s w e re
cu t in
a s h o rte r
p e rio d
of
tim e
th a n
th e
t e c h n i q u e ;can
d i s c e r n . E ach s u r f a c e h a s a l a r g e p e a k ( F i g s . 10—14) c e n t e r e d a ro u n d 6 .5
m ic r o n s w i t h
p r o b a b ly
a ran g e
re fle c t
o rig in a lly
o n g o in g
fro m 6 t o
m u lti- m o d a l
7 m ic r o n s .
d is trib u tio n s ,
n o t u s e d t o make i n f e r e n c e s
a n a ly s e s
by
R ossi
(1 9 9 0 ,
B e c a u se
d a ta
p a ra m e tric
a b o u t th e
p e rso n a l
th e
s e ts
m o st
s ta tis tic s
w e re
p o p u la tio n s .
comm.)
s h p u ld
H ow ever,
p r o v id e
m ore
r e l i a b l e e s t i m a t e s o f t h e c e n t e r o f t h e p e a k s an d t h e s t a n d a r d e r r o r o f
th e s e
e s t i m a t e s by m eans o f p a r a m e t r i c
th e c e n te r
c u rv e f i t t i n g .
F or th e p r e s e n t,
(mode) o f t h e l a r g e p e a k f o r e a c h t e r r a c e l e v e l
is
th e b e s t
m e a s u re o f r i n d t h i c k n e s s .
The
firs t
m e th o d
u sed
to
o b ta in
a
d a te
fo r
th e
te rra c e s
a p p l i c a t i o n t o th e c a l i b r a t i o n c u rv e fro m P i e r c e a n d o t h e r s
21)
o f an h y d r a t i o n v a l u e
th a n
P in e d a le
m o rp h o lo g y t o
a r e y o u n g e r t h a n f u l l P i n e d a l e m o ra in e s
d e g la c ia l
d a te th e
minimum 1ZhC d a t e
young,
( F ig .
o f 6 .5 + 0 .5 m ic r o n s , w h ic h y i e l d s an ag e o f
2 0 ,0 0 0 + 3 , 0 0 0 y r . T h is age a g r e e s w i t h P i e r c e and o t h e r s
th e t e r r a c e s
(1976)
w as
d e p o s its
("1 2
ka) .
N ash
t e r r a c e s by c a l i b r a t i n g
( tM30. k a ) b u t o l d e r
(1 9 8 4 )
th e
o f 7 ,1 0 0 + 50 y r f o r T e r r a c e T4.
(1976) i n t h a t
used
sc arp
te c h n i q u e a g a i n s t a
If
t h i s , d a te i s
to o .
t h e d a t e s o b t a i n e d from t h e u p p e r s c a r p s w i l l a l s o be to o y o u n g .
F ig u r e 22 shows t h e a g e s N ash (1 9 8 4 )
d e riv e d f o r th e
te rra c e s
com pared
t o a g e s f o r t h e t e r r a c e s d e r i v e d by t h e f i r s t m ethod i n t h i s s e c t i o n . As
can
be
because
seen
N ash
from
th is
(1 9 8 4 )
c o m p a ris o n ,
e s tim a te d
m o st
of
t h a t ■t h e
th e
ages
te rra c e s
do
a re
not
o v e rla p
s ig n ific a n tly
y o u n g e r th a n e s t i m a t e s from t h i s s tu d y .
A seco n d
m eth o d
used
to
o b ta in
an
age
fo r
th e
f o r m a ti o n
of
th e
t e r r a c e s w as t o u s e h y d r a t i o n r a t e c o n s t a n t s c a l c u l a t e d f o r t h e O b s id ia n
60
P in ed ale deglacia
d ep o sits
M a d iso n R iver
te r ra c e s (P e a k 2)
M a d iso n R iver
t e r r a c e s ( P e a k 1)
P in e d a le term inal m o ra in e s
W e s t Y e llo w s to n e flow
• =
R a n g e of m o d a l
values ( th i s s t u d y )
I=
± 1 S.D. ( f r o m P i e r c e
and others, 1976)
Bull L a k e t e r m i n a l m o r a i n e s
I
5
6
7
l
l
8
i
9
10
11
12
13
14
15
16
Rind thickness (microns)
F i g u r e 21 - H y d r a tio n c a l i b r a t i o n c u rv e sh o w in g a g e s o f M adison R iv e r
t e r r a c e s and an i n t e r p r e t e d o l d e r e v e n t (h eav y l i n e s , t h i s s tu d y ) i n
r e l a t i o n t o g l a c i a l d e p o s i t s i n t h e W est Y e llo w s to n e a r e a ( a f t e r P i e r c e
and o t h e r s , 1 9 7 6 ) .
61
CORRELATIONS
P in ed ale terminal
moraines
I- - - - - - - - —
■
I
T e r r a c e TO
Tl
fimtmmimn]
T2
|iu u iu u u m n
T3
T4
fm rom m nfl
I
EXPLANATION
illliilS
▼ This s tu d y
P inedale deglacial
deposits
Nash (1984)
Modern stream I
Pierce and others (1976)
G
10
20
30
40
A G E ( I O1 y e a r s )
F ig u r e 22 - C o r r e l a t i o n c h a r t s h o w in g a g e s
g e o lo g i c f e a t u r e s i n t h e W est Y e llo w s to n e a r e a .
of
s e le c te d
su rf ic ia l
62
C liff
flo w
( M ic h e ls 9 1985) t o g e t h e r w i t h an e s t i m a t e d
e ffe c tiv e
h y d ra­
t i o n t e m p e r a t u r e (EH T). T h is m eth o d a ssu m e s t h a t t h e o b s i d i a n i n t h e OSP
is
e ith e r
th e
d e r i v e d fro m
same r a t e .
t h e O b s id ia n
C liff
F rie d m a n and O b ra d o v ic h
flo w o r h y d r a t e s
(1981)
at
e x a m in ed e i g h t
r o u g h ly
o b s id ia n
flo w s i n Y e llo w s to n e N a t io n a l P a rk a n d fo u n d t h a t a l l o f th e flo w s w e re
c h e m ic a lly
s im ila r
to
th e
O b s id ia n
C liff
flo w .
T h e r e f o r e 9 th e y
p o s tu ­
l a t e d t h a t t h e r e w as no d i f f e r e n c e i n h y d r a t i o n r a t e among t h e f lo w s .
P ie rc e
and o t h e r s
(1976)
re p o rte d
t h a t m ost o f t h e m a t e r i a l i n t h e OSP
was p r o b a b ly d e r i v e d fro m t h e W est Y e llo w s to n e f lo w , w h ic h w as i n c l u d e d
i n t h e a n a l y s i s by F rie d m a n and O b ra d o v ic h ( 1 9 8 1 ).
The A r r h e n iu s e q u a t i o n u s e d by M ic h e ls
(1985)
to
re la te
h y d ra tio n
r a t e t o t e m p e r a t u r e i s t h e same a s t h a t u s e d by F rie d m a n and Long (19 7 6 )
and l i s t e d
e a r lie r in th is
th e s is .
The w o rk in g v e r s i o n o f t h i s e q u a t i o n
f o r t h e O b s id ia n C l i f f flo w t a k e s t h e fo rm :
k ' = 7 .0 5 e x p [7 7 5 9 6 /8 .3 1 7
( 1 /4 7 3 .1 6 - 1 / T 1) ]
w h e re k ' i s an unknown ( h y d r a t i o n r a t e a t T 1) an d T 1 i s e q u a l t o t h e EHT
in K f o r th e s i t e
t o be d a te d . To c o n v e r t t h e EHT from °C t o K use.:
Te (K) = Te ( 0 C) + 2 7 3 .1 6
The e q u a ti o n t h a t c o n v e r t s t h e r a t e c o n s t a n t s t o t h e h y d r a t i o n r a t e i s :
k ' ( 3 6 5 .2 6 ) ( 1 0 0 0 ) = r a t e e x p r e s s e d a s m ic r o n s ^ /1 0 0 0 y e a r s
F rie d m a n a n d O b ra d o v ic h
(1 9 8 1 )
e s tim a te d
th a t
th e
p rese n t
EHT on
t h e W est Y e llo w s to n e flo w i s 3 .0 °C a n d t h e EHT d u r in g g l a c i a l tim e s w as
0
°C.
(1976)
T h is
is
o f 3 .9
e le v a tio n
som ew hat d i f f e r e n t
°C ( p r e s e n t day) a n d - 2 . 1
d iffe re n c e
s ta n d a rd v a lu e
th a n
o f 0 .5
b e tw e e n
th e
e s t i m a t e s by P i e r c e
°C ( g l a c i a l ) .
OSP a n d
and o t h e r s
To a d j u s t f o r t h e
th e W est Y e llo w s to n e
flo w
a
°C w as ad d e d t o a l l e s t i m a t e s o f EHT. P i e r c e and
63
o th e rs
to
(1 9 7 6 ) c o n s i d e r e d p o s t g l a c i a l EHT1s t o h a v e b e e n i n e f f e c t fro m 0
11 k a and g l a c i a l EHT1s t o h a v e b e e n i n e f f e c t from 11 t o 75 k a and
127 t o
170 k a . The t e r r a c e s
a re
th o u g h t t o be post-m axim um P i n e d a l e i n
ag e (< 20 k a ) , s o g l a c i a l EHT1s h a v e b e e n o p e r a t i n g f o r ro u g h ly h a l f t h e
tim e a n d p o s t g l a c i a l EHT' s h a v e b e e n i n e f f e c t f o r t h e r e m a in d e r o f t h e
tim e
fo r
th is
is
th is
s ite .
In th is
an a v e ra g e
e le v a tio n
th o u g h t
of
d iffe re n c e )
to
rep re sen t
s tu d y
p rese n t
as
a n EHT o f 1 .4
and
e s tim a te d
g la c ia l
te m p e ra tu re
by P i e r c e
an i n te g r a t e d
°C w as c h o s e n b e c a u s e
e s tim a te
and o t h e r s
of
(+ 0 .5
0C fo r
(19 7 6 )
and i s
te m p e r a tu r e s , o p e r a t i n g
from l a t e P i n e d a l e t o t h e p r e s e n t .
An EHT o f 1 .4 0 C c o u p le d w i t h an h y d r a t i o n r i n d t h i c k n e s s o f 6 .5 +
0 .5 m ic r o n s y i e l d s
te rra c e s .
T h is
a n a g e o f 1 5 ,5 2 0
ag e
is
le s s
th a n
+2480 -2 3 0 0 y e a r s
th a t
c a lc u la te d
fo r
fo r
th e
flu v ia l
th e
te rra c e s
by
m eans o f t h e c a l i b r a t i o n c u rv e ( F ig . 2 1 ) , b u t i s i n th e same r a n g e .
It
is
h y p o th e s iz e d
h e re
th a t
te rra c e
c u ttin g
m e d i a te l y upon r e t r e a t o f f u l l P i n e d a l e i c e .
not
u n r e a s o n a b le
in
d e te r m in e d t h a t r a t e s
an ic e
fro n t.
ra p id ,
but
lig h t
of
w ork
tim e s
of
s lo w e r
in itia te d
im­
R a p id t e r r a c e f o r m a tio n i s
Thompson
and J o n e s
o f i n c i s i o n w e re a s s o c i a t e d w i t h
D u rin g tim e s o f r a p i d
d u r in g
by
w as
g la c ia l
re tre a t,
g la c ia l
re tre a t
(1986)
th e p o s itio n
who
of
i n c i s i o n w as a l s o
or
s till
s ta n d s ,
i n c i s i o n w as s lo w e r o r a g g r a d a t i o n o c c u r r e d .
Y e llo w s to n e L ake
R ew orking P r o c e s s e s
R ew orking i n
t h e b e a c h e n v iro n m e n t i s
G rogan (1 9 4 5 ) s t u d i e d
la rg e ly
th e sh ap es of r h y o l i t e
c a u s e d by a b r a s i o n .
g r a v e l on a L ake S u p e r i o r
64
beach
and
fo u n d
th a t
ro u n d n ess
in c re a s e d
w h i l e t h e o v e r a l l s i z e ch a n g ed v e r y l i t t l e .
away
fro m
th e
so u rc e
a re a ,
T h is i n d i c a t e s t h a t f r a c t u r ­
i n g was p r o b a b ly n o t a n a c t i v e p r o c e s s on t h i s b e a c h , b e c a u s e f r a c t u r i n g
w o u ld t e n d
tim e
to
in c re a s e
d e c re a s in g
ro u n d in g
to
th e
th e
s iz e .
tra c tio n
s tu d ie d is o tr o p ic
a n g u la rity
G rogan
tra n s p o rt
o f th e g ra v e l w h ile a t th e
(1 9 4 5 )
a ttrib u te d
a lo n g
th e
beach
same
th e . in c r e a s e
fac e .
Sames
in
(1 9 6 6 )
( c h e r t a n d q u a r t z i t e ) p e b b le a s s o c i a t i o n s t o d e te r m in e
i f l i t t o r a l and f l u v i a l e n v ir o n m e n ts c o u ld be d i s t i n g u i s h e d on t h e b a s i s
o f r o u n d n e s s an d a n g u l a r i t y . He fo u n d t h a t b o th e n v ir o n m e n ts show a f a i r
d e g re e
of
ro u n d n ess,
but
th e
flu v ia l
p e b b le
a s s o c ia tio n s
had
h i g h e r p e r c e n ta g e o f a n g u la r co m p o n en ts and a w id e r v a r i e t y
D o b k in s
and F o lk
s tr e a m s
and b e a c h e s .
tiv e ly
(1970)
a ls o
s tu d ie d
th e
They fo u n d t h a t ,
r e w o rk in g
w h ile
c o n s t a n t d u r in g s tr e a m t r a n s p o r t a t i o n ,
much
of sh a p es.
p ro cesses
a n g u la rity
a
of
b o th
re m a in e d r e l a ­
a s ig n if ic a n t in c re a s e
in
r o u n d in g o c c u r r e d i n th e b e a c h e n v ir o n m e n t w h ic h w as a l s o a t t r i b u t e d t o
tra c tio n
t r a n s p o r t on t h e b e a c h f a c e .
From t h e a b o v e s t u d i e s ,
i t c a n be
c o n c lu d e d t h a t f l u v i a l p e b b le s a r e re w o rk e d by a c o m b in a tio n o f a b r a s i o n
and f r a c t u r i n g ,
w h e re a s b e a c h p e b b le s a r e
T h is
has
c o n c lu s i o n
im p o r ta n t
re w o rk e d m a in ly by a b r a s i o n .
ra m ific a tio n s
fo r
th is
s tu d y
b ecause
h y d r a t i o n r i n d s w e re m e a s u re d o n ly on f r a c t u r e d s u r f a c e s and c o n s e q u e n t­
l y r e w o rk in g p r o c e s s e s on t h e s h o r e l i n e s
sa m p le m e a su re m e n t
rep re sen t
te c h n iq u e .
s m a ll-s c a le
H ow ever,
fra c tu rin g ,
some
a r e n o t w e l l r e f l e c t e d by t h e
because
a b ra s io n
of
rin d s
th e
s h o r e l i n e s c o u ld d a t e from t h e tim e o f b e a c h a b r a s i o n .
is
th o u g h t
m e a s u re d
on
to
th e
65
Age o f S h o r e l i n e s
T he
rin d
m e a su re m e n t
d a ta
fo r
a ll
s h o re lin e s
(S 1 -S 5 )
d isp la y
a
p ro m in e n t p e a k t h a t r a n g e s from 5 .0 t o 6 .2 m ic ro n s ( F i g s . 1 6 - 2 0 ) . At t h e
o u t s e t of t h e s tu d y i t w as h y p o t h e s i z e d t h a t e a c h s h o r e l i n e h a s a u n iq u e
te m p o r a l
from
s ig n a l
th a t
case.
th a t
is
p a rtic u la r
In s te a d ,
a ll
re fle c te d
su rfa c e .
of
th e
by t h e
H ow ever,
s h o re lin e s
th ic k n e s s
th is
of
h y d ra tio n
rin d s
d o e s n o t a p p e a r t o be t h e
a re v e ry
s im ila r w ith
reg a rd
to
h y d r a t i o n r i n d t h i c k n e s s e s . As w i t h t h e f l u v i a l t e r r a c e s , w h ic h a l s o h ad
v e ry s im ila r (b u t th ic k e r ) r in d th ic k n e s s e s , i t
th e
s h o re lin e s
w e re
fo rm ed
in
a m ore
ra p id
te c h n iq u e
can d is c e r n .
T h is may be t r u e ,
th e
s ig n a l
a ll
rin d
fo r
of
th e
can be h y p o th e s iz e d t h a t
p e rio d
b u t th e
s h o re lin e s
of
tim e
th a n
a u th o r b e lie v e s
is
in h e rite d
from
th e
th a t
some
p r e v i o u s g e o lo g i c e v e n t a n d i s n o t a s s o c i a t e d w i t h t h e f o r m a ti o n o f t h e
s h o re lin e s .
o f 5 .5
As w i t h
m ic r o n s w as
th e te r r a c e s ,
chosen to
a som ew hat a r b i t r a r y
re p re se n t
th e
s h o re lin e s
h y d ra tio n v a lu e
p e n d in g f u r t h e r
s t a t i s t i c a l a n a l y s e s by R o s s i (1 9 9 0 , p e r s o n a l com m .).
The s h o r e l i n e s s t u d i e d a t Y e llo w s to n e L ake a r e n o t o l d e r th a n a b o u t
1 4 .5 k a an d a r e
p r o b a b ly
younger
th a n
12 k a .
L a c u s tr in e
and
a llu v ia l
d e p o s i t s i n t h e Y e llo w s to n e L ake B a s in , h a v e , y i e l d e d , ^ C a g e s o f 1 4 ,3 6 0 +
400
( W a d d in g to n
1 4 ,1 3 0 + 370
1 9 7 6 b ).
ic e
fre e
a n d W rig h t,
( K e lle y
1 9 7 4 ),
and o t h e r s ,
1 4 ,4 9 0
1978)
(R ichm ond,
1 9 7 6 b ),
and 1 3 ,6 5 0 + 650 BP (R ichm ond,
Richm ond (1 9 7 6 a ) e s t i m a t e s t h a t Y e llo w s to n e L ake, w as c o m p le te ly
by a b o u t
12 k a .
At t h r e e l o c a l i t i e s
P eak a s h h a s b e e n i d e n t i f i e d
(R ichm ond,
d a te d
(M e h rin g e r
at
+ 350
1 1 .2
ka
in
M ontana
(1 9 7 6 a ) r e p o r t e d a maximum
a ro u n d t h e l a k e .
1 9 7 6 a ).
and
T h is
o th e rs ,
G la c ie r
a s h h a s been,
1984) .
R ic h m o n d
d a t e o f 9060 + 300 y e a r s a s s o c i a t e d w i t h
66
a n 18—20 m s h o r e l i n e w h ic h he c o n s id e r e d
to
be t h e
firs t
s h o re lin e
to
form a f t e r c o m p le te d e g l a c i a t i o n o f t h e l a k e b a s i n . H ow ever, b e c a u s e o f
d e f o r m a tio n t h i s
le v e l.
s h o r e l i n e i s n o t e v e ry w h e re 1 8 -2 0 m a b o v e p r e s e n t l a k e
As d i s c u s s e d p r e v i o u s l y , M eyer and L ocke (19 8 6 ) r e p o r t e d minimum
1AC a g e s o f 2495 + 130 and 1410 + 160 y r s B .P .
9 .1 m,
re s p e c tiv e ly .
f o r la g o o n s a t 1 8 .4 and
T h ese minimum and maximum a g e s i n d i c a t e
th a t ic e -
m a r g i n a l l a k e s a n d s tr e a m s w e re p r e s e n t i n t h e Y e llo w s to n e L ake B a s in by
about
1 4 .5
ka
and
th a t
t h e b a s i n w as p r o b a b ly
c o m p le te ly
ic e
fre e
by
a b o u t 12 k a .
C hem ical
a n a ly s e s
a t B re e z e P o i n t
a re
from
th e
of
d e trita l
o b s id ia n g ra in s
( A p p e n d ix - C) i n d i c a t e
A s te r
C reek flo w
d iffe re n t
sa m p le
le v e ls .
th a t v ir tu a lly
(Wayne H a m ilto n ,
T h ese g r a i n s w e re ra n d o m ly s e l e c t e d
it
is
a ll
1989,
fro m d i f f e r e n t
T h e refo re,
from t h e s h o r e l i n e s
o f th e
w ritte n
s h o re lin e s
re a s o n a b le
to
g ra in s
com m .).
and fro m
c o n c lu d e
th a t
m o st o f t h e o b s i d i a n g r a v e l on t h e s h o r e l i n e s a t B r e e z e P o i n t i s d e r i v e d
from t h e A s t e r C re e k flo w w h ic h i s
th e lo c a l b e d ro c k i n
th e a re a
( F ig .
2) .
H y d ra tio n
d e te r m in e d
by
ra te
c o n s ta n ts
M ic h e ls
( 1 9 8 8 ).
fo r
T h ese
e s tim a te s f o r r in d th ic k n e s s e s i f
of
t h e A r r h e n iu s e q u a t i o n r e l a t i n g
th e
A s te r
C re e k
flo w
h av e
c o n s ta n ts
a llo w
n u m e ric a l
been
age
t h e EHT i s known. The w o rk in g v e r s i o n
h y d ra tio n r a t e
to
te m p e r a tu r e
ta k e s
t h e form o f :
k ' = 5 .1 4 e x p [8 6 8 3 4 /8 .3 1 7
( 1 /4 7 3 .1 6 - 1 / T ') ]
w h e re k ' i s t h e h y d r a t i o n r a t e a t T 1 a n d T 1 i s e q u a l t o t h e EHT i n K f o r
th e s i t e .
The f i n a l e q u a t i o n t h a t g i v e s t h e h y d r a t i o n r a t e f o r t h e A s t e r
C reek flo w i s :
67
k ' ( 3 6 5 .2 6 ) ( 1 0 0 0 ) = r a t e e x p r e s s e d a s m i c r o n s ^ / 1000 y e a r s
Thus i f
t h e EHT c a n b e m e a s u re d o r e s t i m a t e d ,
g e n e ra te d
th e re i s
u s in g
th e
ab o v e e q u a t i o n .
th e p o s s i b i l i t y
H ow ever,
a n u m e r ic a l
fo r
d a te
rea so n s
c a n be
g iv e n b e lo w ,
t h a t th e h y d ra tio n r a t e c o n s ta n ts f o r th e A s te r
C reek flo w a r e i n e r r o r .
F rie d m a n and O b ra d o v ic h
-I
fo r
used a g l a c i a l
°C and d i r e c t l y m e a su re d p r e s e n t s o i l
v a rio u s
e v e n ts
th e
(1 9 8 1 )
s ite s
in
in
lo w s to n e
a re a
so
h y d ra tio n
day
d a tin g .
of
d a tin g
v o lc a n ic
F rie d m a n an d N o rto n (1981)
m e a s u re
p rese n t
s tu d y
s o il
EHT1s
S o il
te m p e ra tu re
c o u ld
be
in
u sed
used
th e
in
Y e l­
s tu d ie s
t e m p e r a t u r e w as m e a su re d
at
a ro u n d Y e llo w s to n e L ake an d t e m p e r a t u r e s a lo n g t h e w e s t e r n
sh o re
n e a re st
N o rto n
(1 9 8 1 )
g e o th e r m a l
d ire c tly
th a t
e m p lo y in g o b s i d i a n
tw e lv e s i t e s
to
te m p e ra tu re o f
t e m p e r a t u r e t o d e te r m in e EHT1s
th e ir
u s in g o b s i d i a n h y d r a t i o n d a t i n g .
P a llm a n m eth o d
B reeze
P o in t
ran g e
from
5 .7
h y p o th e s iz e d t h a t th e h ig h s o i l
h e a t flu x .
7000 f e e t a s l
P o in t
Y e llo w s to n e
s o il
T h ese
fee t asl
1 0 .6
°C .
(2357 m) a n d a r e
F rie d m a n
te m p e ra tu re s
t e m p e r a t u r e s w e re n o r m a liz e d
(2134 m) a n d i n d i r e c t s u n l i g h t .
a r e 7732
to
re s u lt
to
an d
fro m
a s ite
at
The s h o r e l i n e s a t B r e e z e
sh a d e d b e c a u s e
of
th e
dense
l o d g e p o l e c o v e r . T h e r e f o r e , t h e a c t u a l p r e s e n t EHT f o r t h e s tu d y s i t e i s
p r o b a b ly
fo r
s ite s
lo w e r t h a n
a ro u n d
th e v a lu e s
re p o rte d
Y e llo w s to n e L a k e .
by F rie d m a n an d N o rto n
A s s u m in g
th a t
th e
p rese n t
(1981)
s o il
t e m p e r a t u r e r e p r e s e n t s t h e h ig h end o f t h e ra n g e f o r EHT a n d t h e g l a c i a l
t e m p e r a t u r e r e p r e s e n t s t h e low e n d , t h e a c t u a l EHT p r o b a b ly l i e s b e tw e e n
t h e s e two end p o i n t s .
The ag e o f t h e
th e s h o r e lin e s
g e o lo g i c e v e n t t h a t p ro d u c e d t h e y o u n g e s t r i n d s
on
c a n be e s t i m a t e d by u s in g t h e . A r r h e n iu s e q u a ti o n a n d t h e
68
e s tim a te d
an d m e a s u re d
re s p o n d in g
n u m e ric a l
E H T 's.
ages
T a b le 5 l i s t s
of
a 5 .5
r a n g i n g from - I . °C t o 11 °C.
C le a rly ,
g iv e n
flo w . h a s
th a t
th e
A s te r
C reek
h y d ra tio n
m ic ro n
rin d
ra te s
u s in g
and
c o r­
te m p e r a t u r e s
some o f t h e s e d a t e s a r e e r r o n e o u s
been
K-Ar
d a te d
at
174 + 4
ka
(R ichm ond, 19.86). The EHT f o r t h e B re e z e P o i n t s i t e m u st h a v e b e e n n e a r
o r ab o v e 6 °C ,
a re
c o rre c t.
f lo w
if
th e h y d ra tio n c o n s ta n ts
O th e r w is e ,
its e lf.
A 5 .5
th e
m ic ro n
d e riv e d
r in d
d a te s
y ie ld s
a
c a lc u la te d
by M ic h e ls
a re
th a n
th e
about
48
d a te
t e m p e r a t u r e o f 11 °C (m e a su re d a t G r a n t V i l l a g e )
th a t - t h e
lo w e r ,
EHT h a s b e e n h i g h e r th a n
g iv e n
th e
n e a r-g la c ia l
th is
c lim a te
o ld e r
of
o b s id ia n
ka
if
Y e llo w s to n e
is
p r o b a b ly
P a rk
much
th ro u g h o u t
m o st o f t h e H o lo c e n e (R ichm ond, 1 9 8 6 ).
T a b le 5 . H y d r a tio n r a t e s and n u m e r ic a l a g e s f o r a 5 .5 m ic ro n r i n d and
e f f e c t i v e h y d r a t i o n t e m p e r a t u r e s r a n g in g from - I t o 11 °C f o r
A s t e r C reek o b s i d i a n ( A f te r M ic h e ls , 1 9 8 8 ).
T e m p e ra tu re
- I °C
0
I
2
3.
4 .
5
6
7
8
9
10
11
a
i s u sed . I t i s u n lik e ly
v a lu e and i t
in
(1988)
R a te
0 .1 6 m i c r o n s ^ / 1000 y r s
0 .1 8
0 .2 1
0 .2 6
0 .2 7
0 .3 1
0 .3 6
0 .4 1
0 .4 7
0 .5 4 .
0 .6 1 .
. 0 .7 0
0 .7 9
Age
1 ,1 8 2 ,0 0 0 y r s
9 3 4 ,0 0 0
6 8 6 ,0 0 0
5 2 5 ,0 0 0
4 1 5 ,0 0 0
3 1 5 ,0 0 0
2 3 3 ,0 0 0
1 8 0 ,0 0 0
1 3 7 ,0 0 0
1 0 4 ,0 0 0
8 1 ,0 0 0
6 2 ,0 0 0
4 8 ,0 0 0
69
It
is
p o s s ib le
C reek f lo w
a re
an
th a t
th e ' h y d r a t i o n
ra te
( M ic h e ls , 1988) a r e i n e r r o r .
o rd er
of
m a g n itu d e
le s s
c o n s ta n ts ' f o r
th e
A s te r
The .c o n s t a n t s y i e l d r a t e s
t h a n ; O b s id ia n
C liff
c o n s ta n ts
th a t
fo r
th e
same t e m p e r a t u r e , e v e n th o u g h th e c h e m i s t r i e s a r e v e r y s i m i l a r (A p p e n d ix
C ). F rie d m a n and Long (1976) r e p o r t e d t h a t , in c r e a s e d - . S ip 2 ' i n c r e a s e s
ra te
o f .h y d r a tio n w h ile in c re a s e d
CaO a n d MgO d e c r e a s e
th e
h y d ra tio n r a t e .
C hem ical a n a l y s e s o f A s t e r C reek o b s i d i a n ( M ic h e ls , 1 9 8 8 a , 1988b) show a
h ig h e r
s ilic a
M ic h e ls ,
c o n te n t
1985)
th a n
O b s id ia n
an d v i r t u a l l y
C ). T h ese a n a l y s e s i n d i c a t e
C liff
(F rie d m a n
i d e n t i c a l v a lu e s o f
and Long,
1976;
CaO and MgO ■(A p p en d ix
t h a t t h e A s t e r C reek flo w s h o u ld h y d r a t e a t
a r a t e f a s t e r th a n o r. e q u a l t o t h a t o f t h e O b s id ia n C l i f f flo w .
F rie d m a n
an d
d i f f e r e n t O b s id ia n
O b ra d o v ic h
f lo w s
(1 9 8 1 )
a n a ly z e d
th e
i n -Y e llo w sto n e P a r k .
c h e m is try
The a g e s
of
of
th e s e
e ig h t
f lo w s
r a n g e fro m 77 t o 399 k a . A ll o f t h e f lo w s w e re c h e m ic a lly s i m i l a r t o t h e
O b s id ia n C l i f f flo w w h ic h l e d F rie d m a n and O b ra d o v ic h (1 9 8 1 ) t o c o n c lu d e
t h a t a l l o f t h e flo w s h a d t h e same h y d r a t i o n r a t e a s t h a t c a l c u l a t e d f o r
O b s id ia n . C l i f f .
but i t is
th is a n a ly s is ,
s i m i l a r i n b o th c h e m is tr y an d a g e t o t h e O b s id ia n C l i f f flo w .
From
th e
h y d ra tio n r a t e
1988)
The A s t e r C reek flo w w as n o t i n c l u d e d i n
a re
in
above
d is c u s s io n
c o n s ta n ts
e rro r.
it
is
c a lc u la te d
fo r
M ic h e ls
(1 9 9 0 ,
r e a s o n a b le
to
assum e
t h e A s t e r C re e k flo w
p e rso n a l
comm.)
in d ic a te d
th a t
th e
( M ic h e ls ,
th a t
th e
m o st l i k e l y
s o u r c e o f e r r o r i n d e te r m i n in g h y d r a t i o n r a t e
c a lc u la tin g
t h e a c t i v a t i o n e n e rg y b a s e d on l i n e a r r e g r e s s i o n . o f in d u c e d
h y d r a t i o n m e a s u re m e n ts .
In d u c e d h y d r a t i o n i s
250
so
°C )
te m p e ra tu re s
r e q u i r e d by t h i s
te c h n iq u e
th e
a c c o m p lis h e d a t h ig h
e x tra p o la tio n
c o u ld i n t r o d u c e
c o n s t a n t s w as
to
a m b ie n t
(1 5 0 -
te m p e r a t u r e s
s ig n ific a n t e rr o r in
d e te r­
70
m in in g
th e
a c tiv a tio n
e n e rg y ! o f
a
p a rtic u la r
g la s s .
M ic h e ls
(1 9 9 0 ,
p e r s o n a l comm.) s t a t e d •t h a t he r e q u i r e s a c o r r e l a t i o n c o e f f i c i e n t o f a t
l e a s t 0 .9 9 9 7 i n o r d e r t o a c c e p t t h e d e r i v e d a c t i v a t i o n e n e rg y v a l u e . The
c o rre la tio n
c o e ffic ie n t
A s te r
C reek
flo w
v a lu e
ju s t
p e rso n a l
e n e rg y
m et
is
th e
comm.) .
can
fo r
0 .9 9 9 7 , ( M ic h e ls ,
th e
1988)
m inim um . r e q u i r e m e n ts
An e r r o r
c h an g e
d e te r m in in g
th e
of ju s t
c a lc u la te d
n i t u d e . T h is p o t e n t i a l
as
10 % i n
w h ic h
e n e rg y
in d ic a te s
d e fin e d
ra te s
fo r
th a t
by M ic h e ls
d e te r m i n in g . t h e
h y d ra tio n
so u rc e of e r r o r
a c tiv a tio n
th e
th is
(1 9 9 0 ,
a c tiv a tio n
by . an o r d e r o f mag­
c o u ld a c c o u n t f o r t h e l a r g e d i f ­
f e r e n c e i n . h y d r a t i o n r a t e c o n s t a n t s b e tw e e n t h e A s t e r C re e k and O b s id ia n
C l i f f . f l o w s . A ssum ing t h a t t h e A s t e r C reek h y d r a t i o n r a t e
c o n s ta n ts a re
i n e r r o r , t h e c o n s t a n t s c a l c u l a t e d f o r t h e O b s id ia n C l i f f flo w ( M ic h e ls ,
1985) w i l l be u s e d t o e s t i m a t e a g e s f o r th e s h o r e l i n e s a t B r e e z e P o i n t .
An EHT o f
1 .0
°C w as
used
fo r
th e
s h o re lin e s
at
B re e z e
P o in t
b e c a u s e t h i s t e m p e r a t u r e i s th o u g h t t o a p p ro x im a te a n i n t e g r a t e d a v e r a g e
b e tw e e n g l a c i a l t e m p e r a t u r e s
(-1 °C) a n d p r e s e n t s o i l t e m p e r a t u r e s . L e s s
w e ig h t w as g iv e n t o
s o il
p rese n t
te m p e ra tu re s b e c au se a c o o le r c lim a te
h a s p r e v a i l e d t h r o u g h o u t m o st o f t h e H o lo c e n e ' (R ichm ond, 1 9 8 6 ) . .
■A ,r in d , t h i c k n e s s o f 5 .5 + 0 .5 m ic r o n s c o u p le d w i t h an EHT o f 1 .0 °C
y ie ld s
a n ag e o f 1 2 ,2 7 0 +23.30 -2 1 3 0 y e a r s
f o r th e s h o r e lin e s a t B reeze
P o i n t . T h is a g e a g r e e s w e l l w i t h e s t i m a t e s o f d e g l a c i a t i o n f o r t h e Y e li
lo w s to p e L ake B a s in
-
-
(R ichm ond, 1 9 7 6 a ; 19 7 6 b ; 1986) b u t i s
th o u g h t t o be
to o o ld t o be a s s o c i a t e d w i t h t h e f o r m a ti o n o f t h e s h o r e l i n e s .
(1 9 7 6 a )
re p o rte d
of
b a s in
th e
S h o re lin e
^C
ra n g in g
S7 ( ? )
Richm ond
d a t e s f o r t h e s h o r e l i n e s , fo rm e d a f t e r d e g l a c i a t i o n
fro m
a maximum ag e
(1 8 -2 0 m). t o
o f 9060 + 300 y r s
a minimum age
B .P .
fo r
o f 620 + 250 y r s B .P .
fo r
71
S h o re lin e S 2 (? )
(3 m) . M eyer a n d L o ck e (1 9 8 6 ) r e p o r t e d minimum
ages
f o r S h o r e l i n e s S6 a n d S5 ( S h o r e l i n e s S5 a n d S A - th is s t u d y ) o f 2495 +_130
a n d 1410 + 160 y r s
m inim um
ages
B o P .,
of
re s p e c tiv e ly .
about
6 ka
fo r
L ocke
(1 9 8 9 ) a l s o
S h o r e li n e
S6
r e p o r t e d tw o
(S h o re lin e
S 5 -th is
s t u d y ) . The h y d r a t i o n a g e d i s p l a y e d b y t h e s h o r e l i n e s a t B r e e z e P o i n t i s
c o n s id e ra b ly
s o c ia te d
o ld e r
w ith
th a n
H o lo c e n e
any
of
th e
s h o re lin e s
maximum an d minimum
in
th e
la k e
r i n d s m u st b e a s s o c i a t e d w i t h a n o l d e r r e s e t t i n g
b a s in .
ages
T h e refo re,
as­
th e
e v e n t o r t h e EHT m u st
be h ig h e r.
It
is
h y p o th e s iz e d t h a t th e r in d s
fro m t h e s h o r e l i n e s e f f e c t i v e l y
d a t e t h e d e g l a c i a t i o n o f t h e Y e llo w s to n e B a s i n . A r i n d t h i c k n e s s o f 5 .5
m ic r o n s c l o s e l y m a tc h e s r i n d t h i c k n e s s e s fro m d e g l a c i a l d e p o s i t s i n t h e
O b s id ia n C l i f f a r e a
( F ig .
2 1 ).
P ie r c e and o th e r s
(1 9 7 6 ) a l s o
e s tim a te d
t h a t d e g l a c i a t i o n o f t h e Y e llo w s to n e P l a t e a u o c c u r r e d a b o u t 12 k a . T h is
h y p o th e s is
is
m ech an ism
fo r
e x p e c te d t o
f u r t h e r s u p p o rte d b y th e
t h e b e a c h e n v ir o n m e n t.
la c k
o f an e f f e c t i v e
C o n s e q u e n tly ,
d a t e fro m t h e l a s t e f f e c t i v e
th e
re w o rk in g
r i n d s w ould b e
r e w o rk in g m ech an ism w h ic h w as
t h e w a n in g P i n e d a l e i c e m a s s .
E s t i m a t e s c a n b e m ade a s t o
how t h i c k h y d r a t i o n r i n d s d a t i n g fro m
t h e o c c u p a t i o n o f t h e s h o r e l i n e s w o u ld b e i f
c o a s t a l p r o c e s s e s w e re a n
e f f e c t i v e r e w o rk in g m ec h a n ism . A ssum ing, a n a g e o f fro m 2 t o 9 k a f o r t h e
s h o re lin e s
and
a n EHT o f I
fro m
2 .2
to
about
v a lu e s
in
o c c u p a tio n
4 .7
th is
ran g e
of
g iv e n
a
0C th e
m ic r o n s .
A ll
( A p p e n d ix
s h o re lin e
h y d ra tio n rin d v a lu e s
of
F ).
b u t,
th e
T h ese
s h o re lin e s
rin d s
u n fo rtu n a te ly
s h o u ld
have
may d a t e
th e
ran g e
h y d ra tio n
fro m
th e
n o n p a r a m e tr ic
d e n s i t y e s t i m a t i o n t e c h n i q u e s a s u s e d i n t h i s s t u d y c a n n o t d e te r m in e i f
72
th e s e
th in
r in d s
fo rm
a rg u m e n ts e s t i m a t e s
a
d is c re te
o f th e
c lu s te r
o f p o in ts .
F o r th e
sake
a g e o f t h e s h o r e l i n e s c a n b e made i f
of
th e s e
r i n d s a r e assu m ed t o h a v e fo rm e d b y c o a s t a l r e w o r k in g . U sin g a n EHT o f I
0 Cs h y d r a t i o n r a t e c o n s t a n t s f o r t h e O b s id ia n C l i f f f lo w ( M ic h e ls „ 1 985)
and
minimum r i n d
th ic k n e s s e s
f ro m
2 .7 4
to
3 .7 7
( A p p e n d ix
F) ,
th e
s h o r e l i n e s y i e l d minimum a g e s o f 3050 t o 5770 y e a r s . T h e se a g e s a r e i n
r e a s o n a b le
a g re e m e n t w i t h
some
of
th e
minimum
ages
as
d is c u s s e d
above.
The s h o r e l i n e s a t Y e llo w s to n e L ake m u st h a v e fo rm e d a f t e r 12 k a b u t
u n f o r tu n a te ly th e te c h n iq u e s u sed i n t h i s
th e ages o f th e s e
s tu d y c a n n o t f u r t h e r r e s o l v e
f e a t u r e s w ith any d e g re e o f c e r t a i n t y .
I t i s th o u g h t
t h a t l a r g e r s a m p le s i z e s o f l a k e s h o r e g r a v e l w ould do l i t t l e
in th e d a tin g o f th e s e f e a tu re s b e c au se o f th e r e l a t i v e
to a s s i s t
in e ffe c tiv e n e s s
o f t h e b e a c h e n v ir o n m e n t t o p r o d u c e f r e s h - f r a c t u r e d s u r f a c e s .
I n t e r p r e t a t i o n o f O ld e r E v e n ts
A g g re g a te d a t a fro m T e r r a c e TO ( F i g . 10) fo rm s tw o d i s t i n c t p e a k s ,
in
a d d itio n
to
th e
one c e n te re d
at
a b o u t 6 .5 m ic r o n s ,
th a t
rep re sen t
e v e n t s t h a t o c c u r r e d b e f o r e l a t e P i n e d a l e t i m e . T h e se p e a k s a r e c e n t e r e d
a t a b o u t 12 an d 22 m ic r o n s , r e s p e c t i v e l y .
fits
re a s o n a b ly
w e ll
w ith
h y d ra tio n
g l a c i a t i o n b y P ie r c e and o th e r s
rin d s
(1 9 7 6 )
o f 64 h y d ra tio n r in d s sp re a d o v e r f iv e
of
158 m e a s u re m e n ts w e re t a k e n
o n l y a b o u t 21 % o r 33 r i n d s
m ic r o n s
at
fe ll
The p e a k a t a b o u t 12 m ic ro n s
one
a ttrib u te d
to
B u ll
L ake
( F i g . 2 1 ) . T hey m e a su re d a t o t a l
s ite s b u t in t h is
s ite .
Of t h e
s tu d y a t o t a l
158 m e a s u re m e n ts ,
u n d e r th e peak c e n te re d
a t about
12
( R ic h a r d R o s s i , 1 9 9 0 , p e r s o n a l co m m .). C o n s e q u e n t l y ,• b e c a u s e o f
73
t h e r e l a t i v e l y s m a ll s a m p le s i z e s , i t i s d i f f i c u l t t o d e te r m in e i f t h e s e
tw o
g ro u p s
of
rin d s
came
fro m
th e
sam e p o p u l a t i o n ,
th a t
t h e g ro u p
n a m e ly B u l l L ake
re w o rk e d g l a c i a l p e b b l e s .
A n o th e r h y p o t h e s i s
m ic r o n s d a t e
and o th e r s
is
o f rin d s
c e n te re d
a ro u n d
12
fro m t h e e m p la ce m e n t, o f t h e W est Y e llo w s to n e f lo w . P i e r c e
(1 9 7 6 ) m e a s u re d j u s t s i x
rin d s
in te rp re te d
a s fo rm in g a lo n g
o r i g i n a l c o o l i n g c r a c k s on t h e W est Y e llo w s to n e f lo w , b u t t h e y a r e a l l
c lu s te re d
peak
a ro u n d 1 2 .5 m ic r o n s , w h ic h i s
fro m t h i s
(1 9 7 9 )
who
s tu d y .
s ta te d
T h is
th a t
h y p o th e s is
m o st o f
th e
a c l o s e m a tc h t o t h e 12 m ic ro n
is
fu rth e r
m a te ria l
s u p p o rte d by
in
th e
P ie rc e
OSP w as p r o b a b l y
d e r i v e d fro m t h e W est Y e llo w s to n e f lo w .
The p e a k c e n t e r e d
fit
in to
(1 9 7 6 ).
th e
a b o u t 22 m ic r o n s
h y d ra tio n -e v e n t
The t h i c k e s t
m ic r o n s .
at
P ie rc e
rin d s
an d
o th e rs
m odel
d e v e lo p e d
m e a s u re d
(1 9 7 6 )
(F ig .
in
th a t
10 ) d o e s n o t seem t o
by
P ie rc e
and
o th e rs
s t u d y w e re o n ly a b o u t
a ttrib u te d
th e
th ic k e s t
rin d s
17
to
c r a c k s fo rm ed d u r in g t h e e m p la ce m e n t o f t h e o b s i d i a n C l i f f f lo w . A g a in ,
o n ly a b o u t s i x
p o s s ib le
c ra c k s
th a t
and
a n o m o lo u s ly
r i n d s w e re m e a s u re d t o
rin d s
th a t
th e
th in .
num ber o f r i n d s
c lu s te re d
rin d s
T h is
(" 2 0 )
is
a ro u n d
su p p o rt t h i s
c la im .
22 m ic ro n s d a t e
m e a s u re d b y
s u p p o rte d
P ie rc e
by
th e
an d
fac t
make up t h e p e a k c e n t e r e d
at
It
is
v e ry
o r ig i n a l c o o lin g
o th e rs
th a t
a
(1 9 7 6 )
a re
s u b s ta n tia l
22 m ic r o n s ,
w h ic h
i n d i c a t e s t h a t t h e r e p r o b a b l y w as some e v e n t a s s o c i a t e d w i t h . t h i s p e a k .
And o b v i o u s l y ,
th e s e
rin d s
t h e O b s id ia n C l i f f f lo w
same
ran g e
of
h y d ra tio n
c a n n o t d a te
fro m b e f o r e
th e
e m p lacem en t o f
(a s s u m in g t h a t a l l m a t e r i a l i n t h e OSP h a s t h e
ra te
c o n s ta n ts
as
th e
O b s id ia n
C liff
flo w ).
A ssum ing t h a t t h e r i n d s g ro u p e d a ro u n d 22 m ic ro n s d a t e fro m t h e o r i g i n a l
74
e m p lacem en t o f t h e O b sid ia n .. C l i f f f lo w , a r e c a l i b r a t i o n o f t h e h y d r a t i o n
c u rv e
fro m
P ie rc e
R e c a lib ra tin g t h is
and
o th e rs
(1 9 7 6 ). ( F ig .
c u r v e may h a v e t h e
21)
m ig h t
be w a rra n te d .
e f f e c t o f c h a n g in g th e
d a te s
fo r
t h e B u l l L ake G l a c i a t i o n .
An h y p o t h e s i s
th a t
a n d fro m t h i s s tu d y i s
in te g ra te s
d a ta
from P i e r c e
and o t h e r s
(1976)
t h a t th e p e a k a t a b o u t 12 m ic r o n s d a t e s fro m t h e
E o w is e o n s in (R ichm ond, 1 9 8 6 ) , r i n d s from 17 t o 18 m ic r o n s d a te from B u l l
L ake
tim e
c ra c k s.
and
rin d s
at
The E o w is c o n s in
(R ichm ond, 1986) a n d i s
L ake
and
P ih e d a le
about
22 m ic ro n s
g la c ia tio n
o c c u rre d
fro m
from
o rig in a l
about
80
c o o lin g
to
117
ka
th o u g h t t o b e l e s s e x t e n s i v e th a n b o th t h e B u l l
G la c ia tio n s .
T e r r a c e TO ( F i g . 10)
d a te
Even
th o u g h
th e
a g g r e g a te
d o e s n o t show a p e a k a t 17 t o
d a ta
from
18 m ic r o n s , many o f
t h e d e n s i t y d ia g ra m s ' f o r b o th t h e t e r r a c e s and s h o r e l i n e s
(F ig s .
1 1 -2 0 )
show a c o n c e n t r a t i o n o f r i n d t h i c k n e s s e s i n t h i s r a n g e .
I t i s . n o t known why m easu rem en t d a t a t h i c k e r t h a n a b o u t 6 .5 m ifcrons
f o r th e t e r r a c e s a n d a b o u t 5 .5 m ic r o n s f o r th e s h o r e l i n e s
to c o n s is te n tly
r e w o rk in g
fin d s ,
c l u s t e r a ro u n d one o r s e v e r a l p o i n t s .
d u r in g
th e
m o st
th e re b y , l e a v i n g
recen t
o n ly
a
event
I t is lik e ly th a t
rem oved m o st
f r a g m e n ta r y
rec o rd
d o es n o t seem
of
of
th e
e x is tin g
o ld e r
re w o rk in g
e v e n t s . The s p r e a d c a u s e d by n a t u r a l v a r i a t i o n i n h y d r a t i o n r a t e s w o u ld
be
e x p e c te d
d e e m p h a s iz in g
re fle c t
a
to
be
d a ta
la rg e r
fo r
o ld e r
c o n c e n tra tio n s .
com plex r e w o rk in g h i s t o r y
s tu d y t o d e c i p h e r .
e v e n ts
The l a c k
th a t
is
w h ic h
of
has
th e
c lu s te rin g
bey o n d t h e
e ffe c t
may
scope
of
of
a ls o
th is
75
The O b s id ia n H y d r a tio n T e c h n iq u e
O b s id ia n
h y d ra tio n
d a tin g
c h a e o lo g ic a l
a rtifa c ts
an d
w as
has
o rig in a lly
s in c e
been
d e v e lo p e d
a d a p te d
to
to
d a te
d a te
ar­
g e o lo g ic
e v e n t s a n d d e p o s i t s = I n a l l s t u d i e s known t o t h e a u t h o r , a s i n g l e s e t o f
h y d ra tio n r a t e c o n s ta n ts h as b een u sed to
or
g e o lo g ic
e v e n ts
if
th e
o b s id ia n
is
c a lc u la te ages fo r a r t i f a c ts
th o u g h t
to
be
d e riv e d
fro m
a
s i n g l e s o u r c e . I n some c a s e s , w hen m u l t i p l e s o u r c e s a r e l i k e l y , a s i n g l e
r a t e i s s t i l l a p p lie d
( e . g . F rie d m a n a n d O b r a d o v ic h , 1 9 8 1 ) . The p r a c t i c e
o f u s in g a s in g l e g ro u p o f h y d r a tio n r a t e c o n s ta n ts f o r a g iv e n r in d o r
g ro u p
of
o b s id ia n
rin d s
flo w s
has
th e
e ffe c t
w h ic h may b e
of
th e
ig n o rin g
cau se
of
n a tu ra l
s c a tte r
v a ria tio n
in
th e
w ith in
r in d
th ic k ­
n esses .
The s c a t t e r o f r i n d
th e
te rra c e s
(F ig s .
t h i c k n e s s e s a ro u n d e a c h o f t h e p e a k s f o r b o t h
1 0 -1 4 )
an d
th e
s h o re lin e s
(F ig s .
1 6 -2 0 )
is
a t­
t r i b u t e d t o a num ber o f s o u r c e s . The f i r s t , an d p r o b a b l y m o st i m p o r t a n t ,
i s v a r y i n g c h e m i s tr y b e tw e e n a n d w i t h i n o b s i d i a n f l o w s . H y d r a tio n i s
fu n c tio n
g la s s .
o f b o th
te m p e ra tu re
As d i s c u s s e d
and c h e m i s tr y
of
a b o v e , F rie d m a n an d Long
a p a rtic u la r
(1 9 7 6 )
a
rh y o litic
re p o rte d
th a t
th e
am ount o f S iU g, CaO a n d MgO a f f e c t e d t h e r a t e o f h y d r a t i o n . The am o u n ts
of
th e s e
d iffe re n t
th re e
c o n s titu e n ts
o b s id ia n
flo w s .
cannot be
F r ie d m a n
e x p e c te d
and
to
be
O b ra d o v ic h
id e n tic a l
(1981)
fo r
re p o rte d
d i f f e r e n c e s i n h y d r a t i o n r a t e s f o r many f lo w s a ro u n d t h e w e s t e r n U n ite d
S t a t e s . They a l s o a n a ly z e d e i g h t d i f f e r e n t f lo w s i n Y e llo w s to n e P a rk an d
fo u n d t h a t
d iffe re n t
a ll
f lo w s
had s i m i l a r c h e m i s tr ie s .
in
H ow ever,
Y e llo w s to n e w e re n o t r e p o r t e d ,
c a n n o t b e d e te r m in e d j u s t how s i m i l a r t h e s e
th e
a n a ly s e s
f o r th e
a n d c o n s e q u e n t ly
it
flo w s a r e w i t h r e s p e c t
to
76
t h e i r S iO ^ , CaO a n d MgO c o n t e n t .
The
a p p a re n t
p r o b a b ly
re s u lts
v a ria b ility
fro m
th e
in
c h e m is try . w ith in
te c h n iq u e
u sed
to
an
in d iv id u a l
a n a ly z e
th e
flo w
g la s s
in
a d d i t i o n t o n a t u r a l v a r i a t i o n . A p p e n d ix C (T a b le 7) show s' a to m ic a b s o r p ­
tio n
s p e c tro s c o p y
C reek o b s i d i a n
ity
e x is ts
in
a n a ly s e s
( M ic h e ls ,
fo r
m u ltip le
sa m p le s
198,8b). As c a n be s e e n ,
id e n tifie d
as
A s te r
c o n s id e ra b le v a r i a b i l ­
t h e am o u n ts o f t h e c h e m ic a l c o n s t i t u e n t s . . I n p a r t i c u l a r ,
t h e am ounts o f CaO a n d MgO.v a r y by a s much a s 30 and 50 %, r e s p e c t i v e l y .
A p p e n d ix C ( T a b le 8) l i s t s
two s e p a r a t e
a n a l y s e s o f t h e O b s id ia n
f lo w , w h ic h a l s o show s c o n s i d e r a b l e v a r i a b i l i t y
th is v a ria tio n
p e r c e n ta g e
is
p re su m e d t o b e i n h e r e n t i n
p r o b a b ly
re s u lts
F rie d m a n a n d Long (1 9 7 6 )
i n key e le m e n ts .
th e
g la s s ,
Q iff
Some o f
b u t a c e rta in
from t h e a n a l y t i c t e c h n i q u e . U n f o r t u n a t e l y ,
a n d M ic h e ls
(1 9 8 5 ;
1988b)
d id n o t r e p o r t
th e
e r r o r s a s s o c i a t e d w i t h e a c h o f t h e c h e m ic a l a n a l y s e s .
V a ria tio n
h y d ra tio n
in
ra te
d o u b t on t h e
s h o u ld
p ra c tic e
c o n s ta n ts
fo r
h y d ra tio n
ra te
d ic ta te d
by
k ey
an
e le m e n ts
a
s in g le
a ls o v a ry w ith in
a s in g le
of
s in g le
g e n e ra tin g . a
e n tire
o b s id ia n
c o n s ta n ts
th e
w ith in
fo r
v a ria tio n
in
each
f lo w .
c h e m is tr y
fo r
in d ic a te s
f lo w ,
th e r e b y
g ro u p
T h e re
in d iv id u a l
f lo w
is
of
th a t
f lo w .
c a s tin g
h y d ra tio n
p r o b a b ly
o b s id ia n
th a t
ra te
a
ra n g e
of
flow ,
th a t,
is
T a b le 6 show s
d i f f e r e n t h y d r a t i o n r a t e s f o r t h e O b s id ia n Q i f f f l o w , c a l c u l a t e d f o r t h e
same t e m p e r a t u r e s
by F rie d m a n and Long
d is p a rity
th e s e
b e tw e e n
ra te s
in d ic a te s
(1976)
th a t
a n d M ic h e ls
th e re
v a ria tio n
in
a g iv e n f lo w .
la te d
s u p p l i e d by F rie d m a n an d Long (1 9 7 6 ) a n d M ic h e ls
(1 9 8 5 )
a n d a s su m in g a r i n d
if
The
h y d ra tio n r a te w ith in
u s in g c o n s t a n t s
As an e x a m p le ,
is
( 1 9 8 5 ).
an ag e i s
c a lc u ­
t h i c k n e s s o f 6 .5 m ic ro n s an d ah EHT o f 6 .0
77
o C0 t h e r e i s
a d i f f e r e n c e i n a g e o f a b o u t 14 %. T h is t r a n s l a t e s i n t o an
a p p a r e n t a g e d i f f e r e n c e o f a b o u t 700 y e a r s u s in g t h e s e p a r a m e t e r s .
The v a r i a t i o n o f h y d r a t i o n r a t e
in d iv id u a l
f lo w s
g e o l o g i s t s who
has
use
im p o r ta n t
o b s id ia n
due t o c h e m ic a l d i f f e r e n c e s w i t h i n
ra m ific a tio n s
h y d ra tio n
d a tin g
fo r
a rc h a e o lo g is ts
te c h n iq u e s .
In
th e
and
p a s t,
g e n e r a l l y o n ly o n e s e t o f r a t e c o n s t a n t s w as g e n e r a t e d f o r a n i n d i v i d u a l
flo w
( M ic h e ls ,
1985,
1 9 8 8 ).
T h ese
c o n s ta n ts
a re
p e rio d ic a lly
re v is e d
( J o s e p h M ic h e ls , 1 9 90, p e r s o n a l com m ,), b u t th e u n d e r l y i n g a s s u m p tio n i s
th a t
each
o b s id ia n
flo w
p o ssesses
u n iq u e
c a n be s e e n from t h e a b o v e e x a m p le ,
in d iv id u a l
flo w s i s n o t j u s t i f i e d
h y d ra tio n
ra te
c o n s ta n ts .
t h e a s s u m p tio n o f a s i n g l e r a t e
As
fo r
and may l e a d t o e r r o n e o u s c o n c lu s i o n s
a b o u t th e age o f a p a r t i c u l a r a r t i f a c t ,
a rc h a e o lo g ic a l s i t e
o r g e o lo g i c
r e w o rk in g e v e n t .
T a b le 6 . H y d r a tio n r a t e s and c o r r e s p o n d in g a g e s c a l c u l a t e d f o r a 6 .5
m ic r o n r i n d f o r O b s id ia n C l i f f o b s i d i a n u s in g t h e same te m p e r­
a tu re s .
T e m p e ra tu re (c C)
6 .0
6 .9
1 9 .7
2 2 .7
a fte r
R a te ( m i c r o n s ^ / 1000 y r s )
I
2
3 .1 0
3 .4 0
1 6 .0 0
2 2 ,6 0
2 .8 8
3 .2 1
1 3 .7 6
1 9 .0 0
Age
I
2
4396
3654
i6 5
. 83
.
5094
4100
223
117
( I ) F rie d m a n an d Long (1976) a n d (2) M ic h e ls (1985)
F rie d m a n a n d O b ra d o v ic h (1981) a n a ly z e d e i g h t o b s i d i a n flo w s i n t h e
Y e llo w s to n e
fo re ,
th e y
re g io n
and
p o s tu la te d
b e tw e e n t h e s e
f lo w s .
fo u n d t h a t
th a t
A g a in ,
a ll
had s i m i l a r
t h e r e w as no v a r i a t i o n
th e a n a ly s e s
of th e s e
c h e m is trie s .
in
h y d ra tio n
in d iv id u a l
T h e re ­
ra te s
flo w s w as
78
n o t r e p o r t e d w h ic h m akes i t q u i t e
th e
flo w s .
s id e ra b le
In
lig h t
of
v a ria b ility ,
th e
it
d i f f i c u l t to a s se s s
fac t
d o es
th a t
not
in d iv id u a l
seem l i k e l y
th e s i m i l a r i t y
flo w s
th a t
p o ssess
of
con­
e ig h t
d iffe re n t
u s in g
233
flo w s w o u ld p o s s e s s i d e n t i c a l h y d r a t i o n r a t e c o n s t a n t s .
M ic h e ls
an d B e b r ic h
(1 9 7 1 )
p lo tte d
a
h is to g ra p h
rin d
m e a s u re m e n ts w h ic h ra n g e from a b o u t I t o 5 m ic ro n s fro m an a r c h a e o l o g i ­
c a l s i t e i n M exico ( F ig .
2 3 ) . T h is r a n g e i n r i n d t h i c k n e s s r e p r e s e n t s a
p e r i o d o f tim e from 3584 B .C . t o 1744 A .D. M ost o f t h e m e a su re m e n ts f a l l
b e tw e e n 2 and 3 m ic r o n s w h ic h c o r r e s p o n d s t o an a g e r a n g e fro m 34 B. C.
t o 1077 A .D ., b u t t h e r e a r e many s u b s i d i a r y p e a k s . The s p r e a d a s s o c i a t e d
w i t h t h e s e m e a s u re m e n ts w a s ' a t t r i b u t e d t o "an u n u s u a ll y lo n g and co m p lex
h is to ry
of o c c u p a tio n " .
From t h e ab o v e d i s c u s s i o n ,
much o f t h e s p r e a d i s ,
in s te a d ,
many o f t h e a r t i f a c t s .
T h is m ig h t- im p ly t h a t t h e
th is
s ite
w as
not
as
lo n g
an d
it
is
p o s s ib le
th a t
c a u s e d by d i f f e r i n g h y d r a t i o n r a t e s f o r
co m plex a s
o c c u p a tio n , h i s t o r y
M ic h e ls
and
B e b r ic h
of
(1 9 7 1 )
c o n c lu d e d .
As
can
be
seen
from
th e
ab o v e
e x a m p le s ,
w o r k e rs
u s in g
o b s id ia n
h y d r a t i o n d a t i n g t e c h n i q u e s , m u st r e c o g n i z e t h a t h y d r a t i o n r a t e c o n s t a n t s
can v a ry
b e tw e e n
and w ith in
in d iv id u a l
l i m i t a t i o n s o f u s in g a s i n g l e r a t e
ic a l
s ite
fo r.
The i d e a l m eth o d w o u ld be t o
o b s id ia n
f lo w s .
(o r a s in g le rin d )
T h e refo re,
th e
f o r a n a r c h a e o lo g ­
o r g e o lo g i c re w o rk in g e v e n t m u st be r e c o g n i z e d an d a c c o u n te d
o b ta in
h y d ra tio n
ra te
c o n s ta n ts
fo r
e a c h a r t i f a c t o r sa m p le d a te d . H ow ever, b e c a u s e o b t a i n i n g h y d r a t i o n r a t e
c o n s t a n t s i s a d e s t r u c t i v e and e x p e n s iv e p r o c e d u r e , i t i s n o t a lw a y s
p o s s ib le
due t o
fin a n c ia l
lim ita tio n s
and i s
t o th e c u l t u r a l v a l u e o f o b s i d i a n a r t i f a c t s .
u s u a lly n o t d e s ir a b le
due
Number of sample
79
Microns
F i g u r e 23
H i s t c g r a p h o f 233 r i n d m e a s u re m e n ts from a n a r c h a e o l o g i c a l
s i t e i n M exico ( a f t e r M ic h e ls and B e b r i c h , 1 9 7 1 ).
80
A n o th e r
so u rc e
m e a su re m e n t e r r o r .
of
s c a tte r
fo r
r i n d m e a s u r e m e n ts » b u t i s
by
m e a s u re m e n ts
The m easurem ent, e r r o r f o r t h i s
t o b e 0 .3 m ic r o n s . T h is v a l u e i s
in tro d u c e d
r in d
th e
s ta n d a rd
s tu d y was d e te r m in e d
s ig n i f i c a n t w ith re g a rd to in d iv id u a l
p ro b a b ly n e g li g ib l e
d iffe rin g
is
h y d ra tio n
ra te s
i n c o m p a r is o n t o
as
d is c u s s e d
s c a tte r
above.
O th e r
s o u r c e s o f s c a t t e r i n c l u d e d i f f e r e n c e s i n tim e o f r e w o rk in g and f r a c t u r ­
in g n o t r e l a t e d
to
th e ev en t o f i n t e r e s t .
T h is f r a c t u r i n g may t a k e t h e
fo rm o f b i o t u r b a t i o n ( r o o t th ro w o r b u r r o w in g ) o r s a m p lin g t e c h n i q u e and
p re p a ra tio n .
T he
tifa c ts
u n c e rta in ty
in tro d u c e d
and g e o lo g ic
e v e n ts
by
r in d
m ea su rem e n t
s c a tte r
c a n b e m in im iz e d b y t a k i n g
fo r
m u ltip le
a r­
rin d
m e a s u re m e n ts . To c h a r a c t e r i z e a g e o l o g i c s i t e o r h o r i z o n , w h e re o b s i d i a n
h a s b e e n n a t u r a l l y w o rk e d , a minimum o f a b o u t 150 m e a s u re m e n ts m u st b e
ta k e n
( R ic h a r d
R o s s i,
b e c a u se o fte n tim e s
1990,
o b s id ia n
p e rso n a l
has
co m m .).
gone th ro u g h
an d t h e num ber o f r i n d t h i c k n e s s e s
is
T h is n um ber i s
se v era l
d is trib u te d
re q u ire d
re w o rk in g
e v e n ts
among s e v e r a l m o d es.
The d i s t r i b u t i o n h a s t h e e f f e c t o f l o w e r in g t h e num ber o f r i n d s u s e d t o
c h a ra c te riz e
id e n tifia b le ,
an
in d iv id u a l
e v e n t-s p e c ific
a rc h a e o lo g ic a l s i t e .
e v e n t.
O b s id ia n
a rtifa c ts
rin d s th a t can be used to
have
re a d ily
c h a ra c te riz e
an
T h e r e f o r e , c o n s i d e r a b l y l e s s r i n d m e a s u re m e n ts a r e
n e e d e d t o d e te r m in e a d a t e f o r a n o c c u p a t io n s i t e o r h o r i z o n .
• CONCLUSIONS •
The
o rig in a l
p u rp o se , o f
th is
s tu d y
w as
d a tin g
te c h n iq u e
th a t
c o u ld
be
h y d ra tio n
d e p o s its
th a t
c o n ta i n e d d e t r i t a l
w e re i n v e s t i g a t e d .
o b s id ia n .
to
d e v e lo p
used
to
an
d a te
Two t y p e s o f
o b s id ia n
Q u a te r n a r y
fie ld
The f i r s t was a g ro u p o f f l u v i a l t e r r a c e s
s e ttin g s
c u t by t h e
a n c e s t r a l M a d is o n .R iv e r n e a r W est Y e llo w s to n e , MT in . p o s t - P i n e d a l e t im e .
H y d ra tio n
rin d s
d e te r m in e i f i t
w e re
e x a m in e d
fro m
th e
m odern
s tr e a m
in
o rd er
to
s e r v e s as. a n a p p r o p r i a t e a n a lo g f o r t h e s tr e a m t h a t c u t
th e te r r a c e s .
I t was fo u n d t h a t t h e m odern s tr e a m p o s s e s s e s s i g n i f i c a n t ­
ly
th ic k n e s s ,
m ore z e r o
c o n c lu s io n
th a t
T h e refo re,
th e
rin d s
re w o rk in g
te rra c e s
th a n
does
s h o u ld
th e
te rra c e s
occur
in
p o ssess
w h ic h
le a d s
th e . f lu v ia l
u n iq u e
and
to
th e
e n v ir o n m e n t.
c h a ra c te ris tic
h y d r a t i o n r i n d t h i c k n e s s e s t h a t c a n be u s e d t o d e te r m in e t h e i r a g e s . Be­
c a u s e r i n d s o f s e v e r a l d i f f e r e n t t h i c k n e s s e s on i n d i v i d u a l
a ls o
fo u n d i n
e n v ir o n m e n t.
t h e m odern s t r e a m , . o n ly p a r t i a l
T h is i n d i c a t e s
g r a i n s w e re
r e w o rk in g o c c u r s i n t h i g
t h a t e a c h n a t u r a l l y w o rk ed . O b s id ia n p e b b le
c a n p o t e n t i a l l y r e c o r d s e v e r a l r e w o rk in g e v e n t s .
E x a m in a tio n
O b s id ia n
Sand P l a i n
appear to
th is
of
s ite .
p e b b le s
s a m p le d
( T e r r a c e .. TO)
a f f e c t th e r a te
The a g g r e g a t e
2 0 'em i n c r e m e n t s
in d ic a te s
of h y d ra tio n
d a ta
at
in
th a t
s o la r
rin d
s a m p lin g l e v e l s
h e a tin g
d id
the- u p p e r few d e c im e te r s
from T e r r a c e TO a l s o
O b s id ia n Sand P l a i n m ig h t d a te from s e v e r a l p e r i o d s
o f th e
fro m
in d ic a te s
th e
not
at
th a t
th e
of d e p o s itio n .
A ll
e x c e p t f o r t h e 8 0 -1 0 0 cm l e v e l p o s s e s s a s t r o n g
s i g n a l a t a b o u t 6 .5 m ic r o n s .
The lo w e r l e v e l h a s
s tro n g
peaks a t
82
a b o u t 13 an d 22 m ic r o n s w h ic h p r o b a b ly d a te fro m B u l l L ak e r e w o rk in g and
o rig in a l
c o o lin g
c ra c k s
f lo w . T h e r e f o r e i t
is
a s s o c ia te d w ith
t h e em p la ce m e n t o f an o b s i d i a n
c o n c lu d e d t h a t t h e O b s id ia n Sand P l a i n d a te s fro m
a t l e a s t two p e r i o d s o f d e p o s i t i o n a t t h i s s i t e .
T e r r a c e s T l th r o u g h T4 h a v e a p ro m in e n t r i n d
m ic r o n s ,
s ig n a l
at
a b o u t 6 .5
i n d i c a t i n g t h a t th e y w e re c u t i n a s h o r t e r p e r i o d o f tim e th a n
th e te c h n iq u e
can d is c e r n .
Two m e th o d s w e re
used, t o
o b ta in
an age f o r
t h e t e r r a c e s . The f i r s t w as t o u s e a r i n d v a l u e o f 6 .5 + 0 .5 m ic ro n s and
th e c a l i b r a t i o n c u rv e o f P i e r c e a n d o t h e r s
2 0 ,0 0 0 + 3000 y e a r s .
c o u p le d
w ith
1 .4
°C.
The se c o n d m eth o d w as t o
h y d ra tio n
c a l c u l a t e d by M ic h e ls
ra te
c o n s ta n ts
B o th o f
th e s e
ages
a re
50 y r s B .P . u se d by N ash (1984) i s
young.
It
im m e d ia te ly
is
upon
fo r
th e
h y p o th e s iz e d
re tre a t
th e
same r i n d v a l u e
O b s id ia n
h y d ra tio n
C liff
flo w
te m p e r a tu r e
of
an ag e o f 1 5 ,5 2 0 + 2480 -2 3 0 0 f o r t h e
o ld e r
(1984) f o r t h e . t e r r a c e s . H ow ever, i f
to o
use
(1 9 8 5 ) and an e f f e c t i v e
The s e c o n d m eth o d y i e l d s
te rra c e s .
(1976) w h ic h y i e l d s an a g e o f
th a n
th o se
c a lc u la te d
by N ash
t h e c a l i b r a t i o n 1^C d a t e o f 7 ,1 0 0 +
to o young, h is t e r r a c e a g es a re a ls o
th a t
te rra c e
o f maximum
f o r m a ti o n w as a c c o m p lis h e d
P in e d a le
ic e
fro m
th e
m o u th
of
M ad iso n Canyon.
The s e c o n d f i e l d s e t t i n g i n v o lv e d r a i s e d s h o r e l i n e s o f p o s t - g l a c i a l
Y e llo w s to n e L a k e . The s h o r e l i n e s a l s o
a l l have s im ila r r in d
th ic k n e s s e s
t o one a n o t h e r . A r i n d v a l u e o f 5 .5 m ic r o n s c o u p le d w i t h h y d r a t i o n r a t e
c o n s ta n ts
fo r
t h e O b s id ia n
C liff
flo w
h y d r a t i o n t e m p e r a t u r e o f 1 .0 0 C y i e l d s
th e la k e s h o r e s .
C o n s id e r in g
th a t
a ll
( M ic h e ls ,
1985)
an d an e f f e c t i v e
an ag e o f 1 2 ,2 7 0 +2330 - 2 1 3 0 f o r
d a te d
p o s t-g la c ia l
t h e Y e llo w s to n e L ake b a s i n a r e y o u n g e r th a n a b o u t 9 k a ,
s h o re lin e s
i t is
in
c o n c lu d e d
83
th a t
th e
rin d
r e w o rk in g
s ig n a l
e v e n t.
It
a s s o c ia te d
is
w ith
h y p o th e s iz e d
th e
s h o re lin e s
th a t
th e
rin d s
d a te s
a p re v io u s
on t h e
s h o re lin e s
d a t e fro m l a t e s t i 'i n e d a l e r e w o r k in g .
R ew orking p r o c e s s e s i n t h e f l u v i a l e n v iro n m e n t d i f f e r fro m t h o s e i n
th e
beach
e n v ir o n m e n t
f r a c t u r e w h e re a s t h e
s tu d y
in
th a t
th e
d o m in a n t
d o m in a n t p r o c e s s
p ro ce ss
on b e a c h e s
r i n d s w e re m e a s u re d o n ly on f r a c t u r e d
is
in
s tre a m s
a b ra s io n .
is
In t h i s
s u rfa c e s b e c au se rin d s
on
a b r a d e d e d g e s w e re d i s c o n t i n u o u s an d o f v a r y i n g t h i c k n e s s . The t e c h n i q u e
of
m e a s u r in g
rin d s
o n ly
on
f ra c tu re d
su rfa c e s
th e re b y
e x c lu d e d
m o st
r i n d s t h a t w e re re w o rk e d i n t h e b e a c h e n v ir o n m e n t.
c H y d r a tio n r a t e i s d e p e n d e n t on t e m p e r a t u r e a n d t h e c h e m i s tr y o f t h e
g la s s .
B e c a u s e c h e m i s tr y v a r i e s w i t h i n a n d b e tw e e n o b s i d i a n f lo w s , r a t e
w o u ld
a ls o
be
e x p e c te d
to
v a ry .
T h e refo re,
it
is
not
n e c e s s a rily
a p p r o p r i a t e t o u s e a s i n g l e g ro u p o f h y d r a t i o n r a t e c o n s t a n t s d e te r m in e d
fro m
a
s a m p le s
s in g le
s a m p le
w ith o u t
c a lc u la tin g
to
c a lc u la te
re c o g n iz in g
h y d ra tio n
ra te
ages
th is
c o n s ta n ts
fo r
a rtifa c ts
and
g e o lo g ic a l
l i m i t a t i o n * H ow ever,, t h e
fo r
e v e ry
s a m p le
to
cost
of
b e d a te d
is
p r o h i b i t i v e l y e x p e n s iv e .
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v e r y a p p r o p r i a t e f o r d a t i n g f l u v i a l re w o rk in g e v e n ts b u t d o e s n o t a p p e a r
t o b e a p p l i c a b l e t o d a t i n g m a t e r i a l re w o rk e d i n t h e l a c u s t r i n e e n v i r o n ­
m e n t.
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c a n a l s o b e f o l l o w e d , w i t h m in o r a d a p t a t i o n s ,
d a t e g l a c i a l f e a t u r e s a s h a s b e e n d o n e b y P i e r c e an d o t h e r s
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( 1 9 7 6 ). T h is
Q u a te rn a ry
84
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sand
APPENDICES
APPENDIX A
SAMPLE.PREPARATION PLOW- CHART
92
F i g u r e 24 - Flew c h a r t f o r sam ple p r e p a r a t i o n p r o c e d u r e s .
Air dry
Sieve 2- 4
mm size
Select 50
grai ns
Prepare grinding
slu rry 3 I grit
( WCA I 5T) to
water Should be
like syrup
Grind mounted slides
until half the thickness
of grains is removed
Wash and air
dry
Dry slides
Heat Canada Balsam
on eight labeled
slides for 3 minutes
at 200 C
Place six grains
on each slide and
cover with more
balsam
Heat for three
Cool slides
Place eight new,
labeled slides
on hot plate
(label down)
Place mounted slides on
top of new slides on hot
plate with ground grai n
surfaces flush against
new slides
Heat for two
minutes
Check to see if top slide
can be lifted without ,
disturbing qrains
Check hardness of
balsam
Grai ns
are lifted
S lig h tlij\
softer than thum
Lift off
upper slide
^ \n a il
93
F i g u r e 24 -
(co n tin u ed ).
Place more
balsam on
grains
Arrange grains
so they will fit
under a cover
slip
, Heat for two
Tl minutes
Cool slides
Check hardness
of balsam
/ Slightly
softer than
\ thumbnail
Grind slides until
grains can be seen
through
(about 0 03 mm)
Rinse and
dry slides
Place slides
on hotplate
Place small amount
of additional balsam
over grains
Place cover
slip over
grai ns
Heat for one
minute
Cool slides
94
APPENDIX B
HYDRATION' RIND MEASUREMENT FLOW CHART
95
F i g u r e 25 - Flew c h a r t f o r h y d r a t i o n r i n d m e a s u r e m e n t.
Calibrate image
Splitting eyepiece with
stage micrometer after
Michels and BePrich (19 7 1 )
/
smooth
edge of grain at
Jeast 0 15 mm
^ \long
Obtain formation
constant (fm) after
Michels and Bebrich
(1 9 7 1 )
^
Edge of
grain_L to micro­
scope stage
^
Draw diagram of slide
showing grain location
Rind present
View slide with 10 x
objective for a total of
I S O x d S x eyepiece)
/ /
h gdration\.
^ f r o n t parallel to
edge of grain and X to
stage
Select nnd for
measurement
Record
'O" nnd
96
F i g u r e 25
(co n tin u ed ).
Record zero shear
Designate A
Turn knob on eyepiece
clockwise until
image is exactly split
Record maximum shear
Designate B
Turn knob counterclock­
wise past zero shear until
image is exactly split
Record minimum shear
Designate C
Compute
( B- C) / 2
Record in notebook as
hydration rind
measurement
97
■APPENDIX C
CHEMICAL ANALYSES OF OBSIDIAN GRAINS
98
T ab le 7.
C hem ical a n a l y s e s o f d e t r i t a l b e a c h p e b b l e s fro m t h e B r e e z e
P o in t a re a . S h o re lin e d e s ig n a tio n s a re in p a r e n th e s is . A ll
v a lu e s a r e e x p re s s e d as % / w e ig h t ( a f t e r M ic h e ls , 1988).
Specim en No.
Ns^O
4 5 6 -L 8 7 -1 3 C -1
4 5 6 -L 8 7 -1 5 B -1
4 5 6 -L 8 7 -1 7 C-I
4 5 6 -L 8 7 -1 5 B -2
456-L 87-15D
4 56-L 87-15E
4 5 6 -L 87-15A -3
456-L 87-16A
4 5 6 -L 8 7 -1 7 B -1
456-L 87-16B
45 6 -L 8 7 -1 3 E
4 5 6 -L 8 7 -1 7 C -2
4 5 6 -L 8 7 -1 7 B -2
4 5 6 -L 8 7 -1 3 C -2
4 5 6 -L 8 7 -1 7 B -3
456-L 87-14B
456 -L 8 7 -1 5 A -1
4 5 6 -L 8 7 -1 5 A -2
456—L8 7—I 7A -I
4 5 6 -L 8 7 -1 4 D -2
456 -L 8 7 -1 5 C
456-L87-14A .
456—l 87—14D—I
4 5 6 -L 8 7 -1 7 B -4
(S I)
3 .5 0
5 .2 3
(S4) 3 . 3 5
5 .2 3
(S5)
3 .2 4
5 .3 7
( S4) 3 . 4 0
5 .2 4
(S4)
3 .3 4
5 .5 9
(84) 3 . 1 8 . 5 . 5 4
(84) . 3 .4 6
5 .2 1
(S3) 3 . 4 5
5 .3 3
(S5)
3 .5 9
5 .1 6
(S3) 3 . 5 3
5 .2 2
( S I)
3 .3 8
5 .4 4
(S5) 3 . 3 5
5 .5 1
(S5) 3 . 5 4
5 .3 1
(S I)
3 .4 6
5 .2 4
(85)
3 .5 2
5 .5 6
(S2) 3 . 5 2
5 .2 6
(S4)
3 .4 3
5 .2 6
(84) 3 . 4 5
5 .3 4
(S5)
3 .2 1
5 .5 0
(S2)
3 .3 8
5 .2 6
(S4)
3 .4 4
5 .1 9
(S2) 3 . 3 9
5 .2 0
(82)
3 .4 3
5 .2 2
(85) 3 . 3 8
5 .4 0
KgO
Fe 2 0 S 1
CaO
MgO
1 .4 1
1 .3 9
1 .2 8
1 .4 9
1 .3 8
1 .3 9
1 .4 4
1 .4 7
1 .4 8
1 .3 7
1 .3 8
1 .4 4
1 .4 7
1 .4 6
1 .5 4
1 .4 8
1 .4 2
1 .4 6
1 .4 3
1 .4 1
1 .4 1
1 .4 1
1 .3 8
1 .4 8
0 .4 6
0 .4 0
0 .4 1
0 .4 3
1 .0 5
0 .4 7
0 .4 0
0 .4 1
0 .4 8
0 .4 3
0 .4 4
0 .4 9
0 .4 4
0 .4 7
0 .0 8
0 .0 8
0 .0 8
0 .0 8
1.02
0 .5 0
0 .4 6
0 .5 5
0 .4 9
0 .4 6
0 .5 0
0 .4 8
0 .5 6
0 .5 0
0.12
0 .0 8
0 .0 7
0 .0 7
0 .0 9
0 .0 8
0 .0 8
0 .0 9
0 .0 8
0 .0 9
0 .1 4
0.12
0 .0 9
0 .1 3
0.10
0 .0 9
0.10
0.11
0.12
0.10
S o u rc e
A s t e r Creek- f l o w
A s t e r C reek f lo w
A s t e r C reek f lo w
A s t e r C reek f lo w
U n id e n t, ty p e A
U h id e n t. ty p e B
A s t e r C reek f lo w
A s t e r C reek f lo w
A s t e r C re e k f lo w
A s t e r C reek f lo w
A s t e r C reek f lo w
A s t e r C re e k f lo w
. A s t e r C reek f lo w
A s t e r C reek f lo w
U n id e n t, ty p e A
A s t e r C reek f lo w
A s t e r C reek f lo w
A s t e r C re e k f lo w
U n id e n t. type B
A s t e r C reek f lo w
A s t e r C reek f lo w
A s t e r C reek f lo w
A s t e r C reek f lo w
A s t e r C reek f lo w
T a b l e 8 . Chem ical a n a l y s e s o f O b s i d i a n C l i f f o b s i d i a n . A l l v a l u e s a r e
e x p r e s s e d ■ a s % / w e i g h t ( A f t e r F rie d m a n and L ong, 1976;
M ic h e ls, 1985).
S i°2
AI 2 O3
NagO
K2O
Fe2 03 T
CaO
MgO
7 7 .1
7 6 .7
1 2 .1 4
1 2 .5 0
3 .9 2
3 .3 0
5 .0 7
4 .6 0
1 .2 7
0 .4 3
0 .3 8
0 .4 8
0 .0 4
0 .0 9
TiO 2
0 .0 9
0 .0 7
99
APPENDIX D .
RIND MEASUREMENT DATA FOR INDIVIDUAL SAMPLING
LEVELS FOR TERRACE TO
100
T a b l e 9 . R in d m e a s u re m e n t d a t a f o r i n d i v i d u a l s a m p l i n g l e v e l s f o r
T e r r a c e TO
0 —2 0 cm
2 0 -4 0
4 0 -6 0
1.86
4 .0 0
4 .0 0
4 .1 1
4 .2 3
4 .6 3
4 .6 9
4 .7 4
5 .0 3
5 .2 6
5 .9 4
5 .9 4
6 .1 7
6 .2 3
6 .2 9
2 .3 4
3 .7 1
4 .0 6
4 .8 0
4 .9 1
5 .6 0
5 .6 6
5 .6 6
5 .7 1
5 .8 9
5 .9 4
6 .0 6
6 .1 7
6 .5 1
2 .5 1
2 .6 3
2 .9 1
3 .1 4
3 .2 0
3 .5 4
3 .6 6
3 .7 7
4 .5 1
4 .7 4
4 .9 1
5 .2 0
5 .4 3
5 .8 3
6 .2 3
6 .3 4
7 .5 4
7 .6 6
8 .0 6
8 .0 6
8 .3 4
8 .5 7
9 .0 3
9 .1 4
9 .3 1
1 2 .4 6
1 2 .9 1
1 3 .2 6
1 3 .4 9
1 5 .6 0
2 2 .8 0
6.86
6.68
7 .2 6
7 .2 6
7 .7 1
8 .0 6
8 .5 7
9 .4 3
9 .4 9
1 0 .7 4
1 1 .1 4
1 1 .4 9
1 2 .3 4
1 4 .5 1
1 7 .6 0
1 9 .5 4
6 .7 4
6 .9 1
7 .2 0
7 .3 7
7 .4 3
7 .4 9
8 .0 6
8 .1 7
9 .1 4
9 .1 4
9 .7 7
1 1 .2 6
1 1 .3 1
1 2 .0 6
1 3 .0 9
1 4 .6 9
1 5 .1 4
1 5 .6 6
1 9.43
2 1 .2 6
22.86
2 3 .2 6
. 60-80
8 0 -100
4 .2 3
4 .5 7
4 .6 9
4 .9 7
5 .0 9 '
5 .2 6
5 .2 0
5 .4 9
5 .8 9
6 .0 6
. 6 .0 6
6 .7 4
2 .9 1
5 .6 6
6 .3 4
6 .5 7
7 .9 4
8 .6 9
1 0 .2 3
1 0 .4 0
1 2 .2 3
1 2 .5 7
1 2 .8 0
1 3 .8 9
1 4 .4 0
1 4 .5 1
1 4 .9 7
15.4 3
2 0 .2 3
6.86
6 .9 7
7 .1 4
7 .4 3
7 .7 7
8 .5 7
8 .9 1
9 .0 3
9 .4 4
11.66
12.00
1 2 .3 4
1 2 .9 1
1 3 .3 7
1 4 .1 7
1 4 .9 7
1 5 .4 3
1 6 .1 1
1 8 .0 0
2 3 .7 7
2 3 .7 7
20.86
2 0.97
21.20
2 1 .8 3
22.11
2 3 .0 3
2 3 .8 3
2 6 .0 6
2 6 .6 3
2 8 .7 4
.
l . o
i
APPENDIX E
RIND MEASUREMENT DATA FOR TERRACES
T l .THROUGH TA AND THE MODERN STREAM.
102
T a b l e 10. H y d r a t i o n r i n d m e a s u r e m e n ts f o r T e r r a c e s T l t h r o u g h TA and
t h e m odern s tr e a m ,.
Tl
T2
T3
0
0
0
0
2 . AO
3 . A3
A .11
A.3A
A.3A
A .80
A .97
5 . IA
5 .2 6
5.9A
3 .2 6
3.A 9
A. 23
A. AO
A .57
A .57
A .74
4 .8 0
4 .8 0
5 .0 9
5 .2 0
5 .2 0
5 .3 1
5 .4 3
5 .4 9
5 .8 3
5 .9 4
6 .0 6
6 .1 7
6 .2 3
6 .2 3
6 .2 9
6 .3 4
6 .3 4
6 .4 0
6 .5 7
6 .8 0
6 .8 0
6.00
6 .1 7
6 .1 7
6 .2 3
6 .2 3
6 .2 9
6 .5 7
6 .7 A
7 .2 6
7 .3 7
7 .4 3
7.5A
7 .6 0
7 .8 3
7 .8 9
7.9A
8 .0 6
8.11
8 . AO
8 .6 9
8 ,9 7
8 .9 7
9 .0 3
1 0 .2 9
1 0 .6 3
10.86
1 1 .0 9
1 1 .0 9
1 1 .0 9
1 1 .3 1
11.5A
1 1 . 5A
11.66
1 1 .8 9
1 2 .1 7
6.86
6.86
6 .9 7
7 .0 9
7 .4 9
7 .7 7
7 .8 3
8 .0 6
8.11
8 .1 7
8 .2 3
8 .6 9
9 .0 9
10.00
1 0 .4 6
1 0 .6 9
11.20
TA
0
0
4 .2 3
4 .4 0
4 .0 0
4 .4 6
4 .3 4
. 4 .5 1
4 .6 3
4 .7 4
. 4 .6 9
4 .8 0
4 .9 1 •
4 .9 7
5 .4 9
5 .0 3
5 .6 0
5 .1 4
5 .7 1
5 .2 0
5 .8 3
5 .2 0
5 .8 9
5 .2 6
6.00
5 .3 1
6 .0 6
. 5 .3 1
6 .2 3
5 .3 1
6 .2 9
5 .3 7
. 6 .4 0
5 .5 4
6 .4 6
5 .6 0
6 .5 1
5 .7 1
6 .6 3
5 .7 1
6 .7 4
5 .8 3
6 .8 0
6 .0 6
6 .8 0
6 .1 7
.7 .1 4 .
6 .4 0
7 .1 4
6 .6 3
7 .2 0
6 .8 0
7 .2 0
6 .9 1
7 .5 4
7 .0 9
7 .6 6
7 .0 9
7 .7 1
7 .2 0 .
7 .7 1
7 .2 6
8.11
7 .4 3
8 .3 4
7 .4 3
8 .5 7
7 .5 4
9 .0 3
7 .6 0
9 .1 4
7 .6 6
9 .3 1
7 .6 6
9 .5 4
7 .7 1
. 1 0 .0 6
7 .7 7
1 0 .0 6
7 .8 3 .
10.86
7 .8 9
1 1 ,0 9
8.11
1 1 .2 6
8 .4 6
1 1 .3 7
8 .9 1
1 1 .9 4
9 .1 4
' 1 2 .3 4
9 .2 6
1 2 .5 1
1 0 ,; 06
Modern
0
0
4 .4 6
5 .9 4
6 .5 1
6 .5 1
6 .6 9
6 .7 4
6 .9 7
7 .3 1
7 .5 4
8 .0 6
'
.
8.11
8 .4 0
8 .4 6
8 .4 6
9 .0 3
9 .0 9
9 .2 0
9 .2 6
9 .3 1
9 .8 9
10.00
1 0 .2 9
1 0 .4 0
1 1 .2 6
1 1 .3 7
1 1.43
11.66
1 1 .7 1
1 1 .7 7
1 1 .8 9
1 2 .2 3
1 2 .5 1
1 2 .6 3
1 2 .6 9
1 2 .7 4
1 3 .0 9
1 3 .3 1
1 3 .7 1
1 4 .6 3
1 5 .2 0
1 5 .4 3
1 5 .4 9
1 5 .6 0
1 6 .2 3
1 6 .2 9
.
103
T ab le 10.
(co n tin u ed ).
Tl
1 2 .2 3
1 2 .2 9
1 2 .5 7
1 2 .5 7
1 3 .3 7
1 3 .5 4
1 3 .9 4
1 3 .9 4
1 4 .2 9
1 4 .2 9
1 4 .3 4
1 4 .5 7
1 5 .0 9
1 5 .1 4
1 5 .5 4
1 6 .0 6
1 6 .7 4
1 6 .8 0
1 6 .8 6
1 7 .0 3
1 7 .3 7
1 7 .4 9
1 8 .0 0
1 8 .0 0
1 8 .2 9
1 8 .5 1
1 8 .6 9
1 9 .0 9
1 9 .9 4
2 0 .9 1
2 2 .7 4
2 3 .1 4
2 4 .4 6
T2
1 1 .8 3
12.11
1 2 .1 7
1 2 .2 9
1 2 .6 3
1 3 .4 3
1 3 .5 4
1 3 .7 1
1 4 .0 0
1 4 .3 4
1 4 .4 6
1 4 .8 6
1 4 .9 1
1 4 .9 7
1 5 .5 4
1 5 .8 9
1 7 .0 3
1 7 .4 9
1 7 .6 0
1 7 .6 6
1 8 .2 3
1 8 .9 7
1 9 .3 7
1 9 .4 3
1 9 .8 9
2 1 .3 1
2 1 .4 9
2 3 .4 9
2 3 .7 1
3 1 .3 1
3 8 .5 8
T3
1 2 ,6 9
1 3 .1 4
1 3 .2 6
1 3 .5 4
1 5 .3 1
1 5 .6 6
1 6 .0 0
1 6 .7 4 •
1 7 .3 1
1 8 .2 9
1 8 .3 4
.1 8 ,7 4
2 0 .7 4
2 1 .4 9
3 5 .4 3
T4
1 0 .4 0
1 0 .5 1
10.86
1 1 .0 9
1 1 .0 9
12.00
1 2 .0 6
1 2 .2 3
1 2 .7 4
1 2 .8 0
1 3 .0 9
1 3 .0 9
1 3 .4 3
1 5 .4 9
1 5 .5 4
1 5 .8 9
1 5 .9 4
1 6 .1 7
1 6 .8 0
1 6 .8 0
1 7 .4 9 .
1 7 .7 7
1 8 .1 1
1 8 .3 4
1 8 .4 0
1 8 .5 1
1 8 .6 9
1 9 .0 3
1 9 .1 4
1 9 .2 0
1 9 .5 4
20.11
2 0 .2 9
2 1 .0 9
2 1 .8 3
2 2 .6 3
2 3 .4 3
2 3 .4 9
2 4 .0 6
2 5 .3 7
2 5 .4 3
2 5 .7 1
2 6 .6 9
3 6 .6 3
m odern
1 8 .0 6
1 8 .5 1
1 8 .6 3
1 9 .6 0
2 0 .5 7
2 0 .7 4 .
20.86
2 1 .8 3
2 1 .8 9
2 2 .7 4
2 3 .1 4
2 5 .8 3
4 3 .2 6
104
APPENDIX F ■
RIND MEASUREMENT DATA FOR SHORELINES
105
T a b l e 1 1 . R in d m e a s u re m e n t d a t a f o r S h o r e l i n e s SI t h r o u g h S5 a t
Y ello w sto n e Lake.
SI
S2
0
0
0 .
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
.0
0
0
0
0
0
0
0
0
0
0
0
0
2 .7 4
3 .3 1
3 .4 3
3 .7 1
3 .8 3
3 .8 9
3 .9 4
3 .9 4
4 .0 6
4 .0 6
4 .1 7
-0
0
. o .
.
0
0
0
0
0
0
0
0
0
.0
0
0
0
0
0
.3.77
3 .8 9
4 .0 0
4 .3 4
4 .3 4
4 .4 0
4 .4 6
4 .5 1
4 .5 7
4 .5 7
4 .6 9
4 .6 9
4 .8 0
4 .8 0
4 .8 0
4 .9 1
4 .9 1
4 .9 1
4 .9 7
5 .0 3
5 .0 9
5 .2 0
5 .3 1
5 .3 1
5 .3 7
5 .3 7
5 .3 7
5 .4 3
5 .4 9
.
S3
S4
S5
.0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
2.86
3 .2 6
3 .3 1
3 .5 4
3 .8 9
4 .2 9
4 .3 4
4 .7 4
4 .8 0
4 .8 6
4 .9 1
5 .0 9
5 .2 6
5 .3 1
5 .6 0
5 .8 3
6 .2 9
6 .2 9
6 .4 0
6 .5 1
6 .5 7
6 .7 4
6.86
6 .9 1
6 .9 7
7 .0 9
7 .2 0
7 .4 3
7 .6 0
7 .6 6
7 .8 9
7 .8 9
8 .6 9
3 .2 0
3 .3 1
3 .5 4
3 .7 1
3 .8 9
3 .8 9
4 .1 1
4 .2 3
4 .2 9
4 .3 4
4 .5 1
4 .6 9
4 .6 9
4 .6 9
4 .7 4
4 .8 0
4 .9 1
4 .9 1
4 .9 1
4 .9 7
5 .0 3
5 .0 9
5 .0 9
5 .4 9
5 .4 9
5 .4 9
5 .4 9
0
0
0
0
. 0
0
0
0
0
0
0
0
0
3 .0 9
4 .0 0
4 .0 6
4 .1 7
4 .2 3
4 .3 0
4 .6 3
4 .6 9
4 .6 9
4 .6 9
4 .8 0
4 .8 6
4 .8 6
4 .8 6
5 .3 1
5 .3 7
6.00
6.00
6.86
6 .9 1
7 .6 6
1 1 .3 1
1 1 .4 3
1 1 .5 4
1 1 .8 9
1 2.97
1 4 .4 0
1 6 .2 3
1 6 .6 3
1 6 .8 0
1 9 .3 1
1 9 .6 0
1 9 .9 4
106
T ab le 11.
(c o n tin u ed ).
SI
4 .1 7
4 .2 3
4 .2 9
4 .3 4
4 .3 4
4 .4 6
4 .4 6
4 .6 3
4 .6 9
4 .9 1
4 .9 1
4 .9 1
4 .9 7
5 .0 9
5 .1 4
5 .1 4
5 .2 0
5 .3 1
5 .3 1
5 .3 7
5 .4 9
5 .8 3
6 .0 6
6 .0 6
6 .4 6
6 .6 9
6 .6 9
7 .2 0
7 .3 7
7 .5 4
7 .8 9
7 .8 9
7 .8 9
8 .2 3
9 .6 0
9 .6 6
9 .8 9
9 .9 4
1 0 .1 7
1 0 .2 9
1 0 .4 0
1 1 .1 4
1 1 .3 7
1 1 .8 9
1 2 .3 4
1 2 .4 6
1 2 .8 0
1 3 .9 4
S2
~S3
5 .4 9
5 .4 9
5 .4 9
5 .5 4
5 .6 0
5 .7 1
5 .7 1
5 .8 3
5 .8 3
5 .9 4
5 .9 4
5 .9 4
8 .8 0
9 .2 0
9 .9 4
6.00
6 .1 1
6.17.
6 .1 7
6 .2 9
6 .3 4
6 .4 6
6 .4 6
6 .8 6
7 .0 3
7 .0 9
7 .1 4
7 .2 6
7 .4 9
8 .5 1
9 .1 4
9 .3 1
9 .3 1
1 0 .4 0
1 0 .4 0
1 0 .9 7
1 1 .0 9
1 1 .2 6
1 1 .3 7
1 1 .4 9
11.66
11.66
1 3 .0 3
1 3 .0 3
1 3 .1 4
1 3 .4 9
1 4 .1 7
1 5 .4 3
1 6 .4 6
1 6 .4 6
1 6 .8 0
10.11
1 1 .3 7
1 1 .4 3
1 1 .8 9
1 2 .5 7
1 2 .9 7
1 3 .4 9
1 3 .6 0
1 4 .1 7
. 1 4 ;8 0
1 4 .9 7
1 5 .5 4
1 5 .6 0
1 5 .6 0
1 5 .6 6
1 5 .7 1
1 5 .7 1
1 5 .7 7
1 5 .8 9
1 6 .1 1
1 6 .1 1
1 6 .4 6
1 6 .5 1
1 6 .5 7
1 6 .5 7
1 6 .5 7
1 6 .8 0
1 7 .1 4
1 7 .4 3
1 7 .6 6
1 7 .7 7
1 8 .5 7
1 8 .8 6
1 9 .2 0
1 9 .3 1
1 9 .6 0
1 9 .6 6
2 0 .0 6
2 0 .7 4
2 1 .1 4
2 1 .6 0
2 3 .7 7
2 6 .5 1
2 9 .6 0
3 0 .3 4
S4
5 .6 0
5 .8 9
. 6 .3 4
6 .5 7
6 .6 3
6 .9 7
7 .0 3
7 .0 9
7 .5 4
7 .7 7
8 .1 7
8 .9 7
9 .4 9
1 0 .0 6
1 0 .1 7
1 0 .8 0
1 1 .0 3
1 1 .3 1
1 1 .3 1
1 2 .2 3
1 3 .4 3
1 3 .7 1
1 4 .8 6
1 5 .2 6
1 5 .3 7
1 6 .0 0
1 6 .0 6
1 6 .4 0
1 6 .4 6
1 6 .5 7
1 7 .0 3
1 7 .5 4
1 7 .5 4
2 3 .2 6
S5
1 9 .9 4
1 9 .9 4
2 0 .2 3
2 0 .4 6
2 0 .6 9
2 0 .8 0
2 1 .1 4
2 1 .3 1
2 1 .5 4
2 1 .7 7
2 1 .8 9
2 2 .3 4
2 2 .5 1
2 2 .6 3
2 2 .6 3
2 4 .0 0
2 5 .1 4
2 5 .4 3
107
T a b l e 11» ( c o n t i n u e d ) .
SI
1 4 .0 0
1 4 .5 1
21.7.1 .
2 6 .7 4
~S2
1 6 .9 1
1 7 .2 6
1 7 .6 6
2 1 .4 3
2 3 .2 0
. 2 4 .1 1 .
3 0 .0 6
, ••
~S3
”
,
S4
MONTANA STATE UNIVERSITY LIBRARIES
7 6 2 101
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