November 2014
Volume 36, Number 4
62
New Mexico Geology
November 2014, Volume 36, Number 4
November 2014
Volume 36, Number 4
Hydrogeology of Eastern Union County, Northeast
New Mexico
Geoffrey C. Rawling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Additional Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
Author index to New Mexico Geology, volume 36 . . . . . . . . . 82
Subject index to New Mexico Geology, volume 36 . . . . . . . . . 82
A publication of
New Mexico Bureau of Geology and
Mineral Resources,
a division of New Mexico Institute of
Mining and Technology
Science and Service
ISSN 0196-948X
Editors: Gina D'Ambrosio and L. Greer Price
Design & Layout: Stephanie Chavez
Cover photo: © Adriel Heisey
Cartography and Graphics: Leo Gabaldon and
Stephanie Chavez
EDITORIAL BOARD
Dan Koning, NMBGMR
Greg H. Mack, NMSU
Penelope Boston, NMIMT
Barry S. Kues, UNM
Jennifer Lindline, NMHU
Gary S. Morgan, NMMNHS
New Mexico Institute of Mining and Technology
President
Daniel H. López
New Mexico Bureau of Geology and Mineral Resources
Director and State Geologist
L. Greer Price
BOARD OF REGENTS
Ex-Officio
Susana Martinez
Governor of New Mexico
José Z. Garcia
Secretary of Higher Education
Appointed
Richard N. Carpenter
President, 2009–2014, Santa Fe
Jerry A. Armijo
Secretary/Treasurer, 2009–2014, Socorro
Deborah Peacock
2011–2016, Albuquerque
Debra P. Hicks
2013–2018, Hobbs
Israel Rodriguez-Rios
2013–2014, Socorro
Cover Photo
Seneca Creek meanders along the north
edge of Rabbit Ear mesa miles below
Clayton Lake, in northeast New Mexico.
Rabbit Ear Mountain is on the horizon in
this low aerial view to the southwest.
Adriel Heisey is one of the Southwest’s
foremost aerial photographers, known
for his stunning views of the geologic
landscape from above. For over 25 years
he has flown over and photographed
the Southwest’s natural, manmade, and
ancient landscapes. His work has graced
the covers of National Geographic, Natural
History, American Archaeology, and Nature
Conservancy to name just a few. His 10-year
project photographing the Rio Grande from
its headwaters to the Gulf of Mexico, The
Rio Grande: An Eagle’s View, was published
November 2014, Volume 36, Number 4
by WildEarth Guardians in association
with the University of New Mexico Press in
2011. Visit www.adrielheisey.com for more
information about his work.
Over the years Adriel’s photography
has illustrated the geologic landscape of
New Mexico from above for many of the
bureau’s publications. Therefore we thought
it only fitting to have his work front
and center on this printed issue of New
Mexico Geology, which closes out the year.
In 2015 the journal moves fully into the
digital world, bringing with it new avenues
for articles and enriching the readers'
experience by linking to external data.
We’ll also continue to bring more stunning,
interesting, and awe-inspiring images of
New Mexico geology to our covers.
New Mexico Geology
New Mexico Geology becomes an “electronic only” publication as of 2015. Each issue will be available as a free
Pdf download from the New Mexico Bureau of Geology
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e-mail notices when each issue becomes available at:
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Editorial Matter: Articles submitted for publication should
be in the editor’s hands a minimum of five (5) months
before date of publication (February, May, August, or
November) and should be no longer than 20 typewritten,
double-spaced pages. All scientific papers will be reviewed
by at least two people in the appropriate field of study.
Address inquiries to Gina D' Ambrosio, Managing Editor,
New Mexico Bureau of Geology and Mineral Resources,
Socorro, New Mexico 87801-4750; phone (575) 835-5218
Printer: Starline Printing, Albuquerque, NM 87109
Email: nmgeology@nmbg.nmt.edu
Web page: geoinfo.nmt.edu/publications/periodicals/nmg
63
Hydrogeology of Eastern Union County,
Northeast New Mexico
Geoffrey C. Rawling, New Mexico Bureau of Geology and Mineral Resources,
New Mexico Institute of Mining and Technology, Socorro, NM 87801, geoff@nmbg.nmt.edu
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Concerns over groundwater supplies spurred the geologic work
of Baldwin and Muehlberger (1959) and the hydrologic study
of Baldwin and Bushman (1957). Cooper and Davis (1967) contains well data, water levels, and water chemistry for the whole
county. The US Geological Survey (USGS) has been periodically
measuring water levels in selected wells in Union County on
one and five-year cycles since the late 1960s. These data are
available from the USGS’s National Water Information System
(NWIS; http://nwis.waterdata.usgs.gov/nm/nwis/gw, accessed
several times). Since 2007 water levels have been measured
twice annually in these wells by the Northeastern Soil and
Water Conservation District. (NESWCD) Lappala (1973) studied
the geology and hydrology of northeastern New Mexico and
Cree
ee k
II. Previous Work
Peric o
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The economy of Union County is based on ranching and agriculture. Surface water resources are limited, thus development
of groundwater for livestock and irrigation is important and
extensive. Groundwater is derived from the High Plains aquifer,
which is comprised of the saturated sediments of the Ogallala
Formation and subjacent Cretaceous and older formations that
contain potable water and are in hydraulic continuity with the
Ogallala (Gutentag et al. 1984). Concern has grown amongst
county residents over recent large groundwater appropriations,
the sustainability of the water supply for the town of Clayton,
and large water level declines in the region.
This paper presents results of a hydrogeology study in the
east-central portion of Union County (Rawling 2013). The study
covers approximately 650 square miles and includes the county
seat of Clayton and much of the acreage of irrigated agriculture in
the county (Fig.1). Reconnaissance geologic mapping, subsurface
geologic interpretation, new and historic water level measurements in wells, and chemical analyses of a suite of water samples
were integrated to understand the regional hydrogeology. These
data were used to characterize the aquifer system, quantify
water-level changes since 1954, identify groundwater flowpaths,
and assess groundwater age and recharge mechanisms.
64
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UNION
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This paper presents the results of an aquifer characterization study
in east-central Union County, New Mexico. The Ogallala Formation
and upper Dakota Formation together vary from zero to several
hundred feet in thickness and form a complex unconfined aquifer.
Confinement increases with depth in the lower Dakota Formation
and underlying formations. Shale layers form leaky confining beds.
Water level and saturated thickness declines from the mid 1950s to
the present have been significant, and large portions of the Ogallala–Dakota aquifer have been dewatered. Water levels in deep wells
largely recover after irrigation season ends, but the recoveries are
superimposed on a long-term declining water-level trend. Tritium
and 14C analyses from groundwater samples indicate that there
is no significant recharge occurring to the sampled zones of the
aquifer, consistent with the ongoing water level declines. Seepage
velocity calculations are consistent with a recharge model in which
the groundwater was recharged thousands of years ago, tens of
kilometers west of the study area, by rapid infiltration of playa lake
waters and of precipitation on porous volcanic features, lava flows,
and exposed bedrock of aquifer units.
675000
36°40'N
Abstract
103°10'W
1
Oil test
Qal
Kg
*
#
NWIS
Qsu
Kd
$
+
NMOSE
QTb
Kp
GW-8
To
Jm
0
0
5 mi
5 km
Figure 1—Geologic map of the study area. Wells used for geologic interpretations and
fence line (Fig. 3): Oil test wells are from the NMBGMR petroleum database, NWIS
wells are from the USGS National Water Information System database, NMOSE is the
NM Office of the State Engineer, and GW-8 wells are from Cooper and Davis (1967).
Qal=Quaternary alluvium; Qsu=Quaternary surficial and aeolian deposits, undivided;
QTb=Clayton basalt; To=Ogallala Formation; Kg=Graneros shale; Kd=Dakota Formation;
Kp=Purgatorie Formation; Jm=Morrison Formation.
New Mexico Geology
November 2014, Volume 36, Number 4
AGE
PleistoceneRecent
MiocenePliocene
THICKNESS
(feet)
GEOLOGIC FORMATION
Glencairn
Formation
Purgatoire
Formation Kp
Dakota Group
Dakota
Formation
Kd
Lytle
sandstone
III. Methods
Poor.
Very good in sand0–300 ft stone beds, much
dewatering in
shallow levels of
formation. Becomes
confined at depth.
Probably good in
0–120 ft sandstone beds.
Hydrology
Water levels were measured in accessible wells in conjunction
with water sampling in September 2011. From a specific measuring point on each well, depth to water measurements were
made with a steel tape and repeated until the measurement was
within 0.02 feet of an earlier measurement. Unvented water-level
recorders were installed in four unused wells from March 2011
to December 2012 and collected water level and temperature
data at one hour intervals across two irrigation seasons. The data
were corrected for atmospheric pressure variations with hourly
data from a barometer installed in one of the wells. Recorded
data were calibrated to manual steel-tape measurements made
when the wells were visited to download the stored data. Waterlevel data collected from wells by the USGS, the NESWCD, and
the author from the late 1960s to the present were compiled.
Sixteen water samples were collected from wells chosen
based on location, depth, existence of a drillers log, and ease
of access. Field parameters were recorded during well purging,
and sampling was initiated once they had stabilized. Analytical
procedures for general ion and trace metal chemistry, carbon
isotopes, and tritium are described by Rawling (2013). The quality of the chemical analyses was assessed by analyzing blanks,
standards, duplicate samples, and checking ion balances. The
ion balance errors for the analyses were generally within ±5%.
A subset of the sampled well waters were analyzed for tritium
(3H) and carbon-14 (14C) activity and 13C/12C ratios (δ13C) to
determine groundwater residence time. Accuracy of the tritium
analyses is 0.10 tritium unit (TU) (0.3 pCi/L of water), or 3.0%,
whichever is greater. The stated errors, typically 0.09 TU, are one
standard deviation. Carbon isotope analyses are reported as 14C
activity (in percent modern carbon, pMC) and as the apparent
radiocarbon age (in radiocarbon years before present, RCYBP,
where “present”=1950 CE), with an uncertainty of one standard
deviation. No corrections were made for geochemical effects
November 2014, Volume 36, Number 4
MIddle to Late Jurassic
Geology
The geologic map of Baldwin and Muehlberger (1959; Fig.1) was
revised with some additional details from their original air photos, and reconnaissance geologic mapping performed by Zeigler
Geologic Consulting. Available petroleum and water wells logs
were examined. These data and subsurface information from
Baldwin and Bushman (1957), Baldwin and Muehlberger (1959),
and Cooper and Davis (1967), and well information from the
USGS NWIS, were used to map the base elevation and thickness
of the Dakota Formation and the Graneros Shale (see discussion
below) and the Ogallala Formation. From these a subcrop map at
the base of the Ogallala Formation was created. Wellhead elevations were corrected to a modern 10-meter DEM and formation
top and bottom elevations were adjusted accordingly.
Late Triassic
AQUIFER QUALITY
Alluvium, valley fill,
aeolian deposits Qal 0–30 ft Rarely used as
Clayton basalt QTb 20–40 ft an aquifer.
Very good in sand
and gravel in
Ogallala Formation
0–400 ft paleovalleys, but
To
largely dewatered.
Graneros shale
Kg
Late Cretaceous
adjacent parts of Texas and Oklahoma. This report was never
released and was recently rediscovered in the files of the New
Mexico Office of the State Engineer (NMOSE).
USGS research on the High Plains aquifer system (Weeks and
Gutentag 1981; Luckey et al. 1981; Gutentag et al. 1984; Weeks
et al. 1988) provides geologic and hydrologic context for the
Ogallala Formation in the region. Nativ and Smith (1987) and
Nativ and Gutierrez (1989) studied the hydrogeology and geochemistry of the Ogallala Formation and Cretaceous aquifers in
the southern High Plains of New Mexico and Texas. Lucas and
Hunt (1987) contains four papers pertaining to the hydrogeology
of northeast New Mexico (Kilmer 1987; Trauger and Kelly 1987;
Trauger and Churan 1987; Kelly 1987). Kilmer (1987) provided
ranges and average values for well yield, transmissivity, storage
coefficient, and specific capacity for most of the geologic formations in the study area.
Morrison
Formation
Jm
170–
495 ft
Bell Ranch
Formation
20–95 ft
Entrada
sandstone
Triassic
undivided
Good in sandstone
beds, but probably
low connectivity
amongst beds;
mostly confined
except in SW
portion of study
area.
Very good, but
0–50 ft requires deep
wells. Confined.
500+ ft
Figure 2—Schematic stratigraphic column of geologic units in the study area, after
Baldwin and Bushman (1957).
such as water-rock interaction. The 14C activity and differences
among the apparent 14C ages were used as a relational tool to
interpret hydrologic differences between wells.
Hardness data presented in Cooper and Davis (1967) were
recalculated to Ca and Mg concentrations by performing an
inverse-distance-weighted spatial interpolation of Ca/Mg and
Na/K ratios for the new samples, interpolation of these ratios at
each of the historical well locations, and back-calculation of Ca,
Mg, Na, and K concentrations. Radical differences in groundwater
chemistry over time should be evident with this approach, even
though changes in Ca/Mg and Na/K ratios cannot be detected.
IV. Climate and Precipitation
Clayton has averaged 15.2 inches of yearly precipitation from
1896 through 2011 (Trauger 1987; data since 1987 from http://
www.prism.oregonstate.edu/). Most precipitation falls between
April and October during thunderstorms, which can be intense
(Love 2004), localized and short-lived. Yearly precipitation totals
can vary by more than 100% of the average (e.g. 1940–1941;
Trauger 1987). Several prolonged droughts have occurred during
the period of record (1933–1940, 1951–1958, 1973–1980). The period from 2001 through 2011 has had only three years with annual
precipitation at or above the long term average of 15.2 inches,
with 2011 being the sixth driest year on record in Clayton (9.68
inches). Average annual potential evaporation is many times the
average annual precipitation (Farnsworth and Thompson 1982).
New Mexico Geology
65
0
20
40
60
80
100
120
140
160
180
200
220
240
260
280
300
320
340
360
380
400
420
440
460
480
500
520
540
560
580
600
620
640
660
680
700
sandstone
fine
5 miles
siltstone
Ogallala
Formation
Dakota
Formation
Morad #1
Campbell
Ogallala
Formation
Dakota
Formation
Purgatoire
Formation
Herndon #1
Mock
Ogallala
Formation
C
N
N
N
Clayton Basalt
N
Continental #1
Federal Land Bank
Ogallala Formation
Bell Ranch
Formation
Morrison
Formation
Dakota Formation
Graneros Shale
Clayton well #5
Clayton Basalt
Graneros Shale
Dakota
Formation
Purgatoire
Formation
Morrison
Formation
N
N
Entrada Formation
N
C
?
Entrada
Formation
Nunn Hopson #1
0
C
20
40
60
80
100
120
140
160
180
200
220
Ogallala Formation
240
260
280
300
320
340
360
380
Purgatoire Formation 400
420
440
460
480
500
520
540
560
Morrison
580
Formation
600
620
640
660
680
Bell Ranch
700
Formation
720
740
760
?
?
?
11.9 miles
?
Ogallala Formation
?
?
Dakota Formation
?
Morrison
Formation
Purgatoire Formation
1.7 miles1
medium sandstone
cemented sandstone
coarse sandstone
friable sandstone
siltstone, silty ss
conglomerate and very coarse sandstone
fine sandstone
no samples/data
caliche
limestone
mudstone, claystone, shale, silty or sandy clay
fine
N
N
Bell Ranch
Formation
Entrada Formation
Triassic undivided
10.0 miles
conglamorate
coarse
Morrison
Formation
Bell Ranch
Formation
?
?
10.5 miles
siltstone
Morrison
Formation
?
Entrada Formation
Triassic undivided
?
7.9 miles
sandstone
Datum: base of the Dakota Formation
mudstone
Figure 3—Fence diagram, wells shown in inset. #1 Witt and Nunn Hopson #1 wells described by Zeigler Geologic Consulting, other descriptions from Baldwin and Muehlberger (1959).
7.2 miles
mudstone
#1 Witt
?
Bell Ranch
Formation
coarse
conglamorate
?
C
Oil Exploration
#1 Irwin
N
N
N
N
November 2014, Volume 36, Number 4
New Mexico Geology
66
100 feet
4550
ache
k
Ap
C ree
4500
4450
Se neca C
r
48
00
44
00
44
5
45
46
4,000,000
00
44
36°0'N
103°0'W
Ogallala Fm
absent
0
Ogallala Fm
base elevation
0
36°10'N
0
00
40
39
0
00
103°10'W
Kd + Kg
thickness
5 mi
303 ft
5 km
Paleochannel
axis
103°0'W
Dakota Fm
absent
0
Dakota Fm
base elevation
0
5 mi
5 km
0
Figure 4—Extent and thickness of the Ogallala Formation with contours of the base
elevation. Contours are projected where the formation is absent. Axes of paleochannels
at the base of the formation are shown.
November 2014, Volume 36, Number 4
41
Cr
ek
0
ee
k
36°0'N
C
ros
103°10'W
407 ft
Sedan
"
Tr a
mpe
ros
0
430
re
Ogallala Fm
thickness
420
Pin
a
ek
betes C re
Pinabetes Creek
Tram
pe
4600
36°10'N
Sedan
4650
4,000,000
0
430
0
43
00
46
50
reek
rizo C
Car
00
00
43
00
0
00
4350
ek
C a rrizo Cr e
36°20'N
00
36°20'N
46
0
ico C re
ek
45
e ek
4550
48
36°40'N
00
4600
P er
4,025,000
Cr
0
4850
4,025,000
Clayton
"
P erico
45
Apache C reek
00 4
7
Clayton
e ek
36°30'N
4950
Seneca Creek 4650
4800
5000
4,050,000
0
455
4500
46
00
Seneca
"
36°30'N
4,050,000
36°40'N
505
0
5100
4600
4700
ree
pa C k
Corr um
Creek
Seneca
680,000
4900
Co r
660,000
475
0
4950
4900
0
rum
520
51
50
pa
485
0
680,000
5000
660,000
Figure 5—Extent and thickness of the Dakota Formation and Graneros Shale (Kd +
Kg), combined, with contours of the base elevation. Contours are projected where the
formation is absent.
New Mexico Geology
67
660,000
V. Geology
680,000
mpa
C or ru
36°40'N
Cre ek
4,050,000
" Seneca
36°30'N
Sene c a C re ek
k
Apa
c h e Cree
" Clayton
re e k
36°20'N
4,025,000
Peric
oC
"
36°10'N
P
inab e te s
4,000,000
o Cre ek
Ca rriz
Sedan
C
ree
k
Tram
p
ero
s
36°0'N
eek
Cr
103°10'W
103°0'W
To subcrop
To absent
Kg
0
Kg outcrop
Kd
0
5 mi
5 km
Jm/Je
Figure 6—Geology below the base of the Ogallala Formation and mapped outcrops
of the Graneros Shale. See text for discussion. Kg = Graneros Shale; Kd=Dakota
Formation; Jm/Je=Morrison and or Entrada Formations.
68
Union County consists of rolling uplands and nearly level plateaus
dissected by valleys, arroyos, and canyons of the Canadian and
Dry Cimarron River drainages. Other than the main stem streams,
these drainages are dry except during periods of heavy precipitation. The landscape is underlain by nearly flat-lying sedimentary
rocks and lava flows of the Raton–Clayton field (Figs. 1–3).
Triassic sandstones, siltstones and minor limestones and conglomerates are exposed in the valley of the Dry Cimarron River
north of the study area (Baldwin and Muehlburger 1959; Lucas
et al. 1987). These oldest exposed rocks in the county are overlain
with angular unconformity by the Jurassic Entrada Sandstone,
Bell Ranch Formation, and Morrison Formation. The Entrada
Sandstone is a clean quartz sandstone, the Bell Ranch Formation
is siltstone, and the Morrison Formation consists of interbedded
mudstone and siltstone, with locally thick sandstone beds (Figs. 2
and 3). The Entrada and Morrison Formation sandstone beds are
locally important aquifers in Union County.
The nomenclature of Cretaceous rocks in the region is complex. The Lytle Sandstone and Glencairn Formation of Kues
and Lucas (1987) are equivalent to the Purgatoire Formation of
Baldwin and Muehlberger (1959). The Purgatoire name will be
used in this study. The Dakota group encompasses the Purgatoire
Formation plus the overlying Dakota Formation (Fig. 2; Baldwin
and Muehlberger 1959). Cretaceous rocks include interbedded
sandstones, siltstones, shales and minor coal of the Dakota and
Purgatoire Formations, and fossiliferous sandstones, shales and
limestones of the Purgatoire Formation and Graneros Shale. All of
the Cretaceous sandstones are important aquifers in Union County.
Post-Cretaceous erosion resulted in several hundred feet
of relief between river valleys, which locally cut through the
Dakota Group into Jurassic rocks, and intervening uplands. This
landscape was buried by the Miocene to early Pliocene Ogallala
Formation, composed of conglomerate, sandstone and siltstone
(Frye et al. 1978; Pazzaglia and Hawley 2004). The Ogallala
Formation generally has conglomerate and coarse sandstone at
channel bases and finer-grained aeolian sediments on paleo-upland surfaces (Gustavson and Winkler 1988). The Ogallala
Formation is an important aquifer throughout its 174,000 square
mile extent across eight states, including northeast New Mexico
(Gutentag et al. 1984). Mesa-capping basalt lava flows and the
volcanic vents at Rabbit Ear Mountain are from 2.5 to 3 million
years old (Luedke and Smith 1978; Aubele and Crumpler 2001)
and postdate deposition of the Ogallala Formation.
Multiple buried calcic soils at the top of the Ogallala Formation
indicate landscape stability for thousands of years or longer.
Upland surfaces are typically covered by aeolian deposits comprised of sand sheets and small dunes (Fig. 1; Pazzaglia and
Hawley 2004). The major drainages are eroded through these
calcic soils, and are floored with fluvial and aeolian sediments
(Fig. 1), with sparse outcrops of Dakota Formation and Graneros
Shale. The Purgatoire and Morrison Formations are exposed
along Tramperos Creek at the southwest corner of the study
area, beneath a thin layer of Dakota Formation sandstone. The
Morrison Formation sandstones here appear similar to those of
the Dakota Formation (Baldwin and Muehlberger 1959).
Geology of the study area
The combined thickness of the Ogallala Formation and
Quaternary surficial deposits was determined by subtracting the
base of the Ogallala Formation from the ground surface (Fig. 4).
It is reasonable to combine these units as they cannot be reliably
distinguished on well logs, the Quaternary deposits are rarely
saturated, and few wells are completed in them. The ground
surface was interpolated through the contact at the base of the
basalt flows to account for their thickness (Fig. 1).
The base of the Dakota Formation is a persistent sandstone bed
that makes a good reference horizon (Figs. 2 and 3; Baldwin and
Muehlberger 1959). However, most water well logs and tabulated
New Mexico Geology
November 2014, Volume 36, Number 4
4
Seneca
4800
0
500
0
5000
00
Clayton
48
50
0
4
C
ar
ek
e
Carrizo
36°20'N
50
50
46 0
0
46
0
55
Cr
Cree
k
4598
47
0
50
45
4664
eek
r i zo Cr
00
4540
4,000,000
36°0'N
4550
460
0
0
435
4550
outlier
5 mi
5,177 ft
B and B
(1957)
perched
zone
4,323 ft
To underlain
by Kg
5 km
36°0'N
36°10'N
0
445
4,000,000
Entrada
0
B
103°10'W
Water level
Perched
elevation
zone
103°0'W
0
Cre
4400
Water level
elevation
certain
uncertain
Flow
direction
e ros
ek
4400
ek
Cre
4600
mp
a
p
Ogallala
Cretaceous
Morrison
ek
Cre 0
tes 455
eek 0
Cr 455
s
103°10'W
Quaternary
4438
Tr
e ro
A
GW-8 wells
abe
tes
abe
Tr
am
Sedan
Pin
Pin
Sedan
"
44
36°10'N
45
50
4545
435
0
4700
48
50
46
0
0
46
Perico
48
36°20'N
Cree
k
4,025,000
co
50
Pe
ri
49
00
50
4600
4850
4732
45
50
50
Clayton
"
00
46
k
Ap
Cree
470
Apache C reek
e
ach
4650
46
4655
reek
0
485 Senec a
50
49
49
C
4,050,000
r e ek
475
0
4650
47
50
50
48
47
00
00
36°30'N
50
49
00
0
495
00
48
5000
4950
pa
4750
47 0
0
0
5050
36°40'N
510
5000
50
50
00
49
47
C
4823
"
49
00
4848
Seneca
Creek
Co
rr
36°40'N
4900
50
50
47
50
50
50
48
e
Cr
5100
5100
ek
Seneca
4,025,000
680,000
um
a
mp
00
49
4,050,000
rru
00
Co
5100
660,000
36°30'N
680,000
0
85
660,000
certain
103°0'W
0
0
5 Mi
5 Km
uncertain
inferred
deep
5,177 ft
outlier
4,323 ft
Figure 7a—Water level elevations in 1954 with inferred flow lines. Well data (GW-8) are from Cooper and Davis (1967). Outlier wells differ from the contoured intervals by more than
50 feet. 7b. Water level elevations in 1954 showing interpreted zones of perched water, perched zone mapped by Baldwin and Bushman (1957), and areas where Ogallala Formation
is probably underlain by Graneros Shale. Deep, inferred water level contours are shown under perched zones.
November 2014, Volume 36, Number 4
New Mexico Geology
69
495
0
m
50
00
47 50 4549
46
Clayton
UC-2
4658
4564
49
Peri
co
00
Creek
4916
UC-30
UC-33
Cre
ek
4,025,000
UC-31
4597
4954
4950
36°20'N
4,025,000
Creek
4646
Ap a che
Clayton
UC-14
Pe
rico
UC-13
4724
4703
36°30'N
UC-20
UC-3
C r ee k
UC-34
4725
48
UC-15
UC-36
4581
4571
4571
4872
S eneca C reek
36°30'N
Cre e k
Seneca
4551
36°20'N
UC-18
UC-35
A pache
4666
4671
UC-22
UC-23
UC-21
4,050,000
eca
Cr
e ek
4900
Se n
36°40'N
UC-43
00
47
a
mp
rru
o
C
k
UC-4
Seneca
4,050,000
e
re
u
C
pa
680,000
4550
UC-32
Co r r
660,000
680,000
36°40'N
660,000
UC-1
36°10'N
Sedan
UC-38
o
Carriz reek
C
4516
4388
50
4612
44
4294
4409
Kd
Kd
Jm, Je
Jm, Je
_
Kd
Je
43
50
4,000,000
36°0'N
Kd
0
0
5 mi
Cre
To
Chemistry
samples
4444
5 km
Figure 8—Locations of wells with long records of water level measurements and
chemistry samples. “Declining” and “Varied” hydrographs are presented in Figs. 13 and
14. Unit of completion is based on log interpretation or comparison with subsurface
structure contours. To=Ogallala Formation, Kd=Dakota Formation, Jm, Je= Morrison
and/or Entrada Formations. Background image shows extent of irrigated land (circular
fields around center pivot irrigation sprinklers).
ek
4298
103°10'W
Winter 2011
water level
Jm, Je
4300
To
103°0'W
Data
logger
00
Varied water
levels
Tramp
ero
s
0
450
103°10'W
Declining
water levels
4248
4248
4250
UC-5
4342
44
UC-26
reek
k
ee
UC-44
m pe UC-25
ros
CUC-24
r
Sedan
etes C
Pinab
reek
Tr
a
UC-19
70
45
UC-27
etes C
Pinab
4,000,000
4528
UC-7
UC-28 UC-37
4399
00
4648
00
46
4528
36°10'N
UC-7
UC-29
45
0
5
47
UC-9
UC-10
50
48
Creek
Ca r rizo
36°0'N
UC-39
00
4583
103°0'W
Water level
elevation
certain
uncertain
0
0
5 Mi
5 Km
4,964 ft
4,194 ft
Figure 9—Water level elevations in winter of 2011 with data points and inferred flow lines.
New Mexico Geology
November 2014, Volume 36, Number 4
Creek
r
4666
36°40'N
Cor
Figure 10—Water level change between 1954 and 2011. Declines are negative (red)
and are separated from increases (blue) by the blue “line of no change”. Declines in
areas identified as perched zones on the 1954 map (hatched areas in Figure 7b) are
calculated from the perched zone water level. Declines in the regional aquifer beneath
these perched zones are less.
680,000
um
pa
660,000
4671
4,050,000
Seneca
4872
S e neca Creek
4571
4725
4581
4571
4724
4703
C re e k
4646
Apache
36°30'N
4549
Clayton
4658
4564
4597
4954
Perico
4,025,000
4916
Cree
k
36°20'N
4551
4583
4648
4528
4528
zo
C arri
4399
Creek
4516
4388
4612
4294
36°10'N
Sedan
4248
4248
4342
T
ra
mp
e ros
ek
Cre
4298
36°0'N
reek
etes C
Pinab
4,000,000
4409
4444
103°10'W
Winter 2011
water levels
1954 perched
zone
103°0'W
1954 – 2011
water level change
+ 98 ft
November 2014, Volume 36, Number 4
0
0
well information list only “Cretaceous” or “Dakota” as the formation of completion. Base contours for the Dakota Formation
in this study assume that this sandstone was identified correctly
in the examined wells. This probably introduces elevation and
thickness errors, but they are likely on the order of a few tens of
feet at most. The combined thickness of the Dakota Formation and
Graneros Shale (from 0 to 303 ft) was calculated as the elevation
difference between the base of the Dakota Formation and the base
of the Ogallala Formation and Quaternary deposits, undivided
(Figs. 4 and 5).
The Graneros Shale is a potential aquitard. There are insufficient data to accurately define its extent and thickness, but
these can be inferred as follows (Baldwin and Muehlberger
1959; D. Romero, personal communication 2013). Baldwin and
Muehlberger (1959) estimated the maximum thickness of the
Dakota Formation in Union County as approximately 180 ft, and
that of the Graneros Shale as approximately 125 ft Subtracting
180 ft from the thickness of the Dakota Formation and Graneros
Shale, undivided, gives the extent and potential thickness of
the Graneros Shale. Where greater than 125 ft, the Purgatoire
Formation and perhaps sandstones of the Morrison Formation
may have been included with the Dakota in well log descriptions. This calculation is subject to several cumulative errors:
the contoured surface elevations, interpolated from sparse data
of variable quality, and the assumption of constant unit thicknesses. Comparison of the calculated extent and thickness of the
Graneros Shale with mapped outcrops, and well logs in which
the Graneros Shale can be identified with some confidence,
reveals marginal agreement. However, the presence of only a
few feet of shale may be sufficient to partition aquifers. Results
are shown in Fig. 6 with mapped exposures for comparison.
Like the Dakota Formation, the Purgatoire Formation consists
of interbedded sandstones and shales. It is probable that some
of the well logs conflate and mis-identify these different rock
units. Few, if any, wells are completed in the Graneros Shale.
Henceforth, the terms “Dakota Formation” or “Dakota” are used
in the hydrologic discussions in this report, with the understanding that locally, underlying Cretaceous rocks may be included.
The base of the Dakota Formation is lowest east of Sedan and
highest in the northwest corner of the study area (Fig. 5). The
maximum thickness is approximately 300 ft, with most of the
variation controlled by patterns of pre-Ogallala erosion. This is
most notable where the Dakota has been completely eroded and
the Ogallala Formation rests on Jurassic rocks.
Several paleochannels at the base of the Ogallala Formation
are evident (Fig. 4). It has been completely eroded to varying
degrees along the western extents of all the major drainages in the
study area (Fig. 4). Cretaceous and Jurassic bedrock is exposed
or mantled with thin Quaternary deposits in these areas. The
Ogallala Formation is thickest north of Sedan at approximately
400 ft (Fig. 4).
There is no compelling evidence from the subsurface data for
faulting in the study area and no significant faults are exposed
at the surface. Lappala (1973) mapped several normal faults in
the subsurface at the base of the Dakota Formation along Apache
Creek north of Clayton, but this interpretation is questionable to
the author.
5 mi
5 km
- 249 ft
New Mexico Geology
71
680,000
a
660,000
Creek
Co
Cre
ek
a
mp
r ru
36°40'N
Co r r
680,000
36°40'N
um
p
660,000
Seneca
4,050,000
Cr
ee k
Apac
he
Seneca
ache C re ek
Ap
Clayton
Clayton
P erico
36°20'N
36°20'N
k
Cree
Sedan
reek
etes C
Pinab
eek
s Cr
bete
4,000,000
36°10'N
Creek
Pina
4,000,000
rr i z o
Ca
zo
rri
Ca
Sedan
pe
m
Tra
ro s
ek
36°0'N
Cr
e
103°10'W
Extent of
saturated To in
2011
To absent
To unsaturated
103°10'W
103°0'W
To saturated
thickness
change
1954 – 2011
+ 97 ft
0
0
Kd absent
5 Mi
Kd
unsaturated
5 Km
No change in
saturation
Extent of
saturated Kd in
2011
- 128 ft
Figure 11—Change in saturated thickness of the Ogallala Formation (To) from 1954 to
winter 2011. Declines are negative, in shades of yellow in red. “To unsaturated” shows
areas that were never saturated; hatched areas show the remaining extent of saturation
in winter 2011.
72
36°0'N
s
ro
eek
Cr
Tram
pe
Paleochannel
axis
Cr
e ek
36°10'N
Cre
ek
4,025,000
ric
o
4,025,000
Pe
Creek
36°30'N
Cree k
Se n e c a
36°30'N
4,050,000
Seneca
103°0'W
Kd saturated
0
thickness
change 1954 – 2011
0
+ 51 ft
5 Mi
5 Km
-197 ft
Figure 12—Change in saturated thickness of the Dakota Formation (Kd) from 1954 to
winter 2011. Declines are negative, in shades of yellow and red. “Kd unsaturated” shows
areas that were never saturated; hatched areas show the remaining extent of saturation
in winter 2011. Double hatched areas experienced no change in saturated thickness.
New Mexico Geology
November 2014, Volume 36, Number 4
50
UC-18
UC-33
100
UC-35
UC-5
UC-38
Depth to water (ft asl)
150
UC-44
UC-1
200
UC-7
UC-43
UC-9
250
300
350
1965
1970
To
1975
Kd
1980
1985
1990
1995
2000
2005
2010
2015
Jm, Je
Figure 13—Hydrographs from wells that show an overall steady declining trend. Locations shown in Figure 8. To=Ogallala Formation, Kd=Dakota Formation, Jm, Je=
Morrison and/or Entrada Formations
VI. Hydrology
Groundwater conditions
A potentiometric surface based on the 1954 water-level data was
hand-contoured (Cooper and Davis 1967; Figs. 7a and b). A few
outlier water levels are present, some of which are from wells
with much greater depths than their neighbors. The contours
reflect conditions in both the Dakota and Ogallala Formations.
The lowest gradients correlate best with areas of thick Ogallala
Formation, north and south of Sedan (Figs. 4 and 7a), suggesting relatively high transmissivity in the Ogallala Formation (cf.
Kilmer 1987). Two probable areas of perched water were identified
based on the presence of numerous shallow (100 ft) wells, mostly
completed in the Ogallala Formation, with much shallower water
levels than nearby deeper (>200 ft) wells. Smooth contours could
be drawn through these areas connecting water levels defined
by the deeper wells (Figs. 7a and b). The perched zone east of
Clayton was also noted by Baldwin and Bushman (1957).
Groundwater flow is west to east in the northern half of the
study area and northwest to southeast in the southern half.
Geologic causes for local deviations in this pattern are juxtaposition of rock types along erosional contacts (e.g., Ogallala channel
gravels against Dakota Formation or Morrison Formation shales)
and lateral pinchouts of rock types within the Cretaceous and
Jurassic units.
Winter 2011 water levels from wells with long measurement
records (Fig. 8), and a few additional wells measured recently
by the NESWCD, are contoured in Figure 9. Note that 1954
water table map (Fig. 7) is based on hundreds of measurements,
whereas the 2011 map is based on 32. Groundwater flow is still
generally from west to east, but the water level declines result in
November 2014, Volume 36, Number 4
convergent flow into troughs induced by pumping northeast of
Clayton and east of Sedan (Fig. 9).
Water levels declined from 1954 to 2011 (Fig. 10), before and
after major irrigated agriculture began in the study area in 1967
(Lappala 1973), and range up to 249 feet. Locally along the west
margin of the study area water levels have risen up to 10s of
feet. Large declines around Seneca, and directly east of Clayton,
appear to result in part from dewatering of perched zones present in 1954 (Figs. 7b and 10; Baldwin and Bushman 1957). Water
level changes in the deeper regional aquifer beneath these former
perched zones are likely not as large as indicated in Figure 10.
Extent of saturation and saturated thickness have declined
in both the Ogallala Formation and Dakota Formation aquifers
between 1954 and 2011 (Figs. 11 and 12). In 1954 much of the
Ogallala Formation had no saturation at all, and it was rarely
totally saturated. The areas of greatest saturated thickness
corresponded to paleovalleys at the base of the formation (Figs.
4 and 11). The Dakota Formation aquifer has multiple water
bearing zones, the lower of which are partly confined (Rawling
2013). Thus water level declines in some deep wells probably
represent potentiometric surface declines in confined units, and
in shallower wells represent ongoing dewatering of unconfined
aquifer zones.
Representative hydrographs from wells completed in the
major geologic units to a variety of depths show either a fairly
steady decline in water levels over time (Fig. 13), little change,
or a variety of behavior (Fig. 14). Water levels in wells in Figure
13 are declining at 0.8 to 1.2 ft per year, except for well UC-7,
which is declining at 3 ft per year. The declining slopes and the
lack of correlation between hydrograph character, formation, or
well depth suggests water level changes are controlled by the
New Mexico Geology
73
50
U C -13
100
UC- 34
U C -14
Depth to water (ft asl)
UC- 36
UC- 39
150
U C -37
UC- 3
200
U C -2
U C -15
250
300
1965
1970
To
1975
Kd
1980
1985
1990
1995
2000
2005
2010
2015
Jm, Je
Figure 14—Hydrographs from wells showing a variety of water level trends with time. Locations shown in Figure 8. To=Ogallala Formation, Kd=Dakota Formation, Jm,
Je=Morrison and/or Entrada Formations
location, timing, and amount of groundwater pumping. Biannual
measurements since 2007 show that water level recoveries after
irrigation seasons are superimposed on a long-term decline.
Aquifer stratification and confinement
Water levels of adjacent wells completed at different depths suggest that low-permeability beds stratify the aquifer, cause confined conditions, and allow vertical head variations to persist.
Wells UC-27, UC-28, and UC-29 (Fig. 8) display a drop in water
levels (decreasing head) with increasing well depth. Conversely,
confined conditions in the Entrada Sandstone north of Clayton
are shown by higher heads with increasing depth in wells UC-22
and UC-23 (Fig. 8), and large and rapid water level rises in well
UC-3 when nearby wells cease pumping (recorded with a data
logger; Rawling 2013). Just west of the study area, Cooper and
Davis (1967) reported shallow wells (< 300 ft) in the Entrada
Sandstone that had artesian flow during the 1950s. Continuously
monitored water levels in well UC-1 in the Dakota Formation
showed little change over one irrigation season (Rawling 2013),
despite being in an area with abundant irrigation, suggesting
that the water-bearing zone tapped by UC-1 is isolated from
other productive parts of the aquifer.
VII. Groundwater Chemistry
General chemistry
Table 1 summarizes field parameters, general chemistry, and trace
metal data. The sampled waters are of several types (Fig. 15),
and can be separated into three groups (Fig. 16). Sample UC-19
(Group 1), from the Morrison Formation, has nearly 500 mg/l
total dissolved solids (TDS) and a unique sodium–bicarbonate
74
water type. Samples UC-10, 27, and 31, all from the Dakota
Formation, form Group 2, and are characterized by higher chloride (20–30 %) compared to the other samples (5–15 %). Group
3 (wells UC-7, 20– 26, 28–30, and 32) waters are dominantly
Ca-Mg-HCO3 type with secondary Na, Cl, and SO4. These wells
are in the Entrada, Morrison, and Dakota Formations. There is
no trend of TDS or major chemical constituents between formations or with depth.
There have not been any drastic changes in groundwater chemistry over the nearly 60 years since the Cooper and Davis (1967)
data was collected. The majority of the recalculated historical
water analyses resemble Group 3 (Figs. 16 and 17). Waters from
the Ogallala Formation tended to have less Na + K than waters
from the Dakota, but there is much compositional overlap (Fig.
17). Three of four historical outliers resemble well UC-19 (Group
1, Figs. 16 and 17) with high Na, and low Ca and Mg. Like well
UC-19, they are located near Tramperos Creek and derive water
from the Morrison Formation or alluvium just above it (Fig. 15).
The high Na can be explained by cation-exchange as groundwater moves through fine-grained units in the Morrison Formation.
Cation-exchange has been documented in the Dakota Sandstone
aquifer of South Dakota (Swenson 1968), wherein Ca and Mg in
the water are adsorbed on the clay mineral surfaces and Na and
K are released (Hem 1985). Another possibility is mixing with
waters from underlying Triassic rocks, which in the southern
High Plains are characterized by Na–HCO3 waters (Nativ 1992).
Other Morrison Formation waters are in Group 3 and are similar
to waters from the Dakota Formation and Entrada Sandstone.
Age-dating
Natural groundwater is usually a mix of waters recharged at
different times and in different places. Complexities of flow, such
New Mexico Geology
November 2014, Volume 36, Number 4
Figure 15—Water types and age-dating results. Water types (text below well ID) are
based on major ion chemistry and illustrated with Stiff diagrams which are color-coded
for unit of completion. Tritium data (red) are reported as tritium units, 14C data (blue)
reported as uncorrected years before present (1950).
680,000
660,000
UC-32
Ca-Mg-HCO 3
1180 a
p
m
rru
Cr
e ek
36°40'N
Co
UC-22
Ca-Mg-HCO 3
4,050,000
3090
Seneca
0.02
ec
S en a
UC-21
Ca-Mg-Na-HCO 3
UC-23
Ca-Mg-HCO 3
C ree k
36°30'N
UC-20
Ca-Mg-HCO 3
C re e k
A p a c he
Clayton
VIII. Discussion
ic o
Creek
Groundwater flowpaths and mixing
UC-31
Ca-Mg-HCO 3-Cl-SO4
36°20'N
4,025,000
P er
UC-30
Mg-Ca-Na-HCO 3
UC-10
Mg-Ca-HCO 3-SO4-Cl
izo
Carr
UC-7
Ca-Mg-HCO 3
UC-28
Ca-Mg-HCO 3
5610
3950
Pina
Sedan
bete
4,000,000
UC-29
Ca-Mg-HCO 3
36°10'N
950
Creek
4510
0.62
UC-27
Ca-Mg-HCO 3-Cl
eek
s Cr
UC-19
Na-HCO 3
UC-25
Ca-Mg-Na-HCO 3
r am
11620
pe
ro s Cr
0.06
eek
UC-24
Ca-Mg-Na-HCO 3-SO4
T
5370
370
0.02
36°0'N
UC-26
Ca-Na-HCO3-SO 4
103°10'W
103°0'W
0
Tritium
C-14 age in years
as leakage across aquitards and dispersion, result in mixing of
waters of different ages. This results in groundwater ages that
are weighted averages of the ages of the different water fractions
in the sample. Analyzing for basic chemistry, using multiple
age-dating tracers, and having a good understanding of the
geology and physical hydrology of the sampled area is essential
for proper interpretations.
Sampled tritium values range from 0.02 to 0.62 TU (Fig. 15).
All but the highest value (0.62, UC-10) are smaller than the measurement errors, and thus the tritium content is not significantly
different from zero. UC-10 may receive a small component of
modern (< 50 years old) recharge; the other well waters were
recharged prior to 1952, and probably long before then.
Uncorrected 14C ages range from 1,180 to 11,620 years (Fig.
15), and are consistent with the tritium results. In addition to
having distinct chemistry, well UC-19 has the oldest water.
Adjacent wells UC-29 (240 ft deep, Dakota Formation; 3,950 yrs)
and UC-28 (495 ft deep, Morrison Formation; 5,610 yrs) show
an increase in age with depth. However, all of the data together
show a poorly developed trend of increasing age with depth.
5 mi
Hydrogeologic conceptual model
Unit of completion
< 2,000
Dakota
200–4,000
Morrison
4,001–6,000
Entrada
> 6,000
November 2014, Volume 36, Number 4
0
5 km
Stiff Scale
(millequivalents/liter)
Na
Ca
Mg
10 8 6 4 2
Regional groundwater flow is from west to east, tending towards
the southeast in the southern third of the study area. One may
thus expect groundwater ages to increase in this direction, however the 14C age data do not follow this pattern (Fig. 15). Well
UC-24 (300 ft deep, Dakota Formation) has a younger age than
well UC-28 (495 ft deep, Morrison Formation) ten miles to the
northwest, but it may be on a shallower flowpath. Well pairs
UC-29 and UC-24, and UC-10 and UC-28, show ages and depths
increasing to the southeast (Fig. 15). However, waters from these
four wells are of three different chemical types so a flowpath
explanation is probably too simplistic.
The poorly developed trend of increasing age with well depth
may be due to mixing of some component of younger recharge
with older water. This may occur if geologic conditions allow
hydrologic connections of shallow and/or short and deep and/
or long flowpaths at some point between the recharge area and
the discharging well. However, the chemistry of water from well
UC-19 in the Morrison Formation, the oldest sampled water,
argues for a distinct history and it is not likely that the younger
waters are a result of mixing of more recent recharge with water
of this composition. Well UC-19 is shallow (100 ft deep, Morrison
Formation) and the unique water in this area may discharge to
the surface downstream along Tramperos Creek.
Waters of different ages and from different depths may mix
in a pumping well. Many of the irrigation wells in the study
area have multiple and/or long screens which tap several
water-bearing zones at different depths. This can allow mixing
of waters of different age and chemistry during pumping (e.g.,
Jurgens et al. 2014).
Cl
HCO3
SO
2 4 6 8 10 (meq/l)
The water chemistry, age-dating results, and new and historical
water-level data are consistent with the geologic framework of
the study area, and are incorporated into the hydrologic conceptual model (Fig. 18). The aquifer system is laterally extensive and
vertically layered with multiple water-bearing zones formed by
permeable sandstone beds. Flow is subhorizontal and generally
parallel to bedding. Fine-grained Cretaceous and Jurassic units
(Figs. 2 and 3) act as aquitards and inhibit vertical groundwater
New Mexico Geology
75
(CI
e (S
O4 )
UC
-27
UC
Su
lfat
-31 U C -1
0
SO4
0 100
HC
O3 )
ica
rbo
nat
e(
-19
+B
UC
O3 )
O 4)
UC
-31
-10
40
20
Group 2
UC
-27
Ca
UC
rbo
(K)
nat
um
ssi
e (C
ota
gne
e (S
P
)+
40
60
lfat
Group 1
Na
60
80
Su
m(
Mg
)
diu
siu
m(
0
So
Ma
20
0
20
Ca
100
)
Group 2
Group 3
0
80
0
(Mg
100
40
um
Mg
Kd (Dakota)
Jm (Morrison)
Je (Entrada)
esi
20
gn
40
Ma
60
60
)+
+C
hlo
r
Ca
m(
ide
lc iu
80
80
Ca
)
100
100
80
40
60
Calcium (Ca)
C A TIONS
20
0
Na + K
0
CO3+HCO3
20
%meq/l
40
60
Chloride (CI)
A NIONS
80
100
0
CI
Figure 16—Piper diagram illustrating major ion chemistry of sampled well waters. Sample groups are discussed in the text.
flow. Degree of confinement increases with depth, and the
Entrada Formation appears completely confined (Rawling 2013).
Generally similar water chemistry and ages (~3,000 to ~5,600
years) imply some vertical connectivity amongst sandstone
beds, but this is limited to areas where fine-grained beds are
absent. Perturbation of flow patterns by pumping may have
induced leakage across confining beds and explain some of the
variation in water chemistry and poor correlation of groundwater age with depth. Long-record hydrographs suggest both
connectivity amongst some water-bearing zones (Fig. 13) and
compartmentalization of others (Fig. 14).
The distinct, older, Na-HCO3 waters from well UC-19 in the
Morrison Formation do not appear to mix with any of the other
sampled waters in the study area. This may indicate better development of confining beds in this area and/or flowpaths that allow
these waters to discharge to the surface into Tramperos Creek.
Perched water may be present in the Ogallala Formation
where it overlies the Graneros Shale; elsewhere, it is in good
hydrologic connection with the underlying units, especially
along the sand- and gravel-filled paleochannels. Perched zones
that were present in the Ogallala Formation in the 1950s have
been largely dewatered.
Recharge
The large water level declines and dewatering of perched zones
indicate that the amount of water recharged in the study area
has been far less than groundwater withdrawals over the past
50–60 years. The lack of measurable tritium in most wells and
uncorrected 14C ages of thousands of years show that significant
recharge is not occurring within the study area to replenish the
aquifers tapped by the sampled wells. The sampled waters are
thousands of years old and have likely moved a great distance
76
from the recharge area. Regional flow directions are from west
to east and the youngest groundwater age is in the northwest
corner of the study area. Groundwater flows into the study area
at depth from recharge areas to the west.
Groundwaters sampled by Nativ and Riggio (1989) in the
southern High Plains had slightly more enriched isotopic compositions than local precipitation samples by 1–2 ‰ δ18O. Nativ and
Riggio (1989) and Wood and Sanford (1995) concluded that much
of the present recharge to the Ogallala Formation is by focused
(presumably rapid) infiltration of slightly evaporated playa
water. Wood and Sanford (1995) and other studies summarized
by Gurdak and Roe (2010) showed that groundwaters collected
below and downgradient from playa lake basins on the Southern
High Plains have abundant tritium compared to interplaya areas.
Focused recharge through playa bottoms has become the
accepted model for the vast majority of the present recharge to
the Ogallala Formation and the High Plains aquifer, based on
geologic, hydrologic, and chemical evidence (Gurdak and Roe
2010). Estimated recharge by this mechanism ranges from ~0.25
to > 500 mm/yr, whereas recharge in interplaya areas is estimated at most to be 0–0.25 to 2.3–25 mm/yr. It can be assumed that
recharge beneath playas is 1–2 orders of magnitude higher than
in interplaya areas (Falk 2005; Gurdak and Roe 2010).
The sampled waters in the study area were recharged by runoff
water not only in playas, which are abundant in and west of
the study area, but also in flowing drainages floored by porous
and/or fractured sandstones, or precipitation infiltrating highly
porous basalt flows and/or volcanic edifices. Neither of these
two additional potential recharge environments are present in
the southern High Plains where most of the relevant recharge
studies were conducted. More importantly, the sampled well
waters have negligible tritium and 14C ages of thousands of years.
New Mexico Geology
November 2014, Volume 36, Number 4
Assuming that the effects of local recharge and mixing of
waters of different ages are small, the measured groundwater
ages should be indicative of travel times from the recharge area.
Using ranges of transmissivity from Kilmer (1987), hydraulic
gradients and ranges of saturated thickness from this study,
and typical ranges of sandstone porosity (5–30 %), groundwater
flow velocity in the Dakota Formation can be determined by the
following equation:
Thus, while the sampled groundwaters were recharged by
similar processes and at similar rates to those proposed for the
southern High Plains, the sampled waters were recharged thousands of years ago. Recharge in playas, drainages, and on volcanic
terranes is probably ongoing in Union County, yet the amount of
water contributed to the depths of the aquifer system tapped by
the sampled wells is insignificant relative to the amounts being
withdrawn by pumping. This is due to volumetrically small
recharge amounts, large vertical and horizontal travel distances,
and increasing aquifer confinement with depth. The greater the
degree of confinement, the less likely that that local recharge
at the surface will have any affect on the quantity or quality of
water at depth.
The proposed area of recharge extends approximately 80 km
west from the western edge of the study area to eastern Colfax
and western Union Counties (Fig. 19). This is the approximate
location of the surface drainage divide between streams flowing west to the Canadian River and streams in the Ute Creek
drainage, and those flowing east and southeast, south of the
Dry Cimmaron River. Between the study area and this drainage
divide there are abundant outcrops of the Dakota Group, volcanic edifices composed of porous lava and cinders, surficial basalt
flows, and playa lakes (Fig. 19). West of this divide, the Dakota
Group is overlain by the Graneros and Pierre Shales and dips
gently west into the Raton Basin (New Mexico Bureau of Geology
and Mineral Resources 2003). Spatial trends in historical water
chemistry data (hardness as CaCO3 and specific conductivity;
Griggs 1948; Cooper and Davis 1967) between the study area and
the drainage divide do not preclude waters from the near the
divide being the sources of Group 2 and 3 waters (Figs. 16 and
17) in the study area.
vx=
T dh
bne dl
where vx is horizontal seepage velocity (i.e., true groundwater
flow velocity), T is transmissivity, b is saturated thickness, ne is
the effective porosity through which water can flow, and dh/dl is
the average hydraulic gradient. The negative sign indicates that
flow is down the gradient, to the east in this case. When divided
into the approximately 80 km distance given above, the seepage
velocity yields travel times on the order of several thousand
years, consistent with the measured groundwater ages. All of the
variables in this simple calculation vary over factors of two to ten,
but many reasonable combinations yield travel times of the same
magnitude as the ages. Sample calculations are shown in Table 2.
IX. Conclusion
This study incorporates new and historical geologic and hydrologic data to improve understanding of the aquifer system in
east-central Union County. The Ogallala Formation and Dakota
Formation together vary from zero to several hundred feet in
e (C
hlo
O4 )
40
40
lfat
Su
O3 )
(HC
ate
ica
rbo
n
siu
+B
O3 )
O 4)
40
K)
rbo
nat
m(
siu
e (C
s
ota
gne
e (S
+P
40
60
lfat
Group 1
)
Na
60
80
Su
m(
Mg
)
diu
m(
So
Ma
SO4
0 100
Ca
20
0
0
0
80
Ca
)
100
20
Group 3
0
Q/To (Quaternary or Ogallala)
Kd (Dakota)
J (Jurassic undivided)
(Mg
Group 2
20
Mg
um
esi
e (S
gn
Ma
+C
60
60
)+
Ca
rid
m(
lciu
80
80
Ca
I)
100
20
Group 2
100
100
80
40
60
Calcium (Ca)
C A TIONS
20
0
Na + K
0
CO3+HCO3
20
%meq/l
40
60
Chloride (CI)
A NIONS
80
100
0
CI
Figure 17—Piper diagram illustrating recalculated major ion chemistry of well waters from Cooper and Davis (1967). Sample
groupings for new data (Fig. 16) are shown for comparison.
November 2014, Volume 36, Number 4
New Mexico Geology
77
~W
confinement increasing
Center
pivot
irrigation
shale
Not to scale
Recharge area to west
Windmill
perched
water
1954
water table
water table
1954
1954
2011
2011
1954 1954
~E
QT basalt
To
shale
Kd
To
shale
2011
gravel
and
sand
Jm
Kg
gravel lens
shale
Kg
shale
shale
2011
To
Kd
shale
Kd
gravel
and
sand
Jm
Jm
Je
To Ogallala Formation—Siltstone, sandstone, and conglomerate;
coarser in paleovalleys than over ridges of Kd
Kg Graneros Shale
Jm Morrison Formation—Interbedded shale and sandstone, beds
less continuous than in Kd
Je Entrada Formation—Continous sandstone
ˇ Triassic rocks, undivided—low permeability shale
Kd Dakota Formation—Numerous layers of sandstone and shale,
near-continuous sandstone at base
Flow direction
Figure 18—Hydrogeologic conceptual model. Water-level elevations have dropped considerably since 1954 and much of the shallow Ogallala and Dakota Formations have
been dewatered. Irrigation and domestic wells are now on average much deeper than in 1954 and tap lower, at least partially confined, water-bearing zones. Locally, shallow
groundwater still exists in the Ogallala Formation and continues to supply low-yield stock wells. Groundwater flows readily between underlying units and the Ogallala Formation
where permeable sands and conglomerates are juxtaposed.
thickness and form a complex unconfined aquifer. Deeper levels of the Dakota Formation, the Morrison Formation, and the
Entrada Sandstone are confined to varying degrees. Shale layers
form leaky confining beds amongst these units.
Large and widespread water level and saturated thickness
declines from the mid-1950s to the present have resulted in
dewatering of portions of the Ogallala–Dakota aquifer. It is
clear that ground water extraction from all aquifers in the study
area exceeds recharge. Water levels in deep wells recover after
irrigation season ends, but the recoveries are superimposed on a
long-term declining water-level trend.
With one exception, sampled groundwaters are largely
Ca-Mg-HCO3-SO4 waters, and groundwater chemistry has not
changed significantly since the 1950s. Waters from the Morrison
Formation in the southwest corner of the study area have distinct
Na-HCO3 chemistry that can be explained by cation-exchange
processes occurring on clay mineral surfaces. These waters
appear to be isolated by effective confining layers and probably
discharge to surface drainages.
Recharge processes similar to those operative on the southern
High Plains occur in the study area and to the west, yet tritium
and 14C analyses indicate that there is no significant recharge
occurring to the sampled water-bearing zones of the aquifer. This
is consistent with the large and ongoing water level declines.
Seepage velocity calculations are consistent with a recharge model
in which groundwater travels tens of kilometers from recharge
areas west of the present study area. The sampled groundwaters
were recharged thousands of years ago by rapid infiltration of
playa lake waters and of precipitation on porous volcanic features,
lava flows, and exposed bedrock of the aquifer units.
78
Acknowledgments
Many landowners in Union County kindly granted access to
their property and wells. Kate Zeigler performed geologic mapping and assisted with installation of data loggers. Brigitte Felix
assisted with drafting of figures. I thank Barbara and Randy
Podzemney and the staff of the Northeastern Soil and Water
Conservation District, Dave Romero and Steve Silver of Balleau
Groundwater, Inc., and Alan Cuddy of the New Mexico Office of
the State Engineer. Lewis Land, Nathan Myers, and Jesse Roach
provided constructive reviews that improved the paper.
References
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of the Llano Estacado: New Mexico Geological Society 52nd Field
Conference Guidebook, pp. 69–76.
Baldwin, B., and Bushman, F. X., 1957, Guides for the development
of irrigation wells near Clayton, Union County, New Mexico: New
Mexico Bureau of Mines and Mineral Resources Circular 46, 64 pp.
Baldwin, B., and Muehlberger, W. R., 1959, Geologic studies of Union
County, New Mexico: New Mexico Bureau of Mines and Mineral
Resources Bulletin 63, 171 pp.
Cooper, J. B., and Davis, L. V., 1967, General occurrence and quality of
groundwater in Union County, New Mexico: New Mexico Bureau of
Mines and Mineral Resources Groundwater Report 8, 168 pp.
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southern High Plains Aquifer, Cannon Air Force Base, Curry County,
New Mexico, 2004 [M.S. Thesis]: Albuquerque, University of New
Mexico, 82 pp.
New Mexico Geology
November 2014, Volume 36, Number 4
575,000
600,000
625,000
650,000
Colorado
Dr
675,000
y C i m arr
37°0'N
550,000
on
Rive
r
70
Oklahoma
4,075,000
00
78 km
700
0
UNION
Cr
ee
k
n
0
600
Clayton
6000
Texas
Ut
e
n
adia
Can
4,025,000
COLFAX
36°30'N
600
0
4,050,000
Seneca
4,000,000
80 km
Sedan
MORA
104°30'W
HARDING
36°0'N
er
Riv
6000
104°0'W
103°30'W
103°0'W
Volcanic rocks
2011 flow direction
Study area
0
Dakota Group
Drainage divide
1,000 ft contour
0
10 mi
5
5
10
15 km
Figure 19—Regional map with simplified geology (from New Mexico Bureau of Geology and Mineral Resources, 2003) showing the probable recharge
area, which extends from the study area (outlined in red) to the drainage divide in Harding and eastern Colfax Counties. The width of the area is
approximately 80 km..
Farnsworth, R. K., and Thompson, E. S., 1982, Mean monthly, seasonal,
and annual pan evaporation for the United States: NOAA Technical
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160, 32 pp.
Griggs, R. L., 1948, Geology and ground-water resources of the eastern
part of Colfax County, New Mexico: New Mexico Bureau of Mines and
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Gurdak, J. J., and Roe, C. D., 2010, Review: recharge rates and chemistry
beneath playas of the High Plains aquifer, USA: Hyrogeology Journal,
v. 18, pp. 1747–1772.
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Miocene-Pliocene Ogallala Formation, northwestern Texas and eastern
New Mexico: Geology, v. 16, pp. 203–206.
Gutentag, E. D., Heimes, F. J., Krothe, N. C., Luckey, R. R., and Weeks, J.
B., 1984, Geohydrology of the High Plains aquifer in parts of Colorado,
Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, and
Wyoming: U. S. Geological Survey Professional Paper 1400-B, 63 pp.
Hem, J. D., 1985, Study and interpretation of the chemical characteristics
of natural water: U. S. Geological Survey Water-Supply Paper 2254,
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Jurgens, B. C., Bexfield, L. M., and Eberts, S. M., 2014, A ternary age-mixing model to explain contaminant occurrence in a deep supply well:
Groundwater, DOI: 10.1111/gwat.12170, 15 pp.
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Kelly, H. T., 1987, Hydrologic coefficients for the Ogallala aquifer in the
vicinity of Roy, Harding County, New Mexico, in Lucas, S. G. and
Hunt, A. P., eds., Northeastern New Mexico: New Mexico Geological
Society 38th Field Conference Guidebook, pp. 317–321.
Kilmer, L. C., 1987, Water-bearing characteristics of geologic formations
in northeastern New Mexico—southeastern Colorado, in Lucas, S. G.
and Hunt, A. P., eds., Northeastern New Mexico: New Mexico Geological Society 38th Field Conference Guidebook, pp. 275–280.
Kues, B. S., and Lucas, S. G., 1987, Cretaceous stratigraphy and paleontology in the Dry Cimmaron Valley, New Mexico, Colorado, and
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Mexico: New Mexico Geological Society 38th Field Conference Guidebook, pp. 167–198.
Lappala, E. G., 1973, Ground-water hydrology of the northern high plains
of New Mexico: Office of the New Mexico State Engineer unpublished
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Mexico Geological Society 38th Field Conference Guidebook, 355 pp.
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Mexico Geological Society 38th Field Conference Guidebook, pp.
97–117.
New Mexico Geology
79
Parameter
Unit
Mean
Min
Max
Std. Dev.
Temperature
ºC
17.3
14.7
22.4
2.1
pH
pH units
7.5
7.0
8.2
0.3
SC
μS/cm
536
380
800
131
TDS
mg/L
330
233
496
83
Calcium
mg/L
48
7
65
15
Magnesium
mg/L
21
8
44
8
Sodium
mg/L
33
13
165
37
Potassium
mg/L
3.58
2.10
5.80
0.96
Bicarbonate
mg/L
229
185
370
43
Sulfate
mg/L
47
17
110
27
Chloride
mg/L
24
6
77
20
Nitrate
mg/L
13
4
35
8
Bromide
mg/L
0.21
0.075
0.76
0.18
Silicon
mg/L
11.9
5.6
16.0
2.7
Fluoride
mg/L
0.99
0.57
1.60
0.25
Iron
mg/L
0.30
0.033
0.57
0.38
Boron
mg/L
0.11
0.055
0.37
0.078
Barium
mg/L
0.084
0.016
0.14
0.031
Nickel
mg/L
0.0008
0.0006
0.0013
0.0002
Strontium
mg/L
0.81
0.24
1.80
0.33
Zinc
mg/L
0.025
0.0013
0.14
0.040
Table 1— Statistical summary of chemical parameters for sampled wells. “STD” is standard
deviation, “SC” is specific conductance, and “TDS” is total dissolved solids.
Gradient
(dh/dl)
Transmissivity1
(T, gpd/ft)
Transmissixvity
(T, m3/s)
Saturated
thickness2
(b, m)
Effective
porosity
(ne)
Seepage
velocity
T dh(m/s)
vx= bn
Distance (m)3
e
dl
Travel
time4
(yrs)
0.0265
40,000
1.72 x 10-3
104
0.15
2.87 x 10-6
80,000
0.026
35,000
-3
1.51 x 10
104
0.15
2.51 x 10
-6
80,000
1011
0.026
25,000
1.08 x 10-3
104
0.15
1.79 x 10-6
80,000
1416
0.026
10,000
4.30 x 10-4
104
0.15
7.17 x 10-7
80,000
3540
0.026
5,000
-4
2.15 x 10
104
0.15
3.58 x 10
-7
80,000
7079
0.026
1,000
4.30 x 10-5
104
0.15
7.17 x 10-8
80,000
35397
0.0136
35,000
1.51 x 10-3
104
0.15
1.25 x 10-8
80,000
2023
0.026
35,000
-3
1.51 x 10
104
0.075
5.02 x 10
-6
80,000
506
0.026
35,000
1.51 x 10-3
52
0.15
5.02 x 10-6
80,000
506
0.026
35,000
1.51 x 10
104
0.15
5.02 x 10
40,000
506
-3
-6
1
Ranges of transmissivity from Kilmer (1987); original data in units of gallons per day per foot (gpd/ft).
2
Based on estimated saturated thicknesses for Dakota Formation encountered in wells.
3
Distance from western boundary of study area to drainage divide is approximately 80 km, see text.
4
Distance divided by seepage velocity.
5
First six lines illustrate the effect of varying transmissivity within the ranges given by Kilmer (1987).
6
Last four lines illustrate the effect of varying other parameters with constant transmissivity of 35,000 gpd/ft.
885
Table 2— Sample travel time calculations.
80
New Mexico Geology
November 2014, Volume 36, Number 4
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saturated thickness changes, predevelopment to 1980, in the High
Plains Aquifer in parts of Colorado, Kansas, Nebraska, New Mexico,
Oklahoma, South Dakota, Texas, and Wyoming: U.S. Geological Survey Hydrologic Investigations Atlas HA-652, 2 sheets.
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Hydrology, v. 108, pp. 79–109.
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of precipitation events with implications for groundwater recharge,
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the Ogallala aquifer, southern High Plains: Journal of Hydrology, v.
91, pp. 217¬–253.
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eds., The geology of New Mexico: New Mexico Geologic Society, pp.
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Resources Open-File Report 555, 55 pp.
November 2014, Volume 36, Number 4
Swenson, F. A., 1968, New theory of recharge to the artesian basin of the
Dakotas: Geological Society of America Bulletin, v. 79, pp. 163–182.
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G. and Hunt, A. P., eds., Northeastern New Mexico: New Mexico
Geological Society 38th Field Conference Guidebook, pp. 281–284.
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area, Harding County, New Mexico, in Lucas, S. G. and Hunt, A. P.,
eds., Northeastern New Mexico: New Mexico Geological Society 38th
Field Conference Guidebook, pp. 295–315.
Trauger, F. D., and Kelly, T. E., 1987, Water resources of the Capulin
topographic basin, Colfax and Union Counties, New Mexico, in Lucas,
S. G. and Hunt, A. P., eds., Northeastern New Mexico: New Mexico
Geological Society 38th Field Conference Guidebook, pp. 285–294.
Weeks, J. B., and Gutentag, E. D., 1981, Bedrock geology, altitude of base,
and 1980 saturated thickness of the High Plains Aquifer in parts of
Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota,
Texas, and Wyoming: U.S. Geological Survey Hydrologic Investigations Atlas HA-648, 2 sheets.
Weeks, J. B., Gutentag, E. D., Heimes, F. J., and Luckey, R. R., 1988,
Summary of the High Plains regional aquifer-system analysis in
parts of Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South
Dakota, Texas, and Wyoming: U.S. Geological Survey Professional
Paper 1400-A, 39 pp.
Wood, W. W., and Sanford, W. E., 1995, Chemical and isotopic methods
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New Mexico Geology
81
Author index to New Mexico Geology, volume 36
Allen, Bruce D. 3
Bejnar, Craig 48
Chamberlin, Richard 48
Dunbar, Nelia 48
Krainer, Karl 3
Love, David W. 48
Lucas, Spencer G. 3, 25, 48,
Meyer, Grant A. 32
Morgan, Gary 48
Rawling, Geoffrey C. 64
Sion, Brad 48
Thomson, Bruce 42
Vachard, Daniel 3
Watt, Paula Muir 32
Wilder, Matthew 32
Subject index to New Mexico Geology, volume 36
Ancestral Rio Grande (ARG) 48, 49, 54, 57
Cedro Canyon 4
Bernalillo County 3–26
Manzanita Mountains 3, 4, 5
Bell Ranch Formation 68
Desmoinesian 3
Doña Ana County 54
Camp Rice Formation 54
Dakota Formation 64, 65, 68, 71, 77–79
Dakota Group 68
Entrada Formation 68
Entrada Sandstone 65, 68
climatology
Western Regional Climate Center 33
Cretaceous 64, 68, 76
geochemistry
carbon isotope analyses 65
groundwater chemistry 74, 75
groundwater age dating 75
“Group II” pumice 48
Matanza Arroyo obsidian 53
Matanza Arroyo pumice 54
pumice granules 51, 54
Rabbit Mountain obsidian 51, 53
glaciation
cirques 32
Horace Mesa basalt 32
La Mosca Peak 32, 34, 36, 38
Pleistocene (late) 32, 36
paleo-ELAs 32, 33
Mount Taylor 34
Neogene composit volcano 32
San Mateo Canyon 34
Water Canyon 32
“Great Unconformity” 7
Graneros Shale 65, 67, 71, 76
Herrick’s Coyote Sandstone 4
hydrogeology
Clayton 64, 65, 73
Canadian river drainages 77
Dry Cimarron River drainage 77
groundwater flow 75, 76
High Plains aquifer 64, 65, 76, 77
Ogallala–Dakota aquifer 64, 65, 76
Ogallala Formation 64, 65, 76
Union County 64–77
Ute Creek 77
hydrology
groundwater chemistry 74, 75
groundwater ae dating 75
hardness data 65
tritium analyses 65, 75
water sampling 65
Jurassic 76
82
mapping
1:2,500/ArcGIS 49
Madera limestone 4, 5
Mississipian age 4
Manzanita Mountains 3, 4, 5, 7
Manzano Mountains 3, 5
Morrison Formation 68, 78
Miocene 68
Mount Taylor 31
Navajo Nation 31
Ogallala Formation 64–69, 73, 76, 78, 79
paleoclimate
equilibrium line altitude 36, 37
early Pleistocene 54
paleo-ELA 37
paleontology
Abo Formation
Arroyo Peñasco Formation 4
Atrasado (=Wild Cow) Formation 12
bivalves 8, 11
brachiopods 8, 10, 11, 15
bryozoans 8, 11, 12, 15
Bursum Formation 16
Cedro Peak 3
corals 8
crinoids 10, 15
echinoderms 11
foraminifers 11
fusulinids 3, 8,11, 15
gastropods 12
Gray Mesa (=Los Moyos) Formation 8
Kinney Brick Quarry 12
Lucero Uplift 11
Madera Formation
Major Ranch 16
Mammoth jaw 48, 51, 52, 54
Matanza mammoth jaw 48, 49, 50, 55
Manzano uplift 7
Matanza Arroyo 48, 54
oncoids 15
Oscura Mountains 3
Ostracods 12
Priest Canyon 11
phyloidal algae 15
Sandia Formation 7
Sandia uplift 7
trilobites 12, 15
paleosols
Late Pennsylvanian 25
Pennsylvanian 3, 4, 5, 25
Pliocene 68
Pierre Shale 77
Proterozoic basement 7
Quaternary 68, 71
New Mexico Geology
Rio Grande rift 3, 49
Purgatoire Formation 68, 71
Sandia Mountains 3, 4,
Sandoval County
Manzano Mountains 3, 8
Sierra Ladrones Formation 48
Socorro County
Ancestral Rio Grande (ARG) 48, 49, 54
Matanza Arroyo 48, 54
Socorro Basin 57
Socorro Canyon fan 48, 57, 58
soil science
stage III–IV pedogenic carbonates 48, 52
“Group II” pumice 53
stratigraphy
Ancestral Rio Grande (ARG) 57, 58
Atrasado Formation 14
Bursum Formation 14, 19
Cedro Peak 5, 21
Grey Mesa Formation 14
Matanza mammoth 50, 51, 57, 58
Matanza Arroyo 57
Pennsylvanian 5
Sandia Formation Cedro Peak 7, 9
Santa Fe Group 57
Socorro Basin 57
Socorro Canyon fan 57, 58
Tijeras Canyon 3
Tijeras Ranger Station 17
Tramperos Creek 68, 74
Union County 64–77
Clayton 64, 73
precipitation 1896–2011, 65
Sedan 73
Virgilian-age 3
volcanology
Cerro Toledo eruption 48
Rabbit Mountain obsidian 48
Raton¬–Clayton volcanic field 68
November 2014, Volume 36, Number 4
Additional Resources
To provide more accurate and up-to-date information, to better accommodate our online readers, and to
facilitate the information we provide to all of our readers regarding meetings, events, and service news, we
are now providing links to these features on our website (or, in some cases, to other websites), as follows:
Meetings and other events in and around New Mexico are listed on the bureau’s Upcoming Events
webpage: http://geoinfo.nmt.edu/events/
Bureau of Geology news may be found at: http://geoinfo.nmt.edu/news/
New Mexico Bureau of Geology data repository: http://geoinfo.nmt.edu/repository/
The bibliography of New Mexico geology is an online, searchable index available at:
http://geoinfo.nmt.edu/libraries/gic/bibliography/
New Mexico Geological Society spring meeting abstracts from 2013 back to 2004 are posted on their
website (see following web address, scroll to the bottom of the page to see the list).
http://nmgs.nmt.edu/meeting/
Current spring meeting abstracts are posted prior to the spring meeting (this year April 11th).
http://nmgs.nmt.edu/meeting/abstracts/
New Mexico Mineral Symposium abstracts are posted on the New Mexico Bureau of Geology’s Mineral
Museum website (select a year and enter author or title or keyword).
http://geoinfo.nmt.edu/museum/minsymp/abstracts/
New Mexico Institute of Mining and Technology Earth and Environmental Science Department theses,
dissertations, and independent study papers are available at:
http://www.ees.nmt.edu/outside/alumni/thesis.php
New Mexico State University Department of Geological Sciences theses are available at:
http://geology.nmsu.edu/grad.html
University of New Mexico Department of Earth & Planetary Sciences provides an extensive list of links
for geologists at: http://epswww.unm.edu/escilink.htm
American Geosciences Institute (AGI) open-access journals series is available at
http://www.agiweb.org/georef/about/openaccess.html#internet
These links will provide information that is updated far more regularly than our quarterly journal.
Furthermore, the online version of New Mexico Geology, which is available to all of our readers at no cost, will
have links: Simply click on the selected item and you will be automatically directed to these pages, which
will be updated on an ongoing basis.
If there are meetings or events that you would like to see us display on these pages, you can direct your
suggestions to the Managing Editor at: nmgeology@nmbg.nmt.edu
These links are available on the New Mexico Geology home page by going to:
http://geoinfo.nmt.edu/publications/periodicals/nmg
November 2014, Volume 36, Number 4
New Mexico Geology
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