NMBGMR Open-file Geologic Map 242
NEW MEXICO BUREAU OF GEOLOGY AND MINERAL RESOURCES A DIVISION OF NEW MEXICO INSTITUTE OF MINING AND TECHNOLOGY
Correlation of Map Units
Ti
Ki

daf
Inclined fault-Showing dip value and direction
Qca
Small, minor inclined fault-Showing strike and dip
Qls
Kib
Kib



da
3
Neogene
Q ao




Anticline -Identity and existance certain, location approximate



Mlv


Small, minor vertical or near-vertical joint-Showing stirke
QTp
M
264000
265000
Qayr
observations at one locality-Showing strike and dip
79


Qao1
Qao3
Tat1
Tat2
QTpl
Small minor inclined(dip direction to right) joint, for multiple
QTp Qafh
Qao3
Small, minor vertical or near-vertical joint, for multiple
32°50'30"N
266000
107°30'0"W
10
This draft geologic map is preliminary and will undergo revision. It was produced
from either scans of hand-drafted originals or from digitally drafted original maps
and figures using a wide variety of software, and is currently in cartographic production.
It is being distributed in this draft form as part of the bureau's Open-file map series
(OFGM), due to high demand for current geologic map data in these areas where
STATEMAP quadrangles are located, and it is the bureau's policy to disseminate
geologic data to the public as soon as possible.
Inclined bedding-Showing strike and dip
Tt
Inclined flow banding, lamination, layering, or foliation in

16
igneous rock-Showing strike and dip

Vertical flow banding, lamination, layering, or foliation in

Vent
Tb
Spring
J
Santa Fe Group predating the Palomas Formation (Miocene-Pliocene) – Pebbly sand/sandstone, pebblegranule gravel/conglomerate, and pebble-cobble gravel/conglomerate in matrix-supported, thin to thick,
tabular, massive to weakly cross-stratified beds. Generally finer-grained than QTp (clasts and matrix).
Common silica-cemented beds form prominent ledges and small cliffs. Maximum thickness 204 m.
Thurman Formation (middle to upper Oligocene) – Pebbly to silty sandstone and pebble-cobble
conglomerate, in thickly- to medium-laminated, tabular, broadly cross-stratified beds. Unit fills in small
paleovalley cut into Taqh, Tba1, and Tkn in southwestern part of quad. Silty, very fine-grained sand occurs
in laminated beds. Approximately 30 m thick.
Tertiary volcanic and volcaniclastic units
igneous rock-Showing strike

After this map has undergone scientific peer review, editing, and final cartographic
production adhering to bureau map standards, it will be released in our Geologic Map
(GM) series. This final version will receive a new GM number and will supercede
this preliminary open-file geologic map.
Tsf
observations at one locality-Showing strike
 
Tkn
 29
lvn
7
Cross section line
Tvs
DRAFT
Older basaltic andesite (Eocene) – Dark-gray, weathering grayish-tan, foliated to dense, porphyriticaphanitic, fine-grained basaltic andesite. Forms slopes and occasional ledges. Phenocrysts include 4-6%
plagioclase and 2-4% pyroxene. Perhaps correlative to Trpl. Maximum thickness approximately 37 m.
Rubio Peak Formation (Eocene) – Whitish to medium-dark-gray to greenish, thin- to thick-bedded, typically
massive, poorly to moderately sorted, silty, very fine- to coarse-grained volcaniclastic sandstone with
occasional horizontally-laminated siltstone or lenses of conglomerate. Interbedded with andesitic lava
flows with 4-5% total phenocrysts. Maximum thickness 55 m. Locally subdivided into 2 interbedded units:
Andesite flows of the Rubio Peak Formation – Medium-gray, dense, flow-layered andesite with
10% plagioclase, 4-5% hornblende, and trace biotite phenocrysts. Altered, massive, light-gray
lava contains < 2% plagioclase and 4-5% total phenocrysts; mafic minerals are altered to clay.
Kir
Kit
Kwsm
Kcpm
Basalt flows (lower Pliocene) – Dark-bluish to very dark-gray or black, aphanitic to aphanitic-porphyritic,
fine- to medium-grained basalt. Forms columnar-jointed ledges and cliffs capping mesas. Phenocrysts
include 3-7% pyroxene, 0-5% plagioclase, and 1-3% olivine. Dense to somewhat vesicular; commonly
contains amygdules filled by silica and/or zeolites. The Warm Springs Canyon basalt was dated by Seager
et al. (1984) at 4.2 ± 0.1 Ma (40K/40Ar). Maximum thickness 40 m.
Laharic flow breccia of Copper Flat – Dark-purplish-gray, mostly matrix-supported, massive,
non-vesicular volcaniclastic breccia composed of angular to subangular, pebbles and cobbles.
Pebble content increases up-section. Protruding fragments form rough weathered surfaces.
Exhibits rare trough cross-bedding in finer-grained intervals. Groundmass/matrix typically
aphanitic. May contain jumbled blocks of andesite 10’s of meters across. May interfinger with
Kaf, Kah, and/or Kau.
Abo Formation (lower Permian) – Cross-section only. Reddish-brown to light-brown sandstone
interbedded with grayish-red shale and siltstone. Approximately 121 m thick in the Black Range; top is
likely eroded in cross-section.
Pa
*m
Mu
Magdalena Group (upper to middle Pennsylvanian) – Pink to brownish-gray, very thin- to thickbedded, massive, somewhat cherty, sparsely fossiliferous limestone with subordinate siltstone,
mudstone, and shale. Fossils include bryozoans, echinoderm fragments, fusulinids, ostracods, and
brachiopods. Brachiopods common up-section. Bioturbated by horizontal burrows. Altered or
metamorphosed to jasperoid, skarn, and marble along margins of Copper Flat volcanic system.
130-255 m thick.
Mississippian strata, undivided (lower Mississippian) – Cross-section 94 m in cross-section.
Devonian through Mississippian strata, undivided (upper Devonian through lower Mississippian) –
Includes the Percha Shale and Lake Valley Limestone. Differentiated where identification of individual
units is precluded by alteration, or where access to exposures was denied. Mapped in northern quad.
Lake Valley Limestone (lower Mississippian) – Dark- to light-tannish-gray, thin- to thick-bedded,
massive to horizontally laminated, cherty, fossiliferous, occasionally marly limestone with subordinate
siltstone and mudstone. Chert weathers to dark-orange-brown and occurs as crusts, lacy networks, and
lenses. Crinoid stems often in such abundance as to form crinoid “hash.” Other fossils include small
echinoderm fragments and brachiopods. Forms series of ledges and small cliffs above slopes of Dp.
Maximum thickness 84 m. Locally subdivided into the crinoid-rich Nunn Member:
Mlvn
Mc
OSD
Dp
OS
Nunn Member – Medium-gray, thin- to medium-bedded, massive limestone with many large
crinoid fragments and rare chert nodules. Abundance of crinoids gives unit the appearance of
a crinoid “hash.” Often marly and coarsely crystalline (O’Neill et al., 2002). Maximum
thickness 36 m.
Caballero Formation (lower Mississippian) – Dark-gray, medium- to thick-bedded, massive to crossstratified or laminated, cherty, fossiliferous limestone. Commonly an arenaceous to marly packstone
(O’Neill et al., 2002). Chert occurs as dark-colored masses and networks. Fossils include crinoid and
other echinoderm fragments. 8-10 m thick.
Ordovician through Devonian strata, undivided (lower Ordovician through upper Devonian) –
Includes the El Paso Formation, Montoya Formation, Fusselman Dolomite, and Percha Shale.
Differentiated where identification of individual units is precluded by alteration. Mapped in absence of
upper Paleozoic carbonates (Mc, Mlv, and *m), typically in fault zones.
Percha Shale (upper Devonian) – Dull grayish green to yellowish gray to black, fissile, calcareous shale.
Interbeds with light-purplish-gray, very thinly bedded to laminated, non-calcareous siltstone. Forms
moderate to steep slopes below ledges and small cliffs of Mlv. Fossiliferous in its upper ~15 m,
containing fenestelloids and other bryozoans, as well as numerous brachiopods. Features limestone
nodules upper 6-10 m. Maximum thickness 102 m.
Ordovician through Silurian strata, undivided (lower Ordovician through lower Silurian) – Includes
the El Paso Formation, Montoya Formation, and Fusselman Dolomite. Differentiated where identification
of individual units is precluded by alteration. Mapped where Dp is conspicuously absent.
Fusselman Dolomite (lower to middle Silurian) – Light- to dark-gray, thin- to thick-bedded, massive to
weakly laminated, sparsely fossiliferous, cherty, dolomitic wackestone. Forms a series of ledges and
slopes. Purplish-gray chert, weathers orange to reddish-brown and occurs in veins, crusts, lenses, and
beds 1-7 cm thick. Less cherty in upper part. Contains occasional brachiopods that are commonly
silicified. Brecciated jasperoid beds near the top of the formation. Approximately 22 m thick.
Sf
_O
Cambrian through Ordovician, undivided (upper Cambrian through upper Ordovician) – Includes the
Bliss Sandstone, El Paso Formation, and Montoya Formation. Differentiated where identification of
individual units is precluded by alteration.
Ordovician strata, undivided (lower to upper Ordovician) – Ordovician strata exposed in the Hillsboro
quadrangle commonly feature pervasive alteration to jasperoid, skarn, or marble (McLemore et al.,
1999). Brecciated jasperoids containing clasts of limestone and chert are common in the vicinity of the
Percha Creek box. Where unaltered, these rocks are whitish to very dark-gray, thin- to medium-bedded,
commonly wavy bedded dolostone and limestone. Total thickness 286 m (Hedlund, 1977).
O
Om
Oep
Gabbroic intrusive rocks – Dark-gray to black plug with dark-gray plagioclase and pyroxene
forming a fine- to medium-grained, equigranular matrix.
Monzonitic intrusive rocks – Equigranular plug with a gneissic fabric near its margin. Contains
xenoliths of gabbro near its margin. Medium-grained, equigranular matrix is composed of
plagioclase, potassium feldspar, and biotite; quartz is not present. Chilled margin is porphyritic
with potassium feldspar and altered biotite.
Warm Springs quartz monzonite (upper Cretaceous) – Whitish-gray, ledge- to bouldery-slope-forming,
non- to slightly vesicular, occasionally dense, porphyritic, equigranular, fine- to medium-grained quartz
monzonite. Phenocrysts include 15-20% quartz, 9-12% biotite, 5-8% sanidine, and trace to 2% plagioclase.
McLemore et al. (1999) dated this unit at 74.4 ± 2.6 Ma (40Ar/39Ar). Total thickness unknown.
Volcaniclastic debris flows of Copper Flat – Greenish-gray debris flows with clasts that are
light-colored and fine-grained. Most clasts are < 4 cm, though some are up to 0.5 m across. A
few clasts are porphyritic lava with 3-4% pyroxene and plagioclase phenocrysts; the unsorted
deposits are matrix supported and the clasts are angular. Maximum exposed thickness is 20 m.
Karst fill (Cretaceous?) – Localized deposits usually found in the Ordovician El Paso or Montoya
formations that contain fragments of red siltstone, blocks (10’s of meters across) of Upper Paleozoic
limestone and chaotically deformed Percha Shale in a red, silty matrix. Sinkholes may have formed
during the emplacement and mineralization of the plutons at Copper Flat. The largest deposit on the
east end of Percha Creek Box is about 300 to 400 m in diameter and is atleast 60 m thick.
Feldspar-phyric intrusive rocks – Green-gray, weathering pistachio-green, poorly outcropping,
and aphanitic-porphyritic. Phenocrysts include 3-5% sanidine and trace quartz; may feature a
plagioclase-rich groundmass. South of Copper Flat, Kif plugs contain 5% feldspar phenocrysts in
a black, equigranular, fine-grained matrix with clots of pyroxene up to 10 mm across. Correlates
to unit Kql of Hedlund (1977).
Intrusive rocks of Trujillo Creek (upper Cretaceous) – Dark-bluish-gray, porphyritic, fine- to mediumgrained andesite. Forms rubbly knobs and small ledges. Phenocrysts include 8-10% plagioclase, 5-6%
hornblende, and 2-4% pyroxene. Hornblende and pyroxene may show graphic texture with plagioclase.
Correlates to intrusive andesite Tii of Seager (1986) and hornblende andesite and latite (Krp) of Hedlund
(1977). Maximum thickness 54 m.
Hornblende-phyric andesite flows of Copper Flat – Medium to dark-gray, porphyriticaphanitic, fine- to medium-grained andesite. Forms small benches below Kaf and Kap.
Phenocrysts include 3-8% hornblende, 4-6% plagioclase, and trace pyroxene. Some what
dense/non-vesicular to slightly vesicular. Propylitization increase down-section. Plagioclase
content may increase down-section where unit interfingers with Kab or Kau.
Paleozoic sedimentary rocks, undivided (Cambrian to Permian) – Applied to strongly altered
sedimentary blocks exposed in slivers along the Berrenda fault zone.
|
Biotite-phyric intrusive rocks – White to pink to yellowish-white dikes with 5% phenocrysts of
potassium feldspar, hornblende, and biotite ± pyroxene that are 3 mm across in a fine- to
medium-grained, equigranular matrix.
Rhyolitic intrusive rocks – Pink to white dikes and plugs with 5% phenocrysts of quartz,
sanidine, biotite, and hornblende in an aphanitic to medium-grained equigranular matrix.
Mapped as Tql (Tertiary quartz latite) by Hedlund (1977).
Potassium feldspar-phyric andesite flows of Copper Flat – Greenish-gray, hypidiomorphic
granular, fine- to very coarse-grained andesite. Forms ledges, steep rubbly slopes, and some
hilltops. Phenocrysts include 15-17% sanidine megacrysts, 6% plagioclase, 2-3% pyroxene, and
1-2% hornblende. Dense/non-vesicular.
Paleozoic bedrock
Exotic block of Magdalena Group limestone – Observed in Trujillo Park Canyon. Transported
during major landslide event(s). See *m description.
Intrusive rocks of Copper Flat, undivided (upper Cretaceous) – Greenish-gray to dull-grayish-green,
weathering light-tan to dark-orange-brown, aphanitic-porphyritic to porphyritic, fine- to slightly coarsegrained dikes and plugs intruding andesitic flows and flow breccia of Copper Flat as well as Paleozoic
carbonate units north and south of Copper Flat. Phenocrysts include 5-12% plagioclase, trace to 6%
hornblende, 1-5% pyroxene, and trace biotite. May contain accessory pyrite up to 0.75 mm. Dikes are
commonly 4-8 m wide, but may be up to 38 m wide (McLemore etal., 1999). Subdivided into 5
intrusive facies:
Kim
Palomas Formation limestone (lower Pliocene to middle Pleistocene) – Tan to gray, fine- to
medium-grained crystalline limestone. Unidentifiable bivalve shells are preserved near the top of
the exposure. 3-5 m thick.
L|kf
Mlv
Sugarlump Tuff (upper Eocene) – Pinkish- to tannish-white, non- to somewhat-welded, porphyritic-aphanitic
to porphyritic, fine- to coarse-grained, lithic-rich ash-flow tuff. Forms moderate to steep slopes. Phenocrysts
include 3-15% quartz, trace-9% biotite, and 0-6% hornblende. Lithic fragments make up to 35% of visible
grains and occur as coarse ash to lapilli. Common pinkish-tan pumice fragments up to 3 cm. Densely
welded in upper 1.5-12 m. Interbedded with gray, very thin- to thin-bedded, weakly cross-bedded, poorly
sorted, subangular to subrounded, medium- to coarse-grained sandstone. Clastic grains are up to 70%
quartz. 40Ar/39Ar dated at 35.63 ± 0.15 Ma (McIntosh et al., 1991). Maximum thickness 35 m.
Plagioclase-phyric andesite flows of Copper Flat – Gray, porphyritic, fine- to coarse-grained
andesite. Forms ledges atop ridges of Kaf. Phenocrysts include 20-25% plagioclase, 4-7%
pyroxene, and trace biotite. Contains 2-5% lithic fragments and trace to 3% disseminated
magnetite. Non-vesicular and moderately foliated.
Karst fill
Mimbres Peak Formation rhyolite (upper Eocene) – Light-purplish-gray, dense, strongly flow-banded,
aphanitic rhyolite. Laterally(?) grades into very light-gray weathering, light-tan, flow-banded, porphyriticaphanitic, brecciated block and ash-flow tuff west of Percha Creek narrows. Phenocrysts there include up to
5% sanidine. May contain spherulites. 40Ar/39Ar dated at 34.32 ±0.11 to 34.22 ± 0.16 Ma (O’Neill et al., 2002).
Maximum thickness 52 m.
Kneeling Nun Tuff (upper Eocene) – Gray to dark-maroon-brown, porphyritic, moderately to densely
welded ash-flow tuff. Forms ledges or bold cliffs throughout quadrangle. Phenocrysts include 6-24%
quartz, trace to 6% biotite, trace to 4% hornblende, and trace to 2% plagioclase. Phenocryst content
increases up section. Non- to slightly vesicular, with moderately to strongly flattened pumice in welded
sections. Lower intervals contain spherulites 1-4 cm in diameter. 40Ar/39Ar dated at 35.34 ± 0.10 Ma
(McIntosh et al., 1991). 7-156 m thick.
Pyroxene-phyric andesite flows of Copper Flat – Crystal-rich lava with conspicuous 5-7 mm
pyroxene phenocrysts on weathered surfaces. Phenocrysts include plagioclase and potassium
feldspar in addition to pyroxene. These lavas are exposed beneath Tb on Black Peak; contact
metamorphism there caused copper mineralization in fractures in Kax on the east side of the
peak. Underlain by fine-grained andesite flows. = 35 m thick.
Basaltic intrusion of Copper Flat – Porphyritic intrusion; crystal-rich with 10-15% Ca-plagioclase < 2 mm
long. Minor pyroxene. Occurs in a dike and sill, the latter approximately 3 m thick.
Kb
DM
Kig
Palomas Formation of the Santa Fe Group (lower Pliocene to middle Pleistocene) – Sandy gravel and
conglomerate in clast-supported, medium to very thick, tabular, massive to imbricated beds. Contains
greater percentages of cobbles and boulders than Tsf. Forms gentle to moderate slopes and ledges.
Maximum thickness 15 m.
Kab
Caballo Blanco Rhyolite Tuff (lower Oligocene) – Cross-section only. White to light-gray, crystal-rich ashflow tuff. Phenocrysts include sanidine, oligoclase, and quartz that constitute 25-35% of rock. Common
lithic fragments. 40K/40Ar dated at 29.8 ± 0.8 Ma (Seager, 1984). Maximum thickness approximately 91 m.
Kif
Older Percha Creek narrows landslide deposit (middle Pleistocene?) – Poorly stratified, bouldery
gravel, similar to Qls2, but occupying a lower landscape position. Deposit contains boulders on
2-3° slopes up to 1 km away from steep escarpments of source exposures. Hummocky landscape
underlain by deposit has distinct run-out toes and occasional lobes of open-framework cobbles
and boulders. Thickness unknown.

Tat1
Qao3
8

Mlvn
Volcaniclastic debris flows interbedded with basaltic andesite (lower upper Oligocene) – Maroonbrown volcaniclastic conglomerate, in poorly stratified, medium-to very-thick beds. Massive to
weakly imbricated. Clasts include very poorly sorted, mostly subangular pebbles, cobbles, and
boulders of aphanitic to porphyritic-aphanitic, plagioclase-phyric andesite. Finer-grained
intervals may display flow-banding. Matrix contains 5-10% plagioclase, 5% hornblende, and 2%
quartz phenocrysts. Forms ledges and very steep, rubbly slopes. Maximum thickness 102 m.
Lacustrine sediment (lower to upper Oligocene) – Silty sandstone and sandy siltstone in thick laminae and
thin beds that are horizontally laminated to planar or trough cross-bedded. Siltstone contains dark-brown
laminations of clayey silt occurring at 2-10 mm intervals. Weathers into chips containing coarse, angular
biotite grains. Common limonite concretions and lenses up to 8 cm wide. Maximum thickness 37 m.
Kib
Younger Percha Creek narrows landslide deposit (middle Pleistocene?) – Poorly stratified,
bouldery gravel that is occasionally reverse graded. Clasts often oriented with long axes parallel to
slope. Matrix sand is comprised of 90% lithic grains. Deposit features blocks of andesite 10’s of
meters across with chaotic fracturing, Thickness unknown.
Quaternary-Tertiary basin-fill

QTp

Tat2
263000
24
Mlv
Mlv
9
Qayr
Tat2
Qamh
Small, minor inclined joint-Showing strike and dip


a
Qc
Dp
16
Dp
 1324
Sediment transport direction determined from imbrication
Ki
Landslide deposits, undivided (middle to upper Pleistocene?) – Non-stratified, cobble-boulder gravel.
Larger clasts may be oriented with their long axes pointed downslope. Underlies steep escarpments of
Copper Flat andesite/breccia or Tb. Maximum thickness 10 m. West of Percha Creek narrows, two large
landslide deposits are mapped individually:
Syncline -Identity and existance certain, location approximate

3641 000
Older basaltic andesite (lower to upper Oligocene) – Medium-bluish or purplish-gray to dark-gray,
porphyritic-aphanitic to porphyritic, fine- to coarse-grained andesite. Forms ledges and small cliffs.
Phenocrysts include 2-10% pyroxene, 3-8% plagioclase, 5% olivine, and trace to 6% hornblende. Dense to
vesicular; vesicles filled by chalcedony or drusy quartz. Strongly foliated in middle intervals; occasionally
flow-banded in aphanitic intervals. Correlates to units Tpl of Hedlund (1977) and T4ba of Seager et al.
(1982). Dated by Seager et al. (1984) at 28.1 ± 0.6 Ma (40K/40Ar). Approximately 470 m thick.
Cretaceous volcanic and intrusive units
Colluvium and alluvium, undivided (middle Pleistocene to Holocene) – Poorly sorted, silt to boulders
forming aprons around highlands. Maximum thickness 8 m.
Qls2
_Ob
Montoya Formation (middle to upper Ordovician) – The base of the Montoya Formation is
marked by the 3 to 12 m thick Cable Canyon Sandstone, a poorly sorted quartz arenite with
angular, very fine to fine-grains, and subrounded-medium grains. Sandstone is typically
overlain by dark gray, thin-bedded, tabular, massive, non-fossiliferous, sparsely cherty
dolostone. Chert occurs as crusts. May be altered to a strata-bound jasperoid or
metamorphosed to marble. Contains solitary coral and few brachiopods. Total thickness of
140 m (Hedland, 1977).
El Paso Formation (lower Ordovician) – Medium- to dark-gray, thin- to thick-bedded, tabular,
cherty, somewhat fossiliferous, packstone to lime mudstone. Pink to red chert may be
laminated. Fossils include small bryozoans and sponges, ostracods, and horizontal burrows.
Chert occurs in lacy networks. The El Paso below the Cable Canyon Sandstone has
gastropods, horn coral, stromatolites, and tiny brachiopods. The El Paso just above the Bliss
Sandstone has burrows and poorly preserved brachiopods. Total thickness of 146 m
(Hedlund, 1977).
Bliss Formation (upper Cambrian to lower Ordovician) – Very dark-bluish-gray, well-indurated, tabular,
horizontally to ripple cross-laminated, very well-sorted, subrounded to rounded, very fine- to fine-grained
quartzose sandstone. May be a quartzite with a poorly sorted sandstone protolith containing 95% quartz
and 5% altered grains. Features common vertical burrows occasionally replaced by chert. ~40 m.
Precambrian basement rock
=
Proterozoic rocks, undivided (Paleo- to Mesoproterozoic?) – Cross-section only. Includes granite,
gneiss, and schist.
=g
Granite (Mesoproterozoic?) – Pink to red, medium-grained granite containing quartz, feldspar,
and biotite.
=s
Copper Flat quartz monzonite (upper Cretaceous) – Porphyritic, fine- to medium-grained, plutonic quartz
monzonite. Phenocrysts include 10-20% plagioclase and trace pyroxene and pyrite. McLemore et al. (1999)
dated this unit at 74.93 ± 0.66 Ma (40Ar/39Ar). Total thickness unknown.
Quartzofeldspathic gneiss of Tank Canyon (Paleoproterozoic?) – Pale-brownish-gray, fine- to mediumgrained gneiss containing 70% sericitized albite and 30% quartz. May contain accessory biotite and
ferric oxide minerals. Features thin layers of hornblende schist that strike parallel to foliation observed
in aggregated quartz granules (Hedlund, 1977).
Volcaniclastic deposits, undivided (Oligocene) – Stratigraphically isolated pockets of volcaniclastic debris
flows on Paleozoic rocks south of Copper Flat. May contain pebbles and granules of dacite with hornblende
and biotite. 1-5 m thick.
Cross Section A—A’
Comments To Map Users
Cross sections are constructed based upon the interpretations of the author made from geologic
mapping, and available geophysical, and subsurface (drillhole) data. Cross-sections should be used as
an aid to understanding the general geologic framework of the map area, and not be the sole source
of information for use in locating or designing wells, buildings, roads, or other man-made structures.
8000
2400
North Percha Creek
Grayback Arroyo
Warm Springs Canyon
(Copper Flat)
7000
Qayr
Qao3 Qay
6000
2200
Qaf1
Qaf2
Qary
Qayr
Qahm
Qayr
Qafmh
Qafy
Tss
2000
Qamh
1800
Qayr
Tr
Tsf
Tcb
Oep
Tsf
5000
Kau
Kab
Tba2
_Ob
1600
1400
Kab
Kab
Pa
4000
1200
1000
*m
3000
|
800
Kcpm
|
2000
Mu
Sf
_O b
Oep
0
400
=

=
600
=
Om
1000
|
=
Dp

The map has not been reviewed according to New Mexico Bureau of Geology and Mineral Resources
standards. The contents of the report and map should not be considered final and complete until
reviewed and published by the New Mexico Bureau of Geology and Mineral Resources. The views and
conclusions contained in this document are those of the authors and should not be interpreted as
necessarily representing the official policies, either expressed or implied, of the State of New Mexico, or
the U.S. Government.
A'
Northeast
bend in section

A geologic map displays information on the distribution, nature, orientation, and age relationships
of rock and deposits and the occurrence of structural features. Geologic and fault contacts are
irregular surfaces that form boundaries between different types or ages of units. Data depicted
on this geologic quadrangle map may be based on any of the following: reconnaissance field
geologic mapping, compilation of published and unpublished work, and photogeologic interpretation.
Locations of contacts are not surveyed, but are plotted by interpretation of the position of a given
contact onto a topographic base map; therefore, the accuracy of contact locations depends on the
scale of mapping and the interpretation of the geologist(s). Any enlargement of this map could cause
misunderstanding in the detail of mapping and may result in erroneous interpretations. Site-specific
conditions should be verified by detailed surface mapping or subsurface exploration. Topographic
and cultural changes associated with recent development may not be shown.
A
West




f





Paleozoic

Kib
Kif
Ki


Carboniferous

f

f
Ki

Kif
Cenozoic





Kif
Kif
Ki
KI
Ki

Ki

f1
Qa





Qa
f2
Ki


KI
Ki

Ki
Mesozoic
Ki
Ki
Ki



Kvs

Ki

72
21
Quartz-hornblende andesitic to dacitic flows and flow breccias (upper Oligocene) – Aphanitic andesite and
dacite flows and flow breccias. Phenocrysts include 1-2% total quartz, pyroxene, plagioclase, and altered
hornblende. May contain disseminated magnetite. Breccia is clast- to matrix-supported and contains
angular blocks up to 0.5 m in diameter. = 50 m thick.
*me
Quaternary hillslope and landslide deposits
concealed. Ball and bar on downthrown block
Kvs
Aphanitic trachyandesite (upper Oligocene) – Massive to variably foliated, vesicular, aphanitic to
aphanitic-porphyritic, fine-grained trachyandesite. Phenocrysts include < 3% total plagioclase, biotite,
hornblende, and pyroxene. May contain small quartz xenocrysts. Vesicles may contain acicular zeolites.
~98 m thick
Older piedmont alluvium (middle to upper Pleistocene) – Clast- to matrix-supported, massive- to weakly
imbricated, sandy gravel. Occasionally features stage II-III carbonate morphology. 2.2-3.8m thick.
Dike -Identity and existance certain, location approximate
J






Normal fault -Identity and existance certain, location
Kah
Hydromagmatic deposits in younger basaltic andesite (upper Oligocene) – Gray, sandy hydromagmatic
deposit with tabular, laminated, weakly graded bedding with white to pink altered clasts that make up
2-3% of the rock. 1 m thick.
Trpl
Tsf
Qca

Ki
Ki
Ki
Ki
















Ki




Qay



Ki




a


o2




Qa





o3








Qa


J






Kb
Trp
Kir
Kim
Kig
New Mexico Bureau of Geology and Mineral Resources, 801 Leroy Place, Socorro, NM 87801
2
Department of Geological Sciences, PO Box 30001, Las Cruces, NM 88003
1
Kif
by
Andrew P. Jochems1, Shari A. Kelley1,
William R. Seager2, Colin T.Cikoski1, Daniel J. Koning1
Kib



http://geoinfo.nmt.edu
Ki
June, 2014
Kah
This and other STATEMAP quadrangles are available
for free download in both PDF and ArcGIS formats at:
Kap
[575] 835-5490
Geologic Map of the Hillsboro 7.5-Minute
Quadrangle, Sierra County, New Mexico
Kvs
New Mexico Bureau of Geology and Mineral Resources
New Mexico Tech
801 Leroy Place
Socorro, New Mexico
87801-4796
Mapping of this quadrangle was funded by a matching-funds grant from the
STATEMAP program of the National Cooperative Geologic Mapping Act (Award
Number: G13AC00186), administered by the U. S. Geological Survey, and by the New
Mexico Bureau of Geology and Mineral Resources, (L. Greer Price, Director and State
Geologist, Dr. J. Michael Timmons, Geologic Mapping Program Manager).
Kaf
Quadrangle Location
Ka
y
New Mexico Bureau of Geology and Mineral Resources
Open-file Geologic Map 242
Magnetic Declination
July, 2012
9.2209º East
At Map Center
Qapo
Kaf
Basaltic andesite dike (upper Oligocene) – Mafic dike with a black to dark-gray, aphyric matrix and 1-2%
phenocrysts of plagioclase, olivine, and pyroxene that appears to be the feeder for one of the younger
basaltic-andesite flows.
Younger piedmont alluvium (middle to upper Holocene) – Matrix-supported, massive, pebbly sand. Rarely
features veneers of non- to very weakly varnished pebble-cobble gravel. Occasional, stage I carbonate
morphology in upper 20 cm. 1.7-2 m thick
m
NATIONAL GEODETIC VERTICAL DATUM OF 1929
NEW MEXICO
Kab
Qa
CONTOUR INTERVAL 40 FEET

1 KILOMETER
Kau

7000 FEET
Kcpm

0
6000
Qapy
accurate. Ball and bar on downthrown block
Qls1
3
5000
Kit
f
Tat1
h
Qa
ao
4000
Normal fault -Identity and existance questionable, location
aapproximate. Ball and bar on downthrown block
Qafh
fh
Qa
Qca
 35
Q
0.5
3000
L|kf
da
Q ay
y
Qayr
Mlv
Qafy
Trp
Quaternary piedmont deposits
Dike -Identity and existance certain, location accurate
Qahm
Tsf
Tbao
Alluvial fans graded to the level of Qao1 stream terraces (middle Pleistocene?) – Matrixsupported, massive, sandy gravel. Matrix is more yellowish-brown than Qaf2 and Qaf3 deposits.
Deposit is poorly preserved due to erosion. Maximum thickness 3.5 m.
Qaf1
Normal fault -Identity and existance certain, location

Qca

2000


Tsf

1
1000
1 MILE
Alluvial fans graded to the level of Qao2 stream terraces (middle Pleistocene?) – Sandy-pebble
gravel and occasional, discontinuous lags of cobble-boulder gravel. More commonly matrixsupported than Qaf1 and Qaf3. Calcic horizons or soil carbonate development not typically
preserved due to surface erosion. Typical thickness ~4 m.
Qaf2
Ball and bar on downthrown block

Qapy

Clark
Spring
Canyon

McClede
Mountain

PA
Mountain
0
0
approximate
10
2?

0.5
Alluvial fans graded to the level of Qao3 stream terraces (upper Pleistocene) – Sandy-pebble or
pebble-cobble-boulder gravel with more boulders than Qaf1 and Qaf2. Commonly, overlain by soil
profiles, 60 cm thick with lower Bk horizons exhibiting stage I+ to II carbonate morphology.
1.7-2.3 m thick.
Qaf3
Normal fault -Identity and existance certain, location accurate.

Qapy
Q af
*m
57
*m
Kit
Kit
Contact -Identity and existance questionable, location
Fault (unspecified)-Identity and existance certain, location

*m
Older alluvial fan deposits, undivided (middle to upper Pleistocene) – Sandy gravel occurring in fan
deposits graded to surfaces associated with Qao1, Qao2, and Qao3. Locally subdivided into three fan deposits:
approximate


Hillsboro
Kit
Kit
Tsf
Qafo
Qapy

daf 262000
1:24,000
1000
Kingston
Ql
Older alluvial fan deposits graded to stream terraces of Percha Creek and its tributaries
Contact -Identity and existance questionable, location accurate
Fault (unspecified)-Identity and existance certain, location
11
107°32'30"W
1
Skute
Stone
Arroyo

daf 261000
260000
ar
Tkn
Younger and recent fan alluvium, undivided (present to middle Holocene)
concealed

259000
Ql
Qafyr
Qao2
Qay
ao2
Tsf
60
Qao

Younger and recent (modern + historic) fan alluvium, undivided (present to middle Holocene)
accurate
32°55'0"N
QTp?
14
*m
Dp
Tsf
Tsf
Tmr
3644 000

258000
Qamh
Ql
daf
Qao3
Tsf
31
Qao3
75
Younger fan alluvium (middle to upper Holocene) – Sandy gravel underlying alluvial fans graded to the
surface of Qay. Surface lies up to 2 m above that of Qafh. May be capped by 0.9-1 m soil profiles with 50 cm
Bt horizons featuring clay films on clasts; may also include Btk horizons with stage I+ carbonate morphology.
2.2-3 m thick.
Fault (unspecified)-Identity and existance certain, location
Qao3
Q

Qao2
y
Qay
*m
Mlv
24
Sf
Ql
daf
Qamh
Qayr
Qayr




daf


Qayr
Qapo
Qao3
3645 000
Qapy

Ql
Qah
Qao1
Qam

Qayr
Base map from U.S. Geological Survey 1985, from photographs taken 1978, field checked in 1979.
1927 North American datum, Transverse Mercator projection. Reprojected to UTM projection NAD83 zone 13.
1000-meter Universal Transverse Mercator grid, zone 13, shown in blue.
Saladone
Tank
Tsf
Qafyr
Tcb
Ts
3643 000
Mc
Q
daf
Qay
Qao3
Tsf
Qao3
Qao2
Qahm
107°35'0"W
Bell
Mountain
kf
257000

Qahm
Qafyh
Historic fan alluvium (~50 to ~800 years old) – Sandy gravel underlying lowest inset alluvial fans graded to
the surface of Qah. Features more clast-supported beds than Qafy. Little or no soil development or
varnishing of clasts at surface. 0.8-1.2 m thick.
y
daf

18
Qapo
Tsf
Tsf
107°37'30"W
Apache
Peak

256000
Qao3
Qapy
Qafh
Contact -Identity and existance certain, location approximate
 20

Trp
Qao3
81
14
34 54

21
26 
Tt
17

29

Qao2?
18
13

11


Qafyr
Qayr
Qamh
=s
Tss
Kap
Younger basaltic andesite (upper Oligocene) – Mafic flows with a black to dark-gray aphyric to crystalline
matrix and 1-2% phenocrysts of plagioclase laths, subrounded olivine, and pyroxene. Flows are commonly
strongly foliated in the core and vesicular at the top. North of Percha Creek narrows, this unit correlates to
T4ba of Seager et al. (1982). 300 m thick.
Tba1vs
Historic and modern fan alluvium, undivided (present to ~800 years old)
Kax
Rhyolite (upper Oligocene) – Porphyritic rhyolite flows that are variably massive to flow banded. In the
thicker parts of the section, the flows are more crystal rich (15-25%) and pink at the top, and more crystal
poor (3-10%) and gray near the base. Block and ash deposits near the base are common. Phenocrysts
include sanidine, quartz, biotite, and hornblende. The rhyolite flow unit is intercalated with Tba2 and may
correlate with Tr4 of Seager et al. (1982). This unit was included in T4ba by Seager et al. (1982). Variable in
thickness, ranging from 15 to 120 m; thins toward the south.
Modern and historic fan alluvium, undivided (present to ~800 years old) – Pebbly sand to sandy-pebblecobble gravel in medium to thick, tabular beds. Unconsolidated, matrix-supported, and massive.
Maximum thickness ~3 m.

Tkn
L|

63
Tsf
Qao3
Qay
Qay
5
mh
9
Qao2
4
21

Qa
3642 000

Qay
Td
Qahy

255000
Trp
Qayr

Qao3
Qay
Qah
Taqh
23
2390
Qao3
Qao3b
Qaf1
Qao3
Qao2
Qa
Qapo
Qafhm
Explanation of Map Symbols
 13
 29
10
*m
Qafhm
po
Qay

Qafyr


Qay Ts
16
o3
Qay
Qay
Tba1
Qao3
Qa
Qay

Qao3?
12


Qao3
Qah

Qao3
Tsf
Qay

 Qca
Qao3
Qao3b
Qa
6
o2
Qaf3

Qay

40 Tsf
Qay
Qao3
32°52'30"N
Tkn
Qaf2
Qao3
Qay
Qa

Qao3

Mlv
Oep
Lower andesite of Trujillo Peak – Non-vesicular and strongly foliated. Approximately
120 m thick.
Volcaniclastic debris flows with quartz-hornblende andesite/dacite clasts (upper Oligocene) –
Well indurated, heterolithic volcaniclastic debris-flow deposit containing blocks up to 0.5 m in
diameter. Blocks are poorly sorted, angular, and are found in a pink, sandy matrix. Other
intervals may consist of fine-grained sandstone containing 3-5% granules of volcanic rocks,
including Taqh. Maximum thickness ~27 m.
Volcaniclastic deposits and lava flows on the northwestern side of Copper Flat, undivided (upper
Cretaceous) – Lava flows (labeled/assumed to be Ka) and dikes (Ki) in this area were determined using
photogrammetry and have not be field checked due to restricted land access. Kau is likely dominated by
volcanic deposits with a few interbedded andesite flows.
Andesite flows and flow breccia of Copper Flat, undivided (upper Cretaceous) – Grayish green to
medium-bluish or dark-gray, porphyritic-aphanitic to porphyritic, fine- to coarse-grained andesite.
Forms ledges or moderate to steep, rubbly slopes. Phenocrysts include 4-17% plagioclase, 0-8%
hornblende, 0-5% biotite, and 0-5% pyroxene. Plagioclase phenocrysts up to 2 cm are found in upper
intervals. Vesicularity increases up section. May contain xenoliths of intermediate to silicic
compositions. McLemore et al. (1999) dated an andesite flow at 75.4 ± 3.5 Ma (40Ar/39Ar). Hedlund
(1977) cites total thickness of andesite flows as 830 m based on drill core data. Locally divided into
seven volcanic or volcaniclastic subunits:
Ka
Tuffaceous volcaniclastic sediment of Tank Canyon (upper Oligocene) – Laminated, tabular beds of weakly
sorted volcaniclastic conglomerate with minor volumes of laminated fine-grained ash beds, ignimbrites,
and fluvial conglomerate and sandstone. Laminated, hyperconcentrated deposits are interbedded with
conglomerates and sandstone with fluvial cross-bedding and scoured channels. 30 to 60 m thick.
Quaternary alluvial fan units
O
Scale change
*m
Qapy
Mlv
29
Om
_O
=g
Oldest terrace deposit (middle Pleistocene?) – Loose, subrounded to rounded cobbles and
boulders on the south side of Percha Box. Tread is 36-38 m above modern grade. 1-2 m thick.
Qao0
Contact -Identity and existance certain, location accurate
Qao2
Qa
Qapo

Qay
18
y?
Qay
Td
17
36
ap

Ts
Qay
Q
Qay
o
Tsf
Qayr
2
Qao3b
Qafh
Qaym




Qaf3 Qaf3
23
Qaf3
Qay
Qay
T ba
Qao3
Qaf1
53
Qao3

Qao3b
45
Qafo
Qayr
Tavs


Qao3
 11  11
Mc
7
Qafo
Tsf
Td
Qayr
Qayr
 12
Qao3
Tk
Qaf2 Ts n
Trp
 6Qca
Qao3
Tb
Qafy


Tavs

9
Qay
Mlv

*m
Sf
Cambrian
Tsf
Dp
18
First terrace deposit (middle Pleistocene?) – Sandy pebble-cobble-boulder gravel with wellvarnished clasts at surface. Matrix is browner than Qao2 and Qao3 deposits. May be variably
deflated or mixed with eolian material at surface. Features stage I+ carbonate morphology. Tread
is 20.8-21.5 m above modern grade. 2.1-4.1 m thick.
Dp
=
Taqh
Second terrace deposit (middle Pleistocene?) – Similar to Qao1 deposit with variable varnish on
clasts at surface and stage I+ carbonate morphology. Subordinate to Qao1 and Qao3 terrace
deposits. Tread is 13.6-13.8 m above modern grade, except for subordinate deposit Qao2a with a
slightly higher tread height (~15-16 m). 1.7-2.0 m thick.
Upper andesite of Trujillo Peak – Alternately dense and scoriaceous to vesicular. Vesicles
contain silica or calcite amygdules. Lacks hornblende phenocrysts. Approximately 80 m thick.
Kau
Dacite (upper Oligocene) – Medium- to dark-gray, hackly weathering, porphyritic-aphanitic, fine-to coarsegrained, dacitic lava flows, and block and ash breccia. Forms ledges and steep, rubbly slopes. Phenocrysts
include 8% plagioclase, 3-4% pyroxene, trace to 5% quartz, trace biotite, and trace hornblende. Nonvesicular and foliated; coarser grained, and less foliated in upper 15 m (49 ft). Breccia is composed of
monolithologic clasts with 10-15% total phenocrysts of sanidine, biotite, hornblende, quartz, and zoned
potassium feldspar. Maximum thickness is 35 m.
Tavs
Third or youngest terrace (upper Pleistocene) – Sandy pebble-cobble gravel with coarser matrix
than Qao2 and Qao1. Little to no pedogenic carbonate development. Tread is 6.2-8.5 m above
modern grade, except for subordinate deposit Qao3b with a slightly lower tread height (~5 m).
1.7-3.8 m thick.
Qao1
_Ob



Td
Taqh
Qao3
Dp
Ta
Tba1
Qafmh
Dp
22

21
daf
44
24
24
21
Qap
Tbah
Stream terrace deposit, undivided (middle to upper Pleistocene) – Imbricated, sandy gravel occurring in
strath terrace deposits with surfaces higher than those associated with Qay. Clast compositions are
dominated by Tertiary volcanic lithologies with subordinate Paleozoic sedimentary rocks. Locally
subdivided into 3-5 deposits:
|
OS
Tvs
10


11
Qao2
Qaf3
60
Tb
Ta
73
Silurian
Qay


Qao3b
3641000
Qaf2
Qahm
 11
Lacustrine sediment (middle to upper Holocene) – Gray, fine-grained sediment filling the valley of Trujillo
Creek. Horizontally-laminated with weak ripple-lamination in sandier beds. Strongly calcareous, but only
rarely exhibits stage I carbonate morphology. 6.1-9 m thick.
Mc
Devonian

Qay
26

Tsf
Qafo
Qay
24
Qaf3
Trp
Trp

Qam
Trp
Tmr

Tb
Qafyr
Ta
Ta
Tba1vs
Qay
*me
Qay
3

Trp
2
6
Tbi
Younger and recent (modern and historic) alluvium, undivided (present to middle Holocene)
Mlvn
3646 000
Qao3
13
Qao3
 18
kf
Qaf3
Younger and historic alluvium, undivided (~50 years old to middle Holocene)
Qao2
Qah

Qay
Trpl

Qapo
19 Mlv
Mlv
15

Qayr
Trp
Qaf3
Tb

Tr
Younger and modern alluvium, undivided (present to middle Holocene)
Mu
DM
42

24TsTmr
Qao3
3642000

Qay

Qah
Qao3b
Tmr

Qapo
Qaf3
Qaf3
Qaf2
Qao3b


Td

59
 14
Ta
Qayr

Td
8
Younger alluvium, undivided (middle to upper Holocene) – Gravelly sand underlying low-lying terraces in
valley bottoms. Retains subdued bar-and-swale topography with 10-20 cm of local relief. Matrix is browner
than that of Qao. Sandier than Qah, with greater cross-stratification. Tread height 1.6-1.8 m above modern
grade. 3 m thick.
Qao3
QTp
QTp
Qao2
21 Qao1
61
L|
9
Q apo
8
Miss.
QTp
Qay
8
Qay
Qay
Dp
14
Sf
Qao2?
Q ao2
 22 26
13
 14
1937 Trp? Qao2OSD
20 
 Qaf3
OSD Qam
7


12 
Ta


Qca
Taqh
68 Qca
3643000
8
Qayr
Qca
Ts

Tb
Qayr
7
Tttc
Recent (modern and historic) and younger alluvium, undivided (present to middle Holocene)
Qao2a
Tsf
 14

 14 14
Sf
Tvs
Tsf
Tb
Tba1


Qapo
Tsf
Dp
10
3
Qapo
*m
QTp
10
4
L|kf
L|kf
Qao0
Dp
5

Qamh
r
Tsf
54
Qao3

Qapo
Om

72
Qao2

Historic and younger alluvium, undivided (~50 years old to middle Holocene)
Tbao


9
a
Mlv
35


Qc
y
Qa
Qay

Qao3
Tsf
 12
Qah
Qay
Ta
 
14

Qao2
Tsf
Qayr
Qayr
Ts
Ts
8 Oep
Qayr
Qao1
Tba2
Tba1
Mlv Dp
Qay
L|kf
82


Qao2
Qao2
Qao3
daf
Qah
Qao3
Qao2
o3
Qao1
23
Tba1
Qao3
Qao1
Qao3
daf
Qa

Qls1
Tmr
Qah
Tsf
Qao2
Tss
Qao2
Penn.

11
Tbao
Tkn
 45
Qay
9
Historic and modern alluvium, undivided (present to ~800 years old)
?
14
65
 25
Oep
10

Qls2
Tba1
11
Qao3
Qao3

Qao3

Qao3?
Qao2
Qao2
10

 69
Q ao2

 21
Qao3
Qao1
35
 22
?
?
Pa

Tvs
?
QTp
Qca

 35
Qao1
 12
Qao3
Qayr
daf
Om
?
Qao
Qafy

3645000

Qao3
Qao1
Qao1
Qao2
Qay

Qayr
Qao1
Tsf
Qay
Qay
Qao3
9
Tsf

Qay
Q ah
Qao3
9
33
?
?
3647 000
 29 Qam
Trp
20
Kax
Ordovician
Qahm
Tkn
Td
Quaternary stream terrace deposits
OSD
Qay
daf
39
Ts
*me
Mlv
Qayr
11
Qao2 Tsf
QTp
Qca
4


Qls1
Qao3
Ki

Qao2?
 19

L|kf
17
Qay
Qao3
daf
Qao2
Qao2
Qayr
32°55'0"N
Qao3
14
9
Om
Tb
Qaf3
?
Trp
Proterozoic
79
L|kf
3
Qao3
Qca
Qao2
Qao3
Qahm
Qayr
17
Tsf


Qao2
Ki

Tkn
Kaf
Qayh
Ql
Permian
Ki
10

Qao2
Qam
Qah
Qao2
Qahm
53
Qah
Qamh
Qah
Tss
daf
Qao2
Qao3?
L|kf
Tsf
QTp
L|kf
L|kf
Ki

Tss
Qao3
12
4
Qca
50 15
17

Qah
Qahm

Qca
Qafyh
Qay
Qafy


Qao2
Qay Qca
Qao2a
b
25
30
*m
Ki
85
Tss

Qls?
Oep
Om
daf
Ki
Qay
 
7
15
Tsf
Ka
Qaf2

Qls?
35
4
12 8
6
14
Sf
3648 000
Tkn
Kvs
66
 17

Qao3
Q ao 3

14
40 
Mlv


Tbah
Qao2a?
Ki
Qayr
Qay

Qao3
Qao3 Qao3
8
Kwsm
Tsf

Qao2
3
Qay
daf
Qay


3646000
Qca
Qafy
Qao2
35
Qao2

Qao3
Qao2?

m
Tsf
30
15
Tba2 Tr
33
3644000
Qary
QTp
f
o3
12
_Ob
23
QTp
QTp
Ka
81
42
Qay
Qay
72
11
Ki
Qapy
Kah
Kab
p
_Ob
Qca
Qay
Qao3
Kif
s
Kw
f1
Qa
Qao3
Qayr
40
Mlv
27
Kaf
Kvs
Qay
?
?
?
Kwsm
Scale change
daf
QTp
Kaf
Kaf
 Ki
 28 daf

Oe
=g
Qls
Qa
Qao2a?
Qca
Qca
K if
_Ob

3
Qay
Kif
Tb

Kif
Qaf3
2
daf
Kvs
47
af
Qca
Qaf3
Q
2?
3647000
ao
Tb
81
ao
Q
Qahm
Kwsm
Ki
Ki

Qaf2
Kaf
?
Trpl
QTp
Kaf
73
Kah
Kaf
48
Qary
2
Q
Qay
Qary
Ka
67
af
Qayr
Qao3
Qao2?
65
Ka
Kaf
Kaf
Ki

Qaf2
QTp

Q
Qao3
Kaf
3649 000
QTp
Kab
Ka

|
36
Kaf
Kab
Ka
Kab
Kb
Ki
Kif
Kaf

Qaf2
Ka
Kif
52
Ka
Kif
64
48
Qao3
Qafy

Ki
2
Tba2
Kaf
f
74
76
83
Tsf
Q af
Qao2?
Kaf
83
Ka
Ka
Historic alluvium (~50 to ~800 years old) – Sandy pebble to pebble-cobble gravel found in valley bottoms.
Retains bar-and-swale topography with up to 30 cm of relief. May be horizontally laminated. Tread height
0.6-1.2 m above modern grade. Perhaps up to 2.5 m maximum thickness.
daf
Kaf
f
Tat2
Tat1
Qao3b
Ki
Ki
Qayr
Andesite of Trujillo Peak (upper Oligocene?) – Dark-gray to purplish-brown, aphanitic to aphaniticporphyritic, fine- to medium-grained andesite. Forms steep rubbly slopes and ledges below Trujillo Peak.
Locally subdivided into 2 units:
Modern and historic alluvium, undivided (present to ~800 years old)
76
d af
Ki

Tsf
Qao2?
Ki
r
Ki
Qao3
80
32°57'30"N
Tsf
Qls
Kif
|
Kaf
Tt
Tat1
Tcb
Kib
84
20
43
daf
f


2?
Qaf1
Ki
ao

Qafy

80
82
Qaf2
i
Kb
?
Qayh
Tbao
Scale change
daf
Ki
84
83
ay
Tat
Tss
Tmr
Tkn
Ts
37.2
Tsf
Ka
Ki
Ki
Kah

Q
Qay
Ki
Kaf
Ki
61
Ki
4
Kaf
Ki
Qaf2
Qao3
Tr
f
Ki
Kvs



Kah
??
?
Trpl
Tsf
Modern alluvium (present to ~50 years old) – Sandy gravel in ephemeral drainages subject to annual
runoff. Retains bar-and-swale topography with up to 1 m of relief. Thickness is likely 3 m.
Tba2
Tat2
Tr
Tba2
Tsf
3650 000
Tat
?
Tbah
74
Kab
Q
?
?
Td
?
Tba1vs
?
daf
Ki
Kb
Ki
Qaf2
Tss 10
17
Kax


Qao3
74
Kaf

Qaf3
|
Tsf
Qaf2


Qaf2
12
Tb
Tb
Tb
Tba1
Tavs
Eocene
Tsf
daf
Ka
6080 27
Tb
Qaf2
Ki
Kif
Ka
79


Qay
Qao3
Tvs
Kaf
Kah

Tb
Kif
Kab
Ki
30
Kaf
|
45
29
Ki
23
Tsf
Tba2


Tb
Qafy
3648000
Ki
Ki
Qary
Qao3
Kah


Tr
Ki
Kif
33.9
daf
mh
Tvs
QTp
Ki
Tb
Ki
Ki
Tsf
Tb
Tba2

Ki
Ki
Tb
Qa
Kab
Ki
Ki
Tb
55
Ki
Ki
Qay
3649000

9
Ki
Tsf
Qay
Qafmh
daf
Qaym
Ki
Ki
Ki
28
J
Kab
Ki
Ki
Ki

32°57'30"N
Ki
Qaf2
Tr
daf
A’
Qaf2
Ki
Ki

Qao2
3650000
A
Qahm
Ta
?
Taqh
?
Oligocene
Late
Cretaceous

Ki
Qaf1
Ki

Qay
Tttc
Tbi
Qaf1
Qayr
h
Q am
Tsf
Tbah
3651 000
Qaf3
daf
Qaf2
Qay
daf
Tsf
Qah
Ka
5.3
Kab
Disturbed or artificial fill (present to ~50 years old) – Sand and gravel that has been moved by humans to
form earthen dams, or has been removed for construction.
Tb
Kap
Qayr
Qay
Qary
Qayr
Qaf2
Tsf
QTpl
23
Tsf
Tsf
Tba2
3652 000
17
28
Ki
Qahm
Qls1
QTp
Paleogene

Kib
Ki

Tbi

Ki

35
Tba2
Tb
?
?
Pliocene
to early
Pleistocene
Cretaceous
Ka

3651000
Ki


?
daf
Ki
Ki
Kap

42
Tr
?
?
Qayr
Qaf1
Ki

79
?
Qahy
Miocene
Kap
Kab
Qls2
Qah
?
Ki

Tsf
Ki
Kap
Ki
?
?
Ki
Kcpm
Kab
Tba2
32

Ki
Tb
 33
10
f
K if
Kab
Ki
85
Tba2

Ti
Ti
Ti
Ti




Tsf
Tb
Tttc
Ki
Kaf
Tba2
Ki

Qapo
Qao0
0.78

Qca
Qamh
?
f

Ki
QTpl
Tb

Kab
Kau
Ki
f
Qayr
?
Middle
Pleistocene
da
20
Ka
Ki
Tb
3652000
Kau
Ki
Ki
Qca

Ka

Qls
66
Ki
Ki
Qca
Ka
Ki
Ti

Ki

75
Kib
Kif
13
Kif
32
Ki
Ki
Tsf
*m
Kibi
K
Ki
Qls

90 14
85
Qao2
Qao2a
?
Qao1
?
?
Qaf1
Qahm
Kim
Qls
Qao
Qaf2
?
daf
Qca
Qao3
Qafo
15
Qao3
13



Tsf
*m
Kim

Tsf
Qaf3
3653 000
Tb



Ki
Kib
K ir
Tb
Ka
y
ar
Q

Kif
Kif
jasperoid
Kif
5
Ki
Ki
Kig
19
Qao3
Ts
12








7
Ts
Qam
?
Late
Pleistocene
0.13


Kir
Qary
Dp


O
*m
68
DM
Kir
Kir
Ki
KI
Ki
Ki
Tsf

Kir
Ki
Ki
Qls
Ki
7
Ka
85
Mlv
Tb
Om
Qao2
70
Qafy
Qay Qapy
Qao3b
Qao2
daf
Qaym,
Qayr,
Qafyr
Qary
Qayh
Qahy
Ql
Holocene
_O

Ki

Ki
Ki
Sf
0.012
Qao2
_O

Ki
Ka
Qao3
b

OS
Tsf
O
daf
0
Tsf
Ki
Qls
Qah
Quaternary valley bottom units
Age (Ma.)
Qao2
Qao2
Kib
_O
Ki
Qayr
Qafy
Om
Om
33°0'0"N
Ki

Qahm
Qao2

Qay
OS
Oep
Qayr


yr
Qafy
Qayr
Tttc
=s
Qahm
266000
Qao1
Qamh

Qa

Tba2
Qafy
_O
_Ob
Ki
Tsf
daf
Q
Tsf
Ki
Qao2
ah
Qao2
Qao2 265000
Qao3
Qao3 Qamh
264000
263000
K ad
Qafy
Qayr
Om
Ki
Ki
Qay
Qaf3
Ki
Ki
107°30'0"W
Qafhm Qaf3
Ki
Qah
Qayr
Tsf
3653000

daf
262000
Oep
_O
8

261000
=s
Qafy
19
10
Tsf
Tb
Tttc
Tba2
70
Qayr


Qapo
_O
260000
Tb
Tb
Tttc
3654000
259000

33°0'0"N
Tb
258000

257000

256000
Quaternary
107°32'30"W
107°35'0"W
255000

107°37'30"W
Map Unit Descriptions
Qamh,
Qam Qahm, Qafh
Qafm Qafhm Qah
daf
Last Modified June 2014
=
200
0
Intraformational contact -Showing the dip of beds to display the slope of stratovolcano.