NEW MEXICO BUREAU OF GEOLOGY AND MINERAL RESOURCES A DIVISION OF NEW MEXICO INSTITUTE OF MINING AND TECHNOLOGY
8
Qds
Qdp
63642
Qdcp
Qd
Qd
Qd
Qdbp
Qd
Psr
3690000
Qd
Psr
Qdcp
hmp3
Qdcp
Qaf
Qdp
26
Psr
Qd
Qdp
W
Qdbp
hmp3
!
!
!
?
!
Qd
!
Qdbp
Psr
Psr
Hmp1
!
00172
!
!
!
!
33°20'
11
Psr
Hmp2
3688000
Qc
Qd
Qd
15
35
60627
W
Qd
o
o
Qdcp
Qd
Psr
Qaf
Hmp2
Py
Qd
Qds
Qd
Qed
Qd
Qd
Qed
Qd
Qd
Qd
Qdbp
Qd
Psr
Qdp
W
hmp3
Qabp
Qaf
Qvf
Qd
Qdp
Qd
Hmp2
Qd
Qabp
Qabp
Qd
Psr
Qd
Qdbp
Qd
Qdbp
Qa
Qd
Qabp
Qd
daf
Qds
Qd
hmp3
Qvf
Psr
hmp3
Qlt3
hmp3
3682000
Qd
Qabp
Hmp2
Qlt3
Qa
Qaf
Qahd
daf
Qahc
Qvf
daf
Qlt2
Qlt3
Qahf3
Qvf
Qahd
?
!
!
!
!
!
?
!
!
!
!
!
?
!
!
!
!
!
?? ?
! !
!
!
!
!
?
3682000
Qd
Qd
Qdp
}
Py
Hmp2
Qd 3681000
Qd
hmp4
Qd
Qa
5
o
daf
Qa
!
!
daf
Hmp1
Qa
!
!
Psr
Qa
3681000
!
Qd
Qd
Qds
Qvf
Hmp2
hmp3
!
!
daf
Qaf
Qd
Qvf
!
daf
Qa
hmp3
?
Qvf
daf
Qd
Qa
Qabp
Qbs
Qed
Qd
Qds
Qd
Hmp1
Qd
Py
Psr
Qlt2
Qd
Qvf
hmp3
!
Qaf
Qd
!
!
!
!
!
!
!
!
!
Qahf3
!
!
Qa
Qa
17
Qvf
Hmp1
560000
561000
565000
564000
563000
104°20'
104°17'30"
568000
567000
0.5
0
1
L E RANCH
WADE RANCH
0
1000
2000
0.5
3000
1 MILE
4000
5000
0
6000
7000FEET
A
A'
DEXTER EAST
1 KILOMETER
Magnetic Declination
March 2005
8º 45' East
At Map Center
569000
http://geoinfo.nmt.edu
Qlt3
Youngest Lakewood terrace alluvial deposits (upper Pleistocene) — Thickness <1 to 1 m.
Qlt2
Young Lakewood terrace alluvial deposits (upper Pleistocene) —Thickness 1.5 to 5 m.
Qlt1
Older Lakewood terrace alluvial deposits (upper to middle Pleistocene) —Thickness ~2 to 9 m.
View to north-northwest of three coalescing collapse depressions with braided
Pecos River alluvium in between. This alluvial channel is early Holocene - latest
Pleistocene in age when the collapses captured the Pecos River, causing it to flow
directly below the Seven Rivers bluffs. The hill on the skyline, Comanche Hill, is
the location from which the panorama below was photographed.
Mapping of this quadrangle was funded by a matching-funds grant from the STATEMAP program
of the National Cooperative Geologic Mapping Act, administered by the U. S. Geological Survey,
and by the New Mexico Bureau of Geology and Mineral Resources, (Dr. Peter A. Scholle,
Director and State Geologist , Dr. J. Michael Timmons, Geologic Mapping Program Manager).
Inclined bedding showing degrees of dip; dashed where
estimated visually
11
280
W
Geologic map of the Bottomless Lakes quadrangle,
Chaves County, New Mexico.
Strike of vertical joints.
Qdbp
Oil well with last five digits of API number from NM Oil
Conservation Division database.
Qcbp
Qd
Qds
by
Geoffrey Rawling and David J. McCraw
New Mexico Bureau of Geology and Mineral Resources,
Socorro, NM 87801
Pecos River braided alluvial deposits (lower Holocene to upper Pleistocene) — Light reddish-brown (5YR6/4) to reddish
brown (2.5YR4/6), unconsolidated, poorly to moderately sorted, pebbly coarse- to fine-grained sand, silty sand, sandy clay,
and clay. Braided channels and bars typify the surface of Qabp. As discussed above, the thickness of Qabp is greatest on the
western margin of the floodplain, although buried, varies from 10 - 20 m. Large areas of Qabp are found on the floodplain
surface in the center and eastern margins of the valley, here the thickness varies from 3 m to <1 m. Unit primarily occupies
areas mapped as Qflo and Qafs on the preliminary geologic map of the Bottomless Lakes quadrangle (v1p-00, May 2006).
Quaternary depression fill, primarily caused by subsidence (Historic to middle Pleistocene) — Unconsolidated, wellsorted, fine-grained (fine sands to clay) complexes of alluvial, colluvial, eolian, and occasional lacustrine deposits within
closed depressions created by either gradual subsidence or sudden collapse followed by gradual subsidence of underlying
gypsiferous carbonate terrane. These complexes are often significantly modified by stream erosion and deposition, playa
deposition, deflation, and mass wasting. Depression fills have been active since the middle Pleistocene and are usually 1-3
m thick but can reach thicknesses in excess of 30 m. Unit occupies areas mapped as QHsf, where they were mapped, on the
preliminary geologic map of the Bottomless Lakes quadrangle (v1p-00, May 2006).
Quaternary sinkhole deposits, primarily caused by collapse (Historic to middle Pleistocene) — Eastern bluffs: boulders,
slump blocks, gravel, sand, silt, and clay filling dry sinkholes derived from local collapse of Psr. Thickness unknown,
probably 1-5 m for smaller sinks, quite likely several tens of meters for the larger ones (predominantly on the Commanche
Spring quad to the east). Western terraces: occasional cobbles, gravel, and slumped gypsite blocks in a fine-grained sandy
clay matrix. Most are submerged beneath the water table. Thickness <1 to 5 (?) m. Unit occupies areas mapped as QHsf,
where they were mapped, on the preliminary geologic map of the Bottomless Lakes quadrangle (v1p-00, May 2006).
Santa Rosa Formation (upper Triassic) — Unit not observed in the field due to difficulty of land access; mapped with
aerial photos and projections of the top of the Yates formation from well logs. The outcrop pattern is defined by a series
of low hills (< 50 feet high) along the eastern margin of the quadrangle, and is in general agreement with Kelley (1971).
Exposures appear to be poor, with abundant alluvial and eolian cover. Kelley (1971) described exposures approximately
20 miles to the north as composed of grayish to reddish brown thick-bedded sandstones and subordinate red, brown, and
variegated mudstone. Lucas and Anderson (1993) described exposures at Mesa Diablo, seven miles to the north, as grayishred and pale reddish-brown micaceous sandstones, siltstones and mudstones with subordinate yellowish- and greenish-gray
conglomerates. Thickness: Top not exposed; probably <40 m based on cross-section.
Py
Psr
Pqg
Yates Formation (Guadelupian - upper Permian) — Unit not observed in the field due to difficulty of land access and
poor exposure. Unit forms a broad bench across the central portion of the quadrangle. Mapping was performed with aerial
photos and projections from well logs. Surface expression (soil texture and vegetation patterns) on aerial photographs
allows differentiation from both the underlying Seven Rivers Formation and overlying Santa Rosa formation, although unit
is largely obscured by sand sheets and small, stabilized dunes. Generally described by Kelley (1971) as gypsum, dolomite,
and fine-grained, thin-bedded sandstone. Further south in the Lake McMillan area, its described by McCraw and Land
(2008) and Dehler, et al. (2005) as very light gray, massive to vesicular gypsum interbedded with pink dolomite, green to
white and orange to red siltstone and minor sandstone. Folded into domes and basins on a meter to several decimeter scale.
Thickness: Top not exposed; probably <50 m based on cross-section.
Seven Rivers Formation (Guadelupian - upper Permian) — White to pale gray gypsum, brick red, pale red, to orange
very fine sandstone, siltstone, and mudstone, and minor limestone. Gypsum comprises up to 90% of the unit in the area
of Bottomless Lakes State Park. Towards the north edge of the quadrangle, gypsum content decreases to ~ 75%, with
concomitant increase in clastic interbeds. Bedding is irregular and highly variable along eastern Pecos River bluffs due to
sinkhole formation, associated dissolution and collapse, and rotated slump and landslide blocks. Gypsum beds are thin- to
thick- to very thick-bedded, and massive to thin-bedded to laminated internally. Red outcrop color is due to surface wash
from the clastic interbeds. These clastic layers often have veins of gypsum. Bedding is irregular and highly variable where
gypsum content is high. As gypsum content decreases, bedding comes thinner and more planar, with less development of
collapse features and slumping. Thickness: Top not exposed; at least 75 m based on cross-section.
Queen and Grayburg Formations, undivided (Guadelupian - upper Permian) — cross section only.
New Mexico Bureau of Geology and Mineral Resources
Open-file Geologic Map 126
This and other STATEMAP quadrangles are available
for free download in both PDF and ArcGIS formats at:
http://geoinfo.nmt.edu/publications/maps/geologic/ofgm/home.html
Geoffrey Rawling
by
Pya
San Andres Formation (middle to upper Permian) — cross section only on the Bottomless Lakes quad. Two small
outcrops are mapped approximately 4.5 to 5 km west of the Pecos floodplain on the Bitter Lake quad as the Artesia Group
pinches out to the west.
Yeso Formation and Abo formation, undivided (lower to middle Permian) — cross section only.
REFERENCES
Dehler, C. M., Pederson, J. L., and Wagner, S. S., 2005, Preliminary geologic map of the Lake McMillan South
7.5-minute quadrangle, Eddy County, New Mexico: New Mexico Bureau of Geology and Mineral
Resources, Open-file Geologic Map OF-GM 111, scale 1:24,000.
Fiedler, A. G., and Nye, S. S., 1933, Geology and ground-water resources of the Roswell artesian basin, New
Mexico: U.S. Geological Survey Water-supply Paper 639, 372 p.
Kelley, V. C., 1971, Geology of the Pecos country, southeastern New Mexico: New Mexico Bureau of Mines and
Mineral Resources Memoir 24, 78 pp.
Lucas, S. G. and Anderson, O. A., 1993, Triassic stratigraphy in southeastern New Mexico and southwestern
Texas: in: Love, D. W., Hawley, J. W., Kues, B. S., Adams, J. W., Austin, G. S., and Barker, J. M., (eds.),
Carlsbad Region, New Mexico Geological Society Field Conference Guidebook 44, p. 231-235.
Lyford, F. P., 1973, Valley fill in the Roswell-Artesia area, New Mexico: U.S. Geological Survey Open-file Report
73-163, 26 p.
McCraw, D. J., 2008, Preliminary geology of the South Spring quadrangle, Chaves County, New Mexico: N.M.
Bureau of Geology and Mineral Resources, Open-file OF-GM 171, 1:24,000.
McCraw, D. J., and Land, L. A., 2008, Preliminary geologic map of the Lake McMillan North 7.5-minute
quadrangle, Eddy County, New Mexico: New Mexico Bureau of Geology and Mineral Resources, Openfile Geologic Map 169, 1:24,000.
McCraw, D. J., Rawling, G., and Land, L. A., 2007, Preliminary geology of the Bitter Lake Quadrangle, Chaves
County, New Mexico: N.M. Bureau of Geology and Mineral Resources, Open-file OF-GM 151, 32 p. +
1:24,000 map.
CORRELATION OF MAP UNITS
Alluvium, colluvium, eolian,
and anthropogenic deposits
0 ka
Historic
Pecos River
alluvial valley floor
daf water
Holocene
11
Qa
Qvf
Qaf
Qc
Qed
hmp4
hmp3
Hmp2
Hmp1 Qdp
Qdbp Qcbp
Rio Hondo
alluvium
Qbs
Alluvial terrace Depressions,
deposits
sinkholes
Hmh2
Hmh1
View of Lea Lake looking south-southwest showing the state park’s bathhouse
and swiming area in the distance. Lea Lake is both the largest and deepest of the
sinkhole lakes at 2,108 m2 (18.2 hectares) in area and 29.5 m in depth. Piping has
developed in the weathered gypsum, sandstone, and siltstone of the Seven Rivers
Formation in the foreground.
Panoramic view to the south-southeast of two collapse depressions and the early Holocene - lastest Pleistocene Pecos River alluvial channel taken from Comanche
Hill. Warped beds of primarily Permian Seven Rivers Formation gypsum can be seen in the bluffs to the left. The trees in the far distance to the right follow early
Holocene meandering Rio Hondo channels, which were deposited when the Rio Hondo flowed across the entire Pecos floodplain to reach the Pecos River.
Bedrock
Qlt3
Qabp
Qlt2
126
Qlt1
Qahf4 Qahf3 Qahc
Qd
Qds
781
2.6 Ma
3.6
220
248
261
268
275
286
@sr
Py
Psr
Pqg
Psa
Pya
COMMENTS TO MAP USERS
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.
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.
Supercedes
Preliminary geologic map of the Bottomless Lakes
quadrangle, Chaves County, New Mexico
May 2006
Psa
Pemian Artesia Group
Pecos River channel braided alluvium associated with coalescing depressions (middle Holocene to uppermost
Pleistocene) — Light reddish-brown (5YR6/4) to reddish brown (2.5YR4/6), unconsolidated, poorly to moderately sorted,
pebbly coarse- to fine-grained sand, silty sand, sandy clay, and clay. Braided channels and bars are common on the surface.
Deposits primarily extend between Qdp depressions formed during flood events. Thickness 3-10 m. Unit occupies areas
mapped as QHps and Qafs on the preliminary geologic map of the Bottomless Lakes quadrangle (v1p-00, May 2006).
Pecos River crevasse-splay alluvium debouching from Pecos River depression channel alluvium (middle Holocene
to uppermost Pleistocene) — Light reddish-brown (5YR6/4) to reddish brown (2.5YR4/6), unconsolidated, poorly to
moderately sorted, pebbly coarse- to fine-grained sand, silty sand, sandy clay, and clay. Braided channels, bars, and crevasse
splay lobes are common. Deposits formed during flood events when Qdp depressions and Qdbp channels were breached
and when the Pecos River abandoned the eastern depression course and built Hmp1 and Hmp2. The extensive Qcbp deposits
south and west of Comanche Draw are capped by Commanche Draw Qa alluvium. Thickness 3-10 m. Unit occupies areas
mapped as Qafs on the preliminary geologic map of the Bottomless Lakes quadrangle (v1p-00, May 2006).
Other Pemian Sedimentary Rocks
Depression and sinkhole deposits
PALEOZOIC SEDIMENTARY ROCKS
Qabp
(575) 835-5490
Lakewood terrace alluvial deposits (upper to middle Pleistocene) — Alluvial terraces of the Pecos River and its
tributaries were first described in the classic study of Fiedler and Nye (1933). They recognized 3 terraces: (from lowest to
highest) the Lakewood, the Orchard Park, and the Blackdom. The Lakewood terrace, with an elevation of 6 to 9 m above
the floodplain, flanked the inset Pecos floodplain and extended up many of its western tributaries. We now recognize three
distinct low-lying (upper to uppermost middle(?) Pleistocene) “Lakewood terraces,” the highest and oldest of which would
be Fiedler and Nye’s original (McCraw, et al., 2007; McCraw, 2008). Surface tread elevations above the floodplain for
these three are: <1-1 m, 1.2-6 m, and 6-9 m, respectively. We differentiate these terraces by their location either in the Pecos
valley, in the tributary valleys of the Rio Hondo and Borrendo Creek on the Bitter Lake quad west of the Pecos valley, and
in the Comanche Draw valley east of the Pecos valley. All of the Pecos valley Lakewood terrace deposits vary between:
1) the west side, with light gray (2.5Y7/1) to very pale brown (10YR7/4) to reddish brown (2.5YR4/6), unconsolidated,
well-sorted, medium- to fine-grained gypsiferous sand, silt, and sandy clay, and 2) the east side, made up of light reddishbrown (5YR6/4) to reddish brown (2.5YR4/6), unconsolidated, moderately sorted, pebbly, fine-grained, gypsiferous sand,
silty sand, and clay. Mostly non-gypsiferous. These units were incorrectly mapped collectively as the Orchard Park alluvial
terrace (Qopt) on the preliminary geologic map of the Bottomless Lakes quadrangle (v1p-00, May 2006).
Location of geologic cross section.
April 2010
New Mexico Bureau of Geology and Mineral Resources
New Mexico Tech
801 Leroy Place
Socorro, New Mexico
87801-4796
Pecos River channel alluvium occupying coalescing depressions (middle Holocene to uppermost Pleistocene) — Light
reddish-brown (5YR 6/4) to reddish brown (2.5YR4/6), unconsolidated, well sorted, fine-grained, gypsiferous sand, silty
sand, and clay thinly draped over the floor of depressions developed primarily in gypsum. Forms the lowest inset fluvial
deposit of the Pecos floodplain. The timing of the collapse or subsidence of the depressions is unknown, but their capture
of the Pecos River is constrained to lower Holocene – uppermost Pleistocene prior to Hmp1 development and probably
in the waning phases of active Qabp deposition. This is clear because the tributary Rio Hondo built two lower to middle
Holocene meander belts (Hmh1 and Hmh2) across Qabp. Hmh1 and Hmh2 are clearly distinguished from any meandering
Pecos River deposit by differing lithologies, sediment chararacteristics, and especially meander geometries (Rio Hondo
meanders are an order of magnitude smaller than those of the Pecos), and are clearly visible in aerial photos completely
crossing the Pecos floodplain to the eastern margin, where it joined the Pecos in its Qdp channel. While Qdp flows could
have occurred concurrently in the depression channel(s) and parts of Hmp1, it was not until an avulsion occurred upstream
during the middle Holocene, which caused Hmp1 to build out across Hmh1 and Hmh2 in the vicinity of the historic meander
belts, thereby cutting these lower belts off and causing the Rio Hondo to develop Hmh3 to the south and west. Pecos River
alluvium is very thin in these channels (<1 to 2 m thick) and very little bank or bar formation occurred while Qdp was active.
Thickness 3-10 m. Unit occupies areas mapped as QHps and Qafs on the preliminary geologic map of the Bottomless Lakes
quadrangle (v1p-00, May 2006).
Rio Hondo alluvial fan channel deposits (Holocene to upper Pleistocene) — The Rio Hondo alluvial fan complex
contains numerous alluvial channel deposits, ranging from old, abandoned channels to historic ephemeral streams (formerly
perennial – artesian spring-fed). Only the youngest (equilavent to Qahc3 on the South Spring quad) were mapped on the
Bottomless Lakes quad. These channel sediments are usually comprised of brown (10YR5/3) to dark yellowish brown
(10YR3/4), unconsolidated, moderately sorted, coarse- to fine-grained sand, often containing clay drapes, with occasional
gravels of limestone, sandstone, and igneous rocks and are slightly inset into alluvial fan lobe deposits. At their distalmost
ends, the often form a “deltaic” distributary fan complex (Qahd). These units were incorrectly mapped as the Orchard Park
alluvial terrace (Qopt) on the preliminary geologic map of the Bottomless Lakes quadrangle (v1p-00, May 2006).
Alluvial terrace deposits
104°15'00"W
Horizontal bedding.
NATIONAL GEODETIC VERTICAL DATUM OF 1929
BAR C BAR RANCH
QUADRANGLE LOCATION
Qahd
Geologic contact. Solid where exposed or known, dashed where
approximately known, queried where uncertain, dotted where
concealed.
?
00175
DEXTER WEST
Qahc
@sr
Headscarp of landslide or slump block.
SOUTH SPRING
Younger Rio Hondo alluvial fan lobe deposits (upper Pleistocene) — Thickness 1 to 4 m.
Younger Holocene meander belt deposits (Historic to upper Holocene) — Very pale brown (10YR7/4) to reddish brown
(2.5YR4/6), unconsolidated, moderately to well sorted, occasionally pebbly, coarse- to fine-grained sand, silty sand, and
sandy clay. Meander geometries are similar to hmp1, and while much of this is obscured by more recent meander belt
deposition and/or agriculture, amplitudes are estimated to average about 1 km in width with one amplitude of about 2 km
in width. Thickness 3-10 m. Unit occupied areas mapped as Qfly on the preliminary geologic map of the Bottomless Lakes
quadrangle (v1p-00, May 2006).
33°15'00"N
CONTOUR INTERVAL 10 FEET
BOTTOMLESS
LAKES
Qahf3
EXPLANATION OF MAP SYMBOLS
1:24,000
1000
NEW MEXICO
Youngest Rio Hondo alluvial fan lobe deposits (upper Pleistocene) — Thickness 1 to 3 m.
MESOZOIC SEDIMENTARY ROCKS
daf
Qaf
1
COMANCHE SPRING
Qahf4
Psr
Qvf
Base map from U.S. Geological Survey 1950, from photographs taken 1947, field checked in 1949-1950.
1927 North American datum, UTM projection -- zone 13N
1000-meter Universal Transverse Mercator grid, zone 13, shown in red
BITTER LAKE
On the South Spring quad, four distinct fan lobes are mapped, prograding east to northeast (Qahf1-4). The distal reaches
of the two youngest fan lobes (Qahf4 and Qahf3) reach the westernmost part of the Bottomless Lakes quad. These are
comprised of sands and a few gravels with a distinct petrographic Rio Hondo signature. While limestone, sandstone, and
chert, could’ve originated anywhere within the Sacramento Mountains and along its eastern flanks, the porphyritic igneous,
mafic igneous, and rhyolitic gravels common throughout these deposits could only have originated from Sierra Blanca,
the headwaters of the Rio Hondo. These gravels are supported by a matrix of brown (10YR5/3) to dark yellowish brown
(10YR3/4), unconsolidated, moderately sorted, coarse- to fine- grained sand, silty sand, silt (largely calcareous), and sandy
clay. Pedogenic carbonate varies from stage II to I, west to east and northeast for these youngest fan lobes. These units
were incorrectly mapped collectively as the Orchard Park alluvial terrace (Qopt) on the preliminary geologic map of the
Bottomless Lakes quadrangle (v1p-00, May 2006).
1939-1940 meander belt deposits (Historic) — Very pale brown (10YR7/4) to reddish brown (2.5YR4/6), unconsolidated,
moderately to well sorted, coarse- to fine-grained gypsiferous sand in the Historic channel and adjacent bar crests, grading
to silty sand and sandy clay with distance from these older channels. Throughout the upper Holocene, extensive point
bar development, with some minor channel bar development has taken place. This has resulted in a series of sweeping
meanders, with meander amplitudes >1 km in width common, the largest reaching about 1.8 km in width. In terms of
estimating thicknesses of this meander belt, the Holocene meander belts, and the braided Pleistocene deposits, we consider
a valley-fill thickness map based upon interpretations of data from numerous wells throughout the Roswell artesian basin by
Lyford (1973). This map depicts the valley fill thickness dropping from approximately 30 m on the western valley margin to
< 1 m to the east. Based upon this fact that the meander belts are built on a wedge of Pleistocene braided alluvial valley fill,
present at the surface aside hmp2 and buried with a ~30-m base alongside the western bluffs, the thickness of hmp1 ranges
from <1 m to 3-10 m where it overlies Holocene meander belts, and up to15 m where it buries Qabp. Unit occupies areas
mapped as Qfly on first version of the Bottomless Lakes preliminary geologic map (v1p-00, May 2006).
Older Holocene meander belt deposits (upper Holocene to lower (?) Holocene) — Very pale brown (10YR 7/4) to
reddish brown (2.5YR4/6), unconsolidated, well sorted, fine-grained, gypsiferous sand, silty sand, and sandy clay. Meander
geometries are significantly smaller with meander amplitudes averaging only 0.5 km in width. It appears that this meander belt
was first to develop, switching the river from flowing in a braided, coarser-grained Qabp floodplain into a small meandering
stream, which probably co-existed with active Qabp channels throughout much of the lower Holocene. Thickness <1 to 3
m. Unit occupies areas mapped as Qfly and Qflo on the preliminary geologic map of the Bottomless Lakes quadrangle (v1p00, May 2006).
Older Holocene meander belt deposits (middle Holocene to lower (?) Holocene) — Thickness 1-3 m.
Rio Hondo alluvial fan lobe deposits (upper Pleistocene to lower Pleistocene) — During most of the Pleistocene, the Rio
Hondo debouched from the western uplands into the Pecos valley south of its current location. It flowed from approximately
latitude 33° 17’ 30” N, roughly due east through what is now known as Rocky Arroyo onto the valley floor, three quads
west of the Bottomless Lakes quad. From here, it built a very large alluvial fan complex out over Pleistocene Pecos River
terraces. It prograded east until a stream capture occurred within the western uplands, sometime in the upper Pleistocene.
This capture, located at the current site of the dry Twin Rivers reservoir, on the Hondo Reservoir 7.5-minute quad, turned the
Rio Hondo northeast into its present channel and cut off fluvial and sediment input to the distal reaches of its fan complex
in both the South Spring and Bottomless Lakes quads (McCraw, 2008).
10
hmp3
559000
Eolian dune sand, undivided (Holocene to uppermost Pleistocene) — Very pale brown (10YR8/2) to light brown
(7.5YR6/4), unconsolidated, moderately to well-sorted sand, silty sand, and sandy clay. Forms extensive thin sheets and low
dunes. Deposits are along the eastern margin of the quadrangle appear to be localized by the low bluff formed by outcrops
of Triassic Santa Rosa formation (@sr). Largely stabilized by vegetation other than in blowouts. Sand sheets appear to be
common throughout the quadrangle east of the bluff composed of Seven Rivers formation, but these deposits could not be
consistently delineated on aerial photographs Thickness commonly <1 m to about 5 m.
Modern meander belt deposits (Historic) — Very pale brown (10YR7/4) to reddish brown (2.5YR4/6), unconsolidated,
moderately to well-sorted, occasionally pebbly, coarse- to fine-grained sand in the modern channel and adjacent bar crests,
grading to silty sand and sandy clay with distance from the channel. Modern meander amplitudes are only approximately
0.2-0.6 km in width. This has greatly reduced both channel and overbank deposition, thus the majority of modern meander
belt deposits are <1 m thick, but reach about 1.5 m thick in a few places. Unit occupies areas mapped as Qfly on the
preliminary geologic map of the Bottomless Lakes quadrangle (v1p-00, May 2006).
Warped gypsum beds of Permian Seven Rivers Formation ring the 10.5 m-deep
Devil’s Inkwell, named for its steep sides and dark water resulting from a higher
algal concentration relative to the other sinkhole lakes in the state park.
Young meander belt deposits (middle Holocene) — As described above, the two oldest Hondo meander belts (Hmh1 and
Hmh2) built up on top of both upper Pleistocene Rio Hondo braided alluvium (Qabh) and upper Pleistocene Pecos braided
alluvium (Qabp, Qdbp),with Hmh2 often building on top of Hmh1. Thickness 1-3 m.
Rio Hondo alluvial fan complex deposits
Qd
o
Qaf
Qabp
33°15'00"N
104°22'30"W
Hmh1
Py
Psr
hmp3
Qlt3
Colluvium, undifferentiated (Holocene to uppermost Pleistocene) — Light reddish-brown (5YR6/4) to reddish brown
(2.5YR4/6), unconsolidated to poorly consolidated, poorly to moderately sorted sand and silty sand, with rubble blocks
of gypsum, sandstone, siltstone, and mudstone, and minor limestone. Deposits range from less than 1 m to about 3 m in
thickness.
Hmh2
3680000
Qd
o
Hmp2
Qlt2
11
Qdp
Qabp
Qaf
Qahc
Qlt1
Hmp2
o
hmp3
!
Psr
Psr
3680000
Alluvial-fan deposits, undivided (Historic to uppermost Pleistocene) — Predominantly quartzite, chert, and carbonate
cobbles to gravel, often in stringers, in a light reddish-brown (5YR6/4) to reddish brown (2.5YR4/6), unconsolidated, poorly
sorted, and coarse- to fine-grained gypsiferous sand to silty sand. These fans are built along the base of the Seven Rivers
formation (Psr) eastern bluffs and interfinger with and/or spread out onto Pecos floodplain deposits. They are locally incised
by small drainages floored with recent alluvium (Qa). Most are stabilized by vegetation and apparently not currently active.
Thickness <1 m at their distal margins to 8 (?) m.
!
!
Qd
Qa
Qahc
3683000
Qd
Qd
Qds
Qlt3
Qahf4
Hmp2
!
Qahf4
Qahf4
Qd
Qds
Qlt3
Qahf4
Qvf
Qd
Qa
Qaf
Qdp
Hmp2
Qahc
Qd
Qvf
Qa
Qlt3
Qahf4
Qahf4
Qdbp
hmp4
Qaf
33°17'30"
Qd
daf
Qds
Psr
Psr
Pay
Qd
Qd
!
Hmp2
Qahd
daf
Qd
Qdbp
Qd
Qd
!
Qahf4
3684000
Qd
Psr
Qd
Qahf4
Qahf4
Qd
Py
Qaf
Qds
Qd
Hmp1
Qaf
Qaf
Qed
!
daf
Qds
Qdbp
Qa
Hmp2
Qlt3
Qd
daf
Qvf
hmp3
Qd
!
Qahc
Psr
Qds
Psr
Qd
?
Qahf4
Qd
daf
Psr
Qd
Qa
Qabp
daf
!
3684000
daf
Qa
Qaf
Qd
hmp3
Qaf
Qaf
Qd
Qd
Qa
Qd
Qd
Psr
hmp3
Hmp2
Qd
3685000
@sr
Qdbp
Qds
Qdp
Qd
hmp4
!
Qlt2
Qabp
Qd
Qd
Psr
Qa
Qd
Qd
Qd
Psr
Qdbp
Qbs
Qaf
Qdbp
Qdbp
Qd
Qd
Qa
Qdbp
daf
Hmp2
Qd
Qd
!
3685000
hmp3
Qbs
Qd
Qd
Qd
Qd
Qa
?
Qahd
Qd
Qc
Qdbp
Py
!
hmp4
Qd
water
Qd
Qds
Qd
hmp3
Qbs
Psr
Qaf
Qed
!
Qlt3
3686000
Qd
5
Qd
Qaf
Qd
Psr
Qaf
Qd
Qd
Qd
Qa
o
Qbs
Qds
Qd
Quaternary valley-fill alluvium, undifferentiated (Holocene to upper Pleistocene) — Brown (7.5YR4/2) to pale
brown (10YR6/3) unconsolidated, poorly sorted, pebbly sand, silt, and clay, probably deposited by alluvial processes with
subordinate sheetwash and colluvial processes. Grades into minor alluvial and colluvial fans on toes of hillslopes. Heavily
vegetated and often incised by active drainages too small to map, which are floored by Qa. Thickness 0 to 5 (?) m.
Pecos River meander belt alluvial deposits (Historic to lower (?) Holocene) — During the Holocene, the Pecos River
built four distinguishable meander belts on top of an upper Pleistocene Pecos River braided alluvial valley-fill deposit
(Qabp), which is the basal unit of the floodplain. Consisting of channel, channel bar, and point bar deposits, undivided, these
meander belt deposits are differentiated based upon aerial photographic work into two older Holocene units and two Historic
units, first described on the Bitter Lake quad (McCraw, et al., 2007): 1) the modern meander belt was mapped from both
2005 digital 1-m resolution, color orthophotography and 1981-vintage color aerial photography produced for the U.S.D.I.Bureau of Land Management, and 2) a 1939-1940 meander belt was mapped using vintage U.S.D.A. – Soil Conservation
Service black and white aerial photography. The 1939-40 meander belt, in places, also incorporates areas where meander
migration clearly continued up at least until around 1962, the issue date of the Bitter Lake topographic quadrangle (before
photo-revision). All aerial photography was georeferenced and plotted onto the 2005 orthophotography using ArcGIS. The
historic units are differentiated from the Holocene units by using a lower case “h” on the unit labels.
Py
Qd
Qaf
Qd
hmp3
Qvf
o
Qa
Qd
Qd
8
Rio Hondo meander belt alluvial deposits (Holocene) — Gravels of limestone, sandstone, and igneous rocks in brown
(10YR5/3) to dark yellowish brown (10YR3/4), unconsolidated, moderately sorted, coarse- to fine- grained sand, silty
sand, silt (largely calcareous), and sandy clay. At the onset of the Holocene, both the Pecos River and the Rio Hondo
began meandering, building meanderbelts. The earliest two Rio Hondo meanderbelts built across the entire Pecos River
floodplain (Qabp deposits) during the early to middle Holocene, due to the fact that the Pecos River occupied collapsed
karstic depressions along the eastern margin at this time (Qdp and Qbdp deposits) (McCraw, et al., 2007). Responding to an
avulsion of the Pecos River in the middle Holocene on the Bitter Lake quad, the Rio Hondo abandoned these meanderbelts
and was forced to turn south along the western edge of the floodplain, building a third, modern (Hmh3) meanderbelt on
the Bitter Lake quad. While meander geometries are essentially identical between all three Hondo meander belts, Hmh1
certainly exhibited the widest lateral migration (although not necessarily widest meander amplitude). Units occupy areas
mapped as Qflo on the preliminary geologic map of the Bottomless Lakes quadrangle (v1p-00, May 2006).
Pecos River alluvial valley floor
Qds
Py
Qa
3687000
Qd
Qd
Qd
Qd
Qa
Psr
Qdp
Qahd
3686000
3683000
Qa
Hmp1
Qa
33°17'30"
water
Qdbp
Hmp2
Qvf
Qd
Qd
62095
Quaternary tributary alluvium, undifferentiated (Holocene to uppermost Pleistocene) — Brown (7.5YR4/2) (Rio
Hondo fan deposits), pinkish gray (7.5YR6/2) to light reddish-brown (5YR 6/4) to reddish brown (2.5YR4/6) (Pecos
floodplain and eastern Permian uplands), unconsolidated, moderately sorted, pebbly sand, silt, and clay, gypsiferous in many
areas. Varies considerably in thickness from <1 m to 10-12 m. Unit equilavent to QHa on the preliminary geologic map of
the Bottomless Lakes quadrangle (v1p-00, May 2006).
!
A
Qabp
hmp4
Qd
!
hmp3
Hmp2
Py
?
3687000
Open water
!
Qaf
15
Qdp
water
daf
?
!
?
water
Qa
Qabp
60876
Qlt3
3689000
Qd
o
Hmp2
Qd
Qvf
o
Qabp
3688000
Qd
Qd
!
W
305 280
5
Qc
Qds
Qd
Qd
o
Qds
Qdp
water
Qdp
Qdbp
Qd
!
Qdbp
hmp3
Qed
Py
Psr
Qd
Qa
Qd
Qds
ÊÊ
Qabp
@sr
!
o
Qaf
15
Qd
20
daf
Qd
Qd
W
Qds
Qd
3690000
Qd
62635
Qd
60231
10102
8
Qdbp
3689000
33°20'
W
Py
Qd
o
Qaf
daf
Qd
W
Qd
Qds
Qd
hmp3
Qd
Qd
Qdp
hmp4
Hmp1
Qlt3
Qaf
daf
daf
o
Hmp2
water
daf
Psr
o
Qlt2
Qd
Rio Hondo alluvium
Qbs
daf
Py
Qd
W
}
Hmp2
W
daf
60067
Qds
Disturbed areas and/or artificial fill (Historic) — Disturbed areas, dumped fill, and areas affected by other human
disturbances. Mapped where deposits or extractions are areally extensive. Includes borrow or gravel pits.
00175
Qd
Qd
Alluvium, colluvium, eolian, and anthropogenic deposits
Floodplain alluvial backswamp deposits (Historic to upper Pleistocene) — Light gray (2.5Y7/1) to very dark gray
(7.5YR3/1), unconsolidated, well-sorted, gypsiferous silty sand, sandy clay, and clay in low-lying, poorly drained areas
below the bluffs of the Lakewood terrace. These areas commonly only receive fine-grained, slack-water flood deposition.
Thicknesses range from 3-15 (?) m. Unit occupies areas mapped as Qflo on the preliminary geologic map of the Bottomless
Lakes quadrangle (v1p-00, May 2006).
Quaternary/Neogene
Qd
daf
daf
e
Qbs
daf
W
Psr
hmp3
Qlt3
Qd
Qd
Qdp
Qabp
3691000
!
Hmh2
DESCRIPTION OF MAP UNITS
A'
Qdp
daf
Hmh2
Pya
Qd
@sr
daf
Qdcp
Qvf
1,000'
Pya
0' Mean Sea Level
Qd
?
Hmp2
Qa Qvf
daf
Qd
Qds
!
hmp3
Pya
Qa
Qdbp
hmp4
Pya
2,000'
Psa
Mean Sea Level 0'
Qa
!
Hmp1
daf
Pya
Psa
3,000'
upper
Hmh2
1,000'
Qd
Qlt2
Qd
Qds
5
Pqg
middle
Qdbp
hmp3
3691000
Hmh1
Qlt2
Qlt2 Qa
Qlt2
Py
lower
Hmp2
4
Qlt2
Psa
4,000
Feet (ASL)
@sr
Psr
Pqg
upper
Qd
Qlt2
Pqg
Psa
Py
Psr
Santa Rosa
Fm
Qabp
Qlt2
3692000
o
Qd
Qd
o
Qabp
Qds
Qds
Psa
Pqg
Py
62365
63642
Artesia Group
Seven
QueenGrayburg Fms Rivers Fm Yates Fm
Qds
Hmh2
Pay
Qdbp
Qdbp
2,000'
Psr
60175
60231
Yeso, San Andres
Abo Fms
Fm
Qds
!
Hmh2
Qd
60067
60627
Pleistocene
Hmh1
Qds
Pqg
10102
62095
Pliocene
Qd
Qa
Psr
!
3692000
Qd
Qds
3,000'
Psr
Triassic
Qd
Qd
Hmh2
@sr
daf
Qd
60876
Psr
Permian
Qabp
4,000
Feet (ASL)
Qa
o
Qd
Pecos
River
Southwest
Psr
Psr
Qdp
Qdbp
Qd
Qd
Qd
Qd
Qa
A΄
Northeast
Quaternary
Qd
104°17'30"W
33°22'30"N
569000
568000
Neogene
Qd
Psr
Psr
567000
Mesozoic
Qd
104°17'30"
565000
564000
563000
!
Qd
104°20'
561000
?
33°22'30"N
560000
559000
GEOLOGIC CROSS SECTION
A
Paleozoic
104°22'30"W
NMBGMR Open-file Geologic Map 126
Last Modified April 2010
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.