U.S. DEPARTMENT OF THE INTERIOR OPEN-FILE REPORT 2009–1189 U.S. GEOLOGICAL SURVEY Version 1.0

Tm 105°15’ Qc Qac 105°7’30” Qac QTso 105° 37°30’ Qls 37° CORRELATION OF MAP UNITS 30 m deep, respectively, and are deflation basins (Pillmore, 1976). Some of the Contact—Solid where location is certain; dashed where approximately located Tsfc Qc Tsfr Qls Ku Qa Tsfc Qac other natural closed depressions in the eastern part of the map area may also have Qa Qls ^s Scratch boundary—Arbitrary line that separates sedimentary rocks mapped as Ku Qbao Kv SURFICIAL DEPOSITS formed chiefly by eolian deflation. Estimated thickness 2 m Jm Tpc TKr (Tpc) and (TKr) east of line, from Tm Qls Tm Qa QTsy BEDROCK TKpr Qac Alluvial and Eolian those mapped as Poison Canyon and Raton Formations, undivided ( ) Qc mass-movement Mass-movement deposits Qa Tsfc Qf Tps Alluvial deposits deposits Tsfr Ku Qbey deposits Rocks that postdate the Laramide orogeny, Subdivided into: Shoreline Tsfr Tsfc Qc Jm Qls Tiom Tm Tpc Sedimentary rocks Tsfc Tat Tm Qa Holocene Tsfr Qbeo Tvf Conglomerates, mainly prevolcanic (lower and )—Boulder Lineament Qls Qsw Qac Qf Qt Qbs Tvf Ta ^s Qc Qls conglomerates with clasts of various local lithologies, especially 68 Ta Ta Qsw Qty ? Normal fault—Solid where location is certain; dashed where approximately located, Qsw Qgp Qbay Ku Qa quartzite; but including much lesser clasts of andesites (Ta) in uppermost part; dotted where concealed. Bar and ball on downthrown block. Dip symbol and Tsfr Kdp Qa Qsw Qe Tsfc Tsfc Tat Qbai Qti Qgb Qbai boulders range to at least 2 m and are generally well rounded; matrix consists of number indicate measured dip of fault plane Qc ? ? ? QTsy deep maroon colored red clay where locally (rarely) exposed; generally equiva- Tat Qto Qbao Qac Qc TKr lent to “Prevolcanic sedimentary rocks” of Lipman and Reed (1989) Thrust fault—Solid where location is certain; dashed where approximately located, Tvf P*sc Je QTsy Qc dotted where concealed. Sawteeth on upper (tectonically higher) plate Ta Qls Jm Qbey ( to Oligocene)—Syntectonic sedimentary and volcanic rocks deposited as fill in basins of the Rio Grande rift; everywhere divided into: Strike-slip fault, left-lateral offset—Solid where location is certain; dotted where Tvf Ku Kt Ku Qbeo concealed. Arrows show relative motion Qac Qbao Tiom Tsfc Alluvial facies—Pebble to cobble sand-matrix conglomerate, pebbly sandstone Tm Qls TKr Qsw ? Qa Qa QTsy and siltstone; poorly to moderately consolidated; ochre-colored to light red; large Strike-slip fault, right lateral offset—Solid where location is certain. Arrows show Ta Qa clasts derived mainly from local Proterozoic bedrock and much lesser local relative motion Qc ^s Jm Qsw QTso Tvf ? volcanic rocks (andesite, rhyolite, and tuff; Ta, Tfl, and Tat); only very locally Je Qc Ku Quaternary normal fault Qls present below Amalia Tuff (Tat), and there lacking in local volcanic clasts; Tps stratigraphically high exposures are commonly capped by mafic lava flows Kv Tps BEDROCK (Tm); thus probably ≥ 12 Ma (Kirkham and others, 2005) throughout most if not Landslide scarp Xgg Kdp Qbai Qsw all of map area Sedimentary Volcanic Intrusive Bedding lines Qc Tsfr Volcaniclastic facies—Boulder to pebble sand-matrix conglomerate of mainly Qa Qbao Tm Tmi Horizontal bedding Tiom Miocene volcaniclastic composition; clasts of local andesite, rhyolite, and tuff (Ta, Tfl, |Zg P*sc Tvf Qbey Qsw Qa Tat 30 Qbeo and ), along with much lesser intermixed clasts of local Proterozoic bedrock; Inclined bedding—Showing strike and dip Je Qc Tsfc Tsfr includes minor tuffaceous layers which appear to be reworked rather than ^ Qa 3 Qac s Ku Inclined bedding—Showing strike and dip. Top direction of beds known from local Qac Qto Tfl Tiof juvenile Qa Tps Tiom features. Top of bed indicated by ball Kdp Qty Tat Volcanic rocks Jm Qsw TERTIARY Xgg Ta Vertical bedding Qc Qa Tiom Qa Qa Tm Mafic lava flows (Miocene)—Basalt and basaltic andesite lava flows with sparse Tvf Qti Oligocene Qbao Kt plagioclase and olivine phenocrysts; dated at ~12 to ~15 Ma to the north of map 39 Ta Qc Ta Tioa Overturned bedding—Showing strike and dip *Mme Qsw (40Ar/39Ar, whole-rock; Kirkham and others, 2005); interbeds of alluvial facies Tat Qc TKr 15 Qac Qls Qbay of Santa Fe Group (Tsfc) locally included where too thin to map separately Inclined flow foliation or layering in igneous rock—Showing strike and dip Qa TKpr Tvf 53 Tfl Ku Qf Tfl Rhyolite lava (Oligocene)—Rhyolite lava with <0.5 percent phenocrysts of feldspar Inclined foliation in metamorphic rock—Showing strike and dip Tat Ta TKr Eocene Xgg Ku Tiom and quartz in a light grayish-blue groundmass; locally sperulitic or reddened by 40 Qbeo Qc Inclined foliation in igneous rock—Showing strike and dip Qa oxidation; probably equivalent to “rhyolitic lava flows (Tr)” mapped by Lipman Qc Qc Qsw Tfl and Reed (1989) southwest of map 31 Lineation—Showing bearing and plunge Xgg Qa Tpc Ku Qa Tat Amalia Tuff (Oligocene)—Peralkaline rhyolite ash-flow tuff; mainly densely welded, Overturned anticline Qc Qbay TKpr TKprc Qac Qty Kv with 10 to 20 percent phenocrysts of quartz and alkali feldspar (transitional Tsfr Qac Qls TKr sanidine-anorthoclase), and sparse to rare pyroxene, fayalite and sodic bed Qsw Tiom Qty Qsw amphibole; dated at 25.5 Ma (40Ar/39Ar, feldspar; Lipman and Reed, 1989) Dry hole Kv Unconformity Tiom Qbao Ta ^s Qbay Ku Qf Andesites (Oligocene)—Thick sequence of lava flows, tuffs, lahars, and lesser Qgb Je Kdp Ku Kv Qc Kt Upper interbedded volcaniclastic conglomerates and sandstones; mainly of andesitic Qa Tmi Qls Qbey Kv Kt CRETACEOUS composition but includes some dacites and rhyolites; equivalent to Conejos Qbai Ku Qa Qbao Qsw Interior Formation of the San Juan Mountains; equivalent rocks to southwest of map have Tsfc Qa seaway Ku been called “precaldera volcanic rocks,” which Lipman and Reed (1989) divide Qc Qc TKpr into 15 map units ranging in age from ~30 to ~26 Ma Qgb Tiom Qc Qty Ku Qa Kdp Lower Cretaceous TKr Qgp Qac Unconformity Intrusive rocks INTRODUCTION Tiom Tiom Jm Qc Jm Upper Tmi Mafic dike (Miocene)—Basaltic andesite dike with sparse plagioclase phenocrysts This geologic map covers four 7.5-minute quadrangles: The Wall, NM−CO (New Mexico− JURASSIC Tioa Kt and quartz xenocrysts; presumed to be related to Xenocrystic basaltic andesite Colorado), Vermejo Park, NM−CO, Ash Mountain, NM, and Van Bremmer Park, NM. The study Qsw Qa Je Qc Qbai Post-tectonic area straddles the boundary between the eastern flank of the Sangre de Cristo Mountains and the Qty Qsw Qls Ku Unconformity (Tbx) of Lipman and Reed (1989), to south of map. If this proposed correlation Qac Qac is correct, Tmi is similar in age to the oldest of the Mafic lava flows (Tm) of western margin of the . This foreland basin formed immediately eastward of these QTsy Kt ^s Qls Qc Qti Qbao northern part of map area, based on stratigraphic position mountains during their initial uplift, in the through early Eocene Laramide orogeny QTso Qa Lower PERMIAN (Lindsey, 1998). Subsequently, the Sangre de Cristo Mountains were extensively modified during P*sc Tiom Basalt and lamprophyre intrusions (Miocene to late Oligocene)— Dikes and sills formation of the Rio Grande rift, from ≥26 Ma to present (Chapin and Cather, 1994). One effect of P*sc Ku Colorado of basalt and lamprophyre composition, with a visibly granular groundmass; Ku Qf that modification is that the Sangre de Cristo Mountains now consist of several contiguous, but Xfa Qc Qc Trough presumed to be related to the intrusive complex at Spanish Peaks (~20 to ~26 Je Qbay topographically distinct, component ranges. In that context, the map area covers part of the Kv Qls Kt Kv Qsw *Mme Ma); not related to any known local volcanic rocks southern Culebra Range, as well as the northeastern part of the Devil’s Park graben (Kirkham and Qac Kt Tiof Felsic intrusion of Ash Mountain (Oligocene)—Very large hypabyssal intrusion of others, 2005)—a small intermontaine basin that is satellitic to the San Luis Basin, that is an Ku Unconformity Qac rhyolitic composition, probably a sill emplaced within very steeply dipping beds; outlying, early-formed part of the Rio Grande rift, and that separates the Culebra Range from the Tiom TKr appears identical to rhyolite lava (Tfl) in phenocryst and groundmass character Taos Range, to the southwest. The major local part of the Rio Grande rift is the San Luis Basin, TKpr which lies to the west of map area. Dikes |Zg EARLY PALEOZOIC Tioa Intermediate-composition intrusions (Oligocene)—Hypabyssal sills and dikes of Je Ku QTsy Field work for this map was carried out by Fridrich, Shroba, and Hudson during the summer of andesitic (diorite porphyry) composition; probably related to andesites (Ta) Mixed 2006. This new mapping was built upon earlier mapping by Pillmore that was conducted primarily Qf Qa Laramide-age syntectonic sedimentary rocks of Raton Basin Tioa Qsw Metaintrusive metavolcanic during the 1970s. Pillmore’s mapping of the eastern half of the study area (the Vermejo Park, NM− and CO, and Van Bremmer Park, NM quadrangles) has been published in two U. S. Geological Survey Qsw Qa metasedimentary TKpr Poison Canyon and Raton Formations, undivided (Paleocene and Upper 36°52’30” Xag Kdp open-file reports (Pillmore, 2003a, 2003b). His unfinished mapping of the two quadrangles that Qsw 36°52’30” Cretaceous)—Combined unit mapped in central to southern part of map area Xgg Xag Xp constitute the west half of the study area was used in this study as a starting point. On Pillmore’s where the distinction between Poison Canyon and Raton Formations becomes Jm maps, the mapping of bedrock contacts is very good from the Dakota Hogback (the prominent ridge Tps Qbeo CRYSTALLINE too subtle to map; consists of pebbly sandstone interbedded with siltstone, Kdp Qc Qbey BASEMENT ROCKS held up by the Dakota Sandstone and the Purgatoire Formation, unit ) eastward, and is little Qac Qsw Qc typically yellow-tan; contains no coal Xfa changed on the current map. The bedrock to the west of the Dakota hogback was remapped in its Qc Qsw Qbao Tpc entirety for the current map by Fridrich and Hudson. Moreover, all structural features on the Je Poison Canyon Formation (Paleocene)—Thick beds of ledge-forming, coarse- Tiof grained, commonly pebbly arkosic sandstones interbedded with slope-forming current map (attitudes and fault geometries) are from the 2006 mapping effort by Fridrich and Qc Qa TKr Qc TKpr sandy micaceous siltstones; typically yellow-tan. Contains no coal, and includes Hudson. All of the surficial deposits on the current map were mapped by Shroba. Xfa P*sc Qc far more Proterozoic clasts than Raton Formation (TKr). Maximum exposed Pillmore’s earlier work in the study area was not primarily a geologic mapping exercise. Rather, it was focused on understanding the Mesozoic and Tertiary stratigraphy and coal resources of the DESCRIPTION OF MAP UNITS andesite clasts, whereas the lower deposit consists of angular to rounded thickness ~60 m Qf Qf Raton Basin (Pillmore, 1969; Pillmore and Flores, 1987, 1990), as well as on certain key geomor- Qsw fragments of metamorphic rocks, quartzite, chert, and sandstone. The probable TKprc Jm Conglomeratic facies of Poison Canyon and Raton Formations, undivided phic features of the study area (Pillmore, 1976; Pillmore and Scott, 1976). Qsw SURFICIAL DEPOSITS source for the andesite is a pluton, about 5 km north of the Colorado–New Qbs Qbey Qa (Paleocene and Upper Cretaceous)—Sandstone with abundant well-rounded Several Quaternary faults are shown in the northernmost part of the Valle Vidal, in the extreme Qa Alluvial deposits Mexico State line (Pillmore and Scott, 1976). San Miguel Creek Alluvium, pebbles to small cobbles, mainly of various local Proterozoic lithologies, strongly southwestern corner of the map. These are compiled from unpublished mapping by C.A. Ruleman Tpc Qa about 80 km southeast of the map area, contains a mandible of a fossil horse of Qac Valley-floor alluvium (Holocene)—Mostly sand and gravel in stream channels; silty cross bedded and well consolidated; found only in a small area near southwest (USGS, Denver; written commun., 2008), completed during the summer of 2008. Ruleman’s Qa Blancan (Pliocene) age (Scott, 1986; Scott and Pillmore, 1993). Estimated sand, sandy silt, and gravel lenses beneath flood plains less than about 3 m above corner of map mapping of these faults is a revision of earlier mapping by Menges and Walker (1990). Qls thickness 3–10 m Tsfc ^s Qc Qbao modern streams. Deposits derived chiefly from sandstone (TKpr and TKr) Qsw commonly consist of slightly pebbly, silty, very fine to medium sand that TKr Raton Formation (Paleocene and Upper Cretaceous)—Interbedded sandstone, QTsy Younger (lower) unit—About 90–110 m above some of the modern streams in the Ku Qc contains a minor amount of coarse sand, granules, and lenses of pebble gravel. siltstone, mudstone, coal, and black shale comprising a deltaic sequence. Basal Qbay central part of the map area, and about 110–120 m above some of the modern Some deposits near The Little Wall and Ash Mountain (ridges composed of the beige-colored sandy conglomerate bears abundant pebbles of Dakota Sandstone. Qsw streams in northeastern part of the map area Ku Qc Qf basal conglomerate of the Raton Formation (TKr) and the felsic intrusion of Ash Thicker coal beds in unit shown with dark blue lines. Maximum thickness ~250 m Tioa Qe Tpc Qbs Tpc Mountain (Tiof), respectively) are nonsorted, clast-supported, bouldery, QTso Older (higher) unit—About 120 m above some of the modern streams in the Qc Sedimentary rocks of the Cretaceous interior seaway REFERENCES CITED Qac flash-flood deposits that contain clasts as long as 1 m. Unit Qa locally includes central part of the map area, and about 130–135 m above some of the modern small sheetwash aprons (Qsw) and small fan deposits (Qf), and probably locally Kv Vermejo Formation (Upper Cretaceous)—Interbedded sandstone, siltstone, Qa Qa streams in the northeastern part of the map area Benson, Larry, Madole, Richard, Landis, Gary, and Gosse, John, 2005, New data for late Pleisto- includes small, poorly drained marsh deposits in low-lying areas in Castle Rock carbonaceous shale, and coal; slope-former; medium brown to black; approxi- Qac cene alpine glaciation from southwestern Colorado: Quaternary Science Reviews, v. 24, p. Park, Van Bremmer Park, and Whitman Vega. Low-lying areas of unit Qa are Tps Pre-San Miguel Creek alluvium (Pliocene)—Gravelly, paleovalley-fill(?) deposits mate thickness of ~40 m Tps 46–65. Kdp cap two of the high ridges about 160–190 m above modern streams in the Xag |Zg Qc subject to periodic stream flooding. Estimated thickness 1–5 m Kt (Upper Cretaceous)—Sandstone, cliff-forming, fine- to very northeastern part of the map area, and two of the high ridges 180–195 m above Benson, Larry, Madole, Richard, Phillips, William, Landis, Gary, Thomas, Terry, and Kubic, Peter, Qc Qsw Sheetwash alluvium (Holocene and late Pleistocene)—Mostly slightly pebbly, fine-grained, calcite-cemented, light-yellowish-tan; maximum thickness ~30 m. 2004, The probable importance of snow and sediment shielding on cosmogenic ages of Qls Qsw modern streams in the northwestern and central parts of the map area. The slightly silty to silty sand that forms aprons deposited by unconfined overland north-central Colorado Pinedale and pre-Pinedale moraines: Quaternary Science Reviews, v. Je TKpr deposit on the south side of Gold Creek is poorly sorted, slightly bouldery, Ku , , , Greenhorn Formation, and Qac Kt TKr flow on gentle slopes chiefly in the eastern part of the map area. Low-lying areas 23, p. 193−206. TKpr cobbly pebble gravel. Some of the boulders in the deposit, composed of gneiss , undivided (Cretaceous)—Silty shale, charcoal gray, with of unit Qsw are subject to periodic sheet flooding, due to unconfined overland Kv Qsw and basaltic rock, are as large as 60–90 cm in diameter. Some of the largest some sparse interbeds of dark-brown arkosic sandstones and medium-gray Chapin, C.E., and Cather, S.M., 1994, Tectonic setting of the axial basins of the northern and Qc Qc flow, and locally to stream flooding and gullying. Estimated thickness 1–5 m Tiof boulders are composed of Dakota Sandstone and measure 170 cm thick, by ≥ 175 limestone. A slope-former; typically poorly exposed. Thicknesses are, from central Rio Grande rift, in Keller, G.R., and Cather, S.M., eds., Basins of the Rio Grande rift: Tpc Geological Society of America Special Paper 291, p. 5−25. Qc Terrace alluvium (late and middle Pleistocene)—Fluvial deposits composed chiefly cm wide, by 390 cm long. The large boulders in this deposit probably were youngest to oldest: Pierre Shale (~550 m), Niobrara Formation (~200 m thick), ^s Cole, J.C., Mahan, S.A., Stone, B.D., and Shroba, R.R., 2007, Ages of Quaternary Rio Grande Xfa Qt of interstratified pebbly sand and poorly sorted, clast-supported, cobbly pebble deposited by flash floods or debris flows. Clasts commonly are subangular, and Carlile Shale (~80 m), Greenhorn Formation (~40 m), and Graneros Shale (~35 |Zg Tioa gravel that underlie terrace remnants along major streams. Clasts commonly are are composed of basalt, basaltic andesite (Tm), and other volcanic rocks, such as m), for a total thickness of ~900 m terrace-fill deposits, Albuquerque area, New Mexico: New Mexico Bureau of Geology and Qc Qa Qls subangular to subrounded; some are rounded. They consist of felsic intrusive the Amalia Tuff (Tat), gneiss, quartzite, quartz, chert, and fragments of the Mineral Resources, New Mexico Geology, v. 29, no. 4, p 122−132. Kdp Dakota Sandstone and Purgatoire Formation, undivided (Lower Cretaceous)- |Zg Qbs rock (Tiof), sandstone, as well as a variety of igneous and metamorphic rocks. Dakota Sandstone (Kdp) and Sangre de Cristo Formation (P*sc). Unit Tps near Fridrich, C.J., and Kirkham, R.M., 2007, Geologic map of the Culebra Peak area, Las Animas and Qc Qls Dakota Sandstone consists of light-tan, cliff-forming, very well-cemented, Qa TKpr TKr Estimated thickness 1–10 m the north end of Ash Mountain consists of upper and lower gravel deposits. The Costilla Counties, Colorado: U. S. Geological Survey Open-File Report 2007−1428, scale upper gravel is composed almost entirely of felsic intrusive rock (Tiof), and is well-sorted, fine-grained, locally cross-bedded but mostly massive quartz arenite 1:50,000. Qc Qa Qty Younger (lower) unit (late Pleistocene)—About 12 m above Leandro Creek and less than 4.5 m thick. The lower gravel is composed chiefly of sandstone and sandstone; ~20 m thick. Underlying Purgatoire Formation is poorly exposed but Kirkham, R.M., Keller, J.W., Lindsay, N.R., and Price, J.B., 2005, Geologic map of the southern Jm Qc the Vermejo River in the eastern two-thirds of the map area. Unit locally includes conglomerate clasts derived from the Sangre de Cristo Formation, lacks clasts of existing outcrops are mainly dark-brown, fissile, silty shale and light-gray half of the Culebra Peak quadrangle, Costilla and Las Animas Counties, Colorado: Colorado a younger (lower) terrace about 6 m above stream level limestone with roughly cylindrical red chert nodules; ~70 m thick Xag Qls Qa felsic intrusive rock (Tiof), and is about 4.5–6 m thick. The lower gravel Geological Survey Open-File Report 2005−3, scale 1:24,000. Qbeo contains a minor amount of sandstone clasts derived from the Dakota Sandstone Kdp TKpr Qti Intermediate unit (late and middle Pleistocene)—About 18 m above the Vermejo Jurassic and Triassic post-tectonic sedimentary rocks Lanphere, M.A., Champion, D.E., Christiansen, R.L., Izett, G.A., and Obradovich, J.D., 2002, as well as clasts of Proterozoic amphibolite gneiss, quartzite, pegmatite, granite, River in the northeastern part of the map area Jm (Upper Jurassic)—Variegated, light-tan, light-gray, or Revised ages for tuffs of the Yellowstone Plateau volcanic field—Assignment of the Huckle- and vein quartz (Pillmore and Scott, 1976). Estimated thickness 10–35 m Qa light-purplish-pink bentonitic siltstone and claystone with interbedded thin berry Ridge Tuff to a new geomagnetic polarity event: Geological Society of America, v. 114, Tsfc P*sc Qto Older (higher) unit (middle Pleistocene)—About 30 m above the Vermejo River Ku Qac sandstone and lesser marl beds, and with traces of gypsum in the lower part; p. 559−568. Je Qa Tpc Alluvial and mass-movement deposits Qa Qc in the northeastern part of the map area Lindsey, D.A., 1998, Laramide structure of the central Sangre de Cristo Mountains and adjacent Xag Qac Alluvium and colluvium, undivided (Holocene and late Pleistocene)—Chiefly maximum thickness ≥100 m Qt Qc Raton Basin, southern Colorado: Mountain Geologist, v. 35, no. 2, p. 55−70. Tioa Outwash gravel (late and middle Pleistocene)—Glaciofluvial deposits composed undifferentiated valley-floor alluvium (Qa), sheetwash alluvium (Qsw), fan Ku Qc Je (Middle Jurassic)—Quartzose eolian sandstone; off-white; ~20 Kt chiefly of slightly bouldery, cobbly, pebble gravel deposited by meltwater deposits (Qf), and colluvium (Qc) along minor streams and on adjacent lower Lipman, P.W., and Reed, J.C., Jr., 1989, Geologic map of the Latir volcanic field and adjacent m thick areas, northern New Mexico: U. S. Geological Survey Map I–1907, 2 sheets, scale 1:48,000. Qc Qbeo streams flowing from former glaciers on the east side of the Sangre de Cristo (toe) slopes where they are too small to map separately. Low-lying areas of unit Qac Mountains about 1.5 km west of the map area. Boulders are 25–30 cm in Qac are subject to periodic stream flooding and locally to debris-flow deposi- ^s Triassic sedimentary rocks—Variegated dark-red and very pale-green pebbly Menges, C.M., and Walker, James, 1990, Geomorphic analysis of scarps along the eastern border of Jm Kv Qa diameter; clasts commonly are subangular. Deposits are a potential source of tion. The adjacent toe slopes may be susceptible to local sheet flooding due to micaceous arkosic sandstone, interbedded with siltstone, shale, and minor the Valle Vidal, north-central New Mexico, in Bauer, P.W., Lucas, S.G., Mawer, C.K., and McIntosh, W.C., eds., Tectonic development of the southern Sangre de Cristo Mountains, New Qf TKpr coarse aggregate. Estimated thickness 3–10 m unconfined overland flow, and locally to gullying. Estimated thickness 3–10 m bright-orange bentonitic(?) claystone and siltstone. Bentonitic(?) beds may Tioa TKpr Mexico: New Mexico Geological Society Guidebook, 41st Field Conference, p. 431−438. Kdp correlate with ashes of Qsw Qsw Qgp Outwash gravel of Pinedale age (late Pleistocene)—Underlies terrace remnants Qf Fan deposits (Holocene and late Pleistocene)—Mostly nonsorted to poorly sorted, Nelson, A.R., Millington, A.C., Andrews, J.T., and Nichols, Harvey, 1979, Radiocarbon-dated Kdp Qbay about 12 m above Costilla Creek, at the western boundary of the map area. slightly bouldery to bouldery, pebble and cobble gravel and locally pebbly and Upper Paleozoic syntectonic sedimentary rocks of the upper Pleistocene glacial sequence, Fraser Valley, Colorado Front Range: Geology, v. 7, p. Tiom Deposits probably are coeval with nearby till, just west of the map area, cobbly silty sand. Boulders in deposits near Ash Mountain commonly are Colorado Trough—Related to the “ancestral Rocky mountains” Tsfc Qsw 410−414. Qbai deposited during the Pinedale glaciation (about 12–30 ka; Nelson and others, composed of felsic intrusive rock (Tiof) as large as 40 cm × 60 cm × 100 cm. P*sc Sangre de Cristo Formation (Lower Permian and Middle Pennsylvanian)—Red, Tiof Qa Pillmore, C.L., 1969, Geology and coal deposits of the Raton coal field, Colfax County, New Qty 1979; Benson and others, 2004, 2005, and references cited therein). Deposits Deposited chiefly by streams and debris flows in fan-shaped accumulations near arkosic, cross-bedded sandstone and conglomerate with interbeds of ripple- Qc Tioa Qa Mexico: Guidebook, Raton Basin field trip: The Mountain Geologist, v. 6, no. 3, p. 125−142. Qac could be as old as 40–47 ka (Cole and others, 2007), and may have been base of moderate to steep slopes. Unit Qf locally includes sheetwash deposits marked siltstone; locally shaly with gray limestone nodules Pillmore, C.L., 2003a, Geologic map of Vermejo Park quadrangle, Colfax County, New Mexico, Qsw Qsw deposited during an early advance of Pinedale ice (Sturchio and others, 1994). (Qsw), colluvium (Qc), and probably hyperconcentrated-flow deposits. Ku TKpr *Mme and Las Animas County, Colorado: U. S. Geological Survey Open-File Report 2003−438, Qsw Low-lying areas of unit Qf are subject to periodic stream flooding, gullying, and Madera (Middle Pennsylvanian) or Espiritu Santo Formation (Mississippian)- Qgb Outwash gravel of Bull Lake age (late and middle Pleistocene)— Underlies Interbedded gray-tan limestone and black shale; exposure is limited to a very scale 1:24,000. Kv terrace remnants about 24 m above Costilla Creek at the western boundary of the locally to debris-flow deposition. Estimated thickness 3–15 m Tsfc Tiom small fault sliver along a thrust fault in northwest-central part of map; definitive Pillmore, C.L., 2003b, Geologic map of Van Bremmer Park quadrangle, Colfax County, New TKpr Qc Qa map area. Deposits probably are coeval with nearby till, just west of the map Mass-movement deposits age and formation assignment would require microfossil identification Mexico: U. S. Geological Survey Open-File Report 2003−437, scale 1:24,000. Qa Qa area, deposited during the Bull Lake glaciation (about 120–170 ka; Sharp and Qt Talus deposits (Holocene and late Pleistocene)—Two deposits on the steep west Pillmore, C.L., 1976, Deflation origin of Adams and Bartlett Lake Basins, Vermejo Park New others, 2003; Pierce, 2004). Lower Paleozoic or Neoproterozoic dikes TKpr flank of Ash Mountain, in southwestern part of the map area, are composed Mexico, in Ewing, R.C., and Kues, B.S., eds., Guidebook of Vermejo Park, northeastern New TKprc |Zg Gabbro (early Paleozoic or Neoproterozoic)—Dikes of nonfoliated quartz-bearing Barela Alluvium (late and middle Pleistocene)—Mostly poorly sorted, slightly chiefly of angular granules to boulder-sized fragments of felsic intrusive rock Mexico: New Mexico Geological Society Guidebook 27, p. 121−124. Qac pyroxene gabbro, which cut foliated Paleoproterozoic rocks but do not cut Qa bouldery, cobbly, pebble gravel that overlies eastward sloping pediment (Tiof) as long as about 2.5 m. Deposits were probably formed chiefly by rock Pillmore, C.L. and Flores, R.M., 1987, Stratigraphy and depositional environments of the Qsw Qsw overlying upper Paleozoic sedimentary rocks surfaces at three levels cut on Cretaceous and Paleocene sedimentary rocks. fall, rock slide, and, perhaps, locally by debris flow. Deposits locally may Cretaceous-Tertiary boundary clay and associated rocks, Raton Basin, New Mexico and Qac Xp Deposits east of Ash Mountain are rich in clasts of felsic intrusive rock (Tiof) contain material derived from the underlying silty shale (Ku). Unit Qt locally Colorado: Geological Society of America Special Paper 209, p. 111−130. Qc Qa Qa CRYSTALLINE BASEMENT ROCKS 36°45’ 36°45’ that commonly are as large as 30–60 cm in diameter. Deposits east of The may include block-slope and block-stream deposits (Qbs). Estimated thickness Metaintrusive Pillmore, C.L. and Flores, R.M., 1990, Cretaceous and Paleocene rocks of the Raton Basin, New 105°15’ 105°7’30” 105° Wall and north of Bernal Creek contain clasts composed chiefly of gneiss, 1–10 m Mexico and Colorado—Stratigraphic-environmental framework, in Bauer, P.W., Lucas, S.G., Xp Pegmatite (Paleoproterozoic)—Granitic pegmatite and aplite, mapped only in Base from U.S. Geological Survey, Wheeler Peak, N. Mex–Colo., 1982 8° SCALE 1:50 000 Field work for this map was carried out by C.J. Fridrich, R.R. quartzite, andesite(?), conglomerate, and sandstone. Most clasts are subangu- Mawer, C.K., and McIntosh, W.T., eds., Tectonic development of the southern Sangre de metric 1:100,000-scale topographic map Shroba, and A.M. Hudson during the summer of 2006 Qbs Block-slope and block-stream deposits, undivided (Holocene and late extreme southwest corner of map. Throughout map area, pegmatites too small to 1 1/ 2 01234 MILES lar; some are angular and subrounded. Low (50 cm) bouldery bars and lobate Cristo Mountains, New Mexico: New Mexico Geological Society Guidebook, 41st Field COLORADO Pleistocene)—Blocky deposits on steep slopes on the east and west flanks of Ash map are found as dikes, sills, and irregular masses cutting all of the Paleoprotero- Projection Universal Transverse Mercator, zone 13 Digital map database by T.R. Brandt bouldery deposits, which contain clasts as large as 90 cm in diameter, are Conference, p. 333−336. 1927 North American Datum Mountain, in southwestern part of the map area, are composed chiefly of angular zoic units below 1.50 1 2 3 4 5 KILOMETERS Editing and digital cartography by L.J. Binder locally present and suggest that some of the deposits within the unit were

TRUE NORTH Pillmore, C.L., and Scott, G.R., 1976, Pediments of the Vermejo Park area, New Mexico, in Ewing, Denver Publishing Service Center blocks of felsic intrusive rock (Tiof) commonly as long as about 1 m. MAGNETIC NORTH deposited by flash floods or debris flows. Estimated thickness 1–5 m Xgg Gneissic granite of Hill Ranch (Paleoproterozoic)—Monzogranite with a weak to R.C., and Kues, B.S., eds., Guidebook of Vermejo Park, northeastern New Mexico: New CONTOUR INTERVAL 50 METERS Manuscript approved for publication September 1, 2009 Block size probably decreases with increasing depth below the top of the APPROXIMATE MEAN NEW MEXICO strong superimposed gneissic foliation; locally includesmasses of pegmatite; Mexico Geological Society Guidebook, 27, p. 111−120. DECLINATION, 2009 SUPPLEMENTARY CONTOUR INTERVAL 25 METERS Qbay Younger (lower) unit (late Pleistocene)—About 12 m above some of the modern deposits. Deposits were probably formed chiefly by creep, freeze-thaw, subdivided by Kirkham and others (2005), to north of map, into “gneissic Pierce, K.L., 2004, Pleistocene glaciation of the Rocky Mountains, in Gillespie, A.R., Porter, S.C., NATIONAL GEODETIC VERTICAL DATUM OF 1929 streams in the western two-thirds of the map area. and possibly by periglacial processes during glacial episodes. Deposits granite” and “granitic augen gneiss” and Atwater, B.F., eds., The Quaternary Period in the United States: Amsterdam, Elsevier, 105°15’ 105°7’30” 105° locally may contain material derived from the underlying silty shale Qbai Intermediate unit (late and middle Pleistocene)—About 18–24 m above some of p. 63−76. 37° 37° (Ku). Unit Qbs locally may grade upslope into talus deposits (Qt). Xag Quartz monzonite of Costilla Creek (Paleoproterozoic)— Gneissic biotite quartz MAP LOCATION 105°15’ 105° the modern streams in the map area Scott, G.R., 1985, Map showing gravel-bearing surficial deposits and basaltic rocks near Trinidad, 37°15’ Estimated thickness 1–10 m monzonite, coarse-grained, moderately to strongly foliated; containing conspicu- Las Animas County, Colorado: U.S. Geological Survey Quadrangle Map MF−1738, scale EL VALLE STONEWALL Qbao ous augen of microcline 0.5 to 5 cm long; locally includes masses of pegmatite; CREEK Older (higher) unit (middle Pleistocene)—About 30–40 m above some of the Qc Colluvium (Holocene to middle? Pleistocene)—Unsorted deposits formed 1:50,000. dated at 1.644 Ga (U-Pb, zircon) by Lipman and Reed (1989), who use the same modern streams in the map area by a variety of mass-wasting processes. Deposits consist of sand and name for this unit but a different symbol (Xqct) Scott, G.R., 1986, Geologic and structural-contour map of the Springer 30' x 60' quadrangle, OF 2007–1428 Beshoar Alluvium (middle Pleistocene)—Mostly poorly sorted, slightly bouldery to finer material and clasts that range in size from granules to large Colfax, Harding, Mora, and Union Counties, New Mexico: U.S. Geological Survey Miscella- 105°22’30” (Fridrich and 104°52’30” bouldery, cobbly, pebble gravel that overlies eastward sloping pediment surfaces boulder-sized fragments. The composition of the deposits reflects that of Mixed metavolcanic and metasedimentary neous Investigations Series Map I−1705, scale 1:100,000. 37°7’30” Kirkham, the bedrock and sediment from which the colluvium was derived. Unit LA VALLEY 2007) TERCIO at two levels cut on Cretaceous and Paleocene sedimentary rocks. Deposits east Xfa Mixed unit of interbedded amphibolite, and various metasedimentary and Scott, G.R., and Pillmore, C.L., 1993, Geologic and structural-contour map of the Raton 30' x 60' of Ash Mountain are rich in clasts composed of felsic intrusive rock (Tiof) that includes material transported chiefly by creep, debris flow, hyperconcen- metavolcanic rocks (Paleoproterozoic)—Unit consists of interbedded CULEBRA PEAK TORRES quadrangle, Colfax and Union Counties, New Mexico, and Las Animas County, Colorado: commonly are as large as 30–50 cm in diameter. Deposits east of The Wall and trated flow, sheetwash, landslide, and probably by periglacial processes high-grade metamorphic rocks of mixed lithologies—about half amphibolite U.S. Geological Survey Miscellaneous Investigations Series Map I−2266, scale 1:100,000. OF 2005–3 (Kirkham and north of Bernal Creek contain clasts composed chiefly of gneiss, quartzite, during glacial episodes. Estimated thickness 3–15 m (metabasalt) and half mixed rock types, including quartzites, quartz-muscovite Sharp, W.D., Ludwig, K.R., Chadwick, O.A., Amundson, Ronald, and Glaser, L.L., 2003, Dating others, andesite(?), conglomerate, and sandstone. Clasts commonly are subangular; schists, and felsic gneiss; includes abundant pegmatite bodies too small to map fluvial terraces by 230Th/U on pedogenic carbonate, Wind River basin, Wyoming: Quaternary 2005) Qls Landslide deposits (Holocene to middle? Pleistocene)—Deposits of 37° some are angular and subrounded. Low (50 cm), bouldery bars and lobate separately; exposure is mostly very poor, possibly owing to brecciation along Research, v. 59, p. 139−150. BIG COSTILLA bouldery deposits, which contain clasts as large as 70 cm in diameter, are locally unsorted and unstratified debris that commonly have hummocky topog- THE WALL VERMEJO CASA adjacent low-angle thrust fault that places this unit over Sangre de Cristo Sturchio, N.C., Pierce, K.L., Murrell, M.T., and Sorey, M.L., 1994, Uranium-series ages of PEAK PARK GRANDE present and suggest that some of the deposits within the unit were deposited by raphy. Many of the landslides and landslide deposits form on unstable Formation (P*sc); not related to “Mixed unit of felsic gneiss and amphibolite travertines and timing of the last glaciation in the northern Yellowstone area, Wyoming- OF 2003–438 flash floods or debris flows. Some of the cobbles and small boulders composed slopes that are underlain by bedrock units that contain shale (Ku), 36°52’30” 36°52’30” (Xaf)” on the map to the north (Fridrich and Kirkham, 2007), which is entirely Montana: Quaternary Research, v. 41, p. 265−277. (Pillmore, of sandstone are weathered flat to the ground surface; some of the surface siltstone (Kv, TKpr, and Tsfc) or clayey volcaniclastic sediments (Ta) in 2003a) the western part of the map area and in Vermejo Park. Younger landslide metavolcanic; instead probably related to “Bimodal and metasedimentary unit Varnes, D.J., and Cruden, D.M., 1996, Slope movement types and process, in Schuster, R.L., and boulders, composed of felsic intrusive rock, have weathering pits several (Xb)” of that map. Equivalent to “Mixed unit of felsic gneiss and amphibolite” 36°52’30” centimeters deep. Older deposits of Beshoar Alluvium, about 70 km northeast of deposits commonly are bounded upslope by crescent-shaped headwall Krizek, R.J., eds., Landslides Investigation and mitigation: Washington, D.C., National COMANCHE ASH VAN BREMMER CASA of Lipman and Reed (1989) to southwest of map SANGRE DE CRISTO MOUNTAIN RANGE scarps and downslope by lobate toes. The unit locally includes material Academy Press, Transportation Research Board Special Report 247, p. 36−75. POINT MOUNTAIN PARK GRANDE SW the map area, locally contain water-lain deposits of 640-ka Lava Creek B ash (Scott, 1985; Lanphere and others, 2002). Estimated thickness 1–5 m displaced chiefly by rock slides, debris slides, debris flows, earth slides, OF 2003–437 and earth flows, as defined by Varnes and Cruden (1996). The composi- (Pillmore, Qbey 2003b) Younger (lower) unit—About 45–50 m above some of the modern streams in the tion of the deposits reflects that of the bedrock and sediment from which Publishing support provided by: northwestern and central parts of the map area This and other USGS information products are available at http://store.usgs.gov/ Denver Publishing Service Center 36°45” the landslide deposits were derived. Landslide deposits are prone to U.S. Geological Survey RED RIVER BALDY ABREU HOUSE Qbeo Older (higher) unit—About 55–65 m above some of the modern streams in the continued movement or reactivation due to both natural and human- Box 25286, Denver Federal Center For more information concerning this publication, contact: PASS MOUNTAIN CANYON CANYON induced processes. Unit Qls locally includes minor sheetwash (Qsw) Denver, CO 80225 Team Chief Scientist, USGS Earth Surface Processes RATON BASIN map area CONVERSION FACTORS Box 25046, Mail Stop 980 and locally may include rock-fall deposits. Estimated thickness 5–45 m To learn about the USGS and its information products visit http://www.usgs.gov/ Denver, CO 80225 San Miguel Creek Alluvium (early Pleistocene or Pliocene)—Bouldery gravel at Multiply By To obtain 1-888-ASK-USGS (303)236-5344 two levels that (1) overlies east sloping pediment surfaces (Pillmore and Scott, Eolian deposits inches (in) 2.54 centimeters (cm) 36°37’30” Qe feet (ft) 0.3048 meters (m) This report is available at: 021 3 4Miles 1976) at and near Adams Lake and Bartlett Lake in the central part of the map Eolian sand (late and middle? Pleistocene)—Wind-deposited, slightly Or visit the Earth Surface Processes Team Web site at: miles (mi) 1.609 kilometers (km) http://pubs.usgs.gov/of/2009/1189 http://esp.cr.usgs.gov/ Index map showing map area, in yellow, and area and (2) forms paleovalley-fill(?) deposits that cap ridges along Wet Canyon clayey, silty sand forms one linear dune-like deposit in Van Bremmer adjacent 7.5-minute quadrangles. For U.S. Any use of trade, product, or firm names is for descriptive purposes only 36°45’ 36°45’ and Gonzales Canyon in the northeastern part of the map area. Clasts in deposits Park. The unit probably was derived by wind erosion from nearby and does not imply endorsement by the U.S. Government. 105°15’ 105°7’30” 105° Geological Survey publications the publication at and near Adams Lake and Bartlett Lake are about 50 percent felsic intrusive sedimentary bedrock sources by westerly(?) paleowinds. Thin, number, author(s), and year of publication are Suggested citation: Digital Elevation Model (DEM) shaded-relief image of the Vermejo Peak rock (Tiof); the other clasts are composed mostly of sandstone of the Sangre de unmapped deposits of unit Qe locally mantles younger deposits of San Although this information product, for the most part, is in the public Fridrich, C.J., Shroba, R.R., Pillmore, C.L., and Hudson, A.M., 2009, Preliminary geologic map map area as illuminated from the northwest. Shaded-relief values derived shown. Cristo Formation (P*sc), quartzite, and chert. San Miguel Creek Alluvium Miguel Creek Alluvium (QTsy) on the east side of Bartlett Lake domain, it also contains copyrighted materials as noted in the text. of the Vermejo Peak area, Colfax and Taos Counties, New Mexico, and Las Animas and Costilla from U.S. Geological Survey National Elevation Dataset (NED, along Wet Canyon and Gonzales Canyon consists of upper and lower gravel (Pillmore, 1976) and probably on the east side of Adams Lake. The natural Permission to reproduce copyrighted items for other than personal use Counties, Colorado: U.S. Geological Survey Open-File Report 2009–1189, 1 sheet, scale must be secured from the copyright owner. 1:50,000. http://ned.usgs.gov/) 10-meter elevation data, 1999–2000. deposits. The upper deposit is rich in pebble- to boulder-size (as long as 1.5 m) closed depressions that contain Adams Lake and Bartlett Lake are about 17 and

PRELIMINARY GEOLOGIC MAP OF THE VERMEJO PEAK AREA, COLFAX AND TAOS COUNTIES, NEW MEXICO, AND LAS ANIMAS AND COSTILLA COUNTIES, COLORADO By Christopher J. Fridrich, Ralph R. Shroba, Charles L. Pillmore, and Adam M. Hudson1 1 Montana State University, Bozeman 2009