NEW MEXICO BUREAU OF GEOLOGY AND MINERAL RESOURCES A RESEARCH DIVISION OF NEW MEXICO INSTITUTE OF MINING AND TECHNOLOGY NMBGMR Open-File Geologic Map 280 Last Modified December 2020 Correlation of Map Units Description of Map
106°37'30"W 106°35'0"W 106°32'30"W 106°30'0"W 000 000 000 0000 000 000 355 356 357 154 358 359 A 360000 1550000 361000 362000 363000 1560000 364000 365000 QUATERNARY SEDIMENTS CRETACEOUS ROCKS Todilto Formation dominated by limestone—In some areas, the Tonque Arroyo 36°22'30"N J Jtl 36°22'30"N Qal Quaternary alluvium—Generally poorly exposed; light to dark brown and/or Cretaceous stratigraphy on the Echo Amphitheatre quadrangle follows that of Owen et al. Member of the Todilto Formation is not present either due to nondeposition, Je? Qal dark grey and/or orangish; loose to friable; fine to coarse-grained; poorly sorted, (2005) and Koning et al. (2006). An excellent geologic history of this part of the Chama Basin erosion, or chemical dissolution (Koning et al., 2006; Kelley et al., 2006). The Kbc? Qt 7300 Luciano Mesa Member is 1–8 m thick* and consists mostly of thinly laminated, 7400 medium to thick-bedded, sometimes weakly calcite cemented; clayey, silty, has been provided by Kelley et al. (2006). 7500 Je dark-gray or yellowish-gray, kerogenic limestone. Beds near the base of the 7200 7100 pebbly sand and sandy silt. Clasts are composed mostly of local Triassic through 7900 7800 7000 Cretaceous rocks, sometimes with variable amounts of quartzite clasts. Pebbles member are usually sandy, and microfolding of the thin limestone laminae is Paguate and Clay Mesa Members of Dakota Sandstone—The Paguate Member Jtl common. Although the Luciano Mesa Member is thin and commonly exposed in 7600 Kdpc 26 6900 and small cobbles of gypsum are particularly distinctive downstream of Todilto Qtch1 Qtca1 is composed of yellowish to tan; Moderately strong to strong; moderately ^cpp Je 30 29 28 6800 27 000 cliffs, we have sometimes exaggerated its thickness (i.e., the width of outcrop) in 28 27 25 4026 Formation outcrops. The unit includes sediment in the active channels and valley well-sorted; subrounded; medium to thick-bedded; very fine- to
order to show its presence. Some small areas where only the Luciano Mesa
Je bottoms, adjacent ‘valley-fill,’ tributary alluvium graded to within ≈2 m of the 7900 medium-grained; commonly burrowed; arkosic quartz sandstone. Sandstones 000 Qtch2 Qtca2 Qf 4026 Jtg Jtl Quaternary Qt Member is present have been lumped into Jtg because they are not able to be Qg Qls Qc present river level, and active stream terraces and gravel bars. On this are mostly coarse-grained near the base, and medium-grained at top. Rare Je mapped at scale and/or relations are not clear (e.g., where the Tonque Arroyo Jtl Je 6700 ^cr quadrangle, Qal also includes some areas of active alluvium found at higher
Qtch3 Qtca3 pelecypod and fragmentary ammonite fossils have been found (Lucas et al., ^cr may be present but buried by Qls). Jsb? elevations (such as within landslides), but these are only mapped where they are Jtg 2009). The Paguate is interpreted as middle and outer shoreface sands (Owen et 7800 particularly extensive and/or clearly active. Quaternary alluvium is only mapped Qtch4 Qtca4 al., 2005). Hand samples are difficult to distinguish from the Cubero Sandstone.
^cr We suspect that in some areas, the Tonque Arroyo Member has been removed where it is clearly >2m thick and/or it obscures large areas of bedrock units and/or Jtg Je Qtp by mass movements (leaving only the Luciano Mesa Member), but it has not Je Qtch5 Qtca5 unit contacts. Chestnut (written communication, 2020) obtained a calibrated Some thin, loose Quaternary sand presumably derived from weathering of the Je radiocarbon age of 978 ± 39 ybp for a terrace 1.4 m above the Rio Chama on the been possible to prove this. Large (up to 100 m+) ‘slabs’ of Tonque Arroyo 7900 Paguate Member is present on the Mesa de los Viejos, but this material is nowhere Member Gypsum are sometimes found within landslides and particularly near ^cr Laguna Peak Quadrangle (immediately to the West of the Echo Amphitheatre exposed and seems to be generally less than 1 m thick. Very rare quartzite pebbles Jtg Quad). Generally, the unit is 1–10 m thick but possibly thicker beneath the Rio the base of landslides. 6700 Qtgh were observed within this loose sand in Section 1 T24N:R3E and would seem to Kdeoc 000 T025N R003E T025N R004E 4025 Chama and Canjilon Creek. indicate the former presence of more extensive Quaternary cover. 6900 6800 7000 7100 In at least one area (in the eastern half of section 11 T24N:R3E) it can be seen that 8000 ^cpp 4025000 Quaternary fans—Poorly exposed; light to dark brown and/or blackish or the Todilto Formation has moved en mass downslope over Quaternary(?)
1950000 1950000 The underlying Clay Mesa Tongue is a very poorly exposed shale and siltstone(?)
Qf hillslope deposits (Figure 1) and large slabs of gypsum are seen at the base of Kdeoc Jtl orangish; loose to friable; fine to coarse-grained; poorly sorted; medium to that sometimes forms a narrow bench beneath the Paguate Member. The Clay Jtl Qal+Qf thick-bedded; sometimes weakly calcite cemented; clayey, silty, pebbly-to-cobbly landslide deposits below this point. The Luciano Mesa Member is not present Kbc Mesa Tongue is not present in the “Highway 84 Section” of Owen et al. (2005) a 33 34 35 36 31 Qls here and may have been removed by mass movements. This sliding of the Todilto 32 33 34 sand and sandy silt. This unit includes Quaternary fans of multiple ages/heights few miles north of Echo Amphitheatre (in the northeast part of this quadrangle). 4 7900 Jtg 7200 above grade. These fans likely have a similar origin to Qal/Qf, but base-level fall Formation seems to have occurred over at least a half kilometer of the outcrop. Jtg However, the Clay Mesa Tongue is identified in the western half of this Qf Kdpc This relationship leads us to believe that the base of the Tonque Arroyo Member 5 Jtl and the subsequent incision has left them above current grade. Some sub-map 8000 Je quadrangle based on uncommon exposures of shale at the base of cliffs formed by scale (generally =75 m wide) fans and fan remnants have not been mapped. Qf and/or the Luciano Mesa Member may have acted as the ‘breakaway’ surface for Qal the Paguate Member and is tentatively inferred in the eastern part, off the Kbc some landslides in the area. If this interpretation is correct, then all of the Jurassic Jsb? deposits sometimes grade up-slope into Qls and have often been derived from
quadrangle, based on a slope break at the base of the Paguate Member in some Qf ^cr Cretaceous Kdpc ^cr 6600 Kdeoc them. ≈2–25(?) m thick. section above the Todilto here is likely also displaced by mass movements. locations. The Clay Mesa Tongue is approximately 2–3 m thick where exposed. Jtg 7500 4024000 However, we have mapped ‘windows’ of the Summerville/Bluff and Morrison 6600 The total thickness of Kdpc ≈18 m thick. Quaternary landslides—Landslide deposits consisting of a chaotic, non-bedded, Formations above here as in-place bedrock because they are not obviously tilted 4024000 Jmb Qls relative to other bedrock units and are no more disturbed than many other such 6700 Kbc friable assemblage of very poorly sorted gravel, sand, silt, and clay derived 3 T025N R004E Qf Cubero, Encinal Canyon, Oak Canyon and Cubero Members of Dakota mostly from Cretaceous rocks and Jurassic rocks younger than the Entrada Kdeoc windows above locations where the Todilto is not obviously displaced. T024N R004E Jtl Sandstone—Mostly poorly exposed; tan to yellow-brown quartzose sandstone, Sandstone and semi-intact blocks of Jurassic rocks up to several tens of meters
Jtl dark-gray and brown carbonaceous shale, and minor greenish- gray mudstone
Qf across. Terrace gravels are sometimes found on/in the lower parts of landslide *An exception to the 2 m minimum thickness of units has been made for the Jsb ^cr Qls and bentonite. Includes, from oldest to youngest: the Encinal Canyon, Oak 7500 Luciano Mesa Member in some locations. ^cpp deposits even when no terrace remnants are preserved. Landslides commonly Canyon, and Cubero Members. Je 8100 ^cpp have the form of Toreva blocks (rotational slumps) where they overlie Cretaceous Qtca3 03 Entrada Formation—Well-exposed; commonly reddish and yellowish but Jtl? Qal+Qf Qf and Jurassic Rocks above the Todilto Formation. Below the Todilto Formation, The Encinal Canyon Member is highly variable in thickness, ranging from 2–24 m Jmb Je sometimes light-brown, orange, whitish or grayish-orange; cross-bedded; Qf they often appear to be earthflows. The surface of the landslides is commonly and averaging 8 m regionally (Owen et al., 2005). This tan, cross-bedded quartz Qf ^cr littered with large blocks of Cretaceous sandstone. Earthflow(?) deposits cross-laminated; very fine- to medium-grained; moderately well-sorted and ripple Qf sandstone with thin- to medium-bedding, sometimes contains carbonized plant 000 laminated, eolian sandstone that commonly forms a prominent cliff. Transport 4023 sometimes seem to have a rough stratigraphy consisting of (from bottom to top): 6500 fragments. The Oak Canyon Member is a black, muddy siltstone interbedded 06 05 Qf Qtca4? chaotic material occasionally including gypsum blocks and slabs up to 100± m; a direction at individual outcrops is variable, but the regional transport direction is with thin (<1 m) beds of ledgy and often lenticular, white to orange, cross-bedded, 4023000 toward the south and southwest (Tanner, 1965). The unit is 60–76 m thick. middle zone of sandstone boulders and deformed-to-relatively intact masses of bioturbated sandstone. The “A bentonite” is found in the lower part of the Oak Qf Jsb and Jmb, and an upper layer characterized by large boulders of Cretaceous 7500 Jurassic Canyon Member and recently provided a direct age of 98.1 ± 2.4 Ma (Peters, 2004). 8000 Jsb sandstone from the Dakota and Burro Canyon Formations in a poorly sorted, tan 7000 TRIASSIC ROCKS They were interpreted as offshore marine deposits (Owen et al., 2005). The Jtg ^cpp Qtca2? to greyish matrix of gravel, sand, silt, and some clay. Not all of these layers are All Triassic strata on the Echo Amphitheatre quadrangle are assigned to the Upper Triassic 8100 Qf Cubero Member is a sometimes well-exposed; yellowish to tan; moderately
present everywhere, and near the edges of mapped deposits (especially in Chinle Group (Lucas, 1993). Triassic stratigraphy follows Lucas and Hunt (1992) and Lucas strong to strong; moderately well- to well-sorted; subrounded to rounded; ^cpp Je 7000 landslides below the Todilto Formation), the uppermost layer is often the only 8100 6500 Jtg Jtl medium- to thick-bedded; very fine to fine; commonly burrowed; quartz et al. (2003, 2005b). An excellent geologic history of this part of the Chama Basin has been
Qf Qls Qf Qt? Qtca5? Qf/Qt one present and/or exposed. Erosion of the uppermost layer often produces provided by Kelley et al. (2006). ^cr sandstone with minor silt and shale approximately 10–15(?) m thick. Bedding
04 Qf/Qt hoodoos (boulder-capped pedestals) between <1 and ≈10 m high along the ^cpp ^cr Qf/Qt features are commonly obliterated by burrowing. Lower contact is sharp to Je Qal? Qt Jtg ^cpp margins of landslides. Je gradational over about 1 m. Upper contact usually sharp. The entire thickness of Qf 000 Chinle Group (Upper Triassic) ^cpp 4022 8000 Qtca5? 36°20'0"N Qal Kdeoc 7500 Je 36°20'0"N is ≈40–56 m. Rock Point Formation—Poorly to well-exposed; reddish- brown to yellowish-red 7900 Qg Qt Quaternary colluvium—Light-tan to brownish; loose to friable; coarse to Qf/Qt
000 Kbc Jtg ^cr
Jtl Kbc Qt Qf beds of siltstone and very fine- to fine-grained; massive or thin to medium, tabular
4022 6500 Qc
fine-grained; very poorly sorted; massive(?); sometimes weakly calcite cemented; Je 7500 Burro Canyon Formation—Whitish to tan; moderately strong to strong; poorly to 0000 7600 6600 1940000 bedded sandstone and reddish-brown mudstone. Where deeply weathered(?), the 194 6700 Qtca2 Qt Qtca5? sandy, silty, pebble to boulder conglomerate and pebbly silty sand. Colluvium is Kbc 7100 Jmb Jsb? moderately sorted; subrounded; medium- to thick-bedded; fine to medium, Rock Point Formation forms an orange slope (slightly less red than the underlying ^cpp Qal/Qf ^cr Jtg Jtl 6600 mapped only where it obscures bedrock units and/or unit contacts—mostly Jmb Jmb? Qtca1 sometimes pebbly; cross-laminated and plane-laminated; sometimes pebbly to Painted Desert Member of the Petrified Forest Formation). The lower contact of the 7000 Jmb within the drainage of the Canada Del Potrero, which is at a relatively high Jsb ^cr cobbly sandstone and red and/or green; sometimes mottled; laminated or Rock Point is mapped at the first persistent bed of sandstone above the mudstone 6900 Jmb? 09 Qt Je Jsb? 07 Qt? elevation and beneath Ponderosa Pine forest. Contacts between Qls and Qc in the Qf Jsb Jtg ^cr 08 6400 massive clay and siltstone. Small-scale trough cross-bedding is associated with of the Painted Desert Member or at the above-noted color change. The top of the Je Qg?
6800 ^cr Jsb Jtg Jtl ^cpp Qtca3 ^crpp Canada del Potrero are somewhat arbitrary as no exposures are available, and
Jtg Jsb? Jtg Jtl 4 the conglomeratic channels, which are more common near the base of the unit in Rock Point is a sharp, unconformable contact with overlying Entrada Sandstone. ^cpp ^cr these two units present very similar surfaces. Although included in Qls as
^cpp Qal/Qf Je Qt ^cpp the Echo Amphitheatre area. Conglomerate clasts are mostly varicolored Width of the outcrop is sometimes exaggerated where exposed in or at the base of ^cpp 6700 Je ^cpp mapped, colluvium/talus is relatively common along the upper contact of Qt Jtg ^cr quartzite and chert pebbles with less common sandstone and limestone(?) clasts. steep cliffs. The unit is up to 70 m thick. 6600 6600 landslide deposits below Dakota and/or Burro Canyon outcrops and on the steep
Qal/Qf ^cpp Je Je ^cpp Clasts are usually < 3 cm in diameter but occasionally up to 20 cm. Laminar,
Qls ^cr 4021000 Qtca1 slopes above the heads of landslides. ^cr ^cr low-angle wedge, and high-angle planar wedge cross-bedding is common in the Painted Desert Member of the Petrified Forest Formation—Poorly to ^cpp ^cpps Qls ^cpp 000 ^cr ^cpp ^cr sandier portions of the unit regionally. This unit is only rarely exposed near the well-exposed; brick-red to reddish-brown; thin- to thick-bedded; bentonitic(?) 4021 6400 36 Qt Qls ^cr Triassic Chinle Group Quaternary gravel—Gravel derived from terrace deposits but found on slopes Qg top of landslides along the edge of the Mesa de los Viejos and in a few other areas, mudstone and claystone intercalated with minor greenish-gray to light- 4 Qls that are either steeper than terrace surfaces or in topographic positions that make and is interpreted as coastal plain, braided stream deposits (Owen et al., 2005). Qf Qf greenish-gray, pebbly sandstone. Local reduction of the mudstone has resulted 6400 Qt ^cpm an origin as true terrace gravels unlikely. This unit represents relatively large ^cpp? The unit is up to ≈50(?) m thick. in cm-to-decimeter scale mottles, fracture linings, streaks, and meter-scale beds Qtch4 Qt areas of regraded terrace gravel and small and/or thin, poorly preserved terrace Qt ^cpp ^cpmo of light-gray, greenish-gray, and light-greenish-gray mudstone. Locally there are Qf Qt remnants(?). Only the thickest/most extensive parts of these ‘aprons’ of gravel 4 Qt Qt ^cpp Qt thin intervals of ripple-laminated to planar-laminated, very fine- to fine-grained Qf/Qt Qtca1 ^cpo below eroding terrace gravels are shown. Commonly the unit is 2–≈10(?) m thick. JURASSIC ROCKS Qtch5? 17 Qtch4 Qt Qt ^cpm Qls? Jurassic stratigraphy on the Echo Amphitheatre quadrangle follows Lucas et al. (2005a), sandstone. The mudstone is in thick to very thick, tabular beds, with minor thin Qtch4 Qal 6500 ^cpm to medium, tabular beds. The greenish pebbly sandstone bodies are lenticular, Qtch4 which is based on the regional stratigraphy of Anderson and Lucas (1992, 1994, 1995, 1996,
Qf ^cpo Qal+Qf Quaternary terraces from near Pedernal Peak—Terrace deposits found in the ^cpm ^cpm ^cpo ^cpp have up to 2.5 m of relief at their base, and may be as much as 3 m thick. The 6500 Qt ^cpm Qal+Qf Qtca2 Qtp 1997) and Lucas and Anderson (1997, 1998). An excellent geologic history of this part of the Qtch5? Qt ^cpp ^csc Cross Section Only southern part of the map and composed of a high percentage of basalt clasts and Qf Qf/Qt Qf/Qt Qtch5 000 Chama Basin has been provided by Kelley et al. (2006). pebbles in these channel fills are composed of light-gray to very dark-gray
^cpp 4020 variable amounts of Pedernal Chert, indicating they are derived from within the
Qt? Qf/Qt 6500 limestone or calcrete(?) pebbles (or concretions?) with very minor mudstone Qf Qf/Qt 2 ^cpp Rio Puerco drainage (from near Cerro Pedernal) to the south. 000 Qtch5? 18 4020 ^cpm ^cpm Brushy Basin Member of Morrison Formation—The unit is a variegated rip-up clasts. Pebbles are up to 2 cm in diameter. Pebbles and sand grains are in
Qf Qf/Qt Qt ^cscPa
Qf/Qt Jmb a greenish, muddy matrix that imparts an overall greenish color. A few
Qal Qtch2 Qal? Qf pale-greenish-gray, grayish, yellow-green, pale-olive, yellowish-brown, and
B Qls? Qt Qf/Qt B' Undivided Quaternary terraces—Generally poorly exposed; loose to friable; J J Qt pale-reddish-brown bentonitic mudstone with a few beds of trough-crossbedded measured trends of channels in the area are W–E and SW–NE (Koning et al., Qtch5 medium to thick-bedded; moderately to moderately well-sorted; mostly Qf/Qt Qf/Qt Qls Qtch5? Qt ^cpo Qf Qf pebbly sandstone. Locally, the base of the Morrison Formation is a thin (up to 8 m 2006). The mudstone is well consolidated but weakly cemented; the coarser Qf subangular; fine to coarse-grained sand, sandy gravel, and cobble conglomerate. Qf Qt Qtch5 Qtch1 ^cpm 4 thick) interval of trough-crossbedded sandstone and interbedded mudstone. channel-fills are locally cemented by calcium carbonate. The base of the unit is Qls Permian Pca Often includes 1–4 m of ‘overbank’ sand and silty sand at the top of terrace
^cpm ^cpm Qf/Qt mapped at the highest, persistent sandstone ledge of the Mesa Montosa Member,
6500 Qtch5 Qtch5 6400 Above that interval, the formation is mostly mudstone. Greenish-white,
Qf deposits and clast-supported cobble conglomerate in the first few meters above ^cpp ^cpm although some reddish sandstone lenses(?) or beds are found in the lowest part Qf Qtch1 5 *Pce medium-bedded sandstones with cross-bedding and mud-rip-up clasts and thin ^cr 6600 Qtch3 strath. Top of some deposits may have been reworked (by eolian[?], sheetwash, ^cpp Qtch3 tabular sandstones are present in a few places near the top of the unit. The basal of the Petrified Forest Member and caution must be used to distinguish these ^cpp Qtch3 and small-scale fluvial processes). Gravel is composed of pebbles through ^cr sandy interval is likely correlative to the Salt Wash Member of the Morrison from the underlying Mesa Montosa Member. The unit is up to 180 m thick. Qf Qt Qg boulders. Clasts are dominated by quartzite with variable amounts of sandstone 6700 000 *gb Formation to the west and south. However, this interval is neither thick enough, Qls ^cpo 4019 and/or limestone, small amounts of Brazos Basalt within the Rio Chama terraces Je Qf? Je ^cpm Qtch5? Sandstone body within the Painted Desert Member of the Petrified Forest 6800 ^cpm persistent enough, nor lithologically distinctive enough to separate from the 000 Qtch2 (and possibly some Jarita Basalt from the Los Pinos Formation) and metamorphic ^cpps 4019 Qls Brushy Basin Member here. Gastroliths (belly-stones), found mostly on the Formation—An isolated body of medium to coarse sandstone is found within
Qtch4 19 clasts. This unit includes all terraces below 13 m and those that do not fall into the Qt = surface of unit Qls, are thought to be derived from this, 41–68 m thick unit. the Painted Desert Member in the south-central part of the map. This body is 0000 Qf/Qt 1930000 strath height ranges defined by Koning et al. (2006). ≈2–10 m thick.
193 Qls approximately 25–30 m thick at its north end and seems to have a steep buttress
Qls Je 6900 Jsb? Jtg ^cr Qtgh Jsb Summerville Formation and Bluff Sandstone—The Summerville Formation is unconformity on its eastern side. As this sandstone is traced to the south, it 6800 Qtch2 Undivided high level terraces—A sandy gravel unit that is present at several
Qtch2 Jsb
Qtch3? Qtgh thinly and cyclically-bedded and composed of the following: maroon, grayish thins, and near its southern terminus, it is a bed of sandstone within ^cpp. An 4 ^cpp relatively high topographic levels and dominated by quartzite clasts. For this Jtl Jtl additional bed of sandstone in a similar stratigraphic position(?) was also Qt? quadrangle, rather than constructing an entirely new terrace hierarchy, we have red and yellowish gray siltstone; sandy siltstone; fine gypsiferous sandstone; and ^cr observed just south of the Rio Chama Campground on the Laguna Peak Qtch4 Qg mudstone. In the Chama Basin, the Summerville Formation is readily divided mapped all terraces above Qtch1/Qtca1 level (≈80m) as Qtgh. The dividing line Quadrangle (immediately north of the Echo Amphitheatre Quad). This body Qls 7400 between Qtgh gravel derived from an ancestral Rio Chama (those with basalt into two informal members, lower and upper. The lower member is 12 to 15 m Jtl Jsb? may represent an ‘axial’ stream portion of the Painted Desert Member. Hand Qls 6900 Qtca1 clasts) and that derived from an ancestral Canjilon Creek is found along the ridge thick and is repetitively-bedded gypsiferous sandstone and siltstone that forms a Qal Qal 000 samples of this sandstone are superficially similar to the sandstone of the Mesa Qt? Qg 4018 that defines the northwest edge of the Llano Del Vado (in the east-central part of ribbed cliff or slope. It is the same unit that Goldman and Spencer (1941) termed Qls Jsb? Jtl Qf Montosa Member and the Poleo Formation and could be mistaken for either. Je Qtch5 the “Bilk Creek Sandstone Member” in southwestern Colorado. The upper 000 the quad). However, some Canjilon Creek gravel has been reworked from this 4018 Jtg Jtg Qf/Qt Qtch3 4 Jsb? Jtg Qg member is 61 to 96 m of siltstone and thinly-interbedded gypsiferous sandstone ^cr ridge and redeposited as unit to the west of this ridge. Gravel consists of 7000 Qtch2 Qt? and mudstone that forms a thick, grayish red and white, banded slope. Strata we Mesa Montosa Member of the Petrified Forest Formation—Poorly to pebbles through boulders. In addition to quartzite, there are subordinate clasts of ^cpp ^cpm well-exposed; very fine- to fine-grained sandstone, siltstone, and mudstone. 6400 4 term Summerville Formation were assigned to the Morrison Formation by Smith 7100 Qt? Qg Mesozoic sedimentary rocks and Proterozoic metamorphic clasts. In deposits Jsb ^cr Qls Qtch5 Siltstone ranges in color from reddish-brown to light-reddish-brown. Sandstone Je Jmb 3 et al. (1961) and Ridgley (1977), though Ridgely (1989) did assign the lower
7200 Qg Qg? Qg derived from the Rio Chama Drainage, Brazos Basalt (and possibly some Jarita
Jtl Qls Qtch5 member of the Summerville Formation to the Wanakah Formation. beds are very thin to medium, tabular, and ripple laminated, wavy laminated, Qls Basalt from the Los Pinos Formation) forms ≈1–10% of terrace deposits. The 7300 36°17'30"N Qg or planar-horizontal laminated. Ripple-marks and troughs commonly give a Jtl Je Qg 6500 36°17'30"N deposit is 2–10(?) m thick. ^cr northwest-to-southwest paleoflow direction (Koning et al., 2006). This unit 7400 Qls Qtch3 Qtca1? It is often difficult to tell if exposed Summerville/Bluff Formation outcrops are in Qls Qtch4? Qt Qg/^cpp represents a gradational facies between the Poleo Formation and the Painted
Jtl Jtg Qls 7500 6300 Qf/Qt place or have been disrupted by landslides (see also , , and descriptions). 6500 Rio Chama Terrace level1—Strath is located approximately 72–80 m above the Jsb? ^cpp Qtch1 Directly above the Todilto Formation, beds of the Summerville are often Desert Member of the Petrified Forest Formation. The unit is 5–20(?) m thick. Jtg ^cpm modern stream grade. Comparison of this strath height with Koning et al. (2011, 4017000 contorted, and this may be due to mass movements. Alternatively, this ^cr ^csc table 3 and figures 5–6) and correlations of Gonzales (1993) would suggest an age Qal 7600 Jsb Qf deformation may be related to dewatering of the gypsum in the underlying Poleo Formation—Well-exposed; tan to yellowish; strong; medium to Qls Qtch1? Qg? range of 330–470? ka (Koning et al., 2006). 4017000 Qtch1 Todilto Formation (see also Todilto Formation description for other possible mass ^cpo thick-bedded; fine- to very coarse-grained; moderately well-sorted; Qf Qg ^cpp 6900 cross-laminated micaceous litharenite and minor pebble-conglomerate. Trough Qal Qt Rio Chama Terrace level2—Strath is located 40–55 m above the modern stream movement features) or dissolution of gypsum within the Todilto (Kelley et al., cross- stratification commonly gives a northwestward to westward paleoflow 7700 6400 Qtch2 2006). We have included many exposures of Summerville rocks directly above Qal Jmb Qls ^cpo Qg grade. Comparison of this strath height with Koning et al. (2011, table 3 and 7000 6800 Qt Qg the Todilto in Qls deposits. “Windows” of Summerville rocks surrounded by unit direction (Koning et al., 2006). The Poleo Formation has a sharp, scoured contact 6600 figures 5–6) and correlations of Gonzales (1993) would suggest an age range of Qls have only been mapped as Jurassic bedrock where the elevation of contacts on the underlying Salitral Formation. It grades upward into the overlying Qls Qls? Pca Qal 200–380? ka (Koning et al., 2006). Qtgh Petrified Forest Formation thru the Mesa Montosa member. Up to 41 m-thick. ^cpm Explanation of Map Symbols and relatively undisturbed bedding (not contorted and conformable with the low ^csc Qtgh regional dip) indicate they have not been displaced. Because there are multiple Je 4 ^cpm Rio Chama Terrace level3—Strath is located 27–30 m above the modern stream ^cpm ^cpp Qtch3 possible causes for deformation of these units, the distinction between disturbed Salitral and Shinarump Formations—The Salitral Formation sometimes forms Qg Contact—The identity and existence are certain. The location is accurate where solid, grade. Grades into unit Qtca3 on the northwest shores of Lake Abiquiu (Koning ^csc Kbc Qg and undisturbed outcrops is sometimes a little arbitrary. Some ‘windows’ are too a slope between the cliff-forming sandstones of the Shinarump and Poleo Jmb 6600 approximate where long-dashed, inferred where short-dashed, or concealed where dotted. et al., 2006). Comparison of this strath height with Koning et al. (2011, table 3 and Jmb Jmb 7800 Jsb Qt Qtgh 4016000 small to show at map scale, and many are queried (i.e., Jsb?) where mass Formations. The Salitral Formation has been divided into two members that are Qf? 7 5 figures 5–6) and correlations of Gonzales (1993) would suggest an age range of
6600 Qg? not mapped separately here (Lucas et al., 2003, 2005b). The lower, Piedra Lumbre
8300 movements may have displaced them. The unit is 74–111 m thick. 000 Qal Internal contact—The identity and existence are certain. The location is approximate. 100–280? ka (Koning et al., 2006). 4016 6700 Member is composed of reddish-brown to light gray mudstone with a persistent Jtg ^cpm 6800 Qtgh Qtgh 7900 Qt sandstone bed (the El Cerrito Bed) at its top. The upper, Youngsville Member is 7800 Qt The overlying Bluff Sandstone is a light gray or pinkish, very fine-grained,
0000 6 0000 Rio Chama terrace level4—Strath is located 22–26 m above the modern stream 7600 Fault (generic)—The identity and existence are certain. The location is approximate.
192 5 ^cpm 192 well-sorted, crossbedded sandstone. This unit consists of two members not mostly composed of reddish-brown mudstone. The lower contact of the Salitral 7200 7000 Qtch4 8000 grade and mostly submerged by the waters of Lake Abiquiu. Based on its strath 7700 ^cpp Formation is a sharp surface where mudstone rests directly on sandstone or 7500 mapped separately. The lower, Junction Creek Member, comprises most of the ^csc ^cpo 5 2 Kdeoc 6900 4 Qt Head or main scarp of landslide—Active, sharp, distinct, and location is accurate. Hachures height, it may correlate to the 20–40 m terrace deposit of Koning et al. (2011) and 8100 7100 conglomeratic sandstone. The upper contact is a sharp, scoured surface where 6400 formation (30–40 m thick) and is mostly pale-yellowish-green and Jtg Qal have an age of 100–160 ka (Koning et al., 2006). However, Chestnut (written point down scarp. 7300 Qf light-olive-gray, very fine-grained, well-sorted sandstone with crossbeds in thick conglomerate/sandstone at the base of the Poleo is incised into the Salitral Kdeoc Kdpc Qtca1? communication, 2020) more recently obtained calibrated radiocarbon ages for Qc 6500 Formation. The unit is approximately 10 m thick.
4 Qal sets. These are primarily eolian deposits similar to the type section of the ^cpps
Qt Pca 5 Direction of downslope movement of landslide terraces between 19 and 22 m above the Rio Chama that ranges from ≈22–41 ka.
Je? Junction Creek Member near Durango, Colorado (Goldman and Spencer, 1941). Qt Qtgh Qtgh The Shinarump Formation consists of quartzose sandstone and siliceous
Qt ^cpm The overlying Recapture Member is 6–14 m thick and is mostly maroon,
Qls Rio Chama Terrace level5—Strath is located 16–20 m above the modern stream
6500 000 Horizontal bedding conglomerate. This formation has previously been called the Agua Zarca 4015 4 6500 Qls Qtch5 pale-brown, grayish-red, and light-greenish-gray gypsiferous siltstone,
Qtgh grade. Comparison of this strath height with Koning et al. (2011, text, table 3, and
fine-grained sandstone, and mudstone. Recapture Member strata resemble Formation (e.g., Wood and Northrop, 1946; Dubiel, 1989; Lucas and Hunt, 1992).
000 8 79
Qf Inclined bedding—Showing strike and dip. figures 5–6) would suggests an age range of 20–100 ka. However, Chestnut (written 4015
Qal Qg Above this is a mottled yellow, orange, red, purple, and white; thin; cross-bedded
underlying Summerville strata (Lucas and Anderson, 1997, 1998; Lucas et al., communication, 2020) more recently obtained calibrated radiocarbon ages for
Pca ^csc
8400 sandstone that appears nodular in places. Conglomerate consists of pebbles of
Qtgh 2005) and is 44–47 m thick.
terraces between 19 and 22 m above the Rio Chama that ranges from ≈22–41 ka.
Sediment transport direction determined from cross-beds
quartz in a fine- to medium-grained quartz sandstone matrix. The basal contact is
8100 Kdpc 6600 Todilto Formation dominated by gypsum—The Todilto Formation consists of a a sharp erosional scour on the underlying Cutler Group. The unit is 6–7 m thick. Jtg Canjilon Creek terrace level1—Strath is located approximately 70–85 m above the Jtg A A' Qtca1 modern stream grade. Koning et al. (2006) suggest a possible correlation with a lower, Luciano Mesa Member composed mostly of limestone and commonly Je ^cpp ^csc Cross section line and label 7900 overlain by the Tonque Arroyo Member, an interval composed mostly of gypsum 8200 6800 Qtgh high terrace along the lower Rio Chama that contains the 620 ka lava Creek B ash. PENNSYLVANIAN–PERMIAN 7800 ^cpo (Lucas et al., 1985, 1995; Kirkland et al., 1995). The ≈30 m thick, Tonque Arroyo 6700 Arroyo del Agua Formation—Well-exposed; mostly brick- red; thin- to Qal Pca 6300 Member, consists of white to light-gray-gypsum interbedded with carbonate that 7600 Canjilon Creek terrace level2—Strath is located approximately 50 m above the thick-bedded; fine to medium arkosic sandstone, muddy sandstone, and Qtgh Qtca2 forms a prominent white cliff in this region. The Luciano Mesa Member is not Jtg ^cpp Pca modern stream grade. Relatively extensive deposit. Comparison of this strath brick-red mudstone. Also, it contains some thick beds of yellowish-red and red 4014000 Jtg ^cpps 6700 6 Qtch2 height with Koning et al. (2011, table 3 and figures 5–6) and correlations of always present in , but such areas were not mapped separately. In at least one mudstone that are commonly bioturbated and locally reduced to
^csc Qtch2?
Pca 000 area where the Todilto Formation seems to have slid over the top of the Entrada light-greenish-gray to light-gray colors. The unit is up to 130 m thick regionally. 8200 8400 01 Gonzales (1993) would suggest an age range of 200–380? ka (Koning et al., 2006). 4014
8300 Qtgh Qtch2?
Sandstone and buried Quaternary hillslope deposits (see below), the Luciano
6 6500 Qf Jsb? Qls Qtch2? Jtg Pca
Mesa Member may have been removed by mass movements. Any area where Je 6300 Canjilon Creek terrace level3—Strath is located 22–27 m above the modern Qtgh CROSS SECTION ONLY UNITS
Jtg Je Qtca3 gypsum is present has been mapped as Jtg (Koning et al., 2006; Kelley et al., 2006).
Jsb? ^csc 6400 stream grade. Comparison of this strath height with Koning et al. (2011, table 3 Combined Rock Point Formation and Petrified Forest Member of the
8000 Pca?
02 The unit is up to 38 m thick. ^crpp
and figures 5–6) and correlations of Gonzales (1993) would suggest an age range Painted Desert Formation
Pca ^cpm
4 Qls ^cpo
04 03 of 100–280? ka (Koning et al., 2006). However, Chestnut (written communication, Kdpc *Actually anhydrite but commonly referred to as ‘gypsum’ here and in the literature. Qtp 2020) obtained calibrated radiocarbon ages for terraces between 19 and 22 m Jsb? Qf? 8400 Qf Qls above the Rio Chama that range from ≈22–41 ka. 8400 Combined Mesa Montosa Member of the Petrified Forest Formation and Qf Je Qtgh? ^cpmo Poleo Formation 8500 ^cpo Qf
Kdpc Canjilon Creek terrace level4—Strath is located 15–22 m above the modern
Jtg 4013000
6900 Qtca4
Qtp ^csc stream grade near Highway 84, but this height increases to 27 m near the Qls 000 4013 6400 confluence with the Rio Chama. Comparison of this strath height with Koning et
8400 Qf 4 Combined Salitral, Shinarump and Arroyo del Agua Formations
J Pca ^cscPa
36°15'0"N al. (2011, text, table 3, and figures 5–6) would suggest an age of 100–160 ka.
36°15'0"N 0000 000 000 000 0000 000 000 000 0000 000 000 000 0000 However, Chestnut (written communication, 2020) more recently obtained 153 355 356 357 154 358 359 A' 360 155 361 362 363 156 364000 365000
106°37'30"W 106°35'0"W 106°32'30"W 106°30'0"W calibrated radiocarbon ages for terraces between 19 and 22 m above the Rio El Cobre Canyon Formation—Brown siltstone, sandstone and extraformational
*Pce
Chama that range from ≈22–41 ka.
conglomerate that overlies Proterozoic basement in the subsurface and is
conformably overlain by the Arroyo del Agua Formation. Siltstone beds of the El
Canjilon Creek terrace level5—Strath is located 13–17 m above the modern stream Cobre Canyon Formation contain numerous rhizoliths and comprise relatively
Qtca5 grade. A comparison of this strath height with Koning et al. (2011, text, table 3, and Base map from U.S. Geological Survey 2020. thin, slope-forming units between multistoried sandstone beds that are arkosic, North American Datum of 1983 (NAD83) figures 5-6) would suggests an age range of 20–100 ka (Koning et al., 2006). micaceous, coarse grained and trough cross-bedded. On the Arroyo del Agua Projection and 1,000-meter grid: Universal Transverse Mercator, Zone 13S, shown in blue. quadrangle, upper part contains numerous vertebrate fossils, primarily of Early 10,000-foot ticks: New Mexico Coordinate System of 1983 (Central zone), shown in red. Permian amphibians and reptiles (e.g., Langston, 1953; Berman, 1993; Lucas et Roads...... U.S. Census Bureau, 2015–2016 al., 2005c). Up to 90 m thick. Names...... GNIS, 2016 Hydrography...... National Hydrography Dataset, 2014 1:24,000 Contours...... IFSAR 4.5 m Digital Terrain Model, 2008 Guadalupe Box Formation—Defined by Krainer et al. (2005) ( =Upper arkosic *gb Wetlands...... FWS National Wetlands Inventory 1977–2014 limestone member of the Madera Group of Northrop and Wood (1946)). 1 0.5 0 1 Mile Interbedded red to green micaceous, arkosic sandstone, gray sandy, arkosic limestone, gray, fossiliferous, sandy arkosic, cross-bedded limestone, and red, green, and black shale and siltstone. Most common fossils are crinoid 1000 0 1000 2000 3000 4000 5000 6000 7000 Feet columnals. Some arkosic clasts are up to 2 cm in diameter and are angular. Upper contact gradational with clastic red beds of the overlying Cutler Group; lower contact not exposed. Navajo Peak Alire Canjilon 1 0.5 0 1 Kilometer Basement Rock =
Contour Interval 20 Feet Echo Laguna Peak Ghost Ranch New Mexico Amphitheater North American Vertical Datum of 1988 A Geologic Cross Section A–A' A' North South 9,000 2,750 Arroyo Frenchy Tank Continental Divide National Scenic Trail Youngsville Canones New Mexico Bureau of Geology and Mineral Resources Del Agua Comments to Map Users Kdp
Magnetic Declination 2,500 Open-File Geologic Map 280 Kbc Jmb July, 2020 A geologic map displays information on the distribution, nature, orientation, and age relationships of rock and deposits 8,000 8º 30' East Rio Chama Intermittent Tank At Map Center and the occurrence of structural features. Geologic and fault contacts are irregular surfaces that form boundaries Jtg Mapping of this quadrangle was funded by a matching-funds grant from the STATEMAP program of the between different types or ages of units. Data depicted on this geologic quadrangle map may be based on any of the Jsb Je 2,250
Quadrangle Location National Cooperative Geologic Mapping Act (Fund Number: G19AC00226), administered by the U. S. following: reconnaissance field geologic mapping, compilation of published and unpublished work, and photogeologic 7,000 Geological Survey, and by the New Mexico Bureau of Geology and Mineral Resources, (Dr. Nelia W. interpretation. Locations of contacts are not surveyed, but are plotted by interpretation of the position of a given contact ^cpo 2,000 Dunbar, Director and State Geologist; Dr. J. Michael Timmons, Assoc. Director for Mapping Programs). onto a topographic base map; therefore, the accuracy of contact locations depends on the scale of mapping and the ^crpp interpretation of the geologist(s). Any enlargement of this map could cause misunderstanding in the detail of mapping New Mexico Bureau of Geology and Mineral Resources 6,000 and may result in erroneous interpretations. Site-specific conditions should be verified by detailed surface mapping or ^cpo ^cscPa 1,750 subsurface exploration. Topographic and cultural changes may not be shown due to recent development. New Mexico Tech *Pce *gb 801 Leroy Place 5,000 Cross sections are constructed based upon the interpretations of the author made from geologic mapping and available 1,500 Socorro, New Mexico Geologic Map of the Echo Amphitheater 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,
87801-4796 1,250 meters above buildings, roads, or other man-made structures. 4,000 feet above mean sea level mean sea level 7.5-Minute Quadrangle, The New Mexico Bureau of Geology and Mineral Resources created the Open-file Geologic Map Series to expedite [575] 835-5490 dissemination of these geologic maps and map data to the public as rapidly as possible while allowing for map revision as geologists continued to work in map areas. Each map sheet carries the original date of publication below the map as Rio Arriba County, New Mexico well as the latest revision date in the upper right corner. In most cases, the original date of publication coincides with the This and other STATEMAP quadrangles are available date of the map product delivered to the National Cooperative Geologic Mapping Program (NCGMP) as part of New for free download in both PDF and ArcGIS formats at: Mexico’s STATEMAP agreement. While maps are produced, maintained, and updated in an ArcGIS geodatabase, at the Geologic Cross Section B–B' time of the STATEMAP deliverable, each map goes through cartographic production and internal review prior to B' uploading to the Internet. Even if additional updates are carried out on the ArcGIS map data files, citations to these maps should reflect this original publication date and the original authors listed. The views and conclusions contained in these B Cañada del Potrero Rio Chama Obama Canyon Road http://geoinfo.nmt.edu East December 2020 map documents are those of the authors and should not be interpreted as necessarily representing the official policies, 2,250 either expressed or implied, of the State of New Mexico, or the U.S. Government. West
7,000
^cpmo 2,000 by ^cpp ^cpp
Scott B. Aby 6,000 ^cscPa 1,750 *Pce
5,000 *gb 1,500 Digital layout and cartography by the NMBGMR Map Production Group: =
Phil L. Miller, Amy L. Dunn, Ann D. Knight, and Justine L. Nicolette Muddy Spring Geology, P.O. Box 488, Dixon, New Mexico 87527 1,250 meters above
4,000 feet above mean sea level mean sea level