Plio-Pleistocenestratigraphy, paleoecology, andmammalian biochronology,Tijeras Arroyo, Albuquerque area, New Mexico by SpencerG. Luus,Thonas E. Williamson,New Mexico Museum of NaturalHistory, 1801 Mountain Road N.W., Albuquerque, New Mexico, 87104; andJaySobus, College ol HumanEcology, 2100 Marie Mount Hall, University ol Maryland, College Park, Maryland 20742-7531

Abstract Strata assignedto the SierraLadrones Formationof the SantaFe Group in Ti- jeras Arroyo near the Albuquerque In- ternational Airport are more than 75 m thick and consistof ,pumi- ceous sandstones,gravels, and minor claystones.These are deposits of a main- stem (axial)Rio Grande that intertongue eastward with alluvial-fan faciesderived from the Sandia and Manzanita uplifts. Fossil mammals from the Sierri La- drones Formation in Tiieras Arrovo in- dicate it is of Plio-(- Irvingtonian)age. Blancan mammals are HypolaguscI. H. gidleyi and Equuscum- minsii; lrvingtonian mammals are GIyp- totheriumcf . G. arimme, Equuscf . E sotti, cf. Camelopssp., Mammuthusmeridion- alis. and M imperator.Fossils of these taxa, their taphonomy, and the enclos- ing sedimentssuggest that during the early Pleistocenethe TijerasArroyo area was a semiarid piedmont plain with a nearby flora dominated by open grass- land or short-grassprairie.

FIGURE 1-Albuquerque Basin with distribu- tion (after Tedford, 1982) of strata(shaded) and key sectionsmentioned in the text: 1, type Ceja Formation; 2, section in Tijeras Arroyo (Figs. 2, 3); 3, type Cochiti For- matron.

Alsoin this issue Laramidestratigrapy of the LittleHatchet Mountains p. 9 Galleryof Geology-Killion Canyon p.16 Geographicnames p. 17 1992Mineral Symposium abstracts p.18 1993NMGS Fall Field Conference p.20 Service/News p.21 Upcomingmeetings p.22 1994NMGS Fall Field area in Fig. 2 Conference p.22 Staffnotes p.23 Introduction 1978).Subsequent mapping by Kelley sparseBlancan vertebrate fauna has been Although Pleistocene mammals were (1977)reflected Lamberfs extension of the describedin the formation (asmapped by first reported from the Albuquerque area upper buff member to east of the Rio Machette, 1978b)in the Ceja del Rio Puerco (Fig. 1) by Herrick and fohnson (1900,p. Grande. However, Kelley (1977) coined escarpmentabout 10km south of the type 224), no serious effort has been under- and applied the name CejaMember of the Ceja Member section (Tedford, 1981).The taken to document these fossils until re- Santa Fe Formation to these rocks, in- Sierra Ladrones depositional environ- cently. This documentation (O'Neill and tending it to replaceBryan and McCann's ment in the Albuquerque Basin has re- Rrgby,1982;Lucas and Logan, 1984;Lucas, (1937)informal term "upper buff." cently been described by Lozinsky et al. 1987; Lucas et al., 1988)has focused on Kelley's (1977)type section of the Ceja (1ee1). the () Member of the SantaFe "Formation" (Fig. mammals collected ftom gravel pits de- 1) is along the Ceja del Rio Puerco (sec. TABLE l-Stratigraphic section veloped in relatively young terrace de- 19 T10N R1E) and representsthe upper of the Sierra part of the section that Bryan and Mc- Ladrones Formations exposed in Tijeras Arroyo, posits inset into the Rio Grande valley, the NE1/+ Cann (1937)originally designated '/upper sec. 17 and NW1L sec. 16 T9N R3E, Ber- Edith Formationof Lambert(1968). Fossil nalillo County, New Mexico. mammalsfrom the Edith Formationwithin buff". Lambert (1968)had already de- the Albuquerque city limits are Glosso- scribed a reference section of his "Upper Thickness theriumharlani,Equus cf . E. occidentalis,Bi- Buff" formation at the same site, but he Unit Lithology (m) son sp., Camelopshesternus and Mammuthus included "middle" Santa Fe beds under- Sierral-adrones F ormation: columbi,a typical assemblageof large Ran- lying Kelley's Ceja Member in this for- mation, as had been previously done by 10. , noncalcareous, cholabrean (Wisconsin-age)mammals. very (N8) Wright (1946; Iight gray and light Older and latest seealso Lambert, t978, p. bluish-gray (58 7/L); me- mammals, however, are alsciknown from 151).Unfortunately, no detailed map- dium-to very coarsegrained within the Albuquerquecity limits. These ping, or tracing of key beds, has ever been in two populations: me- low-diversitv faunas, of Blancanand done between the type Ceja locality and dium- to coarse-grained Irvingtonian age, were first discoveredby the JemezValley (Rincones de Zia,35km (2.0-0.0 {) subrounded to Lambert (1968)and subsequentlydevel- to the north) where Bryan and McCann angular quartz grains and oped by T. R. Logan (1984;Logan et al., originally defined theii lower gray-mid- coarse- to very coarse grained (> 1 rounded 1984)and us during the mid-1980's.Here, dle red-upper buff stratigraphic sequence 0); as the referencesection for their SantaFe pumice grains; trough we describethese fossils that spanthe Plio- crossbedded;top of unit is Formation in the Pleistoceneboundary and interpret their northern Albuquerque airport surface. 1.2.0+ biochronological significance. In this ar- Basin. ticle, NMMNH refers to the New Mexico Manley (1978)and Tedford (1982)have Museum of Natural History, Albuquerque suggestedthat the Ceja Member and the and UNM to the Universitv of New Mex- more broadly defined "upper buff" mem- ico, Albuquerque. ber (formation) interfinger to the north with volcaniclastic sandstone and con- New AAexnc@ glomeratethatBailey et al. (1969)and Smith et al. (1970)termed the GEOLOGY Upper Cenozoic deposits of the Rio of their KeresGroup (seealso discussion Grande rift, from Colorado to Texas,have by Hawley and Galusha, 1978).However, . Scienceand Service generally been referred to as the SantaFe the latter unit has never been well defined tssN 0196-948X Glg.rp (Hawley, 1978; Lucas and Inger- in its JemezMountains type area, and re- Volume 15, No. 1, February 1993 soll, 1981).However, in the Albuquerque cent dating of associatedKeres Group vol- Editor: Carcl A. I{jellming Basin, the term Santa Fe Formation, ln- canics by Gardner et al. (1985)brackets troduced Publishedquarterly by hereby Bryan and McCann (1937, the age of the type Cochiti between 13.5 New Mexico Bureau of Mines and 1938), has long been used. Bryan and and 5.5 million years (mid- to late Mio- Mineral Resources McCann (1937,L938) divided the SantaFe a division of New Mexico lnstitute of cene). Mining & Tchnology Formation in the Albuquerque Basin into CejaMember (upper "upperbuff") strata three informal members:lower gray, mid- BOARD OF REGENTS along the Ceja del Rio Puerco correlate Ex-Officio dle red, and upper buff. The lower gray with at least the middle part of the Sierra Bruce King, Gomor of Nru Muim and middle red members are now iub- Ladrones Formation (Machette L978a,b; Alan Morgan, Superintendeil ol Public In;ttuction sumed APPointed in the of Hawley, L978, chart 1), which has a type Lt. Gen. Leo Marqtez, Pres.,1989-796, Albu4uoque (late Arikareean-Clarendonian) age (Gal- area at the southern end of the Albu- Charfes Zmmerly, Se.lTreas.,1997-7997, Sxorro usha, L966;Gawne, 1981;Tedford, l91l, Diane D. Denish, 1992-1997,Albuquerque querque Basin near San Acacia. A Sierra J. Michael Kelly, L992-I997,Rrewll re82). Ladrones Steve Tores, 7997-797, Albuqwque /'upper Formation referencesection has The overlying buff member" of New Mexico Institute of Mining & Tehnology recently been described in the lower Rio Prqidnt.. ... LaurenceH.Lattman the Santa Fe Formation was originally Puerco valley (Gabaldonbadland area)by New Mexico Bureau of Mines & Mineral Rercurces conceivedby Bryan and McCann-(lg3i, Lozinsky and Tedford (1991).At ttraf lo- Dir@torond StateGNWist . . . Charles E. Chapin pp. 815-816) for buff-colored, generally Subwi/iore: Issued qurterlt FebMry, May, AugusL cality the formation is underlain by "mid- November; subscription price year. coarse-grained("fan deposits") $6.00/calendar stratathat dle" SantaFe Group bedsof Hemphlllian Editorial mattq: Articles submitted for Dubliation are at the top of the Santa Fe Formation (lateMiocene) age iorrelated withihe up- should be in the editor's hands a minimum of five along the Ceja del Rio Puerco west of Al- (5) months before date of publication (Februry per Popotosa Formation of Denny (1940) May, Autust, or November) and should be no longer buquerque (Fig. 1). Lambert (1968)used //upper and Machette (1978a).Machette's type Si- than 20 typwitten, double-spacedpages. All the term buff formation" to refer erra Ladrones comprises ancestral Rio scientific papers will be reviewed by at least two to Bryan people in the apprcpriate field of study. Address and McCann'sunit and also ex- Grande and intertonguing piedmont al- inquirie to Carol A. Hielming, Editor of Nm Meim tended to it into the (current) Albuquer- luvial deposits. It overlies the Popotosa Ceology, New Mexico Bureau of Mines & Minenl Resources,Sorcro, NM 87W4n6- que city limits by identifying it east of the west of San Acacia and south of the Lad- Rio Publishedas publk dowin, thercforereprdrcibk without Grande in the walls of Tiieras Arroyo ron Mountains. Basalt flows interbedded Sourcecredit requested. (secs. Wrmission. 1 and 12 T9N R3E)and in the scarp with the lower SierraLadrones Formation Circulation:1,ffi southwest of the Albuquerque Interna- in the San Acacia and Socorro area have P/irra: University of New Mexico Printing Sewices tional Airport (Fig. 1; see also Lambert, K-Ar ages of 4 to 4.5 million years, and a

February 1993 New Mexico Geology Thickness Unit Lithology (m)

9. Sandstone, noncalcareous, grayish-orange (10YR 7/4), fine- to coarse-grained(0.50- 3.0 Q); subangular quartz and chert; trough cross- bedded. 6.7 Sandstone, slightly calcare- ous, grayish-orange (10YR 714),ftne- to coarse-grained (3.00-0.0Q); subangular i+s6,tqsz quartz and chert; bed has prominent reddish-brown color at a distance, with i+ss,t+sl gravels in the upper 257o; trough crossbedded. 10.1 (T9N.R3E) ,7 Sandstone, noncalcareous, T^8-l(m- pale yellow-brown (10YR6/ Santa Fe 2); in two populations: very fossil Group outcroPs NMMNH fine to medium-grained localities (1.50-3.5 $) quartz and quartzite, and quartz gravel up to 5 cm diameter; poorly sorted and very conglomer- - 1455 MammuthusimPerator atic, with pumice in upper bed; trough crossbedded. 72.2 6. Sandy clay and sand, cal- careous,grayish orange-pink SIERRALADRONES (5YR 7/2) and pinkish-gray (SYR 8/1); in three popula- FORMATION tions: fine- to coarse-grained (2.50-0.0S), subangular quartz grains, clayballs in sandstone, and pumice balls (up to 1.5 cm diameter). 3.4 Sandstone, slightly calcare- ous, yellowish-gray (5Y 8/1), fine- to medium-grained (2.00-0.00); poorly sorted +1452, 1453, 1454, 1456' 1457 subrounded quartz; trough Mam mut hus merid ionalis crossbedded. 6.1 Gtyfrotheilum cl. G' ailzonae Claystone, noncalcareous, sP. Equidae grayish-green (10 GY 5/2). 7.2 cf. Camerops 3 Sandstoneand gravel, non- Equus cf. E. scotfi calcareous,pale yellowish- brown (10YR 6/2); in three 1tl conglomerate populations: very fine- to t medium-grained (1.50-3.5 sanclstone $) poorly sorted quartz and quartzite grains with pum- ice, quartz gravel (up to 5 siltstone cm diameter), and con- 1459 Equus cf. E. scotti glomerates(up to 15cm dia- mud stone meter); trough crossbedded. t3.7 2. Sandstone, noncalcareous, yellowish-gray (5Y 8/1);me- dium-grained (2.5-1.5 0) , '",",. quartz and chert; moder- | ately sorted, frosted, suban- gular to subroundedgrains; high-anglecrossbeds and convolute bedding. 3.4 lowest oumice clasts 1. Sand, noncalcareous,yel- lowish-gray (5Y 8/1),fine- to medium-grained(2.5-1.5 {); quartz, poorly sorted sub- rounded grains; sandstone interbedded with laminar to + 1458 Equus cl. E. cumminsii massive green clay part- Hypolagus cf . H. gidleyi ings, one clay band 20 cm thick; fragmentary bone present; much slope debris. 8.1 Covered. lo- total ?63 FIGURE 2-Measured stratigraphic section in Tijeras Arroyo with inset map showing fossil calities mentioned in text. S6efable 1 for description of lithologic units in measured section'

New Mexico Geology February 1993 The type Ceja Member, as defined by Kelley (1977) and described by Lambert (L978), is a fluvial unit dominated by channelsands and gravels.It was depos- ited by major tributaries to the ancestral Rio Grande that headed in the south- eastern Colorado Plateauand San Pedro- Nacimiento Mountain region northwest of the Albuquerque Basin. In contrast, the upper SantaFe beds exposedin the lower Tijeras Arroyo areaeast of the Rio Grande (discussed in this paper) are deposits of a main-stem (axial) Rio Grande that inter- tongue eastward with alluvial-fan facies derived from the Sandia and Manzanita uplifts. This ancestral fluvial system fol- lowed a course west of the bise of the Sandia-Manzanita piedmont slope that was very closeto the modern incised river valley in the Albuquerque metropolitan area.Upper SantaFe bedseast of the Rio Grande were also assigned to the Ceja Member by Kelley (1977) and tentatively correlatedwith the upper buff by Lambert (1968).However, at least the upper part of these deposits are of late Pliocene to early Pleistoceneage because they contain pumice clastsderived from the 1.6 to 1.1 Ma eruptions of the Toledo Valle Grande calderacomplex (BandelierTuff). As dem- onstratedhere, uppermost SantaFe Group strata in the lower TijerasArroyo areaalso contain a mammalian fauna of late Blan- can and Irvingtonian age (seealso Logan, 1984).We, therefore,propose that the term Ceja Member be restricted, at least at present, to upper Santa Fe Group beds (Sierra Ladrones Formation) exposed in the Puerco Valley area of the western Al- buquerque Basin. Uppermost Santa Fe Group depositsin the lower TijerasArroyo area here are designatedas part of an un- named upper member of the Sierra Lad- rones Formation that is dominated by channel deposits of the ancestralRio Grande. This unit is 64.8m thick in TijerasArroyo Lq and is dominated by sandstone(76Vo-of FIGURE the measuredsection) and lesseramounts 3-Some outcrops in TijerasArroyo: A, SierraLadrones Formation crossbeddedsandstone (Fig. 2, unit 2); of gravel (18%) B, gravelly sandstones,siltstones, and sandstonesof Sierra Ladrones Formation and claystone/siltstone (Fig. 2, units 5-7). (6%). Particularlydistinctive is the dom- inanceof pumice, in sizesfrom sandgrains as well as the relatively limited outcrop unit. We provisionally endorse this con- to cobbles.The pumiceous strataat Tijeras distribution of the pumice-bearingIrving- clusion by terming all these strata Sierra Arroyo presenta striking contrastto un- tonian strata supports the idea that these Ladrones Formation, in part becausethis derlying strata that lack pumice (Table 1; strata are inset into older, Ceia Formation decision is a conservative one that intro- Figs. 2, 3). However, we nonethelessalso strata. Furthermore, as Cather (written duces no new nomenclature. New strat- assign these underlying strata to the Si- c9mm. t992) notes, this inset explains both igraphic nomenclature ma, however, be erra Ladrones Formation based on their the lower elevation of the Llano de Man- necessary if further study demonstrates lithology and stratigraphic position. Al- zano surface relative to the Llano de Al- that the pumice-bearing Irvingtonian shata though we assign the pumice-bearing Ir- buquerque (cf. Kelley, 1977; Machette, exposed at Tijeras Arroyo are a distinct vingtonian strata at Tijeras Arroyo tothe 1978c)as well as the apparent lack of Ir- unit inset into older strata. Sierra Ladrones Formation, we note that vingtonian strata west of the Rio Grande. not only are they younger than the Sierra However, (oral |. Hawley comm. 1992) Vertebrate paleontology Ladrones, which near Socorrois about 5- Fossil mammals occur in two intervals in Tijeras Arroyo (Fig. 2) and are de- scribed below.

pumice first appears on outcrop. He thus Glyptotheriumcf. G. arizonae suggeststhat all strata exposed at Tijeras NMMNH P-12876from locality l4sa (Fig. Arroyo are part of a single stratigraphic 4H-I) is a caudal scute resembling the

February 1993 Nat Mexim Geology FIGURE 4-Mammalian fossils from Tijeras Arroyo: A, Equuscumminsii (NMMNH P-12895),ventral view of palate; B, Equuscumminsii (NMMNH P- 12895),right P-M3; C, Equuscf . E. scotti(NMMNH P-12884),leftupper cheek tooth; D, Equuscf . E. scotti(NMMNH P-72891),right dP:?; E, Equidae (NMMNH P-128S3),right M.; F, Equidae (NMMNH P-12885),second phalanx in plantar view; G, cf . Camelopssp. (NMMNH-PI2887), proximal.end of left astragalusin doisal view; H-1, Glyptotheriumcf. G. arizonaeNMMNH P-I2876)tail scute in lateral view (H) and dorsal view (I); l-K, Hypokgus cf. H. gidleyi (NMMNH P-I2938), P. (right is mesial, top is labial); L, Hypolaguscf . H. gidley (NMMNH P-12938),left dentary fragment with P2 in lingual view; M, Mammuthusmeridionalii (UNM 11028),mandible with right ind left M.. Bar scalesare 1 cm except for A (2 cm), K-L (2.5 mm) and M (10cm).

Neu Mexico Geology February 1992 raised, convexdistal scutesillustrated by TABLE 2-Dimensions of Equusteeth (in mm) (length : 16.7mm, width : 13.7mm). Gillette and Ray (1981,fig. 93),which Lo- from the Sierra Ladrones Formation at Tiieras NMMNH P-12885from locality 1454is a gan (1984)attributed to Glyptotheriumcf. Arroyo.r, length measuredlabially;r, maimum Iargefirst phalanx; the overall dimensions G. arizonae.This is the first teport oI Glyp- width from protocone to mesostyle. 'A of length, width of proximal surface, depth totheriumin New Mexico. glyptodont" of proximal surface, and width of distal was previously reported from the Camp mesiodistal surface fall into the upper size range of E. RiceFormation (a lingual-labial unit correlative,at least lensthr width'z scoffi(Akersten, 1972,table 14;Harris and in part, to the SierraLadrones Formation) Porter, 1980, table 1). NMMNH P-12890 in the Mesilla Basin of southern New NMMNH P-T2895 from locality 1454is a left navicular (an- left P2 40.5 Mexico (Tedford,1981., p.1019). At 35'N 24.0 teroposteriorlength: 47.6mm, width : latitude, the Tijeras Arroyo Glyptotherium left P3 26.7 34.2 left P4 60.7 mm). NMMNH P-L2892from locality is almost the northernmost 24.3 27.9 ociurrence of left Mt 29.3 27.0 1t145is a right innominate with ischium, lhe genus (cf. Gillette and Ray, 1981,figs. left M2 28.0 28.6 pubis, and partial ilium (maximum pre- 2-4). A slightly more northerly occur- left M3 30.6 19.6 served length : 4L0 mm, maximum ac- renceis representedby five scutesof GIyp- NMMNH etabular length : 68.9mm). NMMNH P- p -tgZgl P-1289L tother ium tUUVtNlt collectedtv right dP3? 34.4 77.7 12939is a metacarpal from locality 1454. Wesley Peters at NMMNH locality 154i6 right dPa? 35.2 73.6 Overall size and comparison with Harris in a gravelpit in the NEr/oNEr/oSW/csec. NMMNH P-I2940 and Porter's (1980,p. 59, fig.7) scatter 27 T13N R4E,north ofAlbuquerque near Ieft upper 31.8 32.2 plot of proximal and midshaftwidths sug- Algodones(Fig. 1). This localityalso is in molariform gest a small specimenof E. conaersidensor the SierraLadrones Formation. NMMNH P-1294I a horse of similar size. left upper 35.0 33.6 Hypolaguscf. H. gidleyi molariform cf. Camelopssp. NMMNH P.72884 NMMNH P-12938(Fig. af-L) from lo- left upper 33.1 28.2 NMMNH P-12887from locality 1a56(Fig. cality 1458consists of a right dentary frag- molariform 4G) is a right proximal astragalus. Mor- ment with the root of I, and a very worn NMMNH P-12883 phology (note the wide valley and con- Pr, a left distal tibia, a metacarpil, and right M3 42.0 16.6 vexity of the proximal trochlea and also two phalanges.Tedford (1981)identified NMMNH P-T2936 the high nanow lateral condyle) excludes this specimenasHypolngus sp. White (1987, right lower (36.0) 77.4 the Llamini but typifies the Camelini p. 438)_describedthis specimenas Hypo- molariform (Webb, 1965,p.29). This specimenis re- Iaguscf . H. ringoldensrs.He also statdd it ferred tentatively to Camelopson the basis was "possibly from the Chamita forma- of its resemblanceto the astragalusof C. tion," a unit of MiePliocene (Clarendon- a nomendubium. Tedford (1981) identified hesternusillustrated by Webb (1965, pp. ian-Hemphillian) age restricted to the this specimen as Equussimplicidens, but It 29,31, frg. U). Espaflola Basin of north-central New is too small to pertain to that species.E. Mexico (MacFadden, 1977). This cannot cumminsiiis a Blancan horse (Kurten and Mammuthusmer idionalis be correctbecause this unit is not present Anderson, 1.980). NMMNH P-12894from locality 1452is in the Albuquerque Basin (T€dford, 1981). an incomplete mandible (Fig. 4M) with We assign NMMNH P-12938to Hr1po- Equuscf. E. scotti left and right M, (Fig. 5A). Although the lagus cf. H. gidleyi for the following rea- NMMNH P-12891.from locality L459is mandibular symphysis is incomplete an- sons: 1) I-P, diastemalength (15.imm) a damaged right dentary with itP3 (Fig. teriorly, the spout was relatively short and P, anteroposteriorlength (3.5 1lq mm) 4D) and dPa, and the unerupted frag- not significantly flexed ventrally. The hor- fall within the range of vaiiation for H. ments of P, and M,. Theseteeth are in the izontal rami are relatively long, low, and gidleyi (but outside that of H. ringoldensis: size range of E. scottiand E. giganteus. narrow. What is present of the ascending White, 1987,fig.9); 2) the P, lacls an an- NMMNH l-12940, P-12941,and P-12884 rarni suggests they were relatively low and terior r_eentrant(Fig. 4f-K), which is part are left upper molariform teeth from lo- inclined posteriorly. of the diagnosis of H. gidleyi(White, 1987, cality 1454,P-12940and P-12884being rel- The right M. is better preserved and p. a3Q; and 3) the posteroexternal reen- atively unworn (Fig. aC). NMMNH P- more complete.Both Mrs are heavily wom trant on P. is deflectedposteriorly, a char- 12937ftom locality 1457 is a fragmented and relatively long (282* mm). On the acteristicnot typical of H. ringolderzsrs but lower molariform (Pr?) toofh, and right Mr, six plates are preserved, but the the ran-g-eof variation'o ryilhi" f H. gidleyi NMMNH'J.2936isa lower deciduousmo- position of the anterior alveoli and length (White, 1987,fig.7). Iariform tooth from localitv 1457. These of the anterior worn dentine suggest at teeth are assigned to Equus'cf.E. scottion least two additional plates were present. Equuscf. E. cuminsii the basis of size (Table2). Plate enamel is extremely thick (average NMMNH P-12895from localiry1458 (Fie. enamel thickness : 38 mm), and the plate 4A-B) includesa damagedpalaie contaii- Equidae ratio (4.0) is very low. Becauseof extreme p.-Mr, ing left P2-M3and riglit the max- NMMNH P-12883from locality 1454is wear, it is impossible to estimate accu- illary symphysis,atlas, axis and two a right M, (Fig. 4E) referredto Equuson rately crown height, but it appearsto have cervical vertebrae, incomplete right hu- the basisof occlusalmorphology. NMMNH been low. These features indicate that merus/ distal tibia, and cranial fragments. P-12878from locality L454is a distal tibia, NMMNH P-12894is a very primitive This specimen is referred to Equis cf. E. a proximal humerus and additional bone Mammuthusassignable to M. meridionalis cumminsiion the basis of occlusalmor- fragments. The transverselength and (Lucas and Effinger, 1991). phology (note the absenceof enamel cren- matmum oblique articular length of the ulations and absenceof a hypoconal distal tibia fall in the size range of E. niob- Mammuthusimperator groove: Osborn, 1,91,8,p.270, pi.24; Cid- rarensisand are intermediate between E. NMMNH P-12888(Fig. sB-C) from lo- ley, 1901,p.127, fig.17). This issignment conaersidensand E. niobrarensis,respec- cality 1455is a left M3 in a maxillary frag- remains tentative, however, becausethe tively (Harris and Porter, 1980).NMMNH ment. This tooth has 20+ plates, enamel type specimen of E. cumminsiiCope con- P-12881from locality 1454is a partial max- of moderate thickness (3.0 mm), and a sists of two isolatedupper molariforrnteeth illary symphysiscontaining the alveoliof plate ratio of 6. It is 330+ mm long, 190 and the speciesmay, strictly speaking,be Ir-I3-and fiaghentary rootiof the canines mm high, and 103 mm wide. All metrics

February 1993 New Mexico Geology FICURE S- molars from Tiieras Arrovo: A, Mammuthusmeridionalis (UNM 1102d),occlusal view of right Mr; Id-;C,Mam- muthus imperator(NMMNH P-12888),occlusal view (B) and lateral view (C).

thus place it comfortably within the range of Mammuthusimperator (Madden, 1981; Lucas and Effinger, L991).

Mammuthussp. NMMNH P-12893 from locality 1453 consists of right and left ilia, incomplete pubic bones, and the right acetabulum. The ilia are very wide and flaring, and the innominate is otherwise typical of the Ele- phantidae. Given the relatively large size of the acetabulum (see Olsen, t979), rhis pelvis is assigned to Mammuthussp.

Taphonomy and paleoecology We present here a few taphonomic and paleoecological inferences for the Sierra Ladrones Formation in Tijeras Arroyo based principally on localities 1452,1453, and 1454. The immediate context of the Mammuthuspelvis (locality 1453)was ex- cavated in a controlled manner, so recon- struction of the local sedimentary context was possible. In general, the section is underlain by a clast-supportedbed of gravel- to cobble-sizedrocks of undeter- mined lateral extent. Above this level lie alternating gravel lenses and sand units of varying coarseness,with fine-grained sands typically interbedded with gravel lenses (Fig. 64). Clay bodies (0.5-1.5 m diameter) are present, and medium- to coarse-grainedsands often contain tuffa- ceouspebbles. Gravel lensesin medium- to fine-grained sand units have the ap- pearanceof inverted channels(convex on their upper surfaces),although these do not form continuous structures. Somein- dication of normal grading is evident, but there is no evidence of consistent clast orientation or imbrication. The pubic symphysis of the mammoth pelvis was intact during deposition be- causeboth innominates were in anatom- ical position. The pelvis was oriented N45'W (bearing through the pubic sym- physis and the articular surfaces of the ilia) with a dip of 20'along magneticN25'E. This orientation is consistent with a southward-flowing current, with the long axis of the pelvis parallel to flow. The sedimentary context of the Mam- muthusmandible (locality 1.452)consists of a upward-fining sequence of clast-sup- ported gravels overlain by poorly sorted quartz sandsand 15cm of eolian soil. Clay bodies formed a nearly continuous sur- face on which the mandible lay; such a

FIGURE 6-Mammuthus mandible in situ at lo- cabty 1452(note cobble embedded in right ra- mus and the scouredand weathered condition of the bone).

New Mexico Geology February 1993 surface may represent cut-bank failure or drones Formation at Tiieras Arroyo thus 1992).The section at Tijeras-(Pliocene)-and Arroyo thus accretion on a longifudinal channel bar. were deposited on an-arid or semiarid producesboth Blancan Ir- The sequenceis cappedby about 2 cm oI piedmont plain via a systemof shifting or vingtonian (Pleistocene)mammals. How- fine-grainedsands and pebbly lag-of depos- ephemeralstreams (Lambert, 1968).The ever, it clearly is not a continuous record !t9, Th9 mandible lay at an angle about stratigraphy of the region shows an al- of the Blancan-Irvingtonian transition. It 20' at the foot of a clay bar running south- ternating pattern of matrix-supported does, nevertheless,provide one of the few east-northwest, bearing N50"E. A sub- gravel clasts with interbedded fine-grained documented faunas of Irvingtonian mam- sptrerical clay body apparently fixed the intervals,indicating alternating high- and mals from New Mexico, which includes lett ramus to the clay surface, and the low-energy systems with frequent up- one of the northernmost occurrencesof eroded surfaceof the 6oneindicates a pe- ward-fining depositionalepisodes. On the glyptodonts as well as a very primitive riod of in-place scouring prior to buiial whole, coarser materials become more Mammuthus. (Fig. 68). common as one proceedsup the section, AcrNowr-sDcr'cvrs-This research was Localities L452 and 1.453resemble the which may indicate a gradual transition supported in part by the Societyof Sigma characteristic lithofacies of low-sinuositv from more distal to more proximal fluvial XI. We thank Thomas R. Logan for his fluvial systems (see, for example, Wii- deposition over the region. On a smaller invaluable assistanceduring the early liams and Rust, 1977).Bar migration and scale, localities 1/52 and 1453clearlv in- phase of this research.Critical comments channel shifts produce an alternating sed- dicate the high-energy regime and'dis- on this manuscriptby S. M. Cather,J. W. imentary morphology that is clearly pres- sectedtopography of a low sinuosity river, Hawley, R. P. Lozinsky and R. H. Tedford ent at both Mammuflrzs sites. Inverted both in nature of the local sedimentology improved its contentand clarity. S. Cather gravel lenses (transverse sections of lon- and in fossil assemblages,which are de- and W Mclntosh shared both their ex- gitudinal point bars), rolled subspherical ficientin small,low derisityelements with pertise in the field and unpublished ra- clay bodies, and other large traniported low cross-sectionalareas. Locality 1.454 diometric ages,for which we are grateful. clasts, together with larger clay massesof appears to represent a local, lower energy accretionary origin, all point to a low-sin- variant of such a depositional environ- References uosity, high-energy (braided) fluvial en- ment. Akersten, W. A.,1972, Redlight local fauna (Blancan) vironment with frequent channel shifts and , We can only make the most generalpa- of the Love Formation, southeastern Hudspeth intermittent subaerial exposure. This is leoenvironmental inferencesbased on the County,Texas: Bulletin of the TexasMemorial Mu- characteristic of the present-day Rio vertebrate fossils becausethev are so few seum, v. 20, pp. 1.-53. Grande system. Bailey,R. A., Smith, R. L., and Ross,C. 5., 1969, and scattered. The o..rrr."rr." of large Stratigraphic nomenclatureof volcanic rocks in the The preservation and condition of the grazing mammals such as EquusandCam- Jemez Mountains, New Mexico: U. S. Geological fossils support such an interpretation. elops suggestsa nearby flora dominated Survey, Bulletin 7274-P,79 pp. These sites appear to have been win- by open grassland Behrensmeyer,A. K., 7978,Taphonomic and ecologic or short-grassprairie. infomation from bone weathering: Paleobiology, nowed of all but large, traction-trans- Mammuthuswas presumably both a graz- u. 4, pp.750-162. ported elements corresponding to ing and browsing mammal and therefore Bryan,K., and McCann,F.T.,7937, The Ceiadel Rio transport groups two and three (Voor- indicates either kind of vegetation or a Puerco: a border feature of the Basin and Range hies, 1969). Both Mammufhusspecimens grassland-woodland mosaic. province in New Mexico. I. Stratigraphy and struc- indicate some ture: Journal of Geology, v. 45, pp.801-828. degree of predepositional Bryan, K., and Mdann, F. T., 7938,The Ceia del Rio attrition and transport.The mandibledis- Biochronology Puerco: a border feature of the Basin and Range plays extensive stress-line weathering The fossil mammalsfrom TilerasArroyo province in New Mexico, II. Geomorphology:Jour- along the lateralaspects of the right and indicate nal of Geology, v.46, pp. l-76. that the strataexposed there are Denny, C. S. 9n, Tertiary geologyof the left horizontal rami-andexfoliatio-n of , San Acacia su- of Blancanand Irvingtonian age.Two taxa, area, New Mexico: Journal of Geology,v. 48, no. 1, perficial laminae on the lateral surface of Hypolagus cf. H. gidleyi and Equus cum- pp.73-706. the- right ramus comparable to stages 3 minsii, are found in the lowermost expo- Galusha,T.,7966,The Zia SandFormation, new early and 4 of Behrensmeye{s (L978) wiath- sures to medial Miocene beds in New Mexico: American of the Sierra Ladrones Formation. Museum Novitates, no. 7-72. ering scale,This indicatesperhaps as long 2277, pp. H. gidleyi is known primarily from Blan- Gardner,J. N., Gotr, F., Garcia,S. R., and Hagan, as a year of subaerialexposure before bui- can faunas,although some specimensmay R. C., 1985, Stratigraphic relations and lithologic ial, depending on local climatic condi- be as old as Barstovian(White, 7987).E. variations in the Jemezvolcanic field, New Mexico: of Geophysical v.91,, tions. The accumulationof cobblesaround cumminsiiis a typically Blancanspecies but Journaf Research, no.B.2, pp. the jaw (inctuding 7763-1n8. a 1,0-cmcobble lodged is not known from earliest Blantan local- Gawne, C. E., 1981,,Sedimentology and stratigraphy between the molar and ramus), as well as ities (Kurten and Anderson, 1980).This of the Miocene Zia Sandof New Mexico:Geological extensivesuperficial pitting and scouring, fossiliferouslevel of the Sierra Ladrones Societyof America,Bulletin, v.92, pp.999-7007. suggest in situ abrasion by transported Formation is thus broadly correlativewith Gidley, J. W., 1,901,Tooth charactersand revision of particles. Finally, the North American speciesof the genus E4aas: the articulated condi- other Blancanfaunas in the SantaFe Group Bulletin of the American Museum of Natural His- tion of both pubic and mandibular sym- (e.9., Lucasand Oakes,1986), but a more tory, v.'1.4, pp. 91-142. physes suggeststhat burial was rapid. The precisecorrelation is not possible. Cillette,D. D., and Ray,C. E., 1981,Glyptodonts of transport-resistant nature of both Mam- The fossiliferous interval at Tiieras North America: Smithsonian Contributions to Pa- muthus specimens, leobiology no.40, Washington, D. C., Smithsonian their weathered con- Arroyo in the middle-upperexposuies of Institution Press,255 pp. dition, and the absenceof associated the Sierra Ladrones Formation contains Hanis, A. H., and Porter,L. S. W., 1980,Late Pleis- skeletalelements despite evidence of rapid Mammuthusas its most commonelement. tocene horses of Dry Cave, Eddy County, New burial all imply high-energy deposition. The presenceof mammoth is taken by us Mexico: Journal of Mammalogy, v.61,, pp. 46-65. This contrasts Hawley, J. W. (compiler), 1978,Guidebook to the Rio with the lithology of the as incontrovertible evidenceof its post- Grande rift in New Mexico and Colorado: New fossil-bearingmud unit (locality 1254)that Blancan age. Other mammals present, Mexico Bureau of Mines and Mineral Resources, yielded Glyptotheriumand Equus.The Equuscf. E. scotti,cf. Camelopssp., and Circular 153, 241 pp. massive clay unit suggests the presence Iyptotheriumcf. G. arizonae,suggest an Hawley, J. W., and Galusha, T., 1978, Bernalillo to of an abandoned south of San Ysidro: New Mexico Bureau of Mines channel, and perhaps Irvingtonian age. This age is consistent and Mineral Resources,Circular 153, pp.777-1,83. local sediment stabilization by vegltation. with abundant reworked Guaie Pumice Henick, C. L., andJohnson,D. W.,1900,Thegeology The fragmentary nature of teeth and bones presentin the SierraLadrones Formation of the Albuquerque sheet:Denison University, Sci- appears to be due to recent weathering at TijerasArroyo (Lambert, 1968),which ence LaboratoriesBulletin, v.'1,1,,pp. 175)39. rather than to the Kelley, V. C.,1977, Geology of Albuquerque Basin, original depositional indicates these strata are no older than New Mexico: New Mexico Bureau of Mines and environment. about 1.51Ma (unpubl. QArfeAr date:W. Mineral Resources,Memoir 33, 60 pp. The sands and gravels of the Sierra La- Mclntosh and S. Cather, pers. comm. (Continues on p. 151

February 1993 New Mexico Geology Gillette, D. D., Wolberg, D. L., and Hunt, A. P., 1986, the Cordilleran volcanic arc in southeastern Ari- Mineral Resources,Open-file Report 385 [in French, Tyrannosaurus rex from the McRae Formation zona: implications for regional tectonics and ore with English summary and captions]. (Lancian, Upper ),Elephant Butte Res- deposits: Geological Society of America, Bulletin, Seager,W. R., 1983, Laramide wrench faults, base- eruoir, Siena County, New Mexico: New Mexico v.70/., pp.32-39. ment-cored uplifts, and complimentary basins in Geological Society, Guidebook to the 37th Field Lipman, P W., and Sawyer, D. A., 1985:Mesozoic southern New Mexico: New Mexico Geology, v. 5, Conference, pp. 235-238. ash-flow calderafragments in southeasternArizona PP. 69-76. Harland,W. B., Armstrong,R. L., Cox, A. V, Craig, and their relation to porphyry copper deposits:Ge- Seager,W. R., and Mack, G. H., 7986,Laramide pa- L.E., Smith, A. G., and Smith, D. G., 1990,A geo- ology, v. 13, pp.552-656. leotectonicsof southern New Mexico; in Peterson, . A., (ed.), Paleotectonicsand sedimentationin rhe. logic tine scale1989: Cambridge University Press, Loring, A. K., and Loring, R. 8., 1980,ISAI agesof f Rocky Mountain region, United States:American New York, 263 pp. middle Tertiary igneous rocks from southern New Association of Petroleum Geologists, Memoir 41, Hodgson, S. A.,7991,, The geology and tectonicsof Mexico: Isochron/Vvest,no. 28, pp.17-19. pp. 559-685. the northem Little Hatchet Mountains, Grant and Lucas, Basabilvazo,G. T., and Lawton, T. F., S. G., Seager,W. R., Mack, G. H., Raimonde, M. S., and Hidalgo Counties, southwesternNew Mexico: Un- from the Ringbone 1990,Late Cretaceousdinosaurs Ryan, R. G., 1986,Laramide basement-coreduplift published MS thesis,New Mexico StateUniversity, New Mexico, U.S.A.: Formation, southwestern and basinsin south-centralNew Mexico:New Mex- Las Cruces, 117 pp. CretaceousResearch, v. 11, pp. 343-349. La Rocque,A., 1960,Molluscan faunasof the Flagstaff ico GeologicalSociety, Guidebook to the 37th Field Lucas,S. G., and Gonziilez-Le6n,C.,1990, RePorte Formation of central Utah: Geological Society of Conference, pp. 123-130. preliminar sobre dinosarios del Cret6cicoTaldio de America, Memoir 78, 100 pp. Thoman, C. H., and Drewes, H., 1980,Geologic map ia cuenca de Cabullona, Sonora: Universidad de Lasky, S. G., 7947,Geology and ore deposits of the of the Victorio Mountains, Luna County, south- Departemento Geologia Boletin, v. 7, no. Little Hatchet Mountains, Hidalgo and Grant Sonora, western New Mexico: U.S. Geologic Survey, Mis- 1.,pp. 1-6. Counties, New Mexico: U.S. Geological Survey, cellaneousField Studies MaP MF-1175,vale 1':24,ffi0. ProfessionalPaper 208, 101 pp. Marvin, R. G., Naeser, C. W., and Mehnert, H.H., Wilcox,R. E., Harding, T. P, and Seely,D. R.,1973, Lawton, T. F., and Clemons, R. E., 192, Klondike L978, Tabulation and radiometric ages-including Basic wench tectonics: American Association o{ Basin-late Laramide depocenterin southern New unpublished K-Ar and fission-hackages-for rocks Peholeum Geologists, Bulletin, v. 57, pp. 74-96. Mexico: New Mexico G-eology,v. 14, no. 1, pp. in southeastern Arizona and southwestern New Wilson, D. A., 7997, Depositional environments, 7J. Mexico: New Mexico Geological Society, Guide- provenance, and age deterrnination of the Skunk lawton, T. F., Mack, G. H., Basabilvazo,G. T., Wil- book to the 29th Field Conference, PP.243252. RanchFormation, Little Hatchet Mountains, south- son, D. A., Lucas,S. G., and Kietzke,K. K., 1990, Rosaz, T., 1989, Le passage des Cordilldres nord- westem New Mexico:Unpublished MS thesis,New Uppermost Cretaceousand Paleoceneshata in the am6ricains aux Sienas Madres mexicainesle long Mexico State University, Las Cruces, 87 pp. Little Hatchet Mountains, southwesternNew Mex- du Texas Lineament- G6ologie de SW du Nou- Zeller, R. A., Jr., 1970,Geology of the Little Hatchet ico (abs.):New Mexico Geology,v. 12, no. 1, p. 15. veau-Mexique (USA): Bulletin Centres de Re- Mountains, Hidalgo and Grant Counties, New and Mineral Lipman, P W., and Hagshum, J. T., 1992, furassic chercerExploration-Production Elf Aquitaine, v. Mexico: New Mexico Bureau of Mines ash-flow sheets,calderas, and related intrusions of 13, pp.247-275; New Mexico Bureau of Mines and Resources,Bulletin96,22pp. tr

t-Xl€-tl-ttt:tt-xl--tt-Xt-Xl:tt:tt:llC-ll-ll-)ll-l

Lucas et al. (Continued from p. 8) Kurten, 8., and Anderson, E., 1980,Pleistocene mam- continental deposits of New Mexico: an overuiew: O'Neill, F. M., and Rigby,J. K.,Jr.,1982, A rare-fossil mals of North America: Columbia Universitv Press, Geological Society of America Bulletin, v. 92, pp. skeletonof Carzelopsfrom Pleistocenedeposits near New York, zM2pp. 9r7-932. Albuquerque: New Mexico Geological Society, Lambert, P W., 1958,Quaternary stratigraphy of the Lucas,S. G., and Logan,T. R., 1984,Pleistocene horse Guidebook to 33rd Field Conference.pp. 82-84. Albuquerque area, New Mexico: Unpublished PhD from the Albuquerque area, New Mexico: New Osborn, H. F., 1918,Equidae of the Oligocene, Mi- icono- dissertation, University of New Mexico, 329 pp. MexicoJournal of Science,v.24, pp.29-j2. ocene, and Pliocene of North America, Lambert, P. W., 1978, Upper Santa Fe stratigraphy Lucas, S. G., and Oakes,W., 1985,Pliocene (Blancan) $aphic type revision: Memoir of the American and geomorphic feahrres of the Llano de Albu- vertebrates from the Palomas Formation, south- Museum of Natural History new series, v 2, pp. querque:New Mexico Bureauof Mines and Mineral central New Mexico: New Mexico Geological So- 1_330. Resoutces,Circular 163, p. 151. ciety,Guidebook to 37th Field Conference,pp. 249- Smith, R. L., Bai)ey,R. As., and Ross,C. 5.,1970, Logan, T. R., 1984,Early Iruingtonian (early Pleisto- 255. Geologic map of the JemezMountains, New Mex- cene) mammals from the upper part of the Santa Lucas, S. G., Williamson, T., and Sobus,J., 1988,Late ico: U.S. Geological Survey, Miscellaneous Geo- Fe Group, Albuquerque-Belen Basin, cenkal New Pleistmene (Rancholabrean)mammals from the Edith logic Investigations MaP I-571. Mexico: Geological Society of America, Rocky Formation, Albuquerque, New Mexico: New Mex- Tedford, R. H- 1981, Mammalian biochronology of Mountain Section, Abstracts with Programs,v. 16, ico Journal of Science,v 28, pp. 51-58. the late Cenozoicbasins of New Mexico:Geological no. 4, p. 245. MacFadden, B. J., Dn, Magnetic polarity stratiSra- Society of America Bulletin, v.92, pp- 1008-10a?. Logan, T. R., Lucas,S. G., and Sobus,J. C., 1984, phy of the Chamita Formation shatotyPe (Mio- Tedford, R. H., 1982, Neogene stratigraphy of the Blancan-Iwingtonian boundary in the Ceia Mem- Pliocene) of north-central New Mexico: American northwestem Albuquerque Basin: New Mexico Ge- ber of the Santa Fe Formation, Tileras Arroyo, Al- Journal of Science,v. 277, pp. 769-800. ological Society, Guidebook to 33rd Field Confer- buquerque area, New Mexico: New Mexico Geology, Machette, M. N., 1978a,Geologic map of the San ence,pp. 273J78. v. 6, no. 1, p. 14. Acacia quadrangle, Socorro County, New Mexico: Voorhies, M.,1969, Taphonomy and population dy- Lozinsky,R. P, Hawley,J.W., andLove,D.W.,1991, U. S. GeologicalSurvey, Geologic Quadrangle MaP namics of an early Pliocenevertebrate fauna, Knox Geologic overuiew and PlioceneQuatemary his- GQ-141s. County, Nebraska: University of Wyoming Contri- tory of the Albuquerque Basin,central New Mexico: Machette, M. N., 1978b,Prelininary geologicrnap of butions to Geology, SpecialPaper 2, 69 pp. New Mexico Bureau of Mines and Mineral Re- the Socorro 1" x 2'quadrangle, central New Mex- Webb, S. D.,1965, The osteologyof Camelops:Science sources,Bulletin 737,p.157-162. ico: U.S. Geological Suruey, Open-file RePort 78- Bulletin of the Los Angeles County Museum, v. 1, Lozinsky, R. P., and Tedford, R. H., 1991,Geology ffi7. Y pp. and paleontology of the Santa Fe Group, south- Machette, M. N., 1978c, Quaternary faults in the White, J. A., 1987,The Archaeolaginae(Mammalia, western Albuquerque Basin, Valencia County, New southwestern United States by using buried calcic Lagornotpha) of North America, excluding Arclueo- Mexico: New Mexico Bureau of Mines and Mineral paleosols:Journal of Research,U.S. GeologicalSur- Iagus and Palolax: Journal of Vertebrate Paleontol- Resources,Bulletin 132, 35 pp. vey, v. 5, pp. 359-381. ogy, v. 7, pp. 425-450. Lucas,S. G., 1987,American mastodontfrom the San- Madden, C., 1981, olNorth America:Un- Williams,G. E., and Rust,B. R., 1977,Thresedimen- dia Mountains, New Mexico: New Mexico Journal published PhD dissertation, University of Colo- tology of a braided river: Joumal of Sedimentary of Science,v.27, pp.2912. rado,241.pp. Petrology, v. 39, pp. 649-679. Lucas, S. G., and Effinger, J. A., 1997,Mammuthus Manley, K., 1978, Geologic map of Bernalillo NW Wright, H. E., Jr., 1946,Tertiary and Quaternary ge- from Lincoln County and a review of the mam- quadrangle, Sandoval County, New Mexico; U. S. olbgy of the lower Puerco area, New Mexico: Ge- moths from the Pleistoceneof New Mexico: New GeologicalSurvey, GeologicQuadrangle Map GQ- otogical Socieg of America Bulletin, v. 57, pp. 383- Mexico GeologicalSociety, Guidebook to 42nd Field tMs. 456. Conference, pp. 277282. Olsen, S. J., 1979, Osteology for the archaeologist: Lucas, S. G., and Ingersoll, R. V., 1981, Cenozoic PeabodyMuseum, Cambridge, 186 pP.

Nan Mexico Geology February 1993