Sedimentologyandpaleontology of Lower Permian fluvialredbeds of north-centralNew Mexico- preliminaryreport by DaaidA. Eberth,Graduate Student, Department of Geology, University of Toronto, Toronto, Ontario, and Daaid S. Berman,Associate Curatot Sectionof VertebrateFossils, Carnegie Museum of Natural History, Pittsburgh,Pennsylvania

Introduction from sedimentologists.The goals of this mian) in the San Diego Canyon region of foint application of sedimentologicaland projectare to: L) reconstructthe depositional SandovalCounty and centraland northeast paleontologicalprinciples to researchinvolv- environmentsof these beds by means of a SocorroCounty, and in the Cutler Formation ing terrestrialfluvial units is currently being multivariatebasin analysisapproach (Miall, in El Cobre Canyon near Abiquiu, Rio Arriba employed by many workers who desire a 1980);2)utilize a knowledge of depositional County.The depositsof theseareas also have more complete understanding of paleoen- stylewithin faciesto locatefossiliferous sed- provided a basisfor planning future field re- vironmental and depositional conditions iments; 3) gain a comprehensivepicture of search.All specimenshave been cataloged (Dodson, 1971; Dodson and others, 1980; the vertebratefauna and insights into envi- into the collectionsof the CarnegieMuseum Bown and Kraus, 1981.;Behrensmeyer and ronmental factors that may be affectingthe of Natural History, Sectionof VertebrateFos- Tauxe, 1982).The perspectivegained from distributionpatterns of someof its members; sils; the abbreviationCM is used to refer to such a union is of unquestionablevalue to and 4) provide an understanding of sand- that repository. biostratigrapherand paleoecologistand stone-bodymorphology and geometry as a the Sedimentology servesas an additional tool for the sedimen- possibleguide to mineral and/or hydrocar- tologist investigatinglocal faciesvariations. bon exploration in this resion and in other Sedimentologicalinquiry and data collec- This past summer (7982)a field party rep- u."ur dith similar historiei of deposition. tion in the CutlerFormation exposures of the resentingthe CarnegieMuseum of Natural Field research was carried out in two RioPuerco drainage area resulted in the com- History and the University of Toronto initi- phases.The thick, laterally extensiveexpo- pilation of 32 vertical sections(totaling 2,892 ated a joint researchprogram in the Lower iures of the Cutler Formatiohin the Rio Puerco h) and 17 horizontal sections(documenting Permian redbed fluvial faciesof north-cen- drainageof central Rio Arriba County were three-dimensional sandstone-body mor- tral New Mexico (fig. 1). The excellentex- the subjectof intensivepaleontological, sed- phology). A total of more than 1,100paleo- posuresin this region have in the past received imentological, and stratigraphic investiga- iurrent directionswere measuredduring the only sporadicattention from paleontologists tion. Similar,but cursory,examinations were courseof these investigations.In addition, and stratigraphersand virtually no attention alsomade in the Abo Formation (Lower Per- individual fossil-bearinglocalities, varying widely in taxa and in quantity of individuals yielded, were mapped and sampled in an effort to address the hydraulic controls on fossil distributions within these fluvial de- 'posits. Severaltentative conclusionscan be drawn from the vertical sectiondata of the Rio Puerco drainagearea (fig. 2). Theseconclusions are:

Alsoin this issue: FloridaMountains overthurst belt p.26 Oiland gas discovery wells drilledin 1982 p. 30 Geologyand uranium potential of Sabinosodistrict p. 35 Service/News p. 39 I Comingsoon A Bryozoanand Crustaceanfrom Fruit- landFormation Magnetostratigraphyof Raton Basin core il Uraniumindustry in NewMexico FIGURE 1-LocArtoN oF STUDYAREAA, El Cobre Canyon and B, Rio Puerco drainage area; open circles CoyoteCreek State Park in B represent locations of the three vertical sections oI fig.2. L) sandstone bodies are concentrated at par- ity and channeltrends, and, to a lesserextent, stones and minor sandstones containing var- ticular horizons in a given vertical section river geometry.All recordedsections, as well iable concentrations of vertebrate, and lateral continuity of a sandstone horizon as casualobservations, indicate the presence invertebrate, and plant fossils were sampled, is uncommon, suggesting regular avulsion of two distinct types of channel sandstone mapped, and measured. Previous reference and splay events typical of ephemeral river bodies.One type is U-shaped,of limited lat- (Lahgston, 1953)to these fossil-rich deposits systems; 2) sandstone to mudstone ratios in- eral extent, and of very low sinuosity.The as "pond deposits" can be considered erro- crease upsection; 3) grain sizes ranging pre- sandsare medium grained and well sorted. neous simply on the basis of their channel- dominantly from medium to coarse in the Bedformsand biogenicindicators consist pri- like morphologies and discontinuous lateral sandstone bodies, as well as infrequent con- marily of medium to large scale trough extent. Preliminary evaluation of vertical and glomerates,and abundant channel scouring crossbedding,abundant dewatering struc- horizontal sections, as well as taphonomic suggest a midfan fluvial environment; 4) ca- tures, and calcareoustubular nodules. Low data recorded from fossils collected by us liche beds of varying maturity and lateral width/depth ratios, as well as internal scour and by the University of California (Berkeley) extent are abundant in mudstone deposits surfaces,^suggestvertical accretionperhaps nearly a half century ago, strongly suggest throughout all of the vertical sections but similar to that found in modern anastomos- that these deposits are the remnants of prox- become noticeably rare in the highest por- ing rivers. The second type of sandstone imal crevasse splays. The subsequent rec- tions of the thickest sections; 5) local corre- channelfill is laterallyextensive and flat based ognition of lithologically and morphologically lations of up to 6-7 km are possible using and representsa channel unit that has ex- similar deposits elsewhere in the section, laterally extensive caliche beds; 6) dark stain- perienced longer periods of lateral accretion which are devoid or very sparsely fossilifer- ing of grains, probably because of hematite than the U-shapedunits. Textural parame- ous, demonstrates that crevasse-splay de- (not displayed in fig. 2), becomes noticeably ters and bedformsof the secondtype appear posits are a common feature associated with reduced upsection, a condition that also was comoarableto those of the U-shapedunits, these sandstone units (as would be expected) noticed in the San Diego Canyon and So- perhapsexhibiting more largescile trough and that their fossil content can be highly corro County areas. crossbedding.Paleocurrent measurements variable. Horizontal section data provided the most of scourssuggest low sinuosity. Preliminary sedimentological studies of useful insights into general channel mor- In addition to the studv of the sandstone Lower Permian redbed facies in San Diego phology, bedform interrelationships, sinuos- bodies, U-shapedCeposit! of reducedmud- Canyon, El Cobre Canyon, and northeast and central Socorro Couniy provided us with a 6/l 5/27 means of evaluating some of the strati- graphic data from the Rio Puerco drainage area. These studies also raised questions that will help to direct future field research. Thick (120 m), exclusively fluvial facies in El Cobre Canyon are tentatively considered to be stratigraphically lower than those beds in the Rio Puerco drainage on the basis of their larger grain size and darker color (hematite stain- ing). One other line of evidence suggeststhis relationship. Within the Rio Puerco drainage area, the Chinle Formation (Triassic) cuts New A4exfic@

CAL,CHE GEOLOGV . Scionceand Service Volume 5, No. 2, May 1983

published quarterly by New Mexico Bureau ofMines and Mineral Resources a division of New Mexico lnstitute of Mining & Technology

BOARD OF REGENTS Ex Officio Toney Anaya, Goverror of Ne|| Mexico Leonard Delayo, Slpeintendeil of Public Inslruction Appointed Judy Floyd, Prcs., 1977-1987, Ias Cruces Willim G. Abbott, Secty/Ireas., 1961-1985, Hobbs Donald w. Moris, 1983-1989, Los Alamos Robert Lee Sanchez, 1983-1989, Albuquerque Steve Tores, 196'7-1985, Socorro

New Mexico lnstitute of Mining & Technology ActinqPrcsident ...... CharlesR.Holmes New Mexico Bureau of Mines & MineralResources Director . .. FrankE.Kottlowski Deput) Dircctor George S. Austin M M _ fu1UDSTONE Subscriptions: lssued quarterly, February, May, August, E November; subscription price $6.00/yr. SS- SANDSTONE T possible Dalerial for E Editoriol matte.: Contributions of C - CONGLOMERATE consideration in future issues of NMG are welcome. R .t CoBBLES Address inquiries to Marla D. Adkins-Heljeson, editor of s Nee Mexico Ceology, New Mexico Bureau of Mines & IKM olo- CALICHE Mineral Resources, Socorro, NM 87801 Published as public donain, thercfore rcproducible without permission. Sou rce cred i t rcques ted. FIGURE 2-SrnarrcnerHrc CoLUMNSrnov Lowrn Prmanx Curun FonrraerroNor Rro Putnco DRATNAGE Ciculation: l.4OO (fig. 1); note lateral continuity of thick caliche horizon (datum marker) and lateral discontinuity of P.ntel. University of New Mexico Printing Plant sandstone units.

May 1983 NewMexico Geology down into the underlying Lower Permian tool. However, the relationship between this New Mexico, both from the Cutler Forma- beds, thus forming an angular unconformity upsection decrease in staining and facies tion of the Rio Puercodrainage. There is some that dips at a low angle to the east. Assuming changes is not presently understood and must doubt that these specimenspertain to Bro- continuous eastward downcutting, we may be evaluated before attempting to apply such iliellus,which is basedon good materialsfrom conclude that the Lower Permian beds of El a trend as a chronostratigraphic tool. the Lower Permianof Texas.The specimens Cobre Canyon are stratigraphically lower than A recent development in fluvial sedimen- collectedby us and an excellentlypreserved those of the Rio Puerco drainage area. tology has been toward elucidating and de- skull and partial postcranialskeleton discov- The redbeds in the San Dieg-o Canyon re- fining channel morphologies and geometries ered by one of us (D. S. Berman;about 1.5 gion are particularly interesting in that they with a commensurate de-emphasis on ge- km southeastof Arroyo de Agua) in 7979, show a continuous transgressive sequence netic modeling (Friend, in press). A basin- should not only resolve this confusion but from basal fluvial facies up through eolian analysis approach to the problems concern- greatly increaseour knowledge of the cranial and marginal-marine facies. Paleocurrent di- ing the controls on the geometries and mor- anatomy of the dissorophids.The skulls are rections, color changes, bedforms, and chan- phology is attaining widespread acceptance very much like that illustrated here in fig. 5 nel molphology suggest that at least the lower (Miall, 1980).The need for such an approach for the dissorophid Ecolsoniacutlerensis (see fluvial facies are roughly contemporaneous to the Lower Permian redbed deposits of New below), differirig most noticeablyin having with the Rio Puerco beds. Generally finer Mexico is indicated because none of the ex- a normal size external narial opening (not sediments suggest a more distal fan facies. isting fluvial models is entirely appropriate expandedposteriorly), a posteriorly open otic All of the beds in the Rio Arriba and San- to explain the full range of sandstone param- notch, and approximately one-half smaller doval Counties are thought to have been de- eters displaved in these exDosures. In ad- overall size. The discovery of a captorhinid rived from a common source area, the dition, r-ecent work on the regional Late reptile is also of great interest becausethey Uncompahgre positive area, during the Late Paleozoic tectonic historv of this"area (Kluth are very poorly representedin Lower Per- Pennsylvanian and Early Permian (Baars, and Coney, 1981)has demonstrated the fairly mian collectionsfrom New Mexico.The cap- 1962). In this light, considering these dis- unique nature of the intracratonic orogenic torhinids, which in life had an appearance continuously exposed beds as deposits in a events responsible for alluvial deposition. much like the small iguanid lizards living single, three-dimensional system represent- Thus, our concentration will be on charac- today, are a very diverse, commonly en- ing a progradational terrestrial phase is im- terizing extra-basinal, as well as basinal, con- counteredmember of the Lower Permianof portant. Characterization of the system on a trols on fluvial style. Texasand Oklahoma. regional scale will involve the additional Of further interest is the fact that many of During the course of collecting strati- sampling and compilation of vertical and the recent examples of applied fluvial sedi- graphic data at widely scatteredpoints, we horizontal sections in the El Cobre Canyon mentological research involve delineating encounteredand explored new and poten- and San Diego Canyon areas. distributional patterns of economic minerals tially fossiliferousareas. At one such area Preliminary investigations of the Abo For- and hydrocarbons within fluvial systems. (approximately13 km northeastof Arroyo de mation exposures in Socorro County pro- Implicit in these studies is a need to under- Agua), a largeblock was excavatedthat has vided an opportunity to study distal-fan, stahd sandstone geometry and morphology so far produced four skulls with postcranial lagoonal, and marginal-marine facies (to- as well as lithostratigraphic cycles (Collin- skeletonsof Seymouria,a modest-sized (max- gether considered as a deltaic environment son,1980). imum length of over 70 cm), reptilelike am- by some authors). Although these beds are phibian (fig. 3). The skulls of all four not all derived from the same primary source Paleontology specimensare similar in being small and of area as the northern beds, similarities in tim- identical size (about 8.5 cm in length com- Intensive ing of deposition, lithological content, and prospecting for vertebrate fossils pared to known maximums of over 11 cm) in the Rio fauna and flora suggest strong parallels. Thus, Puerco drainage has resulted in and in exhibiting an incompletestate of os- these beds may be considered a model for a the collection of many pirtial to complete sification.This suggeststhat they are juve- skeletons reasonable extension of the northern facies of either new or incompletelv to niles and probably members of the same poorlv known animals. to the southwest. Such assumptions, while Re-examination of a brood. Until now Seymouiawas known only site discorrered (approxi- not entirely useful in a strict sedimentolo- by D. S. Berman from contemporaneousbeds in southeast mately gical sense, will hopefully help explain ex- 1.5 km northwest of Arroyo de Agua) Utah (Vaughn,1966)and north-centralTexas isting vertebrate-fossil distribution gradients in1979, which at that time produced a partial (White, 1939). skull and disarticulated re- in the northern beds. but associated Of particularinterest was the discoveryof mains of a dissorophid amphibian probably 14 small (1.35-2.50-cmJong)skulls (fig. q, belonging to Broiliellus, has yielded impor- many with partial, articulated postcranial Discussion tant new finds. Most notable among these skeletons,of a microsauramphibian. These Although limited published lithostrati- are: 1) four complete paleoniscoid fish and were found while investigafing the richly graphic data are available from these strictly patches of scales of others; 2) several partial fossiliferouscrevasse-splay deposits approx- fluvial exposures (Williston and Case, 1.912; skulls and partially articulated and associ- imately L km southeastof Arroyo de Agua. Fracasso, 1980), Baars (1962) has shown that ated postcranial materials also probably re- Most of the specimensoccurred weathering accurate correlations between Permo-Car- ferable to Broiliellus; and 3) a partial skull, out of calichenodules or a fine-grainedsand- boniferous redbeds of the Colorado Plateau numerous vertebrae, and some limb ele- stone and littering a 2 m2 surfaceof a small at the stage level are convincing only when ments belonging to a captorhinid reptile. The siltstone hillock some 80 m from the well- interbedded marine deposits are present. paleoniscoid fish are fusiform in shape, mea- known Camp quarry (see Langston, 1953). Similarly, the biostratigraphic data, dis- sure approximately 10 cm in length, and ob- Other specimenswere found in the imme- cussed extensively in the literature (Lang- viously belong to a single species. Previously diatelv adiacentarea. Microsaursconstitute ston, 1.953;Romer, 1950; Vaughn, 7963; paleoniscoid known occurrences of fish from a very diverse group of small amphibians Fracasso, 1980), have been found equivocal the Lower Permian of New Mexico are lim- that range from the Lower Pennsylvanian to at the stage level (see Fracasso, 1.980,for a ited to isolated scales in coprolites and one the Lower Permian of North America and synopsis of arguments). Preliminary results very fragmentary specimen that was tenta- Europe. Their wide range of body forms and from this past season, however, suggest the tively identified (Langston, 1953) Progy- as probably of habitat preferences were seem- validity of using laterally extensive caliche rolepis sp., known otherwise only from the ingly not unlike those of living salamanders, horizons as intrabasinal marker beds at a lo- Lower Permian of Texas. The latter sDecimen apodans, Iizards, and snakes. Those col- cal level. The basin-wide, upsection decrease has not been described To or figured. date, lected by us were probably fossorial in habit in dark staining of sandsfone grains is an only two imperfect skulls probably referable and much like the apodans in appearance. intriguing phenomenon and may eventually to the dissorophid amphibian Br oiliellus hav e Until now microsaurswere representedin prove to be useful as a regional stratigraphic been described from the Lower Permian of

NewMexico Geology May 1983 opening.The new specimensof E. cutlerensis

turesof the Dissorophidae,the elongatedna- rial opening being the only apparentlink to the Trematopsidae.At leastone dissorophid, LongiscitulaDeMar (1966)from the Lbwer Permianof Texas,has been described as pos- sessingan elongated external narial open- rn8. Discussion Prospects for continued successin ex- panding our knowledge of the Lower per- mian vertebrate fauna of the Rio puerco

more complete specimensof those already identifiedon fragmentaryremains. Most im- portantly, however, we hope that a paleon- tological-sedimentologicalapproach-to the Lower Permian redbeds of New Mexico will resolve enigmatic distributional patterns ex- hibited by many membersof the vertebrate Iaunas. The Lower Permian redbeds of the Rio Puercodrainage, El CobreCanyon, and San Diego Canyonareas, though not continuous in outcrop, were derived almost entirely from the samesource, the Uncompahgrepositive area to the north, and their fossiliferous lev-

FIGURE 3-Donser pARrrAL paractus,and three genera of reptiles, Cha- vlEw oF rHREEsKULLS AND vERTEBRALcoLUMN (CM 3g022) or avputnnN Sry- MoURIA masaurus,Bnldutinonus, nnov Cutln FORMATION(Lowrn Penvrax) or Rro Purnco o*arxocg, scale in centimeters. and Nitosaurus, are recognized as unique to El Cobre Canyon. However, the two amphibians have ilose counterparts, Limnosceloidesand Diadectes, in the Rio Puercoarea, whereasthe three rep- tiles are based on very fragmentary speii-^ mens and their d'eterminations are however, considerably smaller. questionable.Genuine faunal differencesmost probably exist between these two areas,but they are not as striking as those between the Rio Puerco and San Diego Canyon areas. Though both areascontain manyiaunal ele-

as a new genus and species of the family Trematopsidae on the basis of a partial skuil lungfish Gnathorhiza(recently discovered by from the crevasse-splay depositsi km south- D. S. Bermanfrom El CobreCanyon but not east of Arroyo de Azua. Until this time no reported), the amphibians Diplocaulus,Tri- brates,resulted in the discovery of associated other materiib of thiianimal had been found. merorhachis,and an embolomere, and the limb and axialelements of an aiaeoscelid rep- E. cutlerensiswas described as possessing an rcptile Dimetrodon.On the other hand, one tile; tentativediagnosis allies it most closeiy unusual combination of dissorophid and tre- can also list numerous fossil genera found in with Araeoscellsfrom the Lower permian of matopsid features, thus reinforcing an earlier the Rio Puerco area but not the San Diego

May 1983 Nau MexicoGeology FIGURE S-Donsel vtrw oF sKULL(CM 41703) oF DIssoRoPHIDAMPHIBIAN EcoL- SONIACUTLERENSISFROM CUTLER FORI\AETION (LOWEN PERMIAN) OT RTOPUSNCO DRATNAGEPortions of lower iaw and shoulder girdle adhering to left side of skull; external naris (EN), orbit (O), and otic notch (ON) indicated'

FIGURE 4-Donsel lrrw oF FouR MrcRosAURAMPHTBTAN srulls (CM 38023) rnov CL'rLen FonvATroN (LowER PrnvreN) or Rto PuEnco DRATNAGE;scale equals 1.5 cm -, Canyon area or other Abo Formation expo- Behrensmeyer, K , and Tauxe, L , 1982, Isochronous flu- 1963,The age and locality of the late Paleozoic vertebratesfrom El Cobre Canyon, Rio Arriba County, sures farther to the south: the amphibians vial svstem in Miocene deDosits^^, of northern Pakistan: Sedimentology. v 29. p 331-352 New Mexico: Journal of Paleontology,v. 37, p. 283-286 Pantulus.the microsaursdescribed here, Za- Beman, D S, and Reisz, R R, 1980, Anew species of -,1966, Seymouriafuomthe Lower Permianof south- trachys, Chenoprosopus, Ecolsonia , Tseaiaia , Sey- Trimerorhachis (Amphibia, Temnospondyli) from the eastern Utah and possible sexual dirnorphism in that mouria, arl'd Limnosceloides,and the reptiles Lower Permian Abo Formation of New Mexico, with genus:Journal of Paleontology,v. 40, p. 603-612 -, evidenceof closerelationship of the Aerosaurusand Oedaleops.Attempts to ex- discussion of Permian faunal distributions in that state: 1969,Further Annales Carnegie Museum, v 49, p 455-485 hematopsid and dissorophid labyrinthodont amphib- plain distributional patterns of the Lower Bown, T M, and Kraus, M l, 1981, Lower Eocene al- ians with a descriptionof a new genus and species: Permian redbed faunas of New Mexico on luvial paleosols (Willwood Formation northeast Wyo- Bulletin of Southern California Academy of Science,v the basisof broad, paleogeographicfeatures ming, USA) and their significance for paleoecology, 68. p 121-130 ol Seymouriabaylorensis ("trulv deltaic" or "coastal plain" versus paleoclimatology, and basin analysis; Paleogeography, White; T. E., L939, Osteology Paleoclimatology, and Paleoecology, v 34, p 3"1-56 Broili: Bulletin of the Museum of Comparative Zoology, "somewhat faunas)have moreupland" been Collinson, J D , 1980, Alluvial sediments, ln Sedimentary Haruard University, v 85, P. 325-409 inadequate(Berman and Reisz, 1980).A re- environments and facies, H G Reading, ed : Elsevier, Williston,S W, and Case,E C, 1912,ThePemo-Car- alisticapproach to this problem must clearly New York. 557 o boniferous o{ northern New Mexico: fournal of Geol- n be based,at leastin greatpart/ on a thorough DeMar, R. E ,1,966, Longiscitula houghae, a new genus of ogy,v.20, p l-'12 dissoroohid amphibian from the Permian of Texas: sedimentologicalstudy that allows recogni- Fieldiana, Geology, v 16, p 55-88 X-tl-tl-Xl-tll-tl tion of the various physical habitats. Dodson, P.,1971,, Sedimentology and taphonomy of the AcrNowLEocMENrs-Field work was sup- Oldman Formation (Campanian), Dinosaur Provincial Park, Alberta (Canada): Paleogeography, Paleoclima- ported by a grant from the New Mexico Bu- '1,0, Geographicnames tology, and Paleoecology, v p 21.-74 U.S Boardon GeographicNames reau of Mines and Mineral Resources.We Dodson, P, and others, 1980, Taphonomy and paleoe- ManzanitaMountains-mountains, 29km (18mi) areindebted to Dr. Donald L. Wolbergof the cology of the dinosaur beds of the Morrison Jurassic from TijerasCanyon to Canon same institution for putting additional re- Fomation: Paleobiology, v 5, p 208-232 long, extend south de los Seis at the north end of the Manzano sourcesat our disposal and for continued Fracasso, M A, 1980, Age of the Permo-Carboniferous Cutler Formation from El Cobre Canvon, New Mexico: Mountains 24 km (15 mi) southeastof Albu- encouragement. we are also grateful to Dr. Journal of Paleontology, v 54, p li37-1,244 querque; Bernalillo, Torrance, and Valencia Donald Brinkman and Mr. Mark Eberth, Friend, P., in press, Towards the field classification of Counties,New Mexico;Tps. 6-10 N., Rgs.4-6 whosetireless and enthusiasticassistance in alluvial architecture or sequence: Intemational Asso- 8., New Mexico Principal Meridian; 35'04'40' was greatly responsible for the col- ciation of Sedimentologists, Special Publication No 6 N., 106"24'15"W. (north end), 34"50'00"N, the field the Kluth, C. F , and Coney, P. J , 1981, Plate tectonics of (south end); not:Manzano Moun- lection of many of the specimensdescribed ancestral Rocky Mountains: Geology, v 9, p. 10-15 706"23'25'W here.Thanks are also due to Ms. Diane Scott, Langston, W 1953, Permian amphibians from New tains , Jr , (30 Erindale Campus, University of Toronto, and Mexico: University of Cali{ornia Publication, Geological Manzano Mountains-mountains, 48 km mi) Mr. Norman Wuerthele, CarnegieMuseum Sciences, v 29, p.349-476 long, extend south from Cafron de los Seis at Miall, A D., 1980, Cyclicfty and the facies model concept the south end of the Manzanita Mountains to of Natural History, who preparedthe fossils in fluvial deoosits: Bulletin of Canadian Petroleum Abo Canvon 32 km (20 mi) east of Belen; Torr- describedhere. Dr. Andrew Miall, Univer- Geology,v 28,p 59-80 anceand'Valencia Counties, New Mexico;Tps. sity of Toronto,critically read the manuscript Romer, A S, 7960, The vertebrate fauna of the New 3-7 N., Rgs. 4 and 5 E., New Mexico Principal and made many helpful comments. Mexico Permian, ln Guidebook of Rio Chama country, 106'19'45'W (north end), E. C. Beaumont and C B Read, eds, New Mexico Meridian; 34'51'25'N., Geological Society, Guidebook 11th field conference, p 34"27'05'N., 106"29'15"W (south end). References 48-54 -"'Bsilr""tf Baars,D L., 1952,Permian System of Colorado Plateau: Vaughn, P P., 1955, The Permian rcptile Araeoscelis rc- b";,,"soondent American Association of Petroleum Geologists, Bull , studied: Bulletin of the Museum of Comparative Zo- v. 46, p 1.49)13 ology, Haruard University, v 173, p.305-467 t-tt:lt-xt:ll-l

New Mexico Geology May 1983