Ananomalously large Exogyra from the Paguate Sandstone Tongue of theDakota Sandstone (Gretaceous, middle Genomanian) byBarry S. Kues,Department ol Earth & PlanetarySciences, University of New Mexico, Albuquerque, New Mexico 87131-1116 and)rin J. Anderson,New Mexico Bureau of Minesand Mineral Resources, Socono, New Mexico 87801

Abstract specimen possibly represents the sepa- the Conlinocerastarrantense through CaIy- rate, rapid evolutionary development of cocerascanitaurinum zones. Of the several A large, thick-shelled specimen of Er- a small population of E. whitneyi-llke Dakota-Mancos tongues and members in o3yra, measuring 165 mm in height, from oysters from an unknown ancestor in this sequence,the PaguateTongue of the the Paguate Sandstone Tongue, is de- west-central New Mexico, rather than a scribed and illustrated. This specimen, Dakota Sandstone contains the greatest relict population of E. whitneyior an im- diversity of marine invertebrates, with which is much larger than any oyster migratedin from mediatedescendant that more than 60 molluscan speciesreported previously reported from the middle the Tethyan province to the south. Cenomanian intertongued Dakota-lower (Cobbanand Hook, 1989).Recently, one Mancos sequence in New Mexico, is of the authors (OA) discovereda speci- Introduction morphologically similar to Exogyra whit- men of an unusually Iarge Exogyra,pre- neyi, an early Cenomanian Tethyan The intertongued upper Dakota-lower viously unknown in this sequence,in a (Texas, southern New Mexico) species. Mancos sequence is well exposed and fos- Paguate outlier in southwestern Cibola The presence of E. whitneyi or a closely siliferous at many localities in west-cen- County, New Mexico. This specimen is related species in the Paguate Tongue is tral and northwestern New Mexico, and surprising because marine connections noteworthv not onlv because of its size its faunas are diverse and well known (e.g., between southem and west-central New but also beiause its iffinities appear to be 1989). Mexico were absent from middle-early Cobban, 1977; Cobban and Hook, with a species,Exogyra whitneyi Bcise, that to middle-middle Cenomanian time and Ammonite biostratigraphy indicates that is confined to early Cenomanian strata in because no large exogyras of this type deposition of this sequence occurred dur- Texasand southern New Mexico. We de- are known from this interval anywhere ing most of middle Cenomanian and the scribe this specimen (11966,University of in the surrounding areas The Paguate beginning of late Cenomanian time, from New Mexico paleontologycollections) here and discusssome of the paleogeographic questions raised by its presencein the Pa- guate SandstoneTongue.

ShatigraPhY The units of the intertongued Dakota- Mancos sequencewere initially named in the Laguna area, northeastern Cibola County, by Landis et al. (1973).Cobban (1977)summarized and illustratedthe di- verse fauna. Hook et al. (1980)extended this terminology into the southern Zuni Basin,and it has been used subsequently in mapping and coal-resourceevaluation work by McClellanet al. (1983),Anderson (1987),and Campbell (1989).Small, iso- lated outcrops of the PaguateTongue oc- cur in the areawest of AtarqueLake (Fig. U = 1), both north and south of the farolosa z Draw lobe of the North Plains basalt field N (Anderson, 1987).The Paguatehas been 3 identified in this area, in the Venadito z Camp quadrangle, on the basis of strati- graphicposition (abovethe lowestpart of the Mancos Shale and below the White- water Arroyo ShaleTongue of the Mancos Shale),as well as by its concretionaryli- thology and characteristicmolluscan fauna locally.The specimendiscussed here was collected from the middle of the Paguate ,Ec Tongue at an isolated outlier (Fig. 2) in the SE1/+SE1/+sec. 11 T5N R20W,Cibola 0 5 10mi County, about 8 mi (13 km) east of the -# New Mexico-Arizona border. Abundant 0 5 10 15km specimensof Exogyraleols Stephenson and Pycnodontecf. P. kellumi(Jones) occur in FIGURE 1-Location map and generalized geology of Atarque Lake area, Cibola County, New the upper part of the Paguateat this out- Mexico. @ marks locality where UNM-11966was collectedfrom the PaguateTongue of the Dakota crop (Fig. 3). The Paguate fauna in this Sandstone Psa, San Andres Limestone; and Triassic rocks (Entrada Sandstoneand |tr, furassic to the Acanthocerasam- Chinle Group); Kdm, intertongued upper Dakota-lower Mancos Shale; Kmha, Moreno Hill For- area is restricted mation and Atarque Sandstone;Kdmt designatesarea to the northeast with more complex stra- phibolumammonite zone, approximately tigraphy that includes the Tres Hermanos Formation; Qb, JaralosaDraw lobe of North Plains in the middle part of the middle Ceno- basalt flow Tertiary sedimentary units not shown. Basemap from Dane and Bachman, 1965. manian stage(Cobban and Hook, 19891

Nm Mexico Geology August 7994 FIGURE2-View to northwestof outcropof PaguateTongue (the light-coloredunit). Spec- imen of E. cf. E. whitneyiwas collectedfrom transitionalunit at baseof blocky,spheroidal weatheringunit in upperpart of exposure.Ta- lus and colluviumare derivedfrom overlying Quaternarybasalt flow (JaralosaDraw lobeof North Plainsbasalt flow).

Description of specimen UNM-11966(Figs. 4A, C, D) is an ar- ticulated specimendisplaying most of the left (larger) valve, with the right valve present but almost completely covered with matrix. The surface of the left valve is severely worn and extensivelyperfo- rated with holes and canals of boring sponges,thus obscuring surficial details of the valve. The specimen is approxi- mately 155 mm high; restoration of miss- ing portions of the ventral margin suggests an original height of 175* mm. Estimated original length is 115 mm and width is approximately 70 mm. The left valve is thick and massive. The beak is inflated, f Locallyan additional6-ft.-thick fossiliferous gently coiled against the posterodorsal I sandstonesimilar to unit below. valve surface,and is stronglyinclined, such -.' Heavilybioturbated and hematite-stained that it approximately parallelsand slightly ' uppersurface suggests subaerial exposure. overhangs the hingeline. The outer sur- face of the beak is depressedrather than T Lowerfine-grained, grayish-orange (10 YR Z4) convex, suggestinga 40-mmJongattach- I quartzosesandstone. Low-angle crossbeds in ment scar.In lateralprofile, the valve sur- smalltrough sets may be tidallyinfluenced; faceis moderatelyand evenly convexfrom spheroidalweathering is common. I Oblate beak to ventral margin, with the maxi- 6' calcareoussandstone concretions uo to 3 ft in diameterare commonand generally mum valve width slightly above mid- fossiliferous.Fauna includes Exogyra levis, height. In dorsal(beak up) view (Fig.4D), 5- Pycnodontect. P. kellumi, and Pinna sp. the profile from anterior to posterior mar- Burrowingis common, gin is strongly convex, flattening slightly + Exogyract. E. whitneyi across the umbonal midline. Valve orna- Uppervery fine to lowerfine-grained, mentation is poorly preserved, but ex- yellowish-gray(5Y 712)to grayish-orange(10 YR amination of the less-worn valve surfaces 714)quat?.ose sandstone with micaceouszones, yielded no indication of significant radial thin,flat bedding;brown-weathering calcareous ribbing and slight suggestion of lamellate sandstoneconcretions up to 3 ft. in diameter; growth lines. 10- sparselyfossiliferous; calcareous cement; slight upward-coarseningtrend. Specimenof Exogyra Taxonomic discussion ct. E. whitneyi found at top of interval. The fauna of the Paguate and related Uppervery fine to lowerfine-grained, tongues of the upper Dakota-lower Man- yellowish-gray(5Y 712)quartzose sandstone cos sequencein west-centralNew Mexico with micaceouszones and small,coalified peat has been well summarized and illustrated b fragments;upper part has thin sets (<0.1ft,) of by Cobban (1977)and Cobban and Hook I low-anglecrossbeds and smallmud clasts; (1989).No exogyrasof this sizeand form 15- I scatteredfossils include small fragments of have been documented from these units, I gastropodsand bivalves(Exogyra? ); nor from coeval strata to the southeastin calcareouscement. Lincoln County (Cobban,1986). The larg- _]- est Paguateexogyras, E. trigeri (Coquand) Section below is covered. and E. cf. E. oryntas(Coquand), only rarely 4 4i attain a height of 100mm. Typical speci- a Qt mens of E. trigeri possessa left valve of low convexity, with prominent lamellate growth lines (e.g., Cobban, 1977,pI. L7, fi Burrowed(trace fossils) figs. 7-10), that differs considerably from A Calc.concretions the much larger, more convex specimen dG Fossiliferous

FEI crossbeddedsandstone FIGURE 3-Measured section of Paguate Tongue, SEI/ISEIL sec. 11 T5N R2OW Cibola lTl rin"-grainedsandsrone County, New Mefco (measuredby O. Ander- son, Sept. 1993).

August 1994 Nan Metico Geology taa1:!

FIGURE 4-Exogyra cf. E. whitneyi (UNM 1f966; PaguateSandstone Tongue, Cibola County), and E whitneyi (UNM 11971;D9l !o clay, Cerro de Cristo Rey); all t 0.5. A, C, D, E. cf. E. whitneyi,right (A), left valve exterior (C) and dorsal (D) views. B, E, E whitneyi,right (B) and dorsal (E)

discussedhere. E. cf. E. oxyntashas prom- Two species of Exogyrafrom the Cen- ratio of 0.41 and is more gently conuex, inent, closely spacedradial costae.Cob- omanian of the WestemInterior-Texas area with maximum width at about mid-height. ban (1977,p. 20)did note specimenswith attain the unusually largesize, thick valves, E. forresterialso has a more acutely convex "very massivethick shellsthat are much and general valve proportions of UNM- antero-posterior profile whereas UNM- distortedby largeattachment scars" in the 11966,butneither has been reported from 17966is more broadly convex. This spec- Whitewater Arroyo Shale Tongue over- the middle Cenomanian.The first is E. imen, though strongly worn, lacks even lying the Paguate Tongue, and he sug- forresteri,which Reeside(1929) estab- residual evidenceof radial ribs, suggest- gested that they might be unusual lished as a variety of E. olisiponensisSharpe, ing that such ribs were very subdued or repre-qentatives E. lacking on the valve beforeit was worn. of E. tr iger i.. P o s sibly _t-lgs-e the same taxonomicrank he accorded specimensare conspecificwith UNM- oxyntas,now considereda seParatesPe- Becauseof these differences,we do not 11966;if so, however, it is very doubtful cies. This speciesgroup occursin strata believe that UNM-11966is conspecificwith that this taxon is an aberrantform of E. in Utah that are significantlyyounger than E.t'onestui, or with its smaller,more highly trigeri, given the differencesnoted above. the PaguateTongue (Cobban , 1977),in the ribbed relatives, E. oxyntas and E. olisi- Specimensidentified by Cobban(1977,pl. upper Cenomanian ammonite zone of 00nens6. 9, figs. 12-20) as E, trigeri from the Pa- Metoicocerasmoswense (Kauffman et al., A second speciesbearing on the iden- guate Tongue in northwestern Catron 1.978;Cobban, 19M, p.80). Cobban'sten- tity of the Paguatespecimen is E. whitneyi County, near the Atarque Lake locality, tative identificationof E. cf. E. oxyntasin Bose. This southern (Tethyan) speciesis appearto be somewhatmore convexand the Paguateand Whitewater Arroyo known only from strata of early- to mid- less lamellate than typical specimens. Tongues suggeststhat E. oxyntas,at least, dle-early Cenomanian age in Texas and However, these Paguatespecimens differ ranges into the middle Cenomanian in southern New Mexico. Bose (1910)orig- significantly from UNM-11966 in having west-centralNew Mexico. Of these spe- inally described this species,as E. pon- a less-convexand more-lamellateleft valve, cies, which typically display well-devel- derosavar. clarki(rn part), from what are with a smaller beak, and in attaining only oped radial ribs, only E. forresteriattains now named the upper Anapra and Del one-third its size.A relativelylarge, unor- exceptionallylarge sizes, and it is further Rio formations at Cerro de Cristo Rey and namented,convex species from the Cub- characterized by a reduction in the size illustrated a specimenabout 190mm high ero SandstoneTongue (below the Paguate) and extentof the radial ribs (Reeside,1929). (Bose,1910, pt.23, fig. 17; pl.24, fig. 6; was identified by Cobban(7977, pl. 5, figs. However, the left valve of E. t'orresteriis pI. 25, fig. 8). Later, Bose (1919)named 23-28) as E. sp. A. Comparedto UNM- considerably wider relative to height the speciesE. whitneyi,and other speci- 17966,E. sp. A has a much smaller,less- (width/height:0.60; seeReeside, t929, pl. mens were describedand illustrated by curved beak, a more symmetrical profile 69, fig.4) than is true of UNM-11965,and Adkins (1928)and Stanton(1947). Cobban along the principal growth axisof the valve, maximum convexity is attained rather (1987)reported it in the upper nodular and a more strongly arched left valve; it abruptly about one-third of the distance zone of the Sarten Sandstonein the is also less than half as large as UNM- from the beak to the ventral margin. The Cooke'sRange, southwestern New Mex- 17966. left valve of UNM-11966has a width./height ico, which he equated with the Buda

Neu Mexico Geology Argust 1994 JI Limestone, which overlies the Del Rio Ceno de Southwesl Atarque area, Formation at Cerro de Cristo Rey and in CristoRey New Mexico west-central Texas.Lucas et al. (1988,figs. 7N, Q) il- & central New Mexico lustrated examplesof E. whitneyifrom the Texas sameinterval of the Sarten in the Cooke's Rio Salado Tongue Upper of Mancos Range. Comparison of UNM-11966with Cenomanian specimensof E. whitneyifrom the Del Rio Formationof Cerrode Cristo Reyand up- per SartenSandstone of the Cooke'sRange reveals many similarities in addition to large size. The left valve of E. whitnerti lacksradial ribs and displaysonly muted Middle E. d. growth lamellae, similar to the inferred Cenomanian E. whitneyi ornamentation of the Paguatespecimen. Further, the curvature and orientation of Dakota the beak, width/height relationships, and (mainbody) curvature and convexity proportions of E. whitneyi closely resemble those of UNM- 7t966. In many specimensof E. tohitneyi, the beak is either somewhat more prom- inent and extended than in the Paguate specimenor is distorted by large attach- ment scarsalong its outer surface.E. whit- neyi appears to be slightly narrower (i.e. Rangeof E. whitneyi the left valve length./heightratio is smaller) in Texas & than UNM-11966.Atypical exampleof E. southwest whitneyi from the Del Rio Formation at New Mexico Cerro de Cristo Rey is illustrated (Figs. 48, E) for comparison with the Paguate specimen.Based on morphologicalsimi- larities, the Paguate specimen is most Albian closely related to, if not conspecificwith, E. whitneyi, although better specimens, FIGURE S-Cenomanian ammonite zones and stratigraphy in southern and west-central with unworn external New valve surfaces,are lvlqicg, showing range of E. whitneyiin southern New Mexico and Texasand stratigraphicposition required from the PaguateTongue for def- of E. cf. E. whitneyi from the PaguateTongue of the Dakota Sandstone.Zonation and correlations inite identification. Here, we refer UNM- based on Cobban(1987),Kenne-dy et al. (1988),Lucas et al. (1988),and Cobban and Hook (1989). 1.1966to E. cf. E. whitneyi.

Biosttatigraphic and paleobiogeographic considerations of the Dakota main body; Cobban, t977). Exogyrawhitneyi apparently becameex- Cobban and Hook Q98a,fig.2) demon- tinct in Texasand southern New Mexico stratedthat ammonite-bearingmarine en- in middle-early Cenomanian time, in the vironments first appearedin west-central Budaicerashyatti ammonite zone (Fig. 5). New Mexico from the east during Conll- No exogyras of this type have been re- nocerastarrantense (early-middle Ceno- ported from the overlying Woodbine For- manian) time, with depositionof the upper mation (middle Cenomanian) of central Oak Canyon Member and Cubero Sand- Texas(Stephenson, 1952), or from thelower stone Tongue, forming "Seboyeta Bay" Boquillas Formation (of middle Ceno- (Fig.6). The southernshoreline of this bay manian, Acanthocerasamphibolum, age), trended approximatelyeast-west through which unconformably overlies the Buda the northern portions of Socorroand Lin- Formation at Cerro de Cristo Reyand other coln Counties (Cobban et al., 1994,fig. 4); locationsin Texas(Kennedy et al., 1988). the marine Cenomanian record of the In the Cooke'sRange, the uppermostSar- Carthage and Carrizozo areas begins in ten Sandstoneis overlain unconformably the middle-middle Cenomanian (Cobban by early-late Cenomanian strata of the and Hook, 1984;Cobban, 1986|'.Farther MancosFormation; strata coeval with the south, in the Love Ranch area of the PaguateTongue are absent(Cobban, 1987; southern San Andres Mountains, a re- Lucaset al., 1988). stricted, 380-meter-thick"middle Creta- Could a relict population of E. whitneyi ceous" section includes the Sarten or an immediatedescendant species have Sandstone (Albian), overlain by Dakota survived into the middle-middle Ceno- and Mancos-correlativestrata (Seager, manian in west-centralNew Mexico?The 1981). Late Cretaceousmarine inverte- persistent unconformities noted abovein- brates(listed by Bachmanand Myers, 1969) dicatethat marine sedimentationwas ab- appear to be limited to the upper part of FIGURE 6-Shoreline configuration in New Mexico and other western statesduring early- sent in southern New Metco from middle- the sectionand areof Turonianage (Seager, early to about middle-middle middle Cenomanian time (zone of Conlinoceras Cenornan- 1981;Kottlowski, written commun., 1994). marine embayment in ian tarrantense);prominent time. Early Cenomanianstrata in west- Although more study of this sequenceis west-centralNew Mexico is SebovetaBav. Bold central New Mexico are nonmarine de- needed, the lack of Cenomanian fossi.ls bounding line indicates relative certainty of posits of the lower Dakota Formation suggests that a marine connection be- shoreline position. Dots identify fossil locali- (lower Oak Canyon Member, or lower part tween this part of south-centralNew ties in this zone (afterCobban et al.. 1994).

August 1994 Nan Meico Geology Mexico and central and west-centralNew explain in the context of early-middle Anderson, O J, 1987,Geology and coal resourcesof Mexico did not exist immediately prior to Cenomanian paleogeographyand known the Atarque Lake 1:50,000quadrangle: New Mexico Bureau of Mines and Mineral Resources,Geologic or during the initial development of the faunal dispersal routes in the Texas- Map GM-61. Seboyeta Bay in early-middle Cenoman- southern Western Interior region. An al- Bachman,G. O., and Myers, D. A.,7969,Geology of ian time. Later, continued eustatic sea- ternative possibility is that UNM-1,I966is the BearPeak area, Dofra Ana Countv, New Mexico: level rise expanded marine environments not related to E. whitneyl,but represents U.S GeofogicalSuruey, Bulletin tZit-lC, +e pp Bcise,E , 1910,Monografia geologicay paieontologica for the first time since the middle-early a speciesthat very rapidly evolved an E. del Cerro de Muleros: Instituto Geologicodel Mex- Cenomanianinto southern New Mexicb whitneyllike morphology from an as yet ico, Bofetin25,1.91 pp. during A. amphibolurr(middle-middle unidentified ancestorin west-centralNew Bose, E., 1,979,On a new Exogyrafrom the Del Rio Cenomanian) time (Cobban and Hook, Mexico. Kauffman (1,9U,p.291) noted a clay and some obseroationson the evolution of Er- ogyrain the TexasCretaceous: University of Texas, 1984, fry. 3; Carey, 1992, fig. 15). Given dramatic increase in faunal diversity in Bulletin 1902,22 pp. these paleogeographic considerations, a the southern Western Interior seawayre- Campbell, F W., 1989,Geology and coal resourcesof population of E. whitneyior an immediate sulting from increased rates of evolution FenceLake 1:50,000quadrangle, New Mexico:New descendantcould not have migrated caused in turn by rising temperature and Mexico Bureau of Mines and Mineral Resources, northward from southern Geologic Map GM-62. to west-central salinity, and he also noted niche parti- Carey, M. A ,1992, Upper Cenomanianforaminifers New Mexico between middle-early and tioning accompanying the mixing of from the southem part of the San Iuan Basin. New middle-middle Cenomaniantime. northern and Tethyan faunal elements. Mexico:U.S. GeoldgicalSuruey, Bulletin 1808,pp. Could a population of E. whitneyi-llke This reached its height in the late Ceno- N1-N17. Cobban, W A., 1,9n, Characteristicmarine mollus- oystershave migrated to westCretaceous),Luna County, New Mex- cl. E. uthitneyihave been reported specimensof the large, thick valveswould ico: U.S GeologicalSurvey, Bulletin 1541-8,17 pp. from the Graneros. be conspicuous and difficult to overlook Cobban, W A, and Hook, S C , 798/.,Mid-Creta- To the southeast, in Texas,the Wood- during collection. Significantly, no spec- ceous molluscan biostratigraphy and paleogeogra- bine Formation unconformably overlies imens have been reported by previous phy of southwestem part of Westem Interior, United States: Geological Association of Canada, Special Washita Group (Buda and older) strata. workers. The wom, heavily bored state Paper 27, pp 257-271. The Woodbine occupiesthe same relative of the valve indicatesa relatively long time Cobban, W. A., and Hook, S. C , 1989, Mid-Creta- position in the early transgressivepart of of exposure on the seafloorbefore burial, ceous molluscan record from west-central New the Greenhorn cyclothem (T-6 transgres- suggestinglittle transportationafter death. Mexico: New Mexico Geological Society, Guide- sion of Kauffman, 1984) as does the in- That book to 40th Field Conference, pp.247-26a this specimen has been reworked Cobban, W A., and Scott, G R ,1972, Stuatigraphy tertonguing Dakota-Mancossequence in from older shata is possible,although long and ammonite fauna of the Graneros Shale and New Mexico(Kauffman et a1.,I977).Dur- exposure on the seafloor better explains Greenhorn Lirnestonenear Pueblo, Colorado: U.S. ing the early Cenomanian, Western In- its worn. bored condition. Even if re- GeologicalSurvey, ProfessionalPaper 645, 108pp. terior marine environments were largely Cobban, W. A , Merewether, E. A., Fouch, T. D., and worked, the possible marine strata in the Obradovich, l. O., 1994, Some Cretaceousshore- isolated from those of the Gulf Coast area that might have been the source are lines in the Western Interior of the United States; (Kauffman, 1984),and their endemic fau- only slightly older than the PaguateTongue in Caputo, M. V., Peterson,J A , and Franczyk, K. nas include no exogyrasthat might be rea- and thus would not affect the paleogeo- J (eds.), MesozoicSystems of the Rocky Mountain sonableancestors region, USA: Society of Economic Paleontologists of the large Paguateform. graphic observations presented above. and Mineralogists, Denver, pp. 393-413 As the transgression continued in the Given the questions the presence of an Dane, C. H, and Bachman,G. O., 1965,Geologic middle and late Cenomanian, Tethyan unusually latge Exogyra in the Paguate map of New Mexico: U S. GeologicalSurvet state faunas spread northward from the iulf Tongue raises, it is unfortunate that the maP Coast area into the Hook, S C., Cobban,W. A, and Landis,E. R, 1980, southern Western In- specimen discussedhere is rather poorly Extension of the intertongued Dakota Sandstone- terior (Kauffman, 1984).The earliest am- preserved. Better specimens are needed Mancos Shale terminology into southern Zuni Ba- monite-bearing Woodbine strata are of to assess in more detail the taxonomic sin: New Mexico Geology, v 2, pp. 42-46 early-middle Cenomanian age (Kauffman status of this form and its relationships to Kauffman, E. G.,l9U, Paleobiogeographyand evo- et al.,1977;Cobban lutionary response dynamic in the Cretaceous and Hook, 1984;Ken- other Cenomanian speciesin the Western Western Interior seaway of North America: Geo- nedy and Cobban, 1990),and by the time Interior seaway. logical Associationof Canada,Special Paper 27, pp. of Paguatedeposition, numerous Wood- AcrNowreocMENTS-The New Mexico 273-306. bine ammonite and pelecypod species,in- Bureau of Mines and Mineral Resources Kauffman, E. G., Cobban, W. A., and Eicher, D. L., cluding several 1978,Albian through lower Coniacian strata, bios- species of oysters, had and the Department of Earth and Plane- tratigraphy and principal events, Western Interior, appeared in west-central New Mexico. tary Sciences,University of New Mexico North America: Annales du Museum d'Histoire However, Woodbine exogyras are small, supported this research. Frank E. Kot- Naturelle de Nice, tome 4, pp.-E., 23.7-23.52 Kauffman, and the fauna lacks any forms related to tlowski, SpencerLucas, and firi Zidek re- E. G., Hattin, D and Powell,J. D, E. whitneyi.If E. whitneyi l9n, Sbatigaphic, paleontologic, and paleoenvi- or a descendant viewed the manuscript and made helpful ronmental analysis of the Upper Cretaceousrocks survived in Texas after the early Ceno- comments and suggestions. We thank of Cimarron County, northwestem Oklahona: Ge- manian and subsequentlymigraied into Lynne Hemenwap who prepared the ological Societyof America, Memoir 149, 150pp. west-central New Mexico, its remains have manuscript, and Kathy Campbell, who Kennedy, W. J., and Cobban, W. A., 1990,Cenoman- not been identified ian ammonite faunasfrom the WoodbineFormation in middle Cenoman- drafted the illustrations. and lower part of the Eagle Ford Group, Texas: ian strata in Texas. Palaeontology,v 33, pp.75-754. Thus, the occurrence of an unusuallv References Kennedy, W. J, Cobban, W. A., and Hook, S C , 1988, Middle Cenomanian (Late Cretaceous)mol- large exogy'a resemblingE. whitneyiin tie Adkins, W. 5., 7928,Handbook of TexasCretaceous Paguate Sandstone Tongue is difficult to fossils: University of Texas,Bulletin 2338,85 pp. (Continuedon p. 54)

Na;l Mexico Geology August 1994 ChristinaLochman Balk honoredby New Mexico Geological Society

For her many contributions to the New Resources1955-57 and a professor of ge- A fellow of GSA, Christina is also a Mexico Geological Society (NMGS), ology for New Mexico Institute of Mining member of AAAS, PS, National Associ- Emerita Professor-ResearcherDr. Chris- & TechnologyI957-t972. Since 1.972she ation of Geology Teachers,NMGS, Sigma tina Lochman Balk has been awarded a has been an emerita professor. Christina Xi, and Phi Beta Kuppa. Her influence as plaque by the NMGS Executive Commit- taught classesand conducted researchfor a teacher and advisor helped many ge- tee, a grateful acknowledgment of Chris- many yearsafter her retirement.She taught ology students learn and enjoy our sci- tina's many services. stratigraphy, paleontology, and sedimen- ence. Professor Rena Mae Bonen, Baylor Christina wrote or was coauthor of tation to both undergraduate and grad- University, is just one (outstanding) ex- stratigraphic correlation charts and lexi- uate students. Her extensiveresearch ample of Christina'sprodigies. High school cons for NMGS guidebooks: 1959 West- centered on Cambrian stratigraphy and teachers enjoyed her summer geology centralNetp Mexico, 1964Ruidoso Country, fossils and ranged from Canada, Mon- courses, taught with Clay Smith. For a 1965Southwestern New MexicoIl, 1967De- tana, and South Dakota to New Mexico, score of vears, Christina was the strati- fiance-Zuni-Mt. Taylor Region, and 1972 Texas, Arizona, and northern Mexico. graphic c6mpiler for NMBMMR, aiding in East-centralNeur Mexico. She was co-editor Christina organized the First Cambrian our computerization of stratigraphic no- of SouthwesternNgw MexicoII in 1965and Symposium at the International Geolog- menclaturewith USGS. coordinated the trail hike to (down) and ical Congressin Mexico in 1956.She has After 41 years in Socorro, Christina from (5,000ft up) PhantomRanch in Grand published numerous articles in Journal of moved to Santa Fe to be near her niece. Canyon for the 1958Field Conference to Paleontology(two BestPaper awards), GSA Perhaps she will have time to help NMGS northern Arizona. She servedas treasurer Bulletin, AAPG Bulletin, Rocky Mountain with its 1995field conferencein that area. of the society in 1972and was awarded Geologist, and IGC Proceedings,as well NMGS reflectscredit on itself by honoring Honorary Membership in 1977. Dr. Balk as in NMGS and NMBMMR publications. this first lady of New Mexico geology. attended. usuallv with manv of her stu- Researchgrants to Dr. Balk camefrom the dents. manv of ihese auturin field con- National ResearchCouncil, GSA, and NSF. -Frank E. Kottlowski ferencesas"well as the spring technical Christina was born in Springfield, Illi- sessions. Most rewarding to the society nois, Octobet 8, t907 to David Julius and was her chairing of the scholarship com- Nellia (Stanton) Lochman. She received Note: Christina Lochman Balk recently mittee of NMGS for several decades, her A.B. (1929)and M.A. (1931)from Smith established the Robert and Christina helping recommend grants for students' College and Ph.D. from Johns Hopkins Lochman Balk fellowship that she desig- geologic projects. University (1933).Before coming to New nated for the benefit of "graduate stu- Christina married Dr. RobertBalk March Mexico, she was on the faculty of Mt. Hol- dents in the field(s) of sedimentation, 15, 1947 and came to New Mexico with yoke College (1935-1947)and then a lec- stratigraphy and/or paleontology at the him in 1952. She was a stratigrapher for turer at University of Chicago (1947)and New Mexico Institute of Mining and Tech- New Mexico Bureau of Mines & Mineral |ohns Hopkins (194tt-49). nology."

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Kuesand Anderson(continued from p. 53) and Pence, R, 1988,Cretaceous stratiSraphy and sionaf Paper 154-I, pp. 267-278. biostratigraphy,Cooke's Range, Luna County, New Seager,W. R., 1981,Geology of Organ Mountains and luscan fauna from the base of the Boquillas For- Mexico: New Mexico Geological Society, Guide- southem San Andres Mountairo, New Mexico: New mation, Ceno de Muleros, Dofra Ana County, New book to 39th Field Conference, pp. 743-1,67. Mexico Bureau of Mines and Mineral Resources, Mexico: New Me{co Bureauof Mines and Mineral Mclellan, M W., Haschke, L R, Robinson, L N , Memoir 35, 97 pp. Resources,Bulletin 114, pp. 35-44 and Landis, E. R., 1983,Geologic map of the Mo- Stanton, T W., 1947,Studies of some Comanchepe- Landis, E R., Dane, C. H., and Cobban,W A., 1973, reno Hill quadrangle, Cibola and Catron Counties, lecypods and gastropods:U.S GeologicalSuwey, Stratigraphic terminology of the Dakota Sandstone New Mexico: U.S Geological Survey, Miscellane- ProfessionalPapet 271,256 pp and Mancos Shale, west-cenhal New Mexico: U.S. ous Field Studies Mao MF-1509. Stephenson, L. W., 1952,Larger invertebrate fossils Geological Suruey, Bulletin 1372-J,U pp. Reeside,J B , lt., 192i, Exogyraolisiponensis Sharpe of the WoodbineFormation (Cenomanian)of Texas: Lucas,S. G., Kues, B S., Hayden, S N., Allen, B and Elogyra costataSay in the Cretaceousof the U.S. GeologicalSuruey, ProfessionalPaper 242, )n6 D, Kietzke, K. K., Williamson, T E , Sealey,P, Westem Interior: U S. Geological Suroey, Profes- PP. U

August 1994 Nan Merico Geology