Extension0fthe intertongued Dakota TABLE l -LocnrtoN oF SEcrtoNSSHowN oN Flc. 2. l-Two Wells-outcrop section from Dane, Landis, and Cobban (1971, p. 318); measuredin NE% sec. 17, T. 12 N., R. 19 W., McKinley County, Sandstone-Mancos Shale terminology New Mexico 2-Atarque-outcrop section measured by C. H. Dane, E. R. Landis,and W. A. Cobban in sec.24, intothe southern Zuni Basin T. 6 N., R. l8 W., ValenciaCounty, New Mexico 3-Tiger StateNo. l-oil testdrilled in sec.8, T.4 byStephen C. Hook, Paleontologist, NewMexico Bureau ol MinesandMineral Resources, Socorro, NM; N., R. l7 W., ValenciaCounty, New Mexico WilliamA.Cobban, Paleontologist, U.S GeologicalSurvey, Denver, C0;and Edwin R Landis,Geologist, 4-Cleary No. I Federal-oil testdrilled in sec.6, T. U S GeologicalSurvey, Denver, C0 3 N., R. l6 W., Catron County, New Mexico S-Huckleberry No. I Federal-oil test drilled in sec.ll, T 2 N., R. 16 W., Catron County, New Since September1978, the U.S. Geological Tongue of the Mancos Shale wedgesout in the Mexico Survey (USGS) and the New Mexico Bureau main body of the Dakota Sandstone between 6-Spanel and HeinzeNo. l-9617-oil testdrilled in of Mines and Mineral Resources have been the Grants and Mount Powell areas (fig. l). sec.27,T.4 N., R. ll W., CatronCounty, New studying the geology and coal resourcesof the Consequently, tongues lower than Whitewater Mexico Salt Lake coal field, Catron and Valencia Arroyo cannot be recognized in either the 7-D Cross Mountain-outcrop section measured Counties. New Mexico. This work forms a Gallup or Two Wells area of the Zuni Basin. by B. Robinsonin secs.8, 21, T. 3 N., R. 8 W., Mexico portion of the regional coal resource-assess- However, fossils collected from the top of the SocorroCounty, New E-The Narrows-outcrop section from Landis, ment program of the Coal Exploratory Pro- main body of the Dakota Sandstone at the Dane, and Cobban (1973, p. J36-J37) measured gram of the USGS. As part of this study the (Dane Two Wells section and others, l97l) in- in secs.3, 4, T. 7 N., R. l0 W., ValenciaCounty, USGS is mapping four 7Vz-minute quad- dicate an age no older than that of the Paguate New Mexico rangles (Moreno Hill, Rincon Hondo, Fence at its type section(Landis and others, 1973). 9-Laguna-outcrop section from Landis, Dane, Lake, and FenceLake SW), and the New Mex- and Cobban (1973,p. J4-J8) measuredin secs.20, ico Bureau of Mines is mapping four lt/z- 21, T. l0 N., R. 5 W., ValenciaCounty, New minute quadrangles (Twentytwo Spring, Can- Mexico taralo Spring, The Dyke, and Cerro Prieto). SANDOVAL os Mapping is nearly complete on the Moreno Hill, Twentytwo Spring, Fence Lake SW, and 20-40 ft (6-12 m) above the top of the Two- Cerro Prieto quadrangles; now a regional wells; the uppermost limestoneis calcarenite, stratigraphic framework that can be applied to 2-6 inches (5-15 cm) thick, composed of map units in these quadrangles must be inoceramid debris. ln the subsurface the established.This paper shows how and why Bridge Creek equivalentproduces a distinctive the nomenclature applied to the intertongued resistivedeflection zone on electriclogs. Dakota Sandstone-Mancos Shale sequenceof Throughout the area of west-centralNew the southeastern San Juan Basin can be ex- Mexico shown in figs. I and 2, we regard the tended into the southern Zuni Basin for use in base of the Bridge Creek equivalent as an the Salt Lake coal field. i I isochronous surface becausethis 6-inch (15- a r R " vo.qa i c oN
August1980 New Mexico Geolog! Gollup-Zunicool field Solt Loke coo I field Dotil Mountoins cool field SonJuon Bosin t? 345 678 9 Tiqer Cleory Huckleberry Soonel-" & Hernze -he TrolY€lls Alorque " 0 CrossM'n. Nor'ows Loguno SloleNo I NoI Fed No.lFed lf. :S5" l
I18OO. Twowells Tongue
Whilewoter Arroyo Tong ue =-'
Poguoie z6 Tongue
Cloy *o Zuni Meso Ss. Tongue =-' tr-Irll Cubero j:-:: i 1 50n0sl0ne "" 2,too Tongue Ook t-----l Chinle Conyon Chinle Fm, Member fr== p0rlly Fm. ll--l c0vered 30T roo Zuni Morrison -"" depthllr) below .ol """F:_:ll----- (orl u0 No horizontolscole 55 I m. surtoce tests) I ".] F! rn,onfo,rtry o-Lo
FIGURE 2-GeNenarrzgD GRAeHIcsEcrroNs sHowrNc coRRELATToN oF THEINTERToNGUTo Dlxom SnNnsroNn-Mencos SHlr-EsequeNcr in the southern part of west-central New Mexico. A tongue of Mancos Shale overlies the Twowells Tongue of the Dakota Sandstone. Both the Zuni Sandstone and Morrison Formation are of Jurassicage; the Chinle Formation is of Triassic age. Precisegeographic locations of the sectionsare presentedin table 1; the line of sec- tion is shownon fis. l.
thick, is present in the Atarque section but is wedge-out point of the Cubero Tongue into Age of the Dakota-Mancos sequence not present to the north either Two in the Mancos Shalein secs.20 and2l, T. 9 N., R. 9 Fossils collected from the intertongued Wefls section (fie. 2, section l) or the Cliff (Maxwell W. , 1977), approximately 1l mi Dakota-Mancos sequencewithin the area en- Dwellers Canyon section (fig. l) of Landis and (17.7 km) northeastof the Narrows measured compassedby the sectionson fig. 2 indicate an others(1973, p. J32, J33).This sandstonecan, (tig. section 2, section 8). Accordingly, the early Late Cretaceous age for the entire however, be correlated to the south with a 60- part informal term "lower of the Mancos sequence. The Twowells and Whitewater ft (18.3-m)sandstone in the Tiger StateNo. I (Landis Shale" and others, 1973,figs. 2,4\ rs Arroyo Tongues are late Cenomanian, wildcat (fig. 2, section3). From the Tiger State point used south of the wedge-out of the whereas the remainder of the member rank well it can be correlated eastward through the part" Cubero Tongue. "Lower as used on fig. units are middle Cenomanian (Cobban, subsurface (fig. 2, sections 3-6) into a surface 2 includes rocks of different time-equivalency 1977a, b). Palynomorphs from the lower part section at D Cross Mountain (fig. 2, section in parts different of west-central New Mexico. of the Oak Canyon Member, originally re- 7). From D Cross Mountain the marine sand- For (fig. example, at the Narrows 2, section garded as late Albian, are now considered to stone can be traced into the type section of the part 8), the lower of the Mancos Shale in- be Cenomanian in age (Cobban, 1971a). Paguate Tongue of the Dakota Sandstone(fig. cludes rocks laterally and temporally The youngest fossils in the Dakota-Mancos 2, section9). equivalent to the Clay Mesa Tongue of the sequenceoccur in the Twowells. We have col- Fossils collected from the top of this sand- Mancos Shale, the Cubero Tongue of the lected the oyster Pycnodonte newberryi (Stan- stone in the Perry Canyon area of the Twenty- Dakota Sandstone, and the upper part of the ton) from the top of the Twowells in the two Spring quadrangle help substantiate this Oak Canyon Member of the Dakota Sand- northeast part of the Twentytwo Spring quad- correlation. These fossils include the am- stone; whereasat Atarque (fig. 2, section 2), it rangle. Pycnodonte newberryiranges from the monite Aconthoceras amphibolum Morrow, probably only includes rocks laterally latest Cenomanian Sciponoceras gracile Zone which has been found only in the Paguate equivalent to the Clay Mesa Tongue. South of into the overlying earliest Turonian Psell- Tongue in west-central New Mexico (Cobban, Atarque, the lower part of the Mancos Shale daspidoceras Zone in central and southwest 1977a,b). In addition, an 8-inch (20-cm) thick may include substantial thicknessesof sand- New Mexico (Hook and Cobban, 1977; Cob- bentonite bed approximately 35 ft (10.7 m) (fig. stone 2, sections 4, 5); detailed mapping ban and Hook. 1979). In addition. we have above the top of the Paguate Sandstone at D may indicate that these sandstones belong collected the ammonite Pseudaspidoceras Cross Mountain is apparently also presentin properly a more in the main body of the Dakota from the top of the Twowells along the New similar stratigraphic position in Perry Canyon Sandstone. Fossils collected from the basal l0 Mexico-Arizona boundary in the Cotton- (fig. l). We have attached considerable im- (3 ft m) of the lower part of the Mancos Shale wood Canyon area (fig. l). These occurrences portance to this bentonite bed becausel) ben- near Hayhurst Tank, Moreno Hill quad- indicate that the top of the Twowells is becom- tonites more than 6 inches (15 cm) thick are rangle, include Pycnodonte cf. P. kellumi ing younger to the southwest. rare in the Dakota-Mancos sequencein west- (Jones), Torrantoceras rototile Stephenson, The oldest fossils in the Dakota-Mancos se- central New Mexico and 2) this bentonite is and Acanthoceras aff . A. alvaradoense More- quence occur in the upper part of the Oak approximately the same age as the marker or man and indicate an age no older than that of Canyon Member at Laguna and near the base "X" bentonite bed, which lies within the the basal part of the Clay Mesa Tongue at its of the lower part of the Mancos Shalein the D Acanthoceros amphibolum Zone and has been type section. Cross Mountain area. These fossils generally dated at 92.1 m.y. (Obradovich and Cobban, The rocks that are called main body of the occur in ferruginous silty to sandy, limy con- t975). Dakota Sandstone on fig. 2 are the marine, cretionary beds and include 34 species of South of Laguna the Clay Mesa Tongue of marginal marine, and nonmarine rocks that bivalves, ll species of gastropods, and five the Mancos Shale is coextensive with the make up the lowest part of the Cretaceous se- species of ammonites (Cobban, 1977a, b). underlying Cubero Tongue of the Dakota quence in west-central New Mexico and that Many of these species have been recorded Sandstone. The term "Clay Mesa Tongue," cannot be included in one of the other named therefore, cannot be extended south of the member-rank units in the sequence. IS
New Mexico Geology August1980 from the WoodbineFormation of Texas.and must have been open to the east; it may, most have beenrecorded from the Thatcher however, have been considerablynarrower, LimestoneMember of the GranerosShale of with a strongernortheasterly trend than indi- southeastColorado (Cobban and Scott, 1972). catedon fig. 3. This faunawill be referredto as the Thatcher SeboyetaBay expandedin three directions fauna and includesthe bivalvesInoceromus (north, west, and south) until early late eulessanus Stephenson, Plicatula arenaria Greenhorntime 0atestCenomanian to earliest Meek, Pycnodonte cf. P. kellumi (Jones), Turonian)when it mergedwith the main body Exogyro columbella Meek, and Oslrea beloiti of the WesternInterior seaway.Limestone Logan; the gastropod.Arrhoges modesta bedswere then depositedthroughout most of (Cragin)?; and the ammonites Turrilites the WesternInterior seaway.In west-central aculus Passy, Calycoceras tarrantense New Mexico the baseof theselimestones is (Adkins), Borissiakocerascompressum Cob- generallywithin the lower 20-40ft (6-12m) of ban, and Johnsonites sulcatus Cobban the Mancos Shale tongue overlying the (Cobban,1977a, b). The Thatcherfauna is Twowells. middleCenomanian in ageand is the ". By logical inference, SeboyetaBay ex- oldest unquestionedCenomanian megafossil panded(transgressed) into the southernZuni zonein the WesternInterior. ." (Cobban, Basinsooner than it did into the northernpart 1961,p.738). becauseof a faster southwesterlytransgres- The oldestCretaceous fossils that we have sion rate.This explanationwould accountfor collectedfrom theSalt Lake coal field areaare the thicker and older sequenceof Cretaceous from the basall0 ft (3 m) of the lower part of rocks in the Salt Lake coal field areawithout the MancosShale near Hayhurst Tank. These havingto invokeinter- and intra-formational fossilsare late middleCenomanian in ageand unconformitiesfor which we have no evi- are younger than those from the Thatcher dence. level,but olderthan thosefrom the top of the Pike (1947)had come to a similar conclu- main body of the Dakota Sandstoneat the sionmore than 30 yearsago. In the discussion Two Wellssection (fig. 2, sectionl). FICURE 3-Mlp op NEw MExrco AND sourHERN of his measuredsection near Atarque, Pike Colonloo sttowtNc LocAltrlEs wne ne Tnnrcgpn (1947,p.36) notedthat thissection ". . dif- SeboyetaBay FAUNAHAs BEENcoLLEcrEo (x) and the approx- fers from thoseto the north in that it showsa imate position of the Late Cretaceous shoreline considerablethickening of that part of the The resultspresented in this paperand sum- during Thatcher time (Middle Cenomanian). MancosShale below the zoneof marizedgraphically in fig. 2 showthat thereis C--) lPycnodontel newberryi. . and in the presenceof a thick a thicker sequenceof marinerocks below the massivesandstone within this enlargedshale TwowellsTongue in the southernpart of the section. . The significanceof theserela- Zuni Basinthan in the northernpart. Fossils of Cenomanian age. As the bay enlarged, tionshipsis ratherimportant in that they seem collectedfrom theserocks indicatethat the theseunits weresucceeded upward by marine to indicatean advanceof the seain this local- baseof this marine sequenceis older to the shaleand sandstonecontaining the Thatcher ity, perhapsin a localembayment, earlier than south,thus ruling out depositionalthickening fauna. Thesemarine beds mergenorthward anywhereelse in the Mesa Verde-Atarque as the only causativeagent. These results are and westwardwith the fluviatile sediments t t incompatiblewith a northwest-southeast-typicalof the main body of the Dakota Sand- area. trending Late Cretaceousshoreline that ad- stone(Landis and others, 1973). Summary vancedlandward in a generallysouthwesterly Fossilsdefinitely of Thatcherage are pres- The stratigraphicnomenclature applied to directionand retreatedseaward in a generally entas far westas sec. 31, T. 15N., R. 12W., Dakota Sandstone-Mancos northeasterlydirection (Petersonand Kirk, McKinleyCounty, just westof the Thoreauto the intertongued of the San Juan Basincan be 1977,p. l7l). Paleontologicand stratigraphic Crownpointroad, wherethey are in sandstone Shalesequence part into Zuni Basin evidence indicates, however, that this 57 ft (17.4m) below the top of the main body extendedin the southern in Lake coal field. The upper northwest-southeast-trendingshoreline was of the Dakota Sandstone.The northernmost for use the Salt Twowells establishedin New Mexicoduring latest Ceno- occurrenceis near Ojito Spring, Sandoval two tonguesof this sequence,the WhitewaterArroyo, be tracedin manianand earliestTuronian time (Hook and County,where the Thatcherfauna occurs5 ft and can sur- face from their type sectionsin the Cobban, 1977,fig. l) and persistedthrough (1.5 m) abovethe main body of the Dakota. sections Zuni Basinto Atarque,just north middle Turonian time (Cobban and Hook, To thesouth, a collectionl0 ft (3 m) abovethe northern of Lake coal field, wherethe Cretaceous 1979, fig. 2) and late Turonian time (Hook top of themain body of the DakotaSandstone the Salt sequenceis coveredby Tertiary basalt.From andCobban, 1979,fig.4; 1980, fig.6). near D Cross Mountain, SocorroCounty, is memberscan be into The marinerocks that includethe Thatcher thelast unquestionable fauna of Thatcherage. Atarquethese correlated surfaceand subsurfacesections in the coal fauna recordthe earliesttransgression of the Southeastof D CrossMountain at Carthage, field to thesouth. Late Cretaceousseaway into New Mexicodur- fossilscollected from the baseof the Mancos An additional marine sandstonetongue, ing middleCenomanian time. Theserocks oc- Shalereveal an ageno older than that of the separatedfrom the main body of the Dakota cur over an areaof west-centralNew Mexico ClayMesa at itstype section. is present with a north-southextent of approximately75 Thus, only to the eastis therea possiblein- Sandstoneby a marineshale tongue, at Atarqueand in the Salt Lake coal field, but mi (l2l km) and an east-westextent of slightly let from the mainbody of theWestern Interior is not presentin thenorthern part of the basin. morethan that. This area,centered roughly on seaway.Unfortunately, we havenot collected from Lake Mount Taylor, is hereincalled Seboyeta Bay, the Thatcherfauna at the sectionsthat crop Paleontologicevidence the Salt field indicatesthat the sandstonetongue for the communityof Seboyetain northeast out in the areawhere it might be present.We coal PaguateTongue ValenciaCounty (fig. 3). havenot yet found a Thatcherlevel in a sec- is of the sameage as the at its shale is no Initial Cretaceousdeposits in and around tion southof SanAntonito, BernalilloCoun- type sectionand that the tongue SeboyetaBay-the lowerpart of theOak Can- ty; nor in a sectionatLamy, SantaFe County; older than the Clay Mesa Tongueat its type section.The sandstonetongue can be corre- yon Memberand time-equivalentrocks in the nor in an intermediatesection between these subsurfaceand surfacesections main body of the Dakota Sandstone-are two, at Rosario,west of Cerrillos, SantaFe latedthrough with Paguate its fluvial conglomeratesand sandstones,fol- County. The regional stratigraphical and the at type sectionsouth of Laguna.The tongueis probablyequiva- lowed by dark marine shale containing paleontologicalresults summarized above shale hystrichospherids,dinoflagellates, and spores absolutelycompel that an avenueto the sea (continuedon p. 46)
August1980 New Mexico Geology of gas-filled cavities when the rock cooled. and passed east of Columbus into Mexico to Mexico. Sierra de Palomas' extension across East of Villa Hill, rocks exposed along the fill playas below Palomas. the Mexican-American border (15 mi to the paths are a typical cross section of volcanic To the southwest are the rugged peaks of west) is the Carrizalillo Hills; the Cedar flows, showing flow basalt that is locally brec- Sierra de Palomas in northern Chihuahua, Mountains form the low skyline ridges to the ciated and contains small angular fragments and on the western horizon is the sharp peak west-northwest. Five miles to the northwest, of the gravels onto which it was extruded. of Big Hatchet Mountain in southwest New bold, jagged triple peaks of the three sisters To the north-northeast is Columbus. and in (Tres Hermanas Mountains) block distant the distance are the rugged Florida Moun- views in that direction. tains. On the eastern skyline, across the irri- Pancho Villa State Park is on the low edges gated sandy Columbus Valley, the low of the large alluvial fan that extends southeast volcanic hills of the West Potrillo Mountains from the Tres Hermanas Mountains. Pebbles, stretch southward into northern Chihuahua. cobbles, and boulders in the park were derived Other volcanic hills and ranges lie to the south from rock outcrops in those mountains; they amid sandy plains south of Palomas in north- include fragments of quartz, feldspar, mon- ern Mexico. Underground water from ancient zonite, rhyolite, latite, basalt, Iimestone, rains, stored in sand and gravel underlying the chert, and andesite. Mines in the northwest plains around Columbus, is now pumped to Tres Hermanas Mountains operated until the irrigate the green fields that circle the town. 1920's and produced about one-half million During past centuries the Mimbres River dollars worth of zinc, lead, silver, gold, and (which rises in the Mogollon and Black Range copper. Present-day outcrops of interest to areas north of Santa Rita) has, during flood rock hounds contain Mexican onyx, calcite, n stage, swept past Deming, rushed around the Solntens oN LooKour erop Vtt-l,q Htll, March 10, spurrite,and dumortierite. (revised1980) north and east sidesof the Florida Mountains. 1916(courtesy New Mexico Historical Society)' F. E. Kottlowski
Dakota-MancosterminologY p. 44) possibilitiesof Catron County, New Mexico: New kontinuedfrom Mexico Bureau of Mines and Mineral Resources, lent to the Clay Mesa Tongue, but that term present understanding of the Upper Creta- Bull. 85, 55 p., 2 pls., 1 table, 11 figs. cannot be extended into the Salt Lake area ceous of New Mexico. Gadway, K. L., 1959, Cretaceous sediments of the North Plains and adjacent areas, McKinley, because of the pinchout of the underlying This paper was critically reviewed by M. E. Valencia, and Catron Counties, New Mexico: Sandstone Tongue Dakota Maclachlan and C. H. Maxwell of the USGS, Cubero of the New Mexico Geological Society, Guidebook lOth (48 with Sandstone into Mancos Shale 30 mi km) Denver, and benefited from discussions field conference,p. 8l-84, 2 figs. southwest of the Laguna section. Conse- C. M. Molenaar, USGS, Denver, and F. E. Hook, S. C., and Cobban, W. A., 1977, Pycno- quently, the informal term "lower part of the Kottlowski, D. E. Tabet, S. J. Frost, and donte newberryl (Stanton)-common guide fossil Mancos Shale" is applied to this unit. Sim- C. T. Bolt, New Mexico Bureau of Mines and in Upper Cretaceousof New Mexico: New Mexico ilarly, the rocks that make up the lowest part Mineral Resources. The correlations of the Bureau of Mines and Mineral Resources,Annual of the Cretaceous sequence in the southern main body of the Dakota Sandstone at the R.efi.1976-77,p. 48-54, 5 figs. Zuni Basin cannot be included in one of Narrows (fig. 2, section 8) are from C. H. 1979, Prionocyclus novimexiconus (Marcou)-common Upper Cretaceous guide the other named member-rank units and are Maxwell. Funding for Hook was provided by fossil in New Mexico: New Mexico Bureau of referred to as the main body of the USGS Grant 14-08- 0001-C525 to the New simply Mines and Mineral Resources, Annual Rept. Dakota Sandstone. Mexico Bureau of Mines and Mineral 1977-78, p. 34-42, 5 figs. Resources. The Dakota-Mancos sequence in the Salt , 1980, Some guide fossils in Upper Lake coal field consists of-from bottom to References Cretaceous Juana Lopez Member of Mancos and top-the Dakota Sandstone(main body), the Cobban, W. A., 1961, The ammonite family Carlile Shales. New Mexico: New Mexico Bureau lower part of the Mancos Shale, the Paguate BinneyitidaeReeside in theWestern Interior of the of Mines and Mineral Resources, Annual Rept. Tongue of the Dakota Sandstone,the White- United States:Journal of Paleontology,v. 35, no' 1978-79,p. 38-49, 7 figs. -7 water Arroyo Tongue of the Mancos Shale, 4, p. 737 58,3 pls., 5 figs. Landis, E. R., Dane, C. H., and Cobban, W. A., -. 1973, Stratigraphic terminology of the Dakota and the Twowells Tongue of the Dakota Sand- 197'7a,Fossil mollusks of the Dakota sand- stone and intertongued Mancos Shale of west- Sandstone and Mancos Shale, west-central New stone. central New Mexico: New Mexico Geological Mexico: U.S. GeologicalSurvey, Bull. 1372-J,44 Bay, an east-west lobe of the Seboyeta Society, Guidebook 28th field conference, p. p.,4 figs. (l2l WesternInterior seawayabout 75 mi km) 213-220,5 figs. Maxwell, C. H., 197'7,Preliminary geological map long and wide, and roughly centered on 1977b. Characteristic marine molluscan of the Los Pilares quadrangle, Valencia County, Mount Taylor, provides an explanation for fossils from the Dakota Sandstone and inter- New Mexico: U.S. Geological Survey, Open-file the thicker and older Dakota-Mancos se- tongued Mancos Shale, west-centralNew Mexico: Rept. 77-240, scaleI :24,000 quence found in the southern Zuni Basin. U.S. GeologicalSurvey, Prof. Paper 1009,74 p., Obradovich, J. D., and Cobban, W. A., 1975, A Seboyeta Bay formed in middle Cenomanian 21 pls.,4 tables,7 figs. time-scalefor the Late Cretaceousof the Western lnterior of North America: Geological Associa- time and expanded in a northerly, westerly, Cobban, W. A., and Hook, S. C., 1979, Collig- noniceras woollgari woollgari (Mantell) ammonite tion ofCanada, Spec.Paper 13,p. 3l-54, 3 figs. and southerly direction until latest Cenoma- fauna from Upper Cretaceous of Western ln- Owen, D. E., 1966,Nomenclature of Dakota Sand- nian to earliestTuronian time, when it became terior, United States:New Mexico Bureau of stone(Cretaceous) in San Juan Basin, New Mex- indistinguishable from the main body of the Mines and Mineral Resources,Mem. 37, 5l p., 12 ico and Colorado: American Association of Western Interior seaway. Deposition of pls., I 2 figs. Petroleum Geologists,Bull., v.50, no.5, marine rocks occurred earlier in the Salt Lake Cobban, W. A., and Scott, G. R.. 1972,Stratig- p. 1023-1028,3figs. coal field than in the northern Zuni Basin raphy and ammonite fauna of the Graneros Shale Peterson,Fred, and Kirk, A. R., 1977,Correlation apparently because of a faster southwesterly and Greenhorn Limestone near Pueblo, Colo- of the Cretaceousrocks in the San Juan, Black transgressionrate. rado: U.S. Geological Survey, Prof. Paper 645, Mesa, Kaiparowits and Henry Basins, southern Soci- Acxrowr-eocunNrs-The concept and 108p.,4l pls.,5 tables,52 figs. Colorado Plateau: New Mexico Ceological Dane, C. H., Landis,E. R., and Cobban,W. A., ety, Guidebook28th field conference,p. 167-178, naming of SeboyetaBay originated with C. H. t971, The Twowells SandstoneTongue of the 4 figs. Dane, E. R. Landis, and W. A. Cobban (un- Dakota Sandstone and the Tres Hermanos Sand- Pike, W. S., Jr., 1947, Intertonguing marine and published manuscript, 1967) during the early stone as used by Herrick (1900), western New nonmarine Upper Cretaceous deposits of New stagesof work that culminated in Landis and Mexico: U.S. Geological Survey, Prof. Paper Mexico. Arizona. and southwesternColorado: others (1973). We gratefully acknowledge 750-B,p. l3l'7-1322 GeologicalSociety of America, Mem. 24, 103p., Dane's contribution to this paper and to our Foster, R. W., 1964, Stratigraphy and petroleum 12pls., 7 figs. tr
46 August1980 New Mexico Geologt