TheMiddle Jurassic Summerville Formation, northern New Mexico -a rebuttalof Gondon,1993 by SpencerG. Luus,New Mexico Museum of NaturalHistory & Science,1801 Mountain Road NW, Albuquerque, NM87104; and 1rin J. Anderson,New Mexico Bureauof Minesand Mineral Resources. Socono. NM 87801

Introduction no way carefully defined as a stratigraphic unit, and Redwall Nothing new is presented in Condon's reply (Condon, 7993) Limestone, introduced by Gilbert (1875)but not named for a ge- to our paper on the Summerville Formation and related strata in ographic location, would have to be considered invalid using northern New Mexico (Anderson and Lucas, 1992). Condon re- Condon's criteria. sorted to trivializing our objection to using preoccupied strati- Condon failsto understandthat long-usedand widely accepted graphic names, calling it specious, and also to searching the stratigraphic names, such as Grabau's term Wanakah, are valid stratigraphic code (NACSN, 1983) for loopholes in order to justify and take priority over later usageseven if the original definitions perpetuating his confusing duplication of names. Clearly usage do not meet current or (what Condon imagines to be) earlier of the name Wanakah as a stratigraphic unit in New York has standards. Failure to understand and implement this basic con- precedence over usage in southwest Colorado. Significantly, Con- cept is a recipe for nomenclatural chaos.Condon's claim that "the don did not choose to defend regional correlations proposed by Wanakah of the eastem Colorado Plateauhas been the subject of workers at the U.S. Geological Survey based on the "Bed at Black much more study than the New York unit" can only mean that Steer Knoll." We interpret this as an admission that regional cor- he is unaware of extensive geological and paleontological litera- relations based on the "Bed at Black Steer Knoll" are unsupport- ture on the New York Wanakah. able. Generally, arguments set forth by Condon only strengthen our The "Beclabito Member of the Wanakah" is correlative with conclusion that the last 25 years of effort bv workers of the U.S. the Summerville Geological Survey to revisi Middle and Lipper Jurassic stratig- At the heart of our disagreementwith Condon and his col- raphy and sedimentation models on the Colorado Plateau have leagues is the correlation of San Rafael Group units on the Col- been based (1) on continued use or creation of redundant and orado Plateau from west-central New Mexico to southwestern parochial stratigraphic names, (2) purported tracing of marker Coloradoto east-centralUtah. The correlationwe proposeis sup- beds that cannot be traced by other investigators in the field, (3) ported by all availablelitho- and biostratigraphy and is advocated postulating regional unconformities for which no stratigraphic or by most workers, including Harshbargeret al. (1957),Imlay(1980), geochronologic evidence exists and using these "unconformities" Kocurekand Dott (1983),and Ridgley(1989), among others.This as formation contacts, and (4) creating sedimentological models correlation (Fig. 1a) recognizesthe main body of the Entrada to which stratigraphic units are retrofitted regardlessbf the actual Sandstone across the Colorado Plateau. The overlying Todilto stratigraphic relationships. Formation in northern New Mexico/southwesternColorado rep- resentsa salinalake (Lucaset al., 1985)or a marine embayment Preoccupied stratigraphic names should not be used (Harshbargeretal.,1,957; Ridgley, 1989) related to a risein regional We pointed out that the term "Wanakah Shales," introduced base level due to the transgressionof the CurtirStump (early- by Grabau (1977) for Devonian strata in New York, has priority middle Callovian) seaway.The SundanceFormation of South Da- over Burbank's (1930) "Wanakah Member of the Morristrn Foi- kota-Wyoming was also deposited during this transgression;the mation." Indeed, the Middle Devonian Wanakah Member of the ichthyofauna of the Todilto Formation is also found in the Sund- Ludlowville Formation (the Hamilton Group) is a well recognized anceFormation, lending further support to the correlation(Schaeffer stratigraphic unit used in many publications, including the Ge- and Patterson, 1984). ologic Map of New York published by the New York State Mu- The Summerville Formation of our usage overlies the Todilto seum of Science/New York Geological Survey (Rickard and Fisher, Formation or, where the Todilto is absent, the main body of the 7970a, b) and more recently by Miller (1991) in a discussion of Entrada Sandstonefrom Cimarron County in western Oklahoma Devonian stratigraphy. Grabau (1917,p.338) introduced the name to near Moab in east-centralUtah. West of Moab, to the SanRafael in a footnote to refer to an already well known unit, "the lower Swell, however, the Summerville overlies the shallow-marine Curtis Hamilton Shales" of western New York. Cooper (1930, p. 225) Formation which, not surprisingly, occupies the same strati- subsequently designated and described a type section foi what graphic position as the Todilto Formation. Regional stratigraphic he termed the Wanakah Member of the Ludlowville Formation relationships, fossils, and lithology thus support the correlation of the Hamilton Group. This unit is listed and described in the advocated by most workers between west-central New Mexico most recent U. S. Geological Survey Lexicon of Geologic Names and the San Rafael Swell of Utah: Entrada : Entrada, Todilto : (Keroher, 1955) and has never been recommended foiabandon- Curtis, and Summerville : Summerville, with the recognition merrt by the original author nor the U. S. Geological Survey. that part of the upper Curtis may grade eastwardor southeast- Condon challenges the idea that Grabau's use of Wanakah has ward into lower Summerville strata (Fig. 1a). priority over Burbank's on the ground that Grabau's introduction Condon and his colleagues (especially O'Sullivan, 1,980a,b), of the name Wanakah Shales did not constitute "an adequate however, propose a very different correlation (Fig. 1b). They claim definition of a new stratigraphic name . . . in 7917." Obviously, that careful tracing of key marker beds shows the "Wanakah For- Condon is alone in this belief, since all stratigraphers who have mation" of southwestern Colorado (and west-central New Mex- worked in western New York, and geologisti o] the New york ico) to be older than the Summerville Formation of east-central Geological Survey, have recognized Grabau's Wanakah Shales as Utah. According to Condon, the Wanakah is correlative with the a valid stratigraphic, unit. Fven Burbank (1930) acknowledged Curtis. This apparently indicates to him that the Todilto is older Grabau's priority, although he thought no confusion would aiise than the Curtis and that the Entrada Sandstone of west-central from giving the same name to two geographically disparate units. New Mexico is older than the Entrada of Utah (Fig. 1b). Ironically, Much confusion would arise if the criteria demanded bv Con- it was Condon's predecessors(Baker et al., 1947)who correlated don were applied to many of the stratigraphic names introduced the Entrada Sandstoneinto the southern San Juan Basin. in the 1800s and early 1900s. Well understood and widely used In our original article we refuted the Wanakah-Curtis corre- names such as Shinarump, casually used by Powell (1876lbut in lation by pointing out that the so-called"marker bed"-"Bed at

August 1993 Nan Merico Geology SanRafael Swell, Utah SanJuan Basin, New Mexico Condon reasserts the erroneous correlation (locally) of the "Bed BrushyBasir at Black Steer Knoll" of O'sullivan (1980b)and refers to O'sullivan Morrison Member MorrisonFormation and Pierce (1983) to argue that strata, which McKnight labelled Formation owermembers Zuni Sandstone Summerville (and which lie above the Moab Tongue of the En- BluftSandstone cross SummervilleFormation trada Sandstone on the southwestern end of McKnight's This is an assertion for which Con- Formation section), are not Summerville. A Summerville don presents no evidence. Furthermore, Condon's statement that CurtisFormation of Moab, which we termed Summerville, "consist TodiltoFormation rocks southeast of Entrada, Curtis, and Summerville equivalents and therefore EntradaSandstone EntradaSandstone cannot be called Summerville" runs contrary to established strat- igraphic practice. These rocks are lithologically similar to, and continuous with, Summerville strata and should be mapped as Summerville Formation even if they include strata correlative with the Curtis Formation. SanRafael Swell, Utah SanJuan Basin, New Mexico The rather superficial reasons for the Summerville-to-Wanakah name change are discussed by Condon and Peterson (1986, p. MorrisonFormation MorrisonFormation 15). In addition, a written communication from Condon to An- derson (February, 1986) states "Had O'Sullivan's revised inter- pretation been known to me earlier, I wouldn't have gone ahead SummervilleFormation CowSprings Sandstone with the name change in the San Juan Basin." The "revisions" B HorseMesa Member alluded to by Condon are those of O'Sullivan in which he ac- CurtisFormation Er knowledged that the Summerville was not cut out entirely by pre- Beclabito*Member four-corners area. The "name change," 6L Morrison erosion in the >c refers to the change from Summerville to Wanakah. A Entrada TodiltoMember of course, Sandstone subsequent written communication from Condon to Anderson 'Although (February, 1988) includes the following: the interpre- EntradaSandstone tation now is that the Summerville is not cut out entirely in areas as far south as Uravan, the fact remains that the nomenclature * = Summerville Formation of A was formally changed in much of south-central and southeast Utah bv O'Sullivan (1980a)." From this we conclude that an un- FIGURE 1-Correlation of Middle and Upper Jurassic units between Utah and northwestern New Mexico: A) correlation suggested by Anderson .t"."mi.y name change was made, and Condon and Peterson and Lucas (7992); B) correlation inferred by Condon. (1986) saw some utility in honoring the change. The reiection of the name Wanakah by us (Anderson and Lucas, 7992) is not the first nor the most significant rejection. We merely pointed out that it was a preoccuppied name, and that it was Black Steer Knoll"-used to support this correlation varies con- inappropriate and superfluous in New Mexico. In fact "Zuni For- siderably in lithology, thickness, and exact stratigraphic position mation" would have been a more enlightened choice if a name and cannot be directly traced(Anderson and Lucas, 1992,p.89, change were needed, and it most definitely has precedence over Wanakah. The first and most significant rejections of the name figs. 2, 5). Since there is no marker bed that can be traced from '50s, '60s,'70s Wanakah in New Mexico were the mappers of the southwestern Colorado to east-centralUtah, the lithostratigraphic '80s basis for a Curtis-Wanakah correlation presented by O'Sullivan and who used Todilto-Summerville-Bluff for these strata, (1980a,b) and cited by Condon and Peterson(1986, p.15) does nearly unanimously. not exist. In the final analysis of critical correlation factors the position, is a separate formation recognition, and extent of the J-3 unconformity may have more The Todilto implications than arguing age relationships of CurtirSummer- Gregory (1916)introduced the term Todilto Limestone as a unit ville (which overlap in part) and the age relationship of both of of formational rank. As presently mapped, the Todilto Formation them to the "Wanakah." The J-3 unconformity at the base of the is present across much of northern New Mexico from the Arizonai Curtis Formation in Utah marks a transgression;a pebbly zone New Mexico state line to as far east as western Quay County and at the base of the Todilto in the southwestern San Juan Basin in southwestern Colorado as far north as Montrose, an area of marks that transgressivesurface. Both lie at the top of the Entrada approximately 88,000 km'z. Virtually all mappers, especially those Sandstone;so stratigraphicposition, regional stratigraphicrela- of the U.S. Geological Survey, have mapped the Todilto across tionships,position in faciestract, and paleogeography,all suggest this area as a unit of formational rank. Condon's assertion that that the pebbly zone at the base of the Todilto is penecontem- the Todilto should instead be regarded as a member of the Wan- poraneous with the f-3 unconformity. This correlation is further akah Formation is similar to his assertions about the invalidity of discussedbelow with regardto the U.S. GeologicalSurvey's per- Grabau's Wanakah; it indicates a lack of understanding of basic ception of the Cow SpringsSandstone. stratigraphic principles and an apparent lack of knowledge of the Condon calls on other evidenceto support the Wanakah-Curtis relevant practice. correlation.He citesO'Sullivan (1980b) and O'Sullivanand Pierce To all those familiar with the Todilto Formation, its carbonates (1983),who have shown the lower and middle Wanakahgrading and evaporites present a striking contrast to the adjacent San northward into the Entrada in east-centralUtah. Condon con- Rafael Group strata that are mostly siliciclastic eolianites (Entrada) cludes that "few, if any, strata previously called Summerville in and tidal flat-sabkha deposits (Summerville). This contrast makes the San Juan Basin can be traced into the type Summerville." the Todilto a readily mappable and traceable unit throughout its What he fails to point out is that O'Sullivan (1980a,b) and O'Sul- outcrop belt, and also one easily recognized from subsurface data. liVan and Pierce (1983)traced the upper part of the Wanakah all For these reasons a vast majority of workers have long recognized the way to the San RafaelSwell where they miscorrelatedit with and readily mapped the Todilto as a unit of formational rank. We the Curtis Formation. The point is that Summerville (: 1,yutlu1un, agree with Condon and the Code of Stratigraphic Nomenclature strata are continuous throughout the Colorado Plateau,although that "formations are fundamental units in lithostratigraphic clas- the unit is relatively thin in southeasternUtah. McKnight's (1940) sification." The Todilto Formation is in fact the most unique, interpretation of the Middle furassic stratigraphy northwest of fundamental, and readily mappable lithologic unit in the San Moab, reproduced by Condon as his figure 2, is endorsed by us. Rafael Group. r?

New Mexico Geology Argust 1993 Eolianites in the Upper San Rafael Group establish formation contacts,as Condon and Peterson (1986)ad- vocated and continue to advocate. The concept of a Morrison Horse Mesa is a redundant name Formation, which locally overlies the Zuni, has suffered pro- gressivedeterioration as a result of chronostratigraphy being sub- Eolianites in the Upper San RafaelGroup on the Colorado PIa- stituted for lithostratigraphy (seesection on Morrison Formation teau have been given a bewildering array of names: Bluff, "Cow below). Springs," Junction Creek, Zuni, Mesita, and Horse Mesa. In With the usage of the name Zuni Sandstonewell established northwestern New Mexico most of the eolianitesrepresent a sin- and defined (it overlies the Entrada and grades northward into gle lithosome which to the name Bluff Sandstone of Gregory the Summerville and Bluff Formations or their equivalents) it is (1938)is properly applied (Anderson and Lucas, 1992).The Hbrs-e obvious that the Zuni Sandstoneis the same unit which Harsh- Mesa Member (1988) of Condon and Huffman is a redundant barger et. al. (1957)projected into westem New Mexico as the name for the Bluff Sandstone.The "subtle" differencesbetween Cow Springs Sandstone.The Cow Springs was a superfluous it and the Bluff Sandstone elsewhere referred to by Condon to name the day it was introduced in New Mexico, and we are at justify recognitionof the Horse Mesa as a distinct unit are very pains to understand why the U.S. Geological Survey did not at subtle indeed. They are minor sedimentologicaldifferences that the time offer an explanation of the relationship between the two do not merit recognitionof the Horse Mesa as a separateunit. units. The failure to do so has thoroughly confused subsequent just as the Horse Mesa is superfluous, so also is the Beclabito workers such as Condon and his colleagues.One example of this Member of the Wanakah Formation which Condon and Huffman confusion is brought to the fore by Peterson(1988, p. 19) who (1988)applied the to SummervilleFormation. An important point, clearly illustrates the type Cow Springs as a member of the En- obvious to all, that is too much nomenclature has been cieated trada Sandstone in a stratigraphic position below the trans- for Middle and f-3 UpperJurassicin the southwesterninterior mostly gressive unconformity, exactly as stated by us (Anderson and by workers of the U.S. GeologicalSurvey. Our work has been Lucas, 1992,p.88). Condon in his reply quotesus out of context, designed to present reproducible lithostratigraphic correlations neglecting to mention that we correctly presentedPeterson's con- of the Middle and Upper Jurassicstrata. These -orrelations (An- cept of the type Cow Springs as a pre-f-3 unit. Condon instead derson and Lucas, 1992)demonstrate that a variety of recently chose to focus on the supplementary information we included, introduced names, including the Horse Mesa and Bethbito Mem- i.e. that Peterson'stype Cow Springswas in addition older than bers of the Wanakah, are unnecessary.Condon's argumentsto the Todilto. Conventional wisdom as well as sound stratigraphic preserve these and other names are based on correlations that principles place the Todilto above the hansgressive surface, we (and others) |-3 cannot replicate. and hence our inferencethat pre-f-3 is pre-Todilto. The j-3 surface at the base of the Curtis Formation in southeasternUtah is a Cow Springs is a superfluous name in New Mexico transgressiveunconformity developedon the Entrada Sandstone, In addition to introducing unnecessarynomenclafure, Condon which is precisely what is seen at the base of the Todilto in the continues to advocatethe use of obsoleteand superfluousno- San juan Basin, albeit with the unconformity or diastem marked menclature in the San Juan Basin. He and his colleagueswould only by a zone of floating pebbles. recognizethe Cow SpringsSandstone, even though previousU. We thus maintain that Peterson'sassertion that the type Cow S. CeologicalSurvey authors (Dane 1956;Dane and Bachman, Springs is pre-j-3 also includes the assertion that it is pre-Todilto. 1965;Maxwell, 1976, 1979,1982) have indicated their preference The confusing aspectof his work derives from his statement that for the name Zuni Sandstone.Zuni has precedencebverCow the type Cow Springs appears to correlatewith the Cow Springs Springs,having beenintroduced by Dutton (1885)for strataover- at Zuni Pueblo where it is demonstrably post-Todilto (post-J-3). lying the Wingate (: Entrada)near Fort Wingate,New Mexico, If, as Peterson suggests, the two do correlate, then the j-3 un- and underlying the Dakota Sandstone.However, when Dutton conformity has been misidentified by him in the type Cow Springs extendedtris type Wingate (: Entrada) from Fort Wingate south- area; this unconformity, if it exists at all in the type area, would ward to Zuni Pueblo, he miscorrelated it with the older Rock be at the baseof the Cow Springs rather than at the top. We thus Point Formation of the Chinle Group. At this localehe thus er- believe the sandstonesin the two areas do correlate for the fol- 1ongu^slyincluded the Wingate (: Entrada) with the overlying lowing reasons: Zuni Sandstone. Our definition of the Zuni Sandstoneas a post-Entrada 1) They have similar lithologies and occupy the same strat- unit(Anderson and Lucas, 1992)takes into accountthe Dutton- igraphic position. miscorrelationplus the fact that Harshbargeret. al. (1957)chose to recognize the Entrada Sandstoneas a distinct unit underlying 2) They both are eolian in origin. their Cow Springs Sandstone at Zuni Pueblo (Cow Springs-wai a new name that they used to describe eolian strati above the 3) The Cow Springs section atZuni grades northward into Entradaat BlackMesa, Arizona). These two factorsplus the pres- Summervilleand Bluff Formations(: Condon's Wan- ence of a depositionalbreak at the top of the Entrida (thelocal akah). expressionof the J-3? unconformity, or the "Todilto notch,,) make it proper, if not imperative, that two Middle Jurassicunits, En- 4) The type Cow Springs grades northeastward into Wan- trada and Zuni, be recognized in the Zuni Basin south of the akah beds (Peterson,1988). Todilto pinch-out_(Anderson,1993). Most of this is apparently unknown to Condon, who refers to our usage of the Ziriri Sand- We nonetheless reject Cow Springs as a stratigraphic name in stone as a corruption of Dutton's original definition. This asser- New Mexicobecause the nameZuni hasprecedence and because tion is incorrect. Current usagerepresents the type of refinement the excellentdevelopment and exposuresof the unit at Zuni Pueblo that comes with a better understanding of stratigraphic relation- justify a local name. ships. Progressiverefinement has indeed resultedin the Todilto, It is illuminating to go back and further pursue the implications Summerville, and Bluff Formations being recognized within the of 3) and 4) above. Given that the Cow Springs strata from both original Zuni interval; where all three are present, the Zuni Sand- areascorrelate with strata of the "Wanakah," they must correlate stone Iocally consistsof only the overlying crossbeddedsandstone with each other (logically,if a:c and b:c, then a:b). We also Salled the -Acoma Tongue of the Zuni, because genetically and know that both the type Summerville and type Curtis lie above lithologicallythese upper strataare relatedto the fype Zuni. This the f-3 unconformity, so arguing whether the "Wanakah" cor- constitutes progressive refinement of a valid lithostratigraphic relates with the Curtis or the Summerville loses significance.Ei- concept.Progressive deterioration results when lithostratigraphy ther correlationresults in a "Wanakah"that is post-f-3, and therefore is abandonedand "unrecognizedtime boundaries" are used tb a Cow Springs Sandstonethat is post-J-3. And it follows that the

August 1993 Nao MexicoGeology Todilto Formation as part of the "Wanakah" is post-J-3. Thus the sedimentation on the Colorado Plateau. Instead he rehashescor- confusing, untenable regional correlations proposed by Peterson relations we refuted and presents nomenclatural arguments (1988)are exposedand resolved,a task undertakenhere because (Wanakah of Grabau not a valid unit; Todilto a unit of member Condon in his reply defendedPeterson. rank; Horse Mesa a distinct unit) that reveal his lack of under- standing of basic stratigraphic principles and practice. His reply/ The Morrison Formation does not include eolianites discussion, in which he explains how he and his colleaguesar- Lithostratigraphic units and the formation concept are appar- rived at their conclusions,only reinforcesour original evaluation and conclusions.To wit, the work of Condon, Petersonand O'Sul- ently unclear to Condon. He would project into the San ]uan Basin an "unrecognizedtime boundary" (Condon and Peterson, livan on this Middle and Upper furassic strata of the Colorado Plateau has confused and obscured a rather straightforward stra- 1986, p. 19), presumably an extension of the perceived J-5 un- conformity, at the base of the Bluff Sandstone(: their Morrison ti$aphy that was quite well understood by the early 1950s. Formation) in southeastern Utah, and utilize that "time bound- ary" as the San RafaelGroupMorrison contact.We assertthis is References not how formation contactsare established.The Condon and Anderson, O. J.,1993, Zuni Sandstoneand Acoma Tongue defined: New Mexico Petersonapproach is to honor all previousU.S. GeologicalSurvey Geology, v. 15, no. 2, pp. 38-39. Anderson,O. f ., and Lucas,S.C.,lDZ,TheMiddleJurassicSummeruille Fomation, work on the Morrison Formation in southeasternUtah, recognize northern New Mexico: New Mexico Geology, v. 74, no. 4, pp.79-92. the J-5 unconformity at a stratigraphic horizon that supports this Baker,A. A., Dane,C. H., and Reeside,J.8.,Jr.,1947,Revised correlation ofJurassic previous work, and by definition, assign all strata above this fomations of parts of Utah, Arizona, New Mexico, and Colorado: American unconformity (unrecognized boundary) Association of Petroleum Geologists,Bulletin, v. 31, no. 9, pp.1664-1.668. time to the Morrison For- Bell, H., IlI, and Post, E. V.,1971, Geology o( the Flint Hill quadrangle, Fall River mation, regardless of lithologies. In this way they can include County, South Dakota: U.S. GeologicalSuruey, Bulletin 1063-M, pp. 505-586. eolianites in the Morrison Formation, even though eolianites are Burbank, W. S., 1930,Revision of geologic stmcture and stratigraphy in the Ouray not in the type area. Not incidentally, we question why the Mor- dishict of Colorado and its bearing on ore deposition: Colorado ScientificSociety, rison Formation correlationsfrom Morrison, Colorado, to the San Proceedings,v. 72, no. 6,237 pp. Condon, S. M., 1993,The Middle JurassicSummeruille Formation, northern New fuan Basin must be done via southeasternUtah. If this correlation Mexicea reply to Anderson and Lucas, 1992:New Mexico Geology, v. 15, no. were to be attempted down the Front Range and thence into the 2, pp.33-37. southeasternSan |uan Basin without knowledge of previous work Condon, S. M., and Huffman, A. C., Ir-, 1988, Revision in nomenclature of the in Utah, eolianites Middle lurassic WanakahFormation, northwestern New Mexico and northeastern would surely not be included in the Morrison; Arizona: U.S. GeologicalSuruey, Bulletin 1533-4, 12 pp. the eolianites would be correctly included with the underlying Condon, S. M., and Peterson,F.,1'986, Stratigraphy of Middle and Upper Jurassic San RafaelGroup on the basisof sandstonetype and lithogenesis. rocks of the San fuan Basin; historical perspective,cunent ideas, and remaining We also exclude eolianites from the Morrison Formation be- problems: American Associationof PetroleumGeologists, Studies in Geology,no. cause "the observed interbedding of eolian rocks with Mor- 22, pp.726. the Cooper, G. A., 1930, Stratigraphy of the Hamilton Group of New York, Part II: rison referred to by Condon does not exist in the southern San AmericanJournal of Science,5th Series,v.19, pp.214-236. fuan Basin. The interbedding referred to by Condon consists of Dane, C. H.,1955, Unpublished internal memo to GeologicNames Committee, U.S. thin (maximum of 1.5 m), lenticularmaroon siltstoneand sand- GeologicalSurvey. stone in Dane, C. H., and Bachman, G. O., 1955, Geologic map of New Mexico: U.S. Ge- beds a dominantly eolian, lighter colored sandstonesec- ological Suruey and New Mexico Bureau of Mines and Mineral Resources,scale tion that overlies the Bluff-Summerville interval. The siltstones 1:500,000. represent interdunal deposits and locally make up 6-8% of the Darton, N. H., 1899,Jurassic formations of the Black Hills of South Dakota: Geo- total section. Where present to that extent, the siltstones bleed logical Society of America, Bulletin, v 10, pp. 383-395. down Dutton, C. E., 1885,Mount Taylor and the Zuni Plateau:U.S. GeologicalSuruey, over the lighter-colored sands, and their thickness thus is 5th Annual Report, 198 pp. exaggerated. The appearanceof this section is (apparently) se- Gilbert, G. K., 1.875,Suwey west of the 100th meridian: U.S. Geological and Ge- ductively similar to what is called the Recapture Member of the ographical Suruey, v. 3, pp. 162-1.97. Morrison Formation, because Condon and his colleagueshave Grabau, A. W., 1917, Age and stratiSraPhicrelations of the Olentangy Shale of included these eolian sandstonesin their Recapture.The problem central Ohio, with remarkson the Prout Limestoneand so-calledOlentangy shales of northem Ohio; Journal ol Geology,v. 25, pp. 337-343. is that the type Recapture is a fluvial sandstone that is coarser- Gregory, H. E., 1916,The Navaio country-a geographicand hydrographic recon- grained and sedimentologically different from the unit that Con- naissanceof parts of Arizona, New Mexico, and Utah: U.S. Geological Suroey, don calls Recapturein the San Juan Basin.We do not deny the Water-Supply Paper 380,219 pp. possibility that the are Gregory, H. E., 1938,The San Juan country, a geologic and geographicreconnais- two chronostratigraphic equivalents, but sanceof southeasternUtah: U.5. GeologicalSuroey, ProfessionalPaper 188, 123 they not are the same lithostratigraphic or lithogentic units. PP. Therefore, we assign the eolianites to the Zuni Sandstone. Harshbarger,J. W., Repenning, C. A., and lrwin, I. H., 7957,Stratigraphy of the Another example of eolian sandstonesin this stratigraphic in- uppermost Triassicand the furassic rocks of the Navaio country: U.S. Geological terval was discussedby Szigetiand Fox (1981).In the BlackHills Suruey, ProfessionalPaper 291,71 pp. Imlay, R. W., 1980,Jurassic paleobiogeography of the conterminous United States of South Dakota the Unkpapa Sandstonewas recognizedby Dar- in its continental setting: U.S. Geological Survey, ProfessionalPaper 1062, 734 ton (1899)as a separateformation between the Sundanceand PP. Morrison Formations.The Unkpapa is as much as 81.4 m thick Keroher,G.C.,1966, Lexiconofgeologicnamesof theUnitedStatesfor1936-1'960: and consists chiefly of massive, fine- to very fine-grained sand- U.S. Geological Suruey, Bulletin 1200,part 2, 4Ul pp. Kocurek, G., and Dott, R. H., Jr., 1983,Jurassic paleogeography and paleoclimate stones. Its status as a formation separatefrom the Morrison For- of the central and southern Rocky Mountains region; in Reynolds, M. W., and mation has long beenupheld, particularlyby mappersof the U.S. Dolly, E. D. (eds.), Mesozoic paleogeographyof the west-centralUnited States: GeologicalSurvey (e.g.,Bell and Post, 1971).Indeed, Szigetiand Rocky Mountain Sectionof Societyof EconomicPaleontologists and Mineralogists, Fox (1981)did not include the Unkpapaeolianites in the pp.101-115. Morrison Lucas,S. G., Kietzke, K. K., and Hunt, A. P., 1985,The JurassicSystem in east- Formation, although Condon, in his reply, cites them when he central New Mexico: New Mexico Geological Society, Guidebook to 36th Field statesthat "eolian rocks in the Morrison have also been described Conference, pp. 21.3-242. in. . . South Dakota." Szigetiand Fox (1981)provided no such Maxwell, C. H., 7975, Geologic map of the Acoma Pueblo quadrangle, Valencia description, County, New Mexico: U.S. Geological Suruey, Geologic Quadrangle Map GQ- but instead argued that the Unkpapa and Morrison 1298.scale 1:24.000. Formations interfinger in the southern Black Hills, although they Maxwell, C.H., L979,Geologic map of the EastMesa quadrangle,Valencia County, noted that "this is partially obscuredby landslidedeposits" (Szi- New Mexico: U.S. GeologicalSuruey, Geologic Quadrangle Map GQ-1522, scale geti and Fox, 1981,p. 333). 7:24,000. Maxwell, C. H., 7982, Mesozoic stratiSraphy of the Laguna-Crants region: New Mexico GeologicalSociety, Guidebook to 33rd Field Conference, pp.261-256. Conclusion McKnight, E. T.,7940, Geology of area between Green and Colorado River, Grand and San Juan Counties, Utah: U.S. GeologicalSuruey, Bulletin 908, pp. 85-f02. , Condon's reply to our article presents no new data to support Milter, K. 8., 1.997,High-resolution conelation within a stom-dominated muddy his interpretations of Middle and Upper Jurassicstratigraphylnd epeiric sea:Taphofacies of the Middle Devonian WanakahMember, western New

New Mexim Geology August 1993 York;.in Landing, E., and Brett, C. E. (eds.), Dynamic stratigraphy and deposi- Powell, J. W., 7876,Geology of easternportion of the Uinta Mountains and a region tional environments of the Hamilton Group (Middle Devonian) inNew york Siate. of the country adiacent thereto: U.S. Geologicaland GeographicalSurvey of the Part ll: New York StateMuseum/Geologiial Survey, Bulletin 469, pp. 129.152. Tenitory, 218 pp. North American Commissionon StratigraphicNomenclature, 19g3, Noith American Rickard, D. V., and Fisher, D W , 1970a,Geologic map of New York, Finger Lakes Stratigraphic Code: American Association of Petroleum Geologists, Bulletin, v. sheet: New York State Museum and ScienceSeruice, Map and Chart series, no 67, no. 5, pp. 841-875. 15, scale1:250,000 O'Sullivan, R. B., 1980a,Stratigraphic sections of Middle JurassicSan RafaelGroup Rickard, D V., and Fisher,D W., 1970b,Geologic map of New York, Niagara sheet: and related rocks from the Green River to the Moab area in east-centralUtah: New York StateMuseum and ScienceService, Map and Chart series,no 15, scale _ U.S. GeologicalSurvey, MiscellaneousField Studies Map MF-1247. 1:250,000. O'Sullivan, R. B., 1980b,Stratigraphic sections of Middle JurassicSan RafaelGroup Ridgley, J. L, 7989, Trace fossils and mollusks from the upper members of the from Wilson Arch to Bluff in southeasternUtah: U.S. GeologicalSuruey, Oil and WanakahFormation, ChamaBasin, New Mexico----evidencefor a lacustrineorigin: Gas InvestigationChart 102 U S GeologicalSurvey, Bulletin 1808-C, pp. C1-C16. O'Sullivan, R. B., and Pierce,F. W., 1983,Stratigraphic diagram of Middle Jurassic Schaeffer,B., and Patterson,C , 1984,Jurassic fishes from the western United States, San Rafael Group and associatedformations from the Sin Rafael Swell to Bluff with comments on Jurassicfish distribution: American Museum Novitates, no. in southeastern Utah: U S. Geological Suruey, Oil and Gas Investigation Chart 2796, pp. r-86 I 19. Szigeti,GJ.,andFox,I.E.,1981., UnkpapaSandstone(Jurassic),BlackHills,South Peterson,F, 1988,Stratigraphy and nomenclatureof Middle Jurassicrocks, western Dakota-an eolian facies of the Morison Formation: Society of Economic Pale- Colorado Plateau, Utah and Arizona: U S Geological Survey, Bulletin 1633_8, ontologists and Mineralogists, SpecialPublication 31, pp 337-3a9 pp. 72-55. n

LoisM. Devlin mineral-resources)information for everyone-publications such NMBM&MRBusiness Services as the Scenic Trips to the Geologic Past, informal road logs to Coordinalor mineral- and fossil-collectinglocalities, and the popular Geologic (1e22-1993) Highway Map by the New Mexico GeologicalSociety. Lois often handled the NMBM&MR and NMGS publication booth at meet- ings of NMGS, GSA, AAPG, and other organizations. Probably more of our "customers" benefited from Lois' advice and service than from most of the scientific-engineering staff. Born in Webster, South Dakota (1922),Lois Sandvig attended the University of South Dakota. During World War II she was secretary to the commander of the Sioux Falls Army Air Force Base. (He later becamepresident of Oklahoma University.) There she met and married (19t14)Edward j. Devlin; after the war they moved to Wellsville, New York, where their two children were born. When they moved to Socorro, Lois joined our staff (1962)as a typist, then secretary,office manager,Director of Publicationsand Business Office, and Business Services Coordinator. Our NMBM&MR was, thankfully, a major part of Lois' life, and to us she was as indispensable as one person can be. Working with ludy Yaiza, Norma Meeks, and coworkers she helped to form the experienced core of our business and administration crew, in- cluding the distribution of our publications and those of NMGS, USGS, and USBM. Her help with managing the millions of dollars of state and federal funds was a real serviceto all of us. Thought- fully, she unobtrusively correctedour errors, thanked us for rou- tine duties, was genuinely sympathetic for problems, and joyful for accomplishments. A valued coworker and to many of the Bureau staff an older sister,Lois had almost a passionfor everyone to enjoy our state's geology, scenery,and people. South Dakota with its rolling Great Plains, grain fields stretch- ing to the horizon, hot humid summers, and frigid winters con- trasted with Socorro's green Rio Grande valley, semiarid bordering slopes, and towering skyline mountains. She enjoyed it, raising lovely Linda Devlin Dixon and expert forester David Devlin. In recent years, she joined her brothers and friends, once or twice a year, to visit the globe, often flying Pan Am while Linda was a flight attendant for the airline. Contrast South Dakota and Socorro with Hong Kong, London, Williamsburg, Frankfurt, |uneau, and San Francisco, all of which she enjoyed. As did she enjoy her many friends in Socorro,work with P.E.O., Women's Golf As- sociation, many bridge clubs, luncheons; always gregarious, cheerful, joyful. Lois' major relationship with our geologiccommunity was her A dear, warm friend, an advocate for practical geology, an interest in-and -promotion of geology for the layperson, although efficient worker for New Mexico, we appreciateall she has meant she was directly involved with all aspectsof Bureau business. to us and our state. She left us 15 |uly as the sun reached its She was fully knowledgeable of our technical publications but zenith. always encouraged writing of and distribution bf geology (and -FrankE. Kottlowski

August 1993 Nm MexicoGeology