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STRATIGRAPHY OF THE SANTA FE , NEW

TED GALUSHA Frick Assistant Curator Department of F7ertebrate Paleontology The American Museum of Natural History JOHN C. BLICK Late Field Associate, Frick Laboratory The American ikIuseum of Natural History

BULLETIN OF THE AMERICAN MUSEUM OF NATURAL HISTORY VOLUME 1.44 :ARTICLE 1 NEW YORK : 1971 BULLETIN OF THE AMERICAN MUSEUM OF NATURAI, I-IIS'I'ORY Volume 144, article 1, pages 1-128, figures 1-38, tables 1-3

Issued April 5, I971

Price: $6.00 a copy

Printed in Great Britain by Lund Humphries CONTENTS ABSTRACT...... 7 INTRODUCTION...... 9 Acknowledgments ...... 16 Historical Sketch ...... 16 Work by Other Geologists ...... 16 Work by the Frick Laboratory ...... 22 STRATIGRAPHY...... 30 Pre- Tertiary Formations ...... 33 El Rito Formation ...... 33 ...... 34 Abiquiu ...... 36 Picuris Tuff ...... 37 Espinaso Volcanics ...... 37 Zia Sand Formation ...... 38 Santa Fe Group ...... 40 ...... 44 Nambt Member. New Name ...... 45 Skull Ridge Member. New Name ...... 53 Pojoaque Member, New Name ...... 59 Chama-el rito Member. New Name ...... 64 Ojo Caliente . New Name ...... 67 . New Name ...... 71 Post-Santa Fe Group Formations ...... 76 Puyt Conglomerate ...... 76 ...... 78 Deposits on Erosion Surfaces ...... 78 ZiaMarl ...... 79 Servilleta Formation ...... 79 Espanola Formation. New Name ...... 80 Varved or Rhythmical Sediments ...... 80 Otowi Flow ...... 82 ...... 82 Cerros del Rio Lava Flows ...... 85 High-Level ...... 86 Volcanic Rocks ...... 88 Rio del Oso Dikes ...... 90 Round Mountain ...... 90 GEOMORPHOLOGY...... 95 Erosion Surfaces ...... 95 Drainage ...... 97 Deposition of Alluvial Plains in Drainage Valleys ...... 98 Superimposed Streams ...... 99 STRUCTURE...... 100 Fault System ...... 101 Age of the Pre-Santa Fe Deformation ...... 104 Age of the Post-Santa Fe Deformation ...... 104 AGEOF THE SANTAFE GROUP...... 106 SUMMARYOF THE GEOLOGICHISTORY OF THE SANTAFE BASIK ...... 112 REFERENCES...... 1 19 4 BULLETIN AMERICAN MUSEUM OF XATURXL HISTORY VOL. TABLES TABLE1 . Geological Survey topographic maps in the 7.5-minute series available (1969) for the type area of the Santa Fe Group. ...... TABLE2. Correlation of names of wash and drainage systems used by Frick Laboratory collec- tors. with names later used on United States Geological Survey topographic maps ... TABLE3. Faunal list and stratigraphic position of the published types of specimens collected in the type locality of the Santa Fe Group as restricted in this report ......

TEXT FIGURES FIG. 1 . Index map showing the type area of the Santa Fe Group. New Mexico ...... FIG. 2 . Map of the -collecting localities in the type area of the Santa Fe Group ..... FIG. 3. Index map showing type areas of Cenozoic rocks in the depression in north-central New Mexico ...... FIG. 4 . General view of a part of the Espanola Valley. New Mexico ...... FIG. 5 . Early map of the Espanola fossil-collecting area ...... FIG. 6. Map of the Espanola area drawn by Joseph Rak in 1924 ...... FIG. 7 . Map of the Espanola area drawn by John C . Blick in 1936 ...... FIG. 8. Round Mountain Quarry. A . Excavation in progress in 1936. B. View showing fossil layer, and the contact of the Chamita Formation with the PuyC Conglomerate ..... FIG. 9 . Composite stratigraphic section and correlation chart of the Santa Fe Group ... FIG. 10. Correlation diagram comparing stratigraphic relations of members of the Santa Fe Group in the Espanola Valley with those in the Abiquiu re-entrant ...... FIG. 11 . Sedimentary contact of the Nambt Member with rocks ...... FIG. 12 . Outcrop map of a contact area between the NambC Member and the Skull Ridge Member ...... facing FIG. 13. Type section of the fossiliferous portion of the NambC Member of the Tesuque Formation ...... FIG. 14 . The NambC Member of the Tesuque Formation ...... FIG. 15. A . Contact area of the Nambt Member and the Skull Ridge Member . B. The Red Wall ...... FIG. 16. Type section of the Skull Ridge Member of the Tesuque Formation ...... FIG. 17. Ideal section of the Skull Ridge Member, showing the ash-bed sequence and the strati- graphic position of fossil specimens ...... facing FIG. 18 . The Three Sisters Buttes ...... FIG. 19. Outcrop map of a part of the East Cuyamunque collecting locality ....facing FIG. 20 . Outcrop map of a locality in South Skull Ridge ...... FIG. 21 . Type section of the Pojoaque Member of the Tesuque Formation ...... FIG. 22 . A . First Wash in the Santa Cruz collecting locality . B . Pojoaque Bluffs ...... FIG. 23 . Columnar ideal section across part of the Espanola Valley ...... FIG. 24 . A profile section in the North Pojoaque Bluffs to show correlation details ..... FIG. 25 . Outcrop map of the West Cuyamunque collecting locality ...... facing FIG. 26 . Correlation detail in the Chama-el rito collecting locality ...... FIG. 27 . Cross sections of deposits of the Chama-el rito Member and the Ojo Caliente Sand- stone ...... FIG. 28 . Stratigraphic relations of the Ojo Caliente Sandstone at three sites ...... FIG. 29 . Type section of the Chamita Formation ...... FIG. 30 . A . Type locality of the Chamita Formation . B. A part of Black Mesa ...... FIG. 31 . A . Battleship Mountain . B. Contact of the Chamita Formation and the PuyC Con- glomerate west of the Rio Grande near Otowi bridge ...... FIG. 32 . Type locality of the Espanola Formation ...... FIG. 33 . Varved or rhythmical deposits. A . A view of part of the deposits . B. Close-up view of the varves ...... 1971 GALUSHA AND BLICK: SANTA FE GROUP 5

FIG. 34. Diagrams of Cerro Azul. Mesa de 10s Ortizes. and Otowi lava flow ...... B4 FIG. 35 . Rio del Oso dikes . A . First basaltic dike in Dike Wash . B . Second basaltic dike and apophysis in Dike Wash ...... 91 FIG. 36. A . Close-up of apophysis in Dike Wash . B . View of large-scale cross-bedding in the Ojo Caliente Sandstone ...... 92 FIG. 37 . Round Mountain ...... 93 FIG. 38 . Geologic map of the type area of the Santa Fe Group, New Mexico ...... (in pocket) ABSTRACT

THE TYPE AREA of the Santa Fe Group is the region Type sections of the NambC and Skull Ridge north of Santa Fe, New Mexico, between the Sangre members of the Tesuque Formation have been desig- de Cristo Mountains on the east and the Jemez nated in the thick belt of alluvial-fan deposits exposed Mountains on the west. This area was part of Hay- between Nambt Creek and the Santa Cruz . den's (1869) type section of the Santa Fe marls, which The type section of the Pojoaque Member of the was later called the Santa Fe Formation by Bryan, Tesuque Formation lies north of the Pojoaque River, Smith, Cabot, Denny, and others. Bryan (1938, northwest of Pojoaque, New Mexico. Most of the p. 205), following part of Hayden's original descrip- sediments of the Pojoaque Member were derived from tion, mentioned the area north of Santa Fe as the type the predominantly granitic rocks of the Sangre de locality of the Santa Fe Formation, but Denny (1938, Cristo Range; these were part of a great system of 1940b) first formally designated a specific type locality coalescing alluvial fans arranged along the mountain for the Santa Fe Formation as given above. Kottlow- front. At the same time that the Pojoaque Member ski (1953, p. 144) first suggested that the Santa Fe was being deposited, as shown by the extensive collec- Formation be elevated to group rank. Spiegel and tion of obtained from each member, another Baldwin (1963, p. 38) proposed an extension of the system of alluvial-fan deposits was being built along term Santa Fe Group to include all the sedimentary the northern and northwestern part of the type area and volcanic rocks related to the Rio Grande trough, of the Santa Fe Group. These volcanic rocks are with a range in age from middle(?) to herein named the Chama-el rito Member of the

Pleistocene(\, ?). Tesuque Formation. They were derived from volcanic The present report proposes to restrict the use of rocks of the San Juan region of northern New Mexico, Santa Fe Group to the rocks of the type and con- and southern and are lithologically distinct tiguous areas. The middle Miocene to middle to from those of the Pojoaque Member, which are upper deposits of the type area, heretofore essentially granitic in origin. Although the Chama-el undifferentiated, are divided among five members of rito was deposited through a long period of time, as is the Tesuque Formation, and the Chamita Formation. shown by the presence of Brachycncs in a locality near This division of the group is based on the results of Abiquiu, New Mexico, which indicates an equiva- field and laboratory studies since 1924 by the Frick lency with a part of the Skull Ridge Member, the Laboratory of the American Museum of Natural greatest part of the member was deposited at the same History. The two formations from lowermost to time as the Pojoaque Member. In the area between uppermost are: (1) Tesuque Formation and (2) Battleship Mountain and the Sacred Spring, the Chamita Formation. Formal names are proposed for uppermost beds of the Chama-el rito are observed to the members of the Tesuque Formation. overlie beds of the Pojoaque Member. Deposits of the Tesuque Formation, which is the The Ojo Caliente Sandstone has been assigned lowest formation of the Santa Fe Group as here recog- member status and is composed of about 450 feet of nized, are divided into five members: (1) the NambC light gray to light pinkish gray, eolian, soft, friable Member, (2) the Skull Ridge Member, (3) the sandstone. These beds interfinger at the base with the Pojoaque Member, (4) the Chama-el rito Member, Chama-el rito Member and obviotlsly represent a and (5) the Ojo Caliente Sandstone. Fossils collected marked change in sedimentary environment. The from the NambC and Skull Ridge members range in southernmost good exposure of the Ojo Caliente age from medial to late Miocene. The Pojoaque, the Sandstone is on Battleship Mountain where it is no Chama-el rito, and the Ojo Caliente Sandstone have more than 40 feet thick and overlies Chama-el rito produced a large collection of early Pliocene mam- beds. The Ojo Caliente Sandstone has been extensively malian fossils. These members are lithologically reworked into the basal beds of the overlying Chamita distinct, and, although they may have been deposited Formation. In some parts of the area, this reworking through the same general period of time, the beds are superficially resembles interfingering, but it is quite advisedly separated as members rather than as different, and also indicates a distinctive change in

facies. sedimentary en\7ironment. ' The Chamita Formation, which is the uppermost Beds of the Chamita Fornlation are lithologically formation of the Santa Fe Group, represents deposits different from all others in the type area of the Santa from a markedly different sedimentary environment Fe Group; they overlie the Ojo Caliente Sandstone, compared with the underlying Ojo Caliente Sand- and, moreover, they contain fossil that stone. Moreover, fossils of medial Pliocene age have show them to be the latest beds of the Santa Fe Group been collected from the beds of the formation, with in the type area. The type section of the Chamita even a few fossils indicative of an early part of the Formation lies 2 miles northwest of the San Juan late Pliocene. Pueblo. 8 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY VOL. 144

The total thickness of the Santa Fe Group, as been included in the Santa Fe Formation but were restricted in this report, is at least 4500 feet and may separated on lithologic criteria, supported by evidence be as much as 4800 feet. These figures were obtained from contained fossils, which were demonstrated to be by our measuring correlated fault blocks in the type early to medial Miocene in age-more precisely, area. The thicknesses assigned to the ideal sections of equivalent within the framework of the North Ameri- members or formations have been the basis for the can Land- provincial classification to late estimates. Arikareean (Harrison Formation equivaIent) to late The sediments of the Santa Fe Group include Hemingfordian (Sheep Creek Formation equivalent) alluvial-fan and eolian deposits, including conglomer- in age. ates, gravel, loosely consolidated , silt- The Rio Grande depression was formed in at least stones, volcanic ash, bentonites, tuffaceous deposits, two distinct periods of deformation, one prior to the conglomeratic sandstones, intraformational breccias deposition of the Santa Fe Group and the other post- and conglomerates, of various kinds, cal- Santa Fe Group in age. The outlines of the two careous and cherty strata, and a small amount of clay. deformations closely but not exactly coincided. In the Interbedded volcanic flows are few and of small earlier structural basin the El Rito Formation and the extent. Galisteo Formation were the first Tertiary deposits to Strata of the Santa Fe Group were deformed by be laid down. A widespread period of volcanism high-angle, normal, strike faults during the post- resulted in the deposition of three formations com- Santa Fe deformation. The faults are closely spaced, posed of volcanic debris, as follows: (1) Abiquiu Tuff, and the strata in the resultant fault blocks in the (2) Picuris Tuff, and (3) Espinaso Volcanics. These Espanola Valley commonly dip westward 3 to 9 were followed by more than 4000 feet of sediments degrees. Maximum dip may be as much as 30 degrees. assigned to the Santa Fe Group that are lithologically North of Black Mesa dips may be easterly. distinct and obviously are from entirely different Detailed correlations in the Tesuque Formation provenances. The Santa Fe overlapped the original were made from studies of the stratigraphic position of structural basins, as is shown by the thick blocks of 38 differentiable volcanic-ash beds. Ash beds are par- Santa Fe sediments caught in footwall blocks along ticularly useful as horizon markers in the Skull Ridge some of the bounding faults of the present Rio Grande Member. Small groups of volcanic-ash strata were depression. used in comparable correlations in the Pojoaque After the post-Santa Fe deformation, previously Member of the Tesuque Formation. Two distinctive isolated sedimentary basins along the original struc- tuffaceous zones are useful for correlations in the tural depression were integrated by a through-flowing Chamita Formation. perennial river-an ancestral Rio Grande. Tremen- About 1000 feet of gray sandstone deposits in the dous volumes of sediments were removed from the Jemez Creek and Northern Ceja del Rio Puerco Rio Grande depression, and the present complex localities, southwest of the type area of the Santa Fe geomorphology of the type area of the Santa Fe Group, were described by the senior author in 1966 as Group remains merely as a fragmentary record of the Zia Sand Formation. These beds formerly had important events. INTRODUCTION

THESANTA FE FORMATIONhas been the subject "iustification for the correlation and are based on of numerous general geological reports and a fauna not compatible in any way with that observations for more than 100 , but in that obtained from the type area. In this way the time few observations on the stratigraphy of the term Santa Fe Formation has been extended to formation have appeared. Almost exactly a include a wide variety of deposits of uncertain century ago Hayden (1869, p. 66) named the age, and its usefulness to and paleont- beds "the Santa Fe marls," and with the passing ology thereby has been greatly diminished. Its of the years the name has been changed to Santa present vague significance is somewhat compar- Fe Formation and finally to Santa Fe Group. To able with that currently applied to the Wasatch, date several circumstances have prevented the the "Loup Fork," and the "" publication of a definitive report on the Santa formations. Fe. The present report, far from being definitive, Spiegel and Baldwin (1963) raised the term is regarded by the writers as an introduction to ~ania~e to group status, but this device merely the stratigraphy of the Santa Fe Group, to transferred the general confusion surrounding which, as an adjunct to the interpretation of the the Santa Fe Formation to an even greater geo- stratigraphy, many data on the structure and graphic area and the faunal connotation of the geomorphology of the region have been added. term Santa Fe to greater segments of geologic Our purpose is to present a reconnaissance study time. Such broad usage is to be deplored, and of the Santa Fe Group in which attention is we hope that the restricted use of theterm Santa directed to those features that we believe are Fe Group as proposed in this report will enable salient to an understanding of the stratigraphic subsequent workers to use both rock-strati- framework of the group. Analyses of individual graphic and faunal data in seeking solutions to sediments or sedimentary structures, petro- problems relating to the Santa Fe Group, and graphic or petrologic analyses of rocks of what- thereby delimit and revitalize the term. ever origin, or complex compilations of minu- Most of the deposits of the Santa Fe type area tiae of many kinds are purposely omitted. were laid down by coalescing alluvial fans in a Detailed investigations of many of the features re-Santa Fe structural basin that conformed mentioned in this report can serve better as pro- rather closely to the outlines of the present Rio jects for in-depth studies by specialists who may Grande depression as defined by Bryan (1938). become interested in the Santa Fe type area. A period of post-Santa Fe deformation fractured Sandy or conglomeratic deposits that crop out and tilted the beds and formed large numbers of at many places in the Rio Grande depression closely spaced fault blocks. These fault blocks from Colorado through New Mexico into Texas were outlined by eastward- and by westward- have been correlated as Dart of the Santa Fe dipping normal strike faults often, but not in Formation. Apparently many of these correla- every case, arranged en echelon. The correlation tions were made because the workers suspected of the numerous fault blocks and the determina- that they were dealing with probably late tion of the relative ages of their sedimentary Tertiary or Pleistocene beds, and, inasmuch as sequences have been major stratigraphical the Santa Fe Formation happened to be the only problems. late Tertiary formation described in the region, We recognize the controversy that exists it was selected as a "wastebasket" formation to among geologists and paleontologists, both receive the problematical beds. Such correla- North American and European, concerning the tions often were made, although the referred precision, applicability, appropriateness, and deposits showed faint, if any, resemblance to the relative usefulness of the time scales that have deposits of the type area of the Santa Fe Forma- been proposed for measuring Tertiary history. tion. Furthermore we are aware of the difficulties that The cumulative effects of a succession of such have arisen as a result of applying to North unfortunate correlations have been a dilution of American rocks and fossil faunas the time terms the concept of the Santa Fe Formation as a rock- for the epochs of the Tertiary Period that were , which is even more confusing originally defined in . One problem of when biostratigraphic data are presented as particular complexity involved the selection of BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY VOL. 144

107O 105"

------COLORADO NEW MEXICO

35O

FIG.1. Index map showing (1) type area of Santa Fe Group, (2) Jemez Creek area, (3) Ceja del Rio Puerco area, and (4) Gabaldon area, all in New Mexico. Dotted outline shows approximate configuration of the Rio Grande depression. GALUSHA AND BLICK: SANTA FE GROUP

FIG.2. Map of fossil-collecting localities worked by Frick Laboratory field parties in the type area of the Santa Fe Group, New Mexico. (1) Nambt; (2) Skull Ridge; (3) East Cuyamunque; (4) Tesuque; (5) Santa Cruz; (6) North Pojoaque Bluffs; (7) Central Pojoaque Bluffs; (8) Lower Pojoaque Bluffs; (9) West Cuyamunque; (10) South San Ildefonso; (1 1) San Ildefonso; (12) Santa Clara; (13) Ojo Caliente; (14) East Ojo Caliente; ( 15) North Ojo Caliente ; (16) Dixon sub-basin ; ( 17) Chama-el rito ; ( 18) Rio del Oso-Abiquiu; ( 19) Hernan- dez ; (20) San Juan ; and (2 1) Osbornoceros-Lyden. 12 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY VOL. 144 the time or age terms that are used throughout time represented by the fauna of the Valentine this report. We provide two charts (figs. 9 and Formation of as revised by Skinner, lo), which are designed to show general age Skinner, and Gooris (1968, p. 404). references and to enable the reader to orient his The chief purpose of this report is to present concepts regardless of his preference for a par- rock-stratigraphic and biostratigraphic informa- ticular scheme of age determinations. tion in an effort to clarify some of the problems We use the European terms Miocene and peculiar to the Santa Fe Group. Other objec- Pliocene in a general way, fully cognizant of the tives are: (1) to enable subsequent workers to probability that further refinement in Europe is identify areas of Santa Fe Group deposits and likely to alter the concepts of the boundaries correlate them with greater precision; (2) to between these epochs. We believe, however, that Dresent the information on the Santa Fe Group the Wood Committee (Wood et al., 1941) North in a manner that can be useful in the field and in American Provincial Ages, or North American the laboratory without the necessity of the field Land Mammal Ages (a change in Wood Com- man's personally working out the details of the mittee terminology suggested by Savage, 1962), geology; (3) to provide a stratigraphic frame- have proved more effective for use in North work on which the extremely large fossil collec- American continental deposits than have the tions from the Santa Fe area in the Frick Collec- terms Miocene and Pliocene, and others of the tion can be based (this will require that the international geological time scale. We use mammalian remains be interpreted according to Land-Mammal Age terms in a general way and, the sequence in which the specimens actually moreover, would favor the introduction of a occur in the rocks); (4) to place emphasis on Land-Mammal Age to represent a segment of description and to hold interpretation to a

FIG. 3. Index map showing type areas, type localities, type sections, or well-exposed, described areas of some Cenozoic rocks in the Rio Grande depression in north-central New Mexico and adjacent areas. Large dotted ellipse shows type area of Santa Fe Group as restricted in this report. Small, numbered, dark circles identify the following localities: 1. Tesuque Formation, Spiegel and Baldwin, 1963 2. Nambe Member, new name 3. Skull Ridge Member, new name 4. Pojoaque Member, new name 5. Chama-el rito Member, new name 6. Ojo Caliente Sandstone, new name 7. Chamita Formation, new name 8. Ancha Formation, Spiegel and Baldwin, 1963 9. PuyC Conglomerate, Griggs, 1964 10. Bandelier Tuff, Griggs, 1964 11. Picuris Tuff, Cabot, 1938 12. Abiquiu Tuff, Smith, 1938 13. El Rito Formation, Smith, 1938 14. Galisteo Formation, Hayden, 1869 15. Servilleta Formation, Montgomery, 1953 16. Carson Conglomerate,Just, 1937 17. Los Pinos Gravel, Larsen and Cross, 1953 18. Ritito Conglomerate, Barker, 1958 19. Vallejo Formation, Upson, 1941 20. Espinaso Volcanics, Stearns, 1953 21. Placita Marl, Cope, 1875 22. Zia Sand Formation, Galusha, 1966 23. , Simpson, I948 24. , Keyes, 1906 25. Baca Formation, Wilpolt and others, 1946 26. Datil Formation, Winchester, 1920 27. , Denny, 1940a 28. Tuerto Gravel, Stearns, 1953 1971 GALUSHA AND-BLICK: SANTA FE GROUP 13 14 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY VOL. 144 minimum, and to attempt to mark plainly hypo- Acacia area, and the Socorro area in New thetical interpretations; and (5) finally, to Mexico. The in Colorado, the present a field report that may prove helpful to Truth or Consequences and Las Cruces areas, workers of the future in preparing more precise and other isolated areas along the Rio Grande and penetrating reports on the geology, strati- in New Mexico have been visited from time to graphy, sedimentology, and paleontology of the time. Santa Fe region than have appeared in the past. Adequate topographic maps were not avail- Childs Frick first sent an expedition into the able for the type area of the Santa Fe Group, as type area of the Santa Fe Group in 1924, and he here restricted, during the years that most of the immediately recognized the need for faunistic as field mapping was done. We mapped directly on well as stratigraphic studies of the deposits. Sub- uncontrolled aerial photographic mosaics taken sequent work carried on each field season since, in 1935-1936 by the Fairchild Aerial Surveys, with the exception of the years 1932, 1943, 1944, Inc., for the United States Soil Conservation 1958, 1961, 1963, and 1965, reflects his un- Service as part of the Rio Grande Watershed wavering interest in the paleontology and stratigraphy of the formation. This report brings together many of the data TABLE 1 obtained by the field collectors of the Frick UNITEDSTATES GEOLOGICAL SURVEY TOPOGRAPHIC Laboratory.1 Necessarily numerous details must MAPSIN THE 7.5-MINUTESERIES AVAILABLE (1969) be eliminated, owing to limitations on the FOR THE TYPEAREA OF THE SANTAFE GROUP, amount of pertinent material that can be pub- NEWMEXICO lished. Workers in the future who will deal with Agua Fria Quadrangle, 1951 the Frick Laboratory collections made in the Santa Fe Quadrangle, 1952 Santa Fe Group in the last 30 years will find Guaje Mountain Quadrangle, 1952 relatively complete documentation in the Frick White Rock Quadrangle, 1952 Laboratory records, field books, and archives. Lyden Quadrangle, 1952 Studies by the field parties of the Frick Puye Quadrangle, 1952 Laboratory in the Santa Fe area previous to El Rito Quadrangle, 1953 1940 were mostly confined to finding and col- Ojo Caliente Quadrangle, 1953 lecting fossils from the principal fossiliferous Espanola Quadrangle, 1953 Cundiyo Quadrangle, 1953 localities and in correlating both faunal and San Juan Pueblo Quadrangle, 1953 stratigraphic data in an effort to differentiate Tesuque Quadrangle, 1953 the late Miocene and early Pliocene deposits. In Chimayo Quadrangle, 1953 1940 we began an intensive study of the strati- Vallecitos Quadrangle, 1953 graphy of the fossiliferous localities, and in 1941, Horcado Ranch Quadrangle, 1953 1942, 1945, 1946, and 1947 extended the Abiquiu Quadrangle, 1953 detailed investigations to include all deposits in Chili Quadrangle, 1953 the type area. Velarde Quadrangle, 1953 Much work also has been done since 1945 in Medanales Quadrangle, 1953 outlying regions in which deposits of presumably Santa Fe age have been reported. The field Project 3500, Identification WO-8979. A map seasons of the period 1949 to 1953, for the most traced from these uncontrolled mosaics serves as part, were spent in correlated areas. Mammalian the base for the geologic map (fig. 38). Inas- fossil remains have been obtained at several much as this geologic map was essentially com- localities, and detailed study and mapping have pleted prior to 1953, the in which the been made of the deposits from which they were United States Geological Survey published a collected. Principal localities studied include series of 7.5-minute quadrangles providing Jemez Creek, Galisteo Creek, and Santo Domin- coverage for the type area, we decided to pub- go valleys; various areas along the Ceja del Rio lish the map as compiled rather than to re-map Puerco, the Belen-Bernardo locality, the San the area, using the quadrangles as bases. Table 1 lists the United States Geological 'The Frick Laboratory was merged with the Depart- ment of Vertebrate Paleontology of the American Museum Survey topographic maps that are now (1969) of Natural History in I 968. available for the type locality. Names for washes 1971 GALUSHA AND BLICK: SANTA FE GROUP 15

TABLE 2 CORRELATIONOF NAMES OF WASHAND DRAINAGESYSTEMS USED BY FRICKLABORATORY COLLECTORS WITH NAMESLATER USED ON UNITEDSTATES GEOLOGICAL SURVEY TOPOGRAPHIC MAPS

Frick Names U. S. Geol. Surv. Names New Mexico Quadrangles

Boundary Wash Unnamed Tesuque, 1953 Rio Tesuque Rio Tesuque Tesuque, 1953 East Cuyamunque Wash Arroyo Cuyamunque Tesuque, 1953 Arroyo Ancho Arroyo Ancho Horcado Ranch, 1953 West Cuyamunque Wash Arroyo Jacona Horcada Ranch, 1953 First large wash north of the south Arroyo Madrid Espanola, 1953 boundary of the Santa Clara Grant Second large wash north of the south Arroyo la Mesilla Espanola, 1953 boundary of the Santa Clara Grant Joe Rak Wash Unnamed tributary of Arroyo Seco Espanola, 1953 Santa Clara Canyon Santa Clara Creek Puye, 1952 Third Wash Arroyo de la Morada Chimayo, 1953 Fourth Wash Arroyo de 10s Martinez Chimayo, 1953 Fifth Wash Arroyo de la Cuesta de 10s Vaqueros Chimayo, 1953 Sixth Wash Arroyo de 10s Ajuelos Chimayo, 1953 Seventh Wash Caiiada del Mogote Chimayo, 1953 Eighth Wash Arroyo de 10s Encinos Chimayo, 1953 Ninth Wash Caiiada del Ojito Chimayo, 1953 Tenth Wash Arroyo de la Caiiada Ancha Chimayo, 1953 Arroyo Seco; Big Wash Arroyo Seco Cundiyo, 1953 White Operation Wash Unnamed Cundiyo, 1953 Nambt Creek Pojoaque Creek Cundiyo, 1953 First Wash Arroyo del Llano San Juan Pueblo, 1953 Second Wash Arroyo Quarteles San Juan Pueblo, 1953 Dike Wash Arroyo del Palacio Chili, 1953 Rio del Oso Rio del Oso Chili, 1953 Spring Wash Arroyo Ojito Chili, 1953 South Wash Arroyo de la Presa Chili, 1953 Three Sand Hills Wash Caiion la Madera Medanales, 1953 Three Sand Hills Wash, Fork Caiion la Madera Medanales, 1953 Three Sand Hills Wash, South Fork Caiion la Madera Medanales, 1953 Tributaries of South Fork of Three Sand Hills Wash 1. Conical Hill Wash Caiion la Madera Medanales, 1953 2. Aelurodon Wash Caiion la Madera Medanales, 1953 3. Lobato Branch Caiion la Madera Medanales, 1953 4. Deer Springs Branch Caiion la Madera Medanales, 1953 5. South Branch Carion la Madera Medanales, 1953 Shorty Moore Wash Arroyo del Torro Medanales, 1953 Chama-el rito Wash Caiiada Honda Medanales, 1953 Kunya Ruins Wash Unnamed Abiquiu, 1953 Junction Wash Unnamed Abiquiu, 1953 First Steep Walled Wash Arroyo de las Mulas Ojo Caliente, 1953 Second Steep Walled Wash Caiiada de Tio Pula Ojo Caliente, 1953 Adobe Walls Wash Caiiada Ancha Ojo Caliente, 1953 Adobe Walls Wash Caiiada Ancha Lyden, 1952 Old Mastodon Wash Caiiada Abeque Lyden, 1952 Mastodon Wash Caiiada de la Cruz Lyden, 1952 Middle Ojo Caliente Wash, North Fork Unnamed Lyden, 1952 Middle Ojo Caliente Wash, South Fork Cafiada de 10s Alamos Lyden, 1952 Prince Ranch Wash Unnamed Lyden, 1952 Cerro de las Minas Wash Arroyo del Perro El Rito, 1953 16 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY VOL. 144 or drainage systems on these topographic maps logical Survey name appears in parentheses after rarely even resemble those used by Frick the Frick Laboratory term. Laboratory field parties for the same washes or Type localities of some of the Cenozoic forma- drainage systems. Therefore, table 2 is included tions in north-central New Mexico are shown in to enable workers of the future, who may be figure 3, whether valid or not, and their authors using Frick collections and records, to correlate and the dates on which they were described are these two sets of names. Where such duplicated also added as an aid to students of the Santa Fe names for washes or drainage systems appear in Group. the body of this report, the United States Geo-

ACKNOWLEDGMENTS

The late Mr. Childs Frick was particularly Taylor read the manuscript, and their help is interested in the stratigraphy and paleontology gratefully acknowledged. of the Santa Fe Group, and we are greatly in- We are especially indebted to Mr. Raymond debted to him for making it possible for us to J. Gooris for his skillful preparation of the study the geology of the Santa Fe area and to figures. prepare this report. It is a pleasure to acknowledge with warm Acknowledgments for aid are due to the appreciation the courtesies and much help that leaders and members of Frick Laboratory field has been given to us by many residents of the parties whose investigations through the years Espanola, New Mexico, area during the several since 1924 in the Santa Fe area have been the years of field work. Those to whom particular basis for some of the concepts of the stratigraphy thanks are due include: Mr. and Mrs. Carl of the Santa Fe Group herewith presented. Holmquist, Mr. C. V. Hunter, Mr. W. P. Cook, Prominent among these field men were the late Mr. Clarence Brashar, and Mr. G. Kenneth Mr. Joseph Rak, the late Mr. Charles H. Brashar, also the late Mr. F. R. Frankenburger, Falkenbach, the late Mr. Carl 0. Long, also the late Mr. Howard Barbee, and the late Messrs. William Klaus and Jack Wilson. Mr. John Davenport. For many years Mr. Mr. Morris F. Skinner studied the horses of Gordon Bond of Albuquerque generously pro- the Santa Fe Group, and Mr. Beryl E. Taylor vided us with permits to work on Bond Company studied the , merycodines, and carni- ranches in the Jemez Creek and Northern Ceja vores. Both gave generously of their interpreta- del Rio Puerco areas. tions of the biostratigraphic correlations. Special thanks are due to the many head men Deep appreciation is expressed to Dr. Glenn of the Indian Pueblos of the Rio Grande and L. Jepsen and to Dr. Franklyn Van Houten for Jemez Creek areas who, over the years, have their criticisms and helpful suggestions in the permitted us to work on Pueblo lands. Without early phases of work on the manuscript. Dr. their kind cooperation many of the localities Malcolm C. McKenna, Dr. Richard H. Ted- covered by this report could not have been ford, Mr. Morris F. Skinner, and Mr. Beryl E. studied.

HISTORICAL SKETCH WORK BY OTHER GEOLOGISTS , , and rocks Early exploring expeditions to the west often of the region, and of the igneous and meta- made Santa Fe, at the end of the Santa Fe Trail, morphic rocks of the Sangre de Cristo Range. one of their outfitting points. Geologists were Cenozoic rocks were considered of secondary occasionally attached to these expeditions, and importance. several of them made reconnaissance geological The first geological observations of the Santa explorations in the vicinity of Santa Fe, but Fe region were those of Wislizenus ( 1848) on his most of their published accounts were of the tour of northern Mexico in 1846 before the 1971 GALUSHA AND BLICK: SANTA FE GROUP 17 annexation of the Territory of New Mexico by logical Survey of Colorado and New Mexico the United States. He was soon followed bv (1869, pp. 66, 69, 70), quoted below, include military expeditions, on which some officers, the original description of the Santa Fe Forma- such as Lt. J. W. Abert (1848) and Major tion: "From Santa Fe to the banks of Gallisteo W. H. Emory (1848), included geological [sic] Creek, eighteen miles, we pass over the observations in their official documents. recent marls and sands which seem to occupy Marcou (1856) and Blake (1856, pp. 3 14-3 19) the greater portiori of the valley of the Rio were connected with railroad surveys of the Grande, above and below Santa Fe' which I west. have called the Santa Fe marls. These are mostlv Newberry (186 1, pp. 97-99) was a member of a light cream-color, sometimes rusty yellow, and two expeditions and was the first to report the sometimes yellowish white, and with layers of presence of Cenozoic rocks in the Santa Fe sandstones, varying in texture from a veky fine region. He mentioned the Cenozoic beds along aggregate of to a moderately coarse the Rio Puerco in his description of his 1858 trip. pudding stone. These marls and sands weather The following year, 1859, he was attached to the into unique forms north of Santa Fe, like the exploring expedition from Santa Fe to the junc- 'Bad Lands' or 'Mauvais Terres' of Dakota. . . . tion of the Grand and Green under From Santa Fe to Embudo Creek and mostly Captain Macomb, and in the report of the expe- even to Taos, the Santa Fe marls cover the dition stated (1876, p. 52) : "Tertiary rocks are country. On the east side of the Rio Grande I not a marked feature in the geology of the vicin- did not observe a single dike, from the Cerrillos ity of Santa Fe, but they are visible in a great to the mouth of the Chama Creek. North of that number of exposures, and usually form isolated the melted material has been poured over the patches of limited area, the remnants of more marl so as to form broad mesas. On the west side extensive deposits, now for the most part re- there are numerous outbursts of igneous matter. moved by surface erosion, to which their yielding These Santa Fe marls reach a ireat thickness nature has offered little resistance, as is true of north of' Santa Fe, in the Rio Grande Valley, patches of Tertiary lying along the eastern bases from one thousand two hundred to one thousand of the mountains. These beds are of very un- five hundred feet, and have tendency to weather equal thickness in different localities, and in into similar monumental and castellated forms, many instances, are mere local accumulations, as in the 'Bad Lands.' The upper portions are filling depressions or excavations in the surfaces yellow and cream colored sandstones, sands, and on which they were deposited. So far as my marls. Lower down are some gray coarse sand observations extended, they contained no beds with layers of sandstone. ~71these marls dip fossils." Newberry also briefly described the westward three to five degrees. The Rio Grande . wears its way through these marls with a bottom LeConte (1868) was the geologist with a about two miles wide. On the west side are dis- survey for the extension of the Union Pacific tinct terraces with the summits planed off Railway from the of smoothly like mesas. The first one is eighty feet to the ~ioGrande. Like the earlier investigators, above the river; the second one. two hundred with the exception of Newberry, he did not feet. These marls extend all the way between the mention the Tertiary deposits of the Santa Fe margins of the Santa Fe Mountains on the east area. and the Jemez Range on the west. Most of the In the summer of 1869 Hayden visited the Chama Hills, and I think the entire hills, are Santa Fe area as part of his survey of the Terri- composed of it. At the junction of the Chama tories of Colorado and New Mexico. He de- Creek with the Rio Grande, a point comes down scribed the deposits at length and named them between the two rivers which is covered with the "Santa Fe marls."l Excerpts from his pre- . This continues into the San Luis Valley liminary field report of the United States Geo- nearly to Fort Garland." The best-known works on the Santa Fe are 1In this Historical Sketch and in subsequent citations in those of Cope, who, in 1874, collected fossils the text, the terms Santa Fe marls, Santa Fe Formation, near Pojoaque and San Ildefonso. Cope (1874a, or Santa Fe Group are used as each author published them, and no attempt is made to discuss them uniformly at 1874b) correlated the Santa Fe marls with the the rank of group. "Loup Fork" of Colorado and Nebraska. He 18 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY VOL. 144 collected late Miocene fossils from the beds north Santa Fe beds as opposed to the lacustrine of Pojoaque, but obtained the bulk of his collec- theory as propounded by Hayden and Cope. tion, consisting of early Pliocene forms, from the Although the deposits that he described were not beds north of San Ildefonso and contiguous a part of the Santa Fe Formation, or of the Santa areas. For more than 90 years the initial mixing Fe Group as here restricted, his observations of the fauna has confused the paleontological and directed attention to the or fluviatile geological literature on the Santa Fe Group. origin of the beds and profoundly affected subse- Cope (1875a, 1875b) did not specifically de- quent work on the Santa Fe. scribe the beds fromwhich he obtained the fossils, Ogilvie (1905) described an erosion surface or but he did describe briefly the geology and surfaces near the south of Santa lithology of the Santa Fe beds in the vicinity of Fe as a high altitude conoplain; these surfaces Embudo, Ojo Caliente, and in the Chama River are known now as the Ortiz pediment or the valley. Cope correlated the fauna as equivalent Ortiz erosion surface. The Ortiz surface has to the "Loup Fork" Formation, then regarded figured prominently in geomorphological studies as Miocene, but repeatedly called the beds of the region. "Pliocene" in his 1874 field notebook, which is Keyes (1907a) cited Santa Fe marls as 500 preserved in the Osborn Library of the American feet thick and later (1907b) showed the Santa Museum of Natural History. Cope (1874a, Fe sands as 800 feet thick, and remarked on the 1874b, 1875a, 187513, 1884a) published a series confusion that existed regarding the beds. of papers on the vertebrate fauna from the Osborn and Matthew (1909) published a Santa Fe marls. bulletin on Cenozoic mammal horizons of North Stevenson (1881) was attached to the Wheeler America and listed Santa Fe mammals. Surveys west of the 100th Meridian in 1878 and Bryan, in 1909, published the first of a long 1879 and studied the Galisteo Creek area south list of papers on the beds of the Rio Grande of Santa Fe, New Mexico. The deposits in that Valley, and of the Rio Puerco, and many of area that he referred to the Santa Fe marls are these have dealt directly with the deposits of the now regarded as . Herrick (1898) Santa Fe Formation. Two of his later papers, wrote several papers on the geology of New published in collaboration with McCann (1937, Mexico, particularly on beds in the Albu- 1938) reported on beds of the Ceja del Rio querque-Belen basin, but he did not correlate Puerco, which these authors correlated with the them with the Santa Fe marls. Matthew (1899, Santa Fe Formation and separated into three pp. 26, 65) in his provisional classification of the divisions: (1) Lower Gray Member,l (2) Middle fresh-water Tertiary of the West, following Cope Red Member, and (3) Upper Buff Member. The and others, regarded the Santa Fe marls as three divisions are not applicable to the beds of beds. He also included a faunal list. Herrick and the type area of the Santa Fe Group for many Johnson (1900) collaborated on the geology of reasons explained at length elsewhere in this the Albuquerque Sheet and for the first time report. Bryan's most significant work on the recognized Tertiary rocks in the Jemez Creek Santa Fe seems to be his report (Bryan, 1938) on valley. the geology and ground-water conditions of the Reagan (1903) was the first to point out that Rio Grande depression in Colorado and New the Rio Grande was younger than Pliocene, and Mexico, in which he made important contribu- to recognize Pliocene strata in the Jemez Creek tions to the knowledge of the deposits along the valley. He cited deposits in several localities that Rio Grande. As would be expected, we have since have been correlated with the Santa Fe found that many of Bryan's generalizations and Formation. conclusions regarding the Santa Fe beds are In 1903, Johnson published a report on the open to other interpretations, and, where a geology of the Cerrillos Hills, and he was the divergence of opinion exists, the subjects are dis- first investigator to write extensively on the cussed under appropriate headings. lithology of the Santa Fe Formation. The de- Writing on the geology and physiography of posits that he described as part of the Santa Fe the Rio Grande Valley as a background for their Formation are now known to be Quaternary, but his excellent and exhaustive descriptions lGalusha (1966) designated this the Zia Sand Forma- established the theory of fluviatile origin of the tion. 197 1 GALUSHA AND BLICK: SANTA FE GROUP 19 studies on Pueblo Culture, Hewett, Henderson, Frick (1933, p. 549) described new remains of and Robbins (1913) presented a surprisingly trilophodont-tetrabelodont mastodonts from the modern account of the beds in the area, par- Santa Fe area and discussed the age of the beds. ticularly those now called the Bandelier Tuff. Simpson (1933) published a glossary and Osborn (19 18, p. 34) regarded the Santa Fe correlation chart of mammal- marls as transitional between the Miocene and bearing horizons, with a brief comment on the the Pliocene, but placed them at the base of his Santa Fe. Pliocene section. At a meeting of the Washington Academy of The first published use of the term Santa Fe Sciences, Hunt (1934) attempted the dating of Formation replacing the old term "Santa Fe structural events in the Mt. Taylor region, marls" was by Darton (1922, pp. 187, 221) in Nacimiento uplift, and on his report on the geologic structure of parts of the basis of the then supposed age of the Santa New Mexico. Fe beds. Simpson (1925) published a short note on the Stirton (1936), Osborn (1936), and Wilmarth Santa Fe Formation, in which he concluded that (1938) all published brief comments on the age the sediments were derived chiefly from the of the Santa Fe Formation. Santa Fe Range to the east. Just (1937) described the Carson Conglomer- Frick (1926a, 1926b, 1926~)described remains ate and also directed attention to beds of the of from the Santa Fe area in 1926; a Santa Fe Formation in the Picuris and Petaca study of the tooth sequence in certain trilopho- areas. dont-tetrabelodont mastodonts appeared later The period 1936 through 1938 saw a quicken- in the same year; and an article in Natural ing of interest in the geology and geomorphology History dealt with the romantic aspects of the of the Santa Fe and adjacent areas. Much of this search for fossils in the area and foreshadowed was due to the work of Bryan (1938), Bryan and his lifelong interest in the Santa Fe beds and McCann (1936, 1937, 1938), and by Bryan's fauna. students or associates. Cabot (1938, p. 88) In his paper on the "Red Beds" and associated reported on the fault border of the Sangre de formations in New Mexico, Darton (1928b) Cristo Mountains north of Santa Fe, New devoted two short paragraphs to the description Mexico, and briefly described the adjacent of the Santa Fe Formation and its fauna, but Santa Fe beds. mapped large areas of unconsolidated later Denny (1938) published a brief note on the Tertiary and Quaternary deposits as Santa Fe, Santa Fe Formation in which he emphasized thus adding to the confusion regarding the and restricted the type area. identity and extent of the formation. The Tertiary geology of the Abiquiu Quad- Renick (193 1) described Santa Fe beds along rangle was described by Harold T. U. Smith Jemez Creek in his report on the geology and (1938, p. 933), who made valuable contributions ground-water resources of western Sandoval to the geology of the area by mapping the El County, New Mexico. Parts of the beds that he Rito Formation and the Abiquiu Tuff. These included in the Santa Fe were removed as the formations previously had been mapped as part Zia Sand Formation by Galusha (1966). of the Santa Fe Formation. Atwood and Mather (1932, pp. 19, 98) listed Church and Hack ( 1939) regarded the basalt several localities in the Abiquiu area in which capping Cerro Pedernal as part of the Santa Fe Santa Fe beds are exposed; they correlated these Formation and cited several hypotheses con- beds with their Conejos and Los Pinos formations cerning the former and present extent of the of Colorado. The principal basis for correlation Santa Fe at the north end of the Jemez Moun- was the presence, in the gravel beds of the tains. Abiquiu localities, of andesite breccia that they Beds in the San Acacia area south of Albu- regarded as derived from, or equivalent to, the querque were treated by Denny (1940a) in con- Conejos Andesite. siderable detail. He correlated some of them with A gravity separation and thin-section study of the Santa Fe Formation, but the fossils that he three selected sedimentary samples from the cited as evidence for correlation are lacking in "Santa Fe Marls" were made by Howard (1932, the deposits of the type area and furthermore pp. 12,21). suggest late Pliocene or early Pleistocene. These 20 BULLETIN AMER1C.W MUSEUhl OF XITURAL HISTORY VOL. 144 rocks are probably nearer in age to the Gila could not have been published widely and thus Conglomerate of Arizona and southern New made more available to the general public. Mexico than to any rocks in the type area of the Kelley (1952, p. 93) dealt with the tectonics Santa Fe Group. Lithologically these beds near of the Rio Grande depression, and some of his San Acacia should be described as a new forma- conclusions relating to the Espanola Valley and tion, and many data can be adduced to show environs are discussed below in the section on that the deposits named the Upper Buff Member Structure. of the Santa Fe Formation by Bryan and Two reports on the Galisteo-Tonque area McCann (1937) should be included in the same were published by Stearns (1953a, 1953b) in Formation. Later, in the same year, Denny which important new pre-Santa Fe formations (1940b) made a reconnaissance of a part of the were described and their relations to supposed Santa Fe Group in the Espanola Valley in the Santa Fe beds were described in detail. The type area. He briefly described the lithology and supposed Santa Fe beds in the Galisteo-Tonque structure and speculated at length on the origin area are discussed in this report under the head- and source of the formation. ing Zia Sand Formation. During 1941 the formations lying north of the Montgomery (1953),working on Precambrian Santa Fe Group received attention, and the geology of the Picuris Range, mapped and Vallejo Formation was described and its relation described the relations of the Santa Fe beds in to the Santa Fe beds was discussed by Upson that locality. (1941). A tectonic map by Kelley (1954) of a part of Stearns (1943) mapped the Galisteo Forma- the Rio Grande area makes no pretense at tion in the Galisteo-Tonque area and removed separating pre-Santa Fe and post-Santa Fe from theSanta Fe Formationlargeareasof Pleisto- faults, which leads to an exaggeration of the cene and other deposits. Beds along the western concept of the fault border of the Sangre de edge of the Galisteo-Tonque area were mapped Cristo Mountains between Chimayo and Santa as part of the Santa Fe Formation, but the ages Fe. of these beds have not been proven. In 1956, in a guidebook for the New Mexico Sayre and Livingston (1945, p. 39) referred Geological Society, Kelley gave his interpreta- deposits in the El Paso area, Texas, to the Santa tion of some of the stratigraphy and structure of Fe Formation and summarized Bryan's (1938a) the Santa Fe type area. That guidebook also work as evidence for the correlation. contained Baldwin's (1956) article in which he Wright (1946) applied Bryan and McCann's first proposed expanding the term Santa Fe to system of division of the Santa Fe Formation to group status, and Montgomery's (1956) con- the Lower Rio Puerco area, the deposits of densed remarks on the Picuris Range. McKinley which he described in great detail. He presented (1956, 1957) dealt with Tertiary volcanic rocks extensive hypotheses relating to the source, to the north of the Santa Fe type area. mode of origin, transportation, and deposition Larsen and Cross (1956), in a paper on the of the Santa Fe Formation. Wright referred geology and petrology of the San Juan region, deposits in the Lower Rio Puerco to the Santa explored still further the relation between the Fe Formation that the present writers believe volcanic rocks of the San Juan region and areas should be included in other formations. in northern New Mexico. Santa Fe beds were Butler (1946) mentioned the Santa Fe beds in reported by Tonking (1957) in the Puertocito his report on the geology of the Tusas-Tres Quadrangle, but that correlation is question- Piedras area. able. Simpson summarized the information known Disbrow and Stoll (1957), working in the concerning the Santa Fe Formation, in Colbert Cerrillos area, added information concerning et al. (1950), for a guidebook for the Fourth the beds underlying the Santa Fe and com- Field Conference of the Society of Vertebrate mented at length on the Ancha Formation about Paleontology. This was probably the first of a six years before the Ancha was formally pro- series of guidebooks for field conferences by posed by Spiegel and Baldwin (1963). various geological societies extending over a Significant additions to the knowledge of the period of about 12 years. It is regrettable that rocks underlying the Santa Fe were provided by some of the information in these guidebooks Sun and Baldwin (1958). 1971 GALUSHA .\ND BLICK: SANTA FE GROUP 2 1 Barker (1958), in the Las Tablas Quadrangle, tions of the relations of the voIcanic rocks of the correlated the Cordito Member of the Los Pinos by Ross, Smith, and Bailey Formation with the Santa Fe Formation. (1961) add greatly to the knowledge of the Powell (1958), working in the San Luis Valley western border of the type area. A paper by in Colorado, correlated a few small exposures Ross and Smith (1961) dealt exhaustively with with the Santa Fe Formation, but stated that ash-flow tuffs in general, and specifically with (p. 20) "The Santa Fe Formation underlies welded and nonwelded ash-flow tuffs of the almost all the San Luis Valley." He cited numer- Jemez Mountains (Valles Mountains). ous well logs as penetrating Santa Fe beds to A voluminous report on the geology and various depths, but also indicated that in some water resources of the Santa Fe area by Spiegel wells the top of the formation was not reached at and Baldwin (1963) unfortunately covered only 3645 feet, and, furthermore, he stated that the the extreme southern portion of the type area of Santa Fe beds may exceed 5000 feet in thickness the Santa Fe Group, as here restricted, and con- in the San Luis Valley. A hypothesis that these sequently only a smalI fraction of the beds were beds may, in fact, represent a distinct formation treated. The terms Santa Fe Group and should be investigated. Moreover, they more Tesuque Formation were formally proposed. nearly may be correlatives of beds in the adja- These, and various subjects covered in their cent Arkansas River valley a few miles to the paper, are discussed in detail under several north than to beds in the Espanola Valley more headings in our report. than 150 miles to the south. Miller, Montgomery, and Sutherland (1963) The Bishop's Lodge Member of the Tesuque mapped beds in the Picuris area of the Sangre de Formation and the Tesuque Formation were Cristo Mountains and made observations on informally proposed by Baldwin (1956). The beds of the Santa Fe Group and on the Servil- Bishop's Lodge Member was studied by Boyer leta Formation. (1959), who suggested that the member and the Siems (1964) summarized the correlation of beds underlying it should be separated from the Tertiary strata in mountain basins in southern Tesuque Formation. Colorado and northern New Mexico and, in so Miller and Wendorf (1959) presented evi- doing, emphasized, and occasionally com- dence for an interpretation of the late terraces in pounded, the problems relating to correlations the Tesuque Valley. in the Santa Fe area. Budding, Pitrat, and Smith (1960), in the Beds overlying the Santa Fe Group along the Guidebook of the New Mexico Geological Sur- western border of the type area were described vey for the Chama River country, described by Griggs (1964), and part of the beds correlated additional areas of the El Rito Formation. They by Spiegel and Baldwin (1963) as the Santa Fe regarded the Abiquiu Tuff as a member of the Group were separated as the Group. Santa Fe Formation and correlated the upper Dane and Bachman (1965) published a part of the Abiquiu Tuff and the lower part of generalized geologic map of New Mexico. Baltz the Santa Fe Formation with the Los Pinos (1965) attempted a correlation of rocks in the Formation in north-central Rio Arriba County, San Luis Valley of Colorado with those of the New Mexico. Santa Fe Group. Kelley and Clinton (1960, p. 53) reported Albritton and Smith (1965) discussed beds in that 9000 feet of Tertiary rocks were drilled in the Sierra Blanca area of Hudspeth County, Humble Oil Company's Santa Fe No. 1 well on Texas, and explored the possibility of correlating the Gabaldon anticline along the southwest side them with the Santa Fe Group, but understand- of the Albuquerque-Belen basin. ably they were unwilling to do more than Kottlowski (1960) mapped the Santa Fe suggest a correlation. Group in the Las Cruces Quadrangle. Lambert (1966) included the Picuris Tuff, Another guidebook by the New Mexico Geo- Tesuque Formation, and Servilleta Formation logical Society carried two useful articles on in the Santa Fe Group in the Taos-Questa area virtually unmapped areas. Spiegel (196 1) sug- and directed attention to several sets of younger gested that two unnamed formations exist in the sedimentary rocks. Santa Fe Group, in the Lower Jemez Creek The Zia Sand Formation in the Jemez Creek region, but failed to name them. Cogent explana- area was described by Galusha (1966). 22 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY VOL. 144 Bingler (1 968) treated Cenozoic rocks quite extends over years of intensive investigation of briefly in his study of the geology and mineral any specific area can result only from a well- resources of Rio Arriba County and expressed planned program carried out with vision and the opinion (p. 38) "that the lower 300 feet of tenacity of purpose. A history of the work of the Precambrian clast gravel included in the Abi- many Frick Laboratory field collectors since quiu Tuff are the lateral equivalent of the Ritito 1924 who have labored in the Santa Fe area Conglomerate and that the upper 1000 feet of can be deciphered partly from a search of the conglomerate represent the southwestern exten- archives of the Frick Laboratory. These archives sion of the ." The Santa Fe are composed primarily of the carefully pre- beds were treated as a formation, not as a group, served copies of Childs Frick's letters to the and were said to intertongue with the Los Pinos leaders of his field parties, and the equally Formation east of El Rito Creek through Ojo complete files of their replies, reports, maps, Caliente, La Madera, and Servilleta Plaza. diagrams, photographs, and specimen lists The recently published circular on the Santa covering their work. Fe Group in the south-central New Mexico Frick's decision to start work in the Santa Fe border region by Hawley and others (1969) area was a direct result of his recognition of summarizes the current knowledge of the beds remains of the genus Hemicyon Lartet in the that are included in the Santa Fe Group in Frick Collections from the Barstow beds of southern New Mexico and parts of west Texas southern California; Hemicyon had been found and northern Chihuahua, Mexico. In our previously only in Europe. He then recognized opinion an unbiased analysis of the data and that a fragment of mandible that Cope had ob- arguments presented in the circular will show tained in the Santa Fe Marls in New Mexico in that the report is its own best unintentional 1874 and had called Canis ursinus was really advocate for the proposal to separate the de- Hemicyon. A short trip to natural history mu- posits of the border area from those of the type seums in and Lyon, France, confirmed his area of the Santa Fe Group. Obsolete terms such identification. On his return to the United as Herritk's (1898) "Rio Grande Series" or States he asked W. D. Matthew, who then was "Rio Grande Gravels," or Bryan's (1909) "Rio leading an expedition for the American Mu- Grande Beds," should be seriously re-examined seum of Natural History in Texas, to undertake for possible change in rank to Rio Grande a survey of the Santa Fe area in the hope that Group as an appropriate name to receive the additional Hemicyon material might be found. deposits of the border area. Matthew sent his assistant, G. G. Simpson, and The Bailey, Smith, and Ross (1969) report on Charles Falkenbach, to the area; within five the stratigraphic nomenclature of volcanic rocks days Simpson and Falkenbach had discovered in the Jemez Mountains, New Mexico, as was the only Hemicyon skeleton that has been found the Hawley circular listed above, arrived too in the Santa Fe area.1 late to be included in the discussions in our The Hemicyon skeleton figured prominently in report, but it contains new and important infor- a report by Frick (1926a) on the Hemicyoninae mation, particularly pertaining to radiometric and an American Tertiary bear, in which he dates of volcanic rocks cropping out in areas succinctly stated a philosophy for collecting contiguous to the type area of the Santa Fe fossils, a philosophy to which he closely adhered Group. throughout the remainder of his life (p. 19) : During the past hundred years the Santa Fe "Curiously enough this was the one and only marls have become known as the Santa Fe specimen of Hemicyon found during some nine Formation and finally as the Santa Fe Group. weeks in the field. This splendid and unique The concept of Santa Fe has grown from the trophy, which the storms and disintegration of original type area to encompass any late Ter- another season might have utterly destroyed, tiary or Pleistocene volcanic or sedimentary beds has greatly increased our knowledge of this in the Rio Grande trough, a distance of 1800 miles. lone additional partial skull of Hemicyon, and a few IVORK BY THE FRICK LABORATORY isolated jaws and teeth, are all the remains of that genus that have been collected under prolonged and intensive Paleontologic and stratigraphic work that search in the area since 1924. FIG.4. General 1,ic.w of part of Espanola Valley lookinq sliyhtly south of wcst from a hiqh riclqe south of C:himayo, New Mexico. Whit(. Operation Wash clrains bctls in forcqrouncl ancl enters Santa Cruz River in right miclcllc clistancc ncar line of trees, markinq coursc of Santa Cruz Ri\,cr ncar its mouth on Rio Grandc at Espanola, Nvw Mexico. Rio Granclc flows from right to left in vallcy (abovc ccntcr of photoqraph), passing throuqh 1':spanola ancl along farther side of Round Mountain (left). Santa Clara Canyon was cut through wc.11-markccl tcrrace underlain by Puyk Conqlomcratc wcst of Rio Granclc (just lcft of town of Espanola). NambC Membcr of 'Tcsuquc 1:ormation unclcrlics forcgrountl ancl covcrs about half of photograph. Rccl Wall is promincnt bluff (slightly above ccntcr, cxtrcmc lcft), and No. 1 Whitc Ash at its base marks start of Skull Ridge Mcmbcr of 'Tcsuquc Formation. Skull Riclgc Member is shown by belt of clifTs on cach siclc of Whitc Operation Wash. Pojoaque Membcr of Tesuquc Formation, somewhat less rugged than Skull Ridqe Membcr, lies beyond it. North Pojoaque B1uff.s lie at extreme lcft, just below and almost in line with Round Mountain. Across the Rio Granclc, sloping surface of Puyi. Conglomeratc shows plainly; highlighted pro- montories of ovcrlying Bandclier Tuff in left two-thirds of photograph visible along base of Jcmcz Mountains. Thickness of Bandelier Tuff increase5 toward south (lcft) ; that of PuyC Conglon~eratedccrcascs toward south. Battleship Mountain is promincnt bluff right of and slightly abovc Rouncl Mountain. 'Tschicoma Pcak is snow-capped pcak on right skyline; Ahiquiu Pcak is at cxtrcmc right. 24 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY VOL. 144 genus, the characters of the skull and skeleton of since the E. D. Cope expedition of 1874. The which have heretofore been unknown. great collection of mastodont specimens from "The recent recognition of Hemicyon in the Santa Fe, made primarily by the Joseph America illustrates the danger, in the present Rak party, formed a large part of two reports on state of paleontological knowledge, of too greatly the mastodonts by Frick. One of these (192613) stressing the absence from any particular fauna concerned the tooth sequence of certain trilo- of any particular , as well as the great phodont-tetrabelodont mastodonts, and the need of active and sustained field work in old as other (1933) described new remains of trilopho- well as new localities. For onlv, bv, the continued dont-tetrabelodont mastodonts. These two re- collection of the remains of the life of the past, as ports were considered by Frick to be contribu- brought to the surface through the seasonal ero- tions to the information being amassed by sion of ancient accumulations of sand and clay, Osborn as a basis for the latter's (1936) mono- data available today and gone forever to- graph on the Proboscidea. morrow, may we learn the history of nature's Two of Joseph Rak's early maps are repro- course in the production of existing forms, of duced (figs. 5, 6). These were made before ade- those that were in the broad sense ancestral to quate base maps were available and, although the faunas of today, and of those strange and not drawn to scale, present a reasonably faithful unthought of forms that predominated in and reproduction of the actual topography as it vanished with the faunas of the past." would be seen in the field. Charles Falkenbach Owing to the excitement gdnerated by the joined Rak's party in 1926 and was later to work discovery of the Hemicyon skeleton, Frick trans- in the Santa Fe area intermittently during the ferred his then main collector, Joseph Rak, to next 25 years. Santa Fe; hence, within five weeks of Simpson The Red Layers of the Santa Cruz locality and Falkenbach's arrival in the Santa Fe area, were worked extensively in 1927, and the field two fossil collecting parties were hard at work. party of 11 men made a very large collection. Rak remained in the field six weeks longer than Much attention was given to geology and Simpson and Falkenbach and was successful stratigraphy as was shown by the exchange of enough that Frick sent him back to the Santa Fe letters for the year. the following spring, thus establishing a collect- In 1928 Frick first brought John C. Blick, ing pattern that continued with scarcely a break who had been collecting at Keam's Canyon in for more than 40 years. Arizona, to the Santa Fe area to join Joseph During the 1925 field season Frick twice Rak. Blick was later to take full charge of the visited the Santa Fe field and for several years Santa Fe field, but, as part of Frick's policy of thereafter made an annual visit to the area. continuity of field work, Blick worked with Rak During this first full year of work Rak had for several years. 1928 was the year in which the Charles Christman of the American Museum as first of several sites and small quarries were dis- an assistant. Frank Naranjo, the first Santa covered in beds that are now called the Chamita Clara Indian assistant, was also hired, setting a Formation. precedent for later Frick Laboratory parties, for Rak had an able young assistant, Jack Wilson, many of the Santa Clara men became excellent working with him in the Barstow beds of Cali- fossil hunters and several of them were hired fornia and during the 1929 summer season took year after year. The greatest number of Indians Wilson with him to Santa Fe. The following that worked at one time was nine in 1927. year, 1930, Rak put Wilson in charge of actual By 1926 Frick began requiring more precision field work, although he retained supervision. in designating the localities from which speci- Rak had developed serious foot trouble, which mens were collected and further expanded the prevented further field work and finally cul- requirements of field correlations within the minated in his death from multiple tuberculosis area. In addition to the report on the Hemi- on August 17, 1932. Jack Wilson remained in cyoninae, Frick (1926~)published a popular charge of collecting through 1931. No work was account of the geology and paleontology of the done in the Santa Fe area in 1932, ostensibly Santa Fe area. This was the era in which the because the collectors were busy in other fossil Santa Fe beds were an essentially virgin field for fields from which information was urgently fossil collecting, not having been prospected needed. FIG.5. First map of Espanola fossil-collrcting arca drawn by Josrph Rak, in 1924, shortly after start of work by thr Frick Laboratory. Highest hills at left are thr central Pojoaque Blufh (United States Geological Survey : Lor Barrancos). I:rc,. 6. Map of Espanola arca drawn by Joscph Rak at cnd of 1924 collcctin~season. Arca was cli~iidcc~into districts to aid in locating specimens in thc ficlcl. 197 1 GALUSHA AND BLICK: SANTA FE GROUP 2 7 John C. Blick assumed control of the Santa Fe pleted (1940, 1941, 1947, 1949, 1968) and has field party in 1933 and began an extensive study included descriptions of several new forms, of the structure and stratigraphy of the area; together with brief remarks on the biostrati- these studies continued through 1934. Blick graphy of the Santa Fe beds based on the became ill in 1935, and consequently Charles oreodonts. Falkenbach was transferred to the area accom- No work was done in 1943 in the Santa Fe panied by his assistant, Everett De Groot. area, but in 1944 and 1945 Blick, Falkenbach, Falkenbach and De Groot continued to lead and George Sternberg collected a few fossils. On parties in the area in 1936; during this period November 1. 1945. Galusha returned to the most of the work in the Round Mountain Santa Fe field to work on geology and resumed Quarry was done. Views of the early stripping leadership of the fossil collecting party as well. in this quarry are shown in figure 8. Blick drew Blick remained actively interested in the geology a map of the area in 1936, which is shown in and made annual visits until 1955, two years figure 7. Blick returned to the field for a few before his death. He generously shared his field weeks in early 1937 but soon left to collect observations with Galusha, and these observa- Pleistocene fossils near Fairbanks, Alaska, leav- tions formed the bases for many of the early ing Everett De Groot in charge, although working hypotheses on the geology and strati- Falkenbach and William Klaus also sent in graphy of the area. Galusha has continued to material that year. Klaus had worked with work in the Santa Fe area to the present time Blick in various fields since 1933 and was in and is responsible for the compilation, organiza- charge of Santa Fe operations from 1938 tion, and interpretation of the field data, and for through 1941 whenever Blick was not in the the writing of this report, which is only a digest field. In 1937 Frick published his monograph on of a small part of the amassed information. the horned ruminants of North America, in An analysis of the work by the Frick Labora- which he recognized or described 17 genera, tory in the Santa Fe beds emphasizes several subgenera, or species of the Cervidae and the salient features, with perhaps the most outstand- , and also two genera of the ing being Frick's profound and unflagging , from the Santa Fe area, New interest in the paleontology, stratigraphy, and Mexico. general geology of the area-an interest suffi- Frick decided to begin intensive work on the ciently great to span a period from 1924 to his geology and stratigraphy of the Santa Fe beds, death in 1965. This interest was so keen that as well as carry on the usual collecting activities, even lean months or years of collecting could not and accordingly, by 1940, Ted Galusha was cause him to abandon the field. The search for transferred from the Hay Springs, Nebraska, new, additional, or better material from strati- field to work with Blick on the stratigraphy of graphically controlled collections was the aim of the area. Blick and Galusha continued to work Frick Laboratory field parties, especially after on the geology through the 1941 field season and 1940, and much work was done on unproductive the early part of the 1942 season. Blick then left or nearly unproductive horizons in attempts to the field, leaving Galusha in charge of collecting fill gaps in the . No other fossil and the study of the geology. field has had a more sustained investigation than The first of Schultz and Falkenbach's studies that of the Santa Fe area, nor has any fossil field of various subfamilies of oreodonts was pub- had a more carefully controlled continuity of lished in 1940. This series was recently com- field work. ]:I(:. 7. Two-part map of Espanola arca clrawn by .John C. Elick in 1!)136. Ins(-t at Icft shows an arm lying north ant1 northwest of that on maill part of lii;ll). Rc.li-rc.ncc. ~~oirltsfor tli(. two l)arts arcx S;tn ,Jr~anl'r~c.l,lo, c.onflr~c.ncc*of Rio C:lia11in ;~litlRio (:rantl(,, and sorlrhwc.stc~~~~~ rip of 13l;rc-k Mesa. FIG. 8. Round Mountain Quarry. A. Excavation at Round Mountain Quarry in 1936. Boulders on slopc at lcft arc latite and porphyritic latitr rroding from PuyC Conglomeratr. 13. I'roductivr fossil layer at Round Mountain Q~iarry(X). William Klaus, party lradcr, srconcl from right. is stand- ing at contact of Chamita Formation with ourrlying I'oyC Conglomcratr: contact can bc secn rlrarly just above light-colored strata (miclway in photo- !?raph). STRATIGRAPHY

THESTRATA OF THE pre-Santa Fe Group appear (1869) and Cope (1875a). Bryan (1938, p. 205) to include the first of the Tertiary system de- stated that these beds had become generally posited in the Rio Grande depression, which is a known as the Santa Fe Formation and then complex series of structural depressions first added "the main body of sedimentary deposits recognized by Lee (1907) but named by Bryan of the Rio Grande depression, from the north (1938, p. 197). Beds in this division that crop out end of the San Luis Valley to and beyond El in the type area of the Santa Fe Group are the Paso, is considered to be of the same general age Galisteo Formation (Hayden, 1869) and the El and to belong to the Santa Fe formation." Rito Formation (Harold T. U. Smith, 1938). Denny (1940b, p. 678) designated the type area Beds outside the type area that may belong in of the Santa Fe Formation as "the region north this grouping are those described by Upson of Santa Fe, New Mexico, between the Sangre (1941) as the Vallejo Formation of the eastern- de Cristo and Jemez Mountains." Moreover, he most re-entrant of the San Luis Valley in Colo- recognized that the unconsolidated deposits in rado. The Baca Formation was described by the Rio Grande depression were divisible into Wilpolt et al. (1946) who stated, "It is quite several formations, both above and below the possible that the Baca formation is correlative Santa Fe Formation. His observations were dis- with the Galisteo sandstone (Tertiary) of the regarded by Spiegel and Baldwin (1963, p. 38) , for lithologically they are simi- who proposed "that the term Santa Fe be raised lar." The age and correlation of the McRae to group status, and that all the basin fill, Formation have not been firmly established, whether Tertiary or Quaternary, be included in although Cretaceous dinosaur material has been the Santa Fe group." In addition they further found in the lower part of it, but Kelley and extended the term (p. 39) to include additional Silver (1952) chose to separate it as a new forma- concepts as follows: "Therefore, the Santa Fe tion rather than to include it in the Baca as pro- group is here considered to be a broad term posed by Wilpolt et al. (1946). including sedimentary and volcanic rocks related Another recognizable broad grouping of beds to the Rio Grande trough, with a range in age overlies the El Rito and Galisteo formations and from middle( ?) Miocene to Pleistocene( ?)." is composed predominantly of tuff or other As restricted by the present writers, the Santa volcanic debris. Three formations in this second Fe Group is comprised of two formations : (1) the grouping are recognized in the type area of the Tesuque Formation and (2) the Chamita Santa Fe Group, i.e., the Abiquiu Tuff (Harold Formation (new name). T. U. Smith, 1938), Picuris Tuff (Cabot, 1938), The Tesuque Formation was formally pro- and the Espinaso Volcanics (Stearns, 195313). posed by Spiegel and Baldwin (1963, pp. 39-40), The Popotosa Formation (Denny, 1940a) of the but that formation in the present report has been Socorro area may belong in this division. The restricted and redefined and now has five mem- upper part of the Datil Formation of Win- bers: (1) the NambC Member, (2) the Skull chester (1920) may also be equivalent. The third Ridge Member, (3) the Pojoaque Member, division contains one formation, the Zia Sand (4) the Chama-el rito Member, and (5) the Ojo Formation (Galusha, 1966), comprised of two Caliente Sandstone. A section of this report is members. The lower or Piedra Parada Member assigned to a discussion of each of the members produced the first early Miocene (Arikareean) of the Tesuque Formation and includes the fauna reported from New Mexico. The upper or details of the rock-stratigraphic and biostrati- Chamisa Mesa Member contained early medial graphic evidence. Miocene fossils of approximately Hemingfordian The uppermost formation of the Santa Fe age. Group, as restricted in this report, is the Cham- In this report most of these formations are ita Formation. The beds of this formation are discussed under separate headings. lithologically and faunistically distinctive and We propose to restrict the term Santa Fe appear to represent deposits that accumulated Group to those deposits that crop out in the through a large portion, but not all, of medial classic type area of the Santa Fe marls of Hayden Pliocene time (Hemphillian). GALUSHA AND BLICK: SANTA FE GROUP

I Scale: inch= 100' -8

FEET

Upper tuffaceous zone

Conical ,.,ill Quarry

. 4 White Ash White Operation Quarry Channel above Ash F

om be' White Ash

The "double purple"

FIG. 9. Composite stratigraphic section and correlation chart of Santa Fe Group. Some of the main ash beds and important stratigraphic horizons are shown. Approximate age relations and thicknesses of strata are included. BULLETIN AlMERICAN MUSEUM OF NATUR.4L HISTORY VOL. 144

Espanola Valley

Charnita Formation

Pojoaque Member

Chama-el rito Member

Skull Ridge Member

~amb6Member

FIG. 10. Correlation diagram showing stratigraphic relations of members of formations of Santa Fe Group in Espanola Valley compared with those of Abiquiu re-entrant. Tpt, Picuris Tuff; Ter, El Rito Formation. Age relations of various members are shown on two geologic-time scales. 1971 GALUSHA AND BLICK: SANTA FE GROUP 33 The Pleistocene and Recent formations that source rocks, at different times, and were are exposed in the type locality of the Santa Fe obviously laid down in a great variety of sedi- Group are diverse lithologically and commonly mentary environments. Distinctive lithologic are of smaIl extent; however, the smalI area characteristics rarely can be correlated between covered by each of these formations is hardly an these basins, and heterogeneity cannot be cited index to its importance in the geologic sequence. logically as a basis for correlation, inasmuch as These post-Santa Fe Group formations include many of the supposedly unfossiliferous beds can a wide variety of deposits. The diversity of these be shown to have been deposited at widely later deposits, even in the type area of the Santa different times. These disparities emphasize the Fe, emphasizes the utter confusion that would need to use every available tool in correlating result if these were to be included in the Santa late Tertiary and Quaternary formations, and Fe Group. Discussed in this report in appropri- the beds of the Santa Fe Group and contiguous ate sections are the following: (1) Puyt Con- beds in particular. glomerate, (2) Ancha Formation, (3) deposits Fossils have not been used as criteria for defin- on erosion surfaces, (4) Zia Marl, (5) Servilleta ing the formations of the Santa Fe Group in this Formation, (6) Espanola Formation, (7) varved report. Fossils have been, however, a most useful or rhythmical sediments, (8) Otowi Lava Flow, tool for our determining in which portion of the (9) Bandelier Tuff, (10) Cerros del Rio lava geologic section intensive search should be made flows, (1 1) high-level basalts, (12) volcanic for observable physical features that would serve rocks, (13) Rio del Oso dikes, and (14) Round as a basis or foundation for the study of the Mountain. stratigraphy of the group. Inasmuch as fossils In the present state of the investigation, an were used as guides to the recognition of useful accurate correlation of events and deposits boundaries that are meaningful for rock strati- corresponding to the Glacial and ~ntergiacial graphic work, it should be apparent at once that stages of the Pleistocene is not possible, but evi- fossils should be utilized further, wherever dence exists in this area and adjacent ones which possible, to add the necessary verification of if properly integrated may lead to surprising stratigraphic position. To do otherwise is to results. accept such premises as that it is impossible to If the mappable formations that crop out assemble a type section (Spiegel and Baldwin, along nearly 1800 miles of the Rio Grande 1963, p. 39), or to present a complete strati- depression were all considered a part of the graphic column (Denny, 1940b, p. 680) because Santa Fe Group, the only characteristics they of faults and variability of the beds, or to know would have in common would be that some of whether the fauna comes from the base or the them would be classified as conglomerate, con- top of the formation (Bryan, 1938, p. 205). We glomeratic sandstone, silty sandstone, siltstone, do not accept these premises, but hereinafter and some clay or claystone. Not even color could present many data drawn from rock-unit and be pressed into service as an aid in correlation. biostratigraphic-unit sources, seeking to provide The beds along the Rio Grande depression were a balanced explanation of the geology, strati- deposited in separate basins, as pointed out by graphy, and some of the broader aspects of the Lee (1907) and elaborated later by Bryan (1938). biostratigraphy of the Santa Fe Group. These deposits were derived from different

PRE-SANTA FE GROUP TERTIARY FORMATIONS

EL RITO FORMATION and the maximum thickness is 200 feet. As The name El Rito Formation was applied by pointed out by Smith, the rock is so well con- Harold T. U. Smith (1938, p. 940) to a narrow solidated at many localities that it will break belt of brick-red deposits along the northwestern across the fragments and pebbles rather than edge of the Rio Grande depression in the Abiquiu around them. The principal localities, as given Quadrangle. The formation consists of well- by Smith, are: in the Ortega Mountains, along consolidated sandstone, conglomerate, and both branches of El Rito Creek, in the badlands breccia, in which quartzite pebbles are dominant west of Cerro de las Minas, on the north bank of 34 BULLETIN AMERICAN MUSEUM OF N.4TURAL HISTORY \'OL. 144 the Chama about 5 miles west of Abiquiu, and (1938, p. 958) placed it as "at least pre-Upper in the vicinitv of Caiiones. Other localities were Miocene, and conceivably it may even be as old cited as cropping out along Arroyo Hondo about as ." The El Rito seems to be the first unit 4 miles south of the town of Santa Fe and along in the Abiquiu area deposited subsequent to the little Tesuque Canyon 5 miles northeast of faulting that formed the original Rio Grande Santa Fe. depression. In the area immediately south of We have found one exposure of the El Rito Santa Fe, New Mexico, this same relation is Formation in the vicinity of Chimayo, New shown by the Galisteo Formation. Stearns Mexico, where the El Rito deposits crop out in a (1953b, p. 468) correlated with his Espinaso short wash on the south side of the Santa Cruz Volcanics certain red conglomeratic beds in River less than 1 mile below the mouth of the Arroyo Hondo that Smith (1938, p. 943) cited Rio Quemado. The beds preserved at this point as typical localities of the El Rito Formation. are remnants of a small fault block bounded on These beds are regarded by the present writers the east by the finer sediments of the Tesuque as part of the red-bed phase of the upper part of Formation of the Santa Fe Group, and on the the Galisteo Formation. The red-bed phase of west by predominantly coarse, reddish to light the Galisteo Formation that crops out along the sand in which ~ebblesand cobbles are numer- escarpments southwest of Lamy, New Mexico, ous. Small, terraced, irrigated fields surrounding and along United States Highway 85 at La the low ridge of El Rito sediments effectively Bajada Hill suggests a close similarity between prevent lateral tracing of the exposure. The low the El Rito Formation and the upper part of the ridge is not more than 15 to 20 feet high and less Galisteo Formation. The La Bajada Hill red than 300 feet long. More than 50 small to very beds also were mapped by Stearns (195313, pl. 1) large blocks of dirk to bright red conglomerate as Espinaso Volcanics, and consequently a con- of jasperoid appearance are associated with this tinuity of correlation is suggested by several ridge of sediments. Some of the blocks are larger workers for this series of beds. Spiegel and Bald- than 15 feet long, 15 feet wide, and 6 feet thick. win (1963, pp. 37, 38) differed from both Smith The rock bre&s smoothly 'across quartzite and Stearns in their interpretation of the beds in pebbles and finer-grained matrix. The coarser Arroyo Hondo. The El Rito Formation was clastics had been originally stratified, and the extended by Budding, Pitrat, and Smith (1960, bedding planes are well marked on weathered p. 82) to additional areas along El Rito Creek surfaces on which the rounded quartzite pebbles and in valleys east of Arroyo del Cobre, east of and cobbles stand out in shar~relief. These large Madera Canyon, and near the crest of Magote blocks indicate that they hai been undercut yn Ridge. They present alternative explanations approximately their present position and then of the origin of the red matrix to that presented slum~edto their Dresent attitude. No block was by Smith, Stearns, and others. obseked to be &sting on an original bedding plane. GALISTEO FORMATION A com~arisonof sam~lesof sediments from Variegated sand and sandstones along the the locality near Chimayo with samples from valley of Galisteo Creek near Los Cerrillos, sites near El Rito, New Mexico, and near New Mexico, were described by Hayden (1869, Abiquiu shows close adherence to the general pp. 40, 67, 90) as the Galisteo sand group and lithologic pattern of the type El Rito Formation. assigned by him to the middle Tertiary. Lee and The Chimayo samples, however, are finer- Knowlton (1917, pp. 184, 185) discussed the grained; the conglomerate is more dense, with relations of the Galisteo sand and suggested that smaller pebbles, but all other characteristics it might be correlative with the Wasatch. Pre- appear common to the three localities, such as viously the Galisteo sand had been considered those cited by Smith (1938, p. 940) as being Triassic by Cope, and Cretaceous by Stevenson, dominantly composed of quartzite pebbles with Johnson, and others. Darton (192813) mapped volcanic material absent, deep red stain, and the Galisteo Sandstone as part of the upper

beingw so well cemented that it breaks across Cretaceous Montana Group but noted that it rather than around the fragments and pebbles. was probably early Tertiary in age (p. 52). The age of the El Rito Formation is uncertain, Stearns (1943, p. 301) redefined the formation for no fossils have been reported from it. Smith and mapped it in greater detail than had any 1971 GALUSHA AND BLICK: SANTA FE GROUP 35 previous investigator. Stearns (1953b), in a later vellowish and white cross-bedded coarse sand. report, greatly increased the detail of his geo- Conglomerates are not so prevalent as in the logic map and speculated at length on the basins type locality near Cerrillos, and in general the of north-central New Mexico and the part the beds are softer, with slightly different weathering Galisteo basin and its deposits played in the geo- characteristics. Red, green, yellow, and brown logic history of the region. Unfortunately, out- colors predominate in the section. These beds of-register color patterns make unclear the exact were mapped by Renick (1931, p. 308) and contact between the Galisteo and the overlying referred by him to the Lower Wasatch, and are Espinaso Volcanics in the critical area along exposed only between the Sierrita fault and the State Highway 10 in and adjoining the old Jemez fault. The small collection of fossils from Sweet's Ranch east of Los Cerrillos, New Mexi- these beds consists of the skull, mandible, parts co. From this general locality, Robinson (1957) of several rami, and other skeletal parts of a reported a molar that indicated an titanothere, and a few fragments- of-teeth and early Eocene age for some of the lower beds. bones of other mammals. Stearns (1943, p. 310) reported the first mam- Brick-red and maroon clay and sandy-clay malian fossils from the formation, and these beds crop out southwest of Lamy, New Mexico, were interpreted as Duchesnean in age. There is and along Highway 85 at La Bajada hill. Thin no general agreement among paleontologists beds ofwhite sandstone are commonly associated and geologists as to whether the Duchesnean with these red beds. As mentioned above in the should be considered latest Eocene or earliest section on the El Rito Formation, we regard . In any event, the Galisteo Forma- these red beds as a part of the upper beds of the tion, on present evidence, appears to have been Galisteo Formation. Disbrow and Stoll (1957, accumulating during most, if not all, of the p. 11) also suggested that the El Rito Formation Eocene . may be correlative with the Galisteo Formation. A small collection of mammalian fossils made The exposures of the El Rito Formation at by the Frick Laboratory in and near the "petri- Chimayo, New Mexico, and at Arroyo Hondo, fied forest" on Sweet's Ranch, east of Los south of Santa Fe, support the hypothesis that Cerrillos, New Mexico, and also south of the El Rito Formation and the Galisteo red-bed Galisteo Creek southeast of the ranch are of late phase are probably equivalent. Fossils are few in Eocene aspect. On the evidence now available, the red-bed phase of the Galisteo, and to date a late Eocene age is indicated for a large part of none have been reported from the El Rito, but the uppermost beds of the Galisteo Formation. eventually fossils may be found in both and pro- The Galisteo Formation is composed of vide the biostratigraphic information needed to fluviatile deposits including sandstone, sand, supplement rock-stratigraphic data. conglomerate, clay, , and water-laid The Galisteo beds of the Pajarito fault wedge, tuff. Silicified wood is abundant in many beds which is situated at the base of St. Peter's Dome of the formation, and at a few localities (notably (Ross, Smith, and Bailey, 196 1, p. 140), contain Sweet's Ranch) large, horizontally lying logs are lenses of cobbles in which occasional boulders fairly numerous; however, smaller fragments as much as 4 feet in diameter have been ob- scattered over the exposures are more typical. served. These cobbles are of limestone, quartzite, Lee and Knowlton (1917) and Stearns (1943, granite, gneiss, sandstone, and other rocks. They p. 308) described and figured Galisteo beds near are not so densely packed nor are they so firmly Hagan, an abandoned mining camp in the held by the red-stained matrix as is characteris- Tonque Wash area at the northeast end of the tic of the El Rito Formation in its type locality. Sandia Mountains. The boulders are larger than any noted by the In the Jemez Creek valley south of the town writers in the Galisteo Formation or in the of San Ysidro we discovered a new locality of the Espinaso Volcanics, but are not so large as some Galisteo Formation. The correlation is based on in the El Rito Formation. At this locality the lithologic similarity; the presence of silicified Galisteo beds dip westward at a high angle and wood, a few logs of which measured more than are estimated to be more than 200 feet thick: 20 feet in length; and mammalian fossil content. they display characteristics that are reminiscent In the new locality silicified wood is fairly of both the El Rito Formation (Harold T. U. abundant and is confined mostly to beds of Smith, 1938) and the red-bed phase of the 36 BULLETIN AMERICAN MUSE1LiM OF NATURAL HISTORY VOL. 144 Galisteo Formation. That these characteristics been written concerning the fact that the occur in the same sequence of beds we believe Abiquiu Tuff and most of the deposits correlated provides proof of the equivalence of at least part with it underlie beds of the Santa Fe Formation, of the two formations, and marks this as a or beds believed to be of Santa Fe age. This has significant, if not critical, outcrop of the Galisteo led to speculation concerning the age of the Formation. A yellowish set of sandstone and Abiquiu Tuff, based primarily on the concept of cobble-conglomerate deposits lies with strong a middle Miocene and early Pliocene age for the angular on some of the red beds. Santa Fe, and this speculation has often influ- The matrix between the cobbles is relatively fine enced the interpretation of age for volcanic and and suggestive of Galisteo lithology, although a other rocks in northern New Mexico and south- similar fine, but red instead of yellowish, matrix ern Colorado. has been observed locally in the El Rito Forma- We collected extremely fragmentary fossils tion in the Abiquiu area. from Abiquiu Tuff deposits, but these fossils The coarse beds of the Pajarito fault wedge were not numerous enough or well preserved suggest the interesting hypothesis that a major enough to prove surely diagnostic for age deter- source of the Galisteo sediments lay to the north minations of the formation. More fossil mam- or northwest. because the clasts in the con- malian material probably could be found in the glomerate in the wedge average significantly Abiquiu Tuff if it were intensively prospected; larger than those found in the type locality of this might prove to be a rewarding research field the Galisteo Formation. for future investigators. Smith found no sharp contact between the ABIQUIU TUFF Santa Fe Formation and the underlying Abiquiu The Abiquiu Tuff was first described by Tuff. We, however, found contacts between the Harold T. U. Smith (1938, p. 944) and is com- Abiquiu Tuff deposits and the Santa Fe Group posed mainly of thick, stream-laid tuff and vol- deposits at several localities. Contacts were canic conglomerate deposits, although concen- observed in the headward forks of Cerro de las trations of granitic and quartzitic cobbles and Minas Wash (United States Geological Survey: boulders are not infrequent, especially in the Arroyo del Perro) ; along the east side of El Rito lower part of the formation. The Abiquiu Tuff Creek; and the best exposure of all is on the rests unconformably on the El Rito Formation flanks of the Ojo Caliente intrusive, which is and older rocks. The deposits range from white about 2 miles southwest of the town of Ojo to purplish gray or brownish gray in color. Con- Caliente. A well-marked and well-exposed un- siderable variation in color and lithology is conformity exists between the Chama-el rito observed laterally in the formation, and almost Member (see p. 64) of the Tesuque Formation as much variation can be seen in the vertical of the Santa Fe Group and the Abiquiu Tuff section. east of the Ojo Caliente intrusive. The Abiquiu Smith (1938, p. 945) stated that "The Abiquiu Tuff, at this point, consists of greenish tuff with Tuff underlies about one-eighth of the total area included, isolated, angular blocks of crystalline of the Abiquiu quadrangle." The outcrop belt is rocks scattered throughout the deposit. The widest west and southwest of the Ortega Moun- included rocks are not numerous and range in tains and in the vicinity of the town of El Rito. size from pebbles to small boulders. The dip of The formation narrows toward the southwest the tuff along most of the contact is about and passes under the Canones Andesite south of 14 degrees east. The dip of the overlying beds of the Chama River in the vicinity of the town of the Chama-el rito Member adjacent to the Abiquiu. Smith (1938, p. 945) cited other contact is about 9 degrees east. The beds are so detached areas in the Abiquiu Quadrangle. closely parallel that it is difficult to differentiate Beds in adjacent areas have been correlated them without instruments. The Santa Fe beds with, or questionably correlated with, the adjacent to the contact consist of thick beds or Abiquiu Tuff by Stearns (1943, p. 31 7; 1953b, lenses of volcanic gravel of usually smaller-than- pp. 469, 496), Disbrow and Stoll (1957, p. 27), cobble size, with rare concentrations of small Budding, Pitrat, and Smith (1960, p. 84), Ross, boulders. The thick gravel beds are loosely Smith, and Bailey (1961, p. 142), Spiegel and cemented by calcium carbonate. Thin strata of Baldwin (1963, p. 57), and others. Much has fine sand, typically buff, tan, or pinkish in color, 1971 GALUSHA AND BLICK: SANTA FE GROUP 3 7 are intercalated among the gravel lenses, and The Picuris Tuff was deposited during the the fine sand may contain very small pebbles or widespread volcanic activity that preceded the granules of the volcanic rock. The color of the deposition of the beds of the Santa Fe Group. gravel deposits, viewed from a distance, is a The sediments equivalent to the Picuris Tuff dark brownish or reddish gray, and on many from Chimayo, New Mexico, southward are slopes the pebbles that have eroded from the dominantly gray tuff, in which the pebbles are gravel lenses form a mantle of rock, which im- mostly volcanic, although much granitic materi- parts a dark color to the hills in contrast to the al is present. Along the mountain front between light shades of buff, tan, or pink that are the Chimayo and Santa Fe, several small remnants usual colors of the finer-grained sediments of the of amygdaloidal basalt flows crop out. One flow Chama-el rito Member. The lithology is very north of Nambd Creek along the base of Pinyon different along the line of contact. Mountain is similar to that mapped by Cabot Another locality on the Ojo Caliente intrusive, (1938, p. 92) near En Medio and Chupadero. farther south and west of the one described Another amygdaloidal flow is exposed just west above, shows an irregular surface of uncon- of the Bishop's Lodge-Santa Fe road, about a formity. At one point all but the lowermost of quarter of a mile south of the entrance to the the Chama-el rito beds at the contact have been Lodge. Gray tuff is quite extensive in this stripped away, and the actual surface of contact locality. These beds, near Bishop's Lodge, have can be studied over a small area. Still farther been described and mapped as the basal part of west, in the vicinity of the west-throwing fault the Tesuque Formation by Spiegel and Baldwin along the southwest side of the intrusive, an (1963, p. 36). South of Santa Fe, in Arroyo angular unconformity has been observed. Hondo, are gray tuff beds associated with fairly Fossil fragments and specimens of Chama-el thick lava flows. The flows and tuff overlie red rito Member age have been collected from the beds that were correlated by Smith (1938, thin, intercalated, buff sand layers, and a few p. 943) with his El Rito Formation, but mapped have been obtained less than 6 feet above the by Cabot as part of the Picuris. Stearns (1953a, contact. Along the south side of the intrusive p. 430; 1953b, p. 468) and Spiegel and Baldwin the Chama-el rito beds are in direct contact with (1963, p. 37) each interpreted them differently. an eroded surface of metamorphosed tuff and The red sediments are regarded by us as part of intrusive rock. the Galisteo Formation, and the overlying gray tuff as part of the Espinaso Volcanics, which PICURIS TUFF crop out in great thickness 10 to 15 miles to the Tuffaceous deposits similar in lithology to south (Stearns, 1943, p. 304). parts of the Abiquiu Tuff crop out at widely We consider the Picuris Tuff as part of the separated points along the western border of the same general period of volcanic activity as that Sangre de Cristo Mountains north of Santa Fe, in which the Abiquiu Tuff and Espinaso Vol- New Mexico; these were described as the canic~were deposited. The problem of strati- Picuris Tuff by Cabot (1938, p. 91). In the type graphic correlation of these three formations area, near the town of Vadito (Badito in Cabot's should receive intensive study by an investigator, report) in the Picuris Range, Montgomery or investigators, who will bring to bear every (1953, p. 52, pl. I) mapped in detail additional available thread of evidence from sedimentology, exposures of the Picuris Tuff. Cabot mapped volcanology, petrology, or related branches of other localities of volcanic rocks north of Santa geology. We hope, as a result of intensive field Fe as part of his Picuris Tuff, and the degree to work, diagnostic fossils may be found that will which isolated outcrops, particularly of volcanic be useful in establishing precise geochronologic rocks, can be shuffled from one formation to correlations. Certainly with the radiometric another by different investigators is well shown techniques now available it would be possible to by the treatment that has been accorded these establish the age of these volcanics. rocks: Harold T. U. Smith (1938, p. 934); Denny (1940b, p. 683); Stearns (1953a, p. 431); ESPINASO VOLCANICS Disbrow and Stoll (1957, p. 24) ; Sun and Bald- Stearns (1943, pp. 303, 309, 310) briefly de- win (1958, p. 22); Boyer (1959, pp. 64, 72); and scribed the Espinaso Volcanics and discussed Spiegel and Baldwin (1963, p. 43). their relation to the underlying Galisteo Forma- 38 BULLETIN AMERICAN MUSEUM OF N.4TUR4L HISTORY VOL. 144 tion. He is undeniably the author of the forma- Mammal ages of , Orellan, Whit- tion, although he credited the name to an un- neyan, and possibly early Arikareean. published manuscript on the Santa Domingo Valley by Bryan and Upson. Ten years later ZIA SAND FORMATION Stearns (1953a, pp. 415-452) published an ex- The Zia Sand Formation described by panded description of the formation, in which Galusha (1966) crops out at several localities in he met all the requirements of establishing a the Jemez Creek drainage basin and in a few of formal name for the Espinaso Volcanics. the canyadas along the northern part of the As stated above, we regard the Espinaso Ceja del Rio Puerco in Sandoval County, New Volcanics, the Picuris Tuff, and the Abiquiu Mexico. No counterpart of this formation occurs Tuff as broadly equivalent. Stearns (1953a, stratigraphically in the type area of the Santa Fe pp. 421, 422) stated that the Espinaso Volcanics Group, for no equivalent beds either lithologic- are unconformably overlain by deposits that he ally or temporally have been recognized; there- assigned with a query to the , fore, the Zia Sand Formation has been removed which further emphasizes the desirability of from the Santa Fe Group. future studies of the three formations. Radio- The Zia Sand was divided into two members metric studies carefully tied to a rock-strati- by Galusha (1966, p. 9): (1) the lower, or graphic framework may provide the desired Piedra Parada Member, which is of late Ari- margin of confidence for positive correlation. kareean age and approximately equivalent to All three of these formations can be traced from the Harrison Formation of the Great Plains, and one to the other with interruptions of only a few (2) the upper, or Chamisa Mesa Member, of miles. They all crop out as isolated deposits Hemingfordian age. around the periphery of the Santa Fe Group These beds were described as belonging in the from Galisteo Creek northward along the west- Santa Fe Formation by Renick (1931, p. 57), ern border of the Sangre de Cristo Range to the and the area selected as the type locality of the Picuris re-entrant near Dixon, New Mexico. Zia Sand by Galusha was cited by Renick as the Basalt mesas and some beds of the Santa Fe area in which the relation of the Santa Fe Group underlie an area a few miles wide that Formation to the Wasatch was exposed. Field separates the Picuris Tuff from the Abiquiu Tuff work by us strongly suggests that Renick's deposits of the Abiquiu re-entrant. On some of Wasatch there was actually a part of the Galisteo their outcrops they are all observed to lie on Formation, for a late Eocene titanothere skull formations that have bright to dark red color, and several jaws were collected a few feet below that is, these volcanic formations lie on the El the contact. Miocene fossils collected in the gray Rito Formation at the north and on the upper sand beds that Renick called Santa Fe were soon beds of the Galisteo Formation at the south. The discovered to be appreciably older than any that Picuris Tuff and the Abiquiu Tuff directly had been collected in the type area of the Santa underlie the deposits of the Santa Fe Group. At Fe Group. The Standing Rock Quarry and its no point have the present writers observed the extensions produced a large collection of Steno- Espinaso Volcanics to underlie beds that they mylus, and many remains of Daphoenodon, Cynarc- regard as part of the Santa Fe Group. toides, Promartes, the Archaeolaginae, and a few These deposits of volcanic debris must certain- rodents. Bryan and McCann (1937, p. 808) ly have marked a distinctive climatic change mapped these same gray sand deposits as their from that characteristic of the El Rito , as lowermost division of their threefold division of was pointed out by Harold T. U. Smith (1938, the Santa Fe Formation, which comprised p. 944). Stearns (1953a, p. 427), however, re- (1) Lower Gray Member, (2) Middle Red garded the Espinaso Volcanics as succeeding the Member, and (3) Upper Buff Member (p. 81 I). Galisteo Formation without a stratigraphic They based the conclusion that the Santa Fe Formation could be extended to the Ceja area break, and ascribed the change in sedimentation on the following: ". . . that [p. 8071 the term to the formation of eruptive centers in and near 'Santa Fe formation' may be properly extended the basin of deposition (p. 428). to this area rests on two lines of evidence: The ages of these three formations can be (1) fossil evidence of equivalent age and (2) bracketed as falling within the provincial Land- continuity of slightly dissimilar and deformed 1971 GALUSHA AND BLICK: SANTA FE GROUP 39 alluvial deposits extending from the city of Santa Santa Fe beds, and here, again, the beds are Fe southwestward to this area." not lithologically similar to those of the Santa Fe Extensive fossil collecting by the present type area nor do they contain fossils that are writers in the Jemez Creek and Ceja del Rio equivalent to those of the Santa Fe type area. Puerco areas has resulted in detailed strati- The beds in the Santo Domingo Valley that have graphic sections on which the stratigraphic posi- been called a part of the Santa Fe Formation tions of all major fossil specimens have been should be described as a new formation separate plotted. Detailed areal maps have been con- and distinct from any in the Santa Fe typd area. structed, and these studies have resulted in the Bryan and McCann (1937, p. 810) stated decision to remove the Lower Gray Member of that: "South of San Felipe and west of Bernalillo, Bryan and McCann from the Santa Fe Forma- fan deposits of a general reddish color are inter- tion partly because the lithology is sufficiently fingered with the river gravel. The river gravel different from that of the Santa Fe type area that at the west end of the bridge over the Rio no basis exists for rock-stratigraphic correlation. Grande at Bernalillo dips 2" to the south. On Moreover, the contained fossils are not equiva- both sides of Jemez Creek, to the north and lent in age to those obtained from any beds that west of this locality, there are poorly exposed, have been referred to the Santa Fe. Bryan and deformed beds consisting largely of alluvial fan McCann (1937, p. 810) attempted to trace the deposits. These beds resemble those of the Lower Santa Fe Formation from its type locality north Gray Member (hereinafter defined) of the Santa and west of the city of Santa Fe to the Ceja. Fe Formation and extend westward to the area Regrettably they failed to recognize that the here considered." The deformed gray sand beds beds they were tracing westward to the Cerros that they cited as occurring on both sides of the del Rio, and south to Galisteo Creek, were Jemez creek to the north and west are not Pleistocene in age, and on rock-stratigraphic equivalent to the Lower Gray (Galusha, 1966) criteria should not have been considered a part but lithologically and faunally are similar to the of the Santa Fe Formation. Spiegel and Baldwin Oiou Caliente Sandstone Member of the Tesuaue (1963, p. 45) recognized that these beds should Formation. This fact emphasizes the care that be separated from the older deposits and pro- must be used in correlating similar-appearing posed the name Ancha Formation to receive beds in any of the areas in which possible Santa them. The beds that Bryan and McCann (1937, Fe equivalents are exposed. Spiegel ( 1961, p. 810) thought were interbedded with basalts of pp. 133, 137) recognized that the Santa Fe beds the Cerros del Rio proved to be part of the in the Lower "Temez Creek could not be de- Ancha Formation (Spiegel and Baldwin, 1963, scribed adequately on the basis of Bryan and p. 51). We determined, as early as 1941, that no McCann's Upper Buff, Middle Red, and Lower beds that we recognized as Santa Fe in age were Grav members and treated them as Lower exposed south of the city of Santa Fe to Galisteo ~niamedFormation and Upper Unnamed Creek east of the Cerrillos Hills, and this deter- Formation, each of which had three or more mination has been substantiated by the mapping members. of Spiegel and Baldwin (1963) except for one The Tesuque Formation (Middle Red of small group of outcrops, which they recognized Bryan and McCann) was traced and prospected as Santa Fe, along Arroyo Hondo, and by for fossils from the Canvada Piedra Parada east- Stearns (1943, 1953b). The geologic map of ward across the various fault blocks that have New Mexico by Dane and Bachman (1965) successively offset the Tesuque (Middle Red shows the area as Santa Fe Group Undivided, Member). The gray sand beds at the top of the following Spiegel and Baldwin's proposal (1963, Tesuque Formation increase in thickness in an p. 39) to broaden the use of the term Santa Fe easterly direction, with maximum thickness Group, which effectively demonstrates how the exposed southwest of Santa Ana Pueblo and generalized use of a group term can negate the south of Jemez Creek where cemented dikes precise mapping of an area, in this case by the commonly associated with fault zones are con- men who proposed the broad term. Bryan and spicuous topographic features. The red deposits McCann (1937, p. 810) cited areas in Santo underlying Santa Ana Mesa north of Jemez Domingo Valley from Rosario Siding to the Creek, and those overlying the gray sand south vicinity of Bernalillo that they interpreted as of Jemez Creek, mentioned above, are part of 40 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY VOL. 144 the same formation. If fossils had not been avail- and temporally distinct from any beds in the able to point the way toward investigation of the type locality of the Santa Fe Group, and it was stratigraphic position of these beds, it would partly on this basis that the formation was have been natural to assume that the gray sand described (Galusha, 1966). The Zia Sand is well was a lateral facies of the Zia Sand, an early and exposed in the East Fork of the Canyada Piedra medial Miocene (Arikareean and Hemin- Parada (where a type section was designated fordian) formation. Actually they belong high and a type section figured by Galusha, 1966, in a set ofstrata of early Pliocene (Clarendonian) p. 3, fig. 2). The type area lies west of the Jemez age. The Tesuque (Middle Red of Bryan and fault in sects. 11, 12, 13, 23, and 24, T. 14 N., McCann) Formation can be shown to be faulted R. 1 E., of the New Mexico Principal Meridian and buried by the Upper Buff in the Lower in Sandoval County, New Mexico. The type Jemez River region.1 The red deposits in the section was designated as starting a few yards Lower Jemez area that have been confused with north of the south line of the NW. f of sect. 11, the Middle Red are interfingered laterally T. 14 N., R. 1 E., Sandoval County, and was toward the west with the buff beds of the Upper then measured through the Standing Rock Buff of Bryan and McCann and presumably are Quarry in a southerly to southeasterly direction essentially a facies of the same formation. across sect. 14 and the northern part of sect. 23. On purely rock-stratigraphic criteria all the The deposits of the Zia Sand Formation are various recognized subdivisions of the formations extremely soft sandstones composed of slightly in the Jemez Creek, Ceja del Rio Puerco, and cemented medium- to coarse-grained quartz Lower Ceja del Rio Puerco should be described sand. A few thin beds of fine-grained sandstone, as separate formations and not correlated direct- siltstone, and calcareous material crop out. In ly with the formations of the type locality of the the Piedra Parada Member, which is the lower Santa Fe Group. member, colors are dominantly light gray. In The Zia Sand Formation of the Jemez Creek the upper member, the Chamisa Mesa Mem- and Ceja del Rio Puerco areas is lithologically ber, colors also are mostly gray, but yellowish gray or pinkish gray bands may be numerous 'Spiegel (1961, p. 132) described and mapped the toward the top of the member. A type section Lower Jemez River Region and directed attention to two was figured for the Chamisa Mesa Member new unnamed formations. (Galusha, 1966, p. 10).

SANTA FE GROUP The predominantly fluviatile, deformed, fossil- north end of the San Luis Valley to and beyond iferous, slightly consolidated sedimentary rocks El Paso, is considered to be of the same general north of Santa Fe, New Mexico, have been age and to belong to the Santa Fe Formation." described by various writers as the Santa Fe One of Bryan's students, Denny (1940b, Formation. The beds were originally named the p. 678), formally established the type locality for Santa Fe marls by Hayden (1869, pp. 66-67) the Santa Fe Formation, but other students who briefly described the beds and the area in followed, understandably, Bryan's broad con- which they were well exposed. Cope (1874a, cept of the Santa Fe as a term to be applied to 1874b, 1875a, 1875b) described fossils that he any late Tertiary, slightly consolidated or un- obtained near Pojoaque and San Ildefonso and consolidated, basin deposits occupying the Rio made some geological observations of the de- Grande depression, and even adjacent areas. posits, which he called the Santa Fe marls. By Bryan (1938, p. 205) based his all-inclusive 1922, Darton (1922, p. 57) recognized the beds concept that the basin deposits were referable to as the Santa Fe Formation, and all subsequent a single period of deposition contemporaneous workers followed that concept. Bryan ( 1938, with the beds of the type locality near Santa Fe p. 205) cited the type locality as being near on four general criteria: "(1) All the beds are Santa Fe, New Mexico, but on the same page slightly cemented, and the finer-grained mem- first expanded the concept of the Santa Fe bers have concretions of calcium carbonate; Formation: "The main body of the sedimentary (2) all the deposits are deformed, mostly by deposits of the Rio Grande depression, from the normal faults, although in the centers of the 1971 GALUSHA ,4ND BLICK: SANTA FE GROUP 41 basins the deformation is so slight as to pass un- volved rocks ranging in age from to noticed except under intensive search; (3) the Recent. Evidence has been presented to show, beds within any one basin are of diverse litho- moreover, that the deposits in the Rio Grande logic types ranging from coarse fanglomerate to trough" have been deformed at different times silt and clay, and abrupt changes in the kind and and at different degrees of intensity. sizes of the contained pebbles are characteristic; Nearly all strata of the Santa Fe Group of and (4) these markedly different materials other authors, south of the Espanola Valley, are attributed to one formation conform in their younger than those of the type area of the Santa arrangement to a geographic pattern consistent Fe Group, as here restricted (this paper, p. 43). with the laws of deposition in basins." Kottlow- (Exce~tionsare the Zia Sand Formation and the ski (1953, p. 144) suggested, and Spiegel and iquivalents of a part of the Pojoaque Member of Baldwin (1963, pp. 38, 39) formally proposed, the Tesuque Formation in the Jemez Creek and that the term Santa Fe be raised to grouD Northern Ceia del Rio Puerco areas. These areas u A .s status. In our opinion such an extension renders are situated in the extreme northwestern corner the term useless, for the Rio Grande is 1800 of the Albuquerque-Belen basin.) Such younger miles long, with its valley now underlain by beds are less deformed than are those of the type Cenozoic sedimentary rocks derived from ex- area, as would be expected, and the fact that the tremely diverse provenances. We are opposed to youngest sediments would normally be deposited applying either the term Santa Fe Formation or near the centers of the basins would seem a Santa Fe Group indiscriminantly to any sedi- plausible explanation of Bryan's observation mentary or volcanic beds related to the Rio that in the centers of basins the deformation is Grande depression. We believe that Bryan's, and slight. In the type area (Espanola Valley) the Spiegel and Baldwin's, proposals should be beds of the restricted Santa Fe Group are examined carefully and objectively, point by strongly deformed. No difference can be detect- point. We also believe that under such scrutiny ed between the amount of deformation of the it will become obvious that the term Santa Fe restricted beds in the center of the valley and Group should be restricted to those beds actu- that of the restricted beds in other parts of the ally cropping out in the type area, or for those valley. Some beds not included in the Santa Fe that can be shown to be traceable from the type Group are only slightly deformed, for example, area to contiguous areas. Ancha Formation, PuyC Conglomerate, Ban- The first of the four general criteria cited by delier Tuff, Espanola Formation (defined in Bryan (1938, p. 205) was, "(1) All the beds are this report), and other later deposits. Where slightly cemented, and the finer-grained mem- these later beds are at the surface, careful search bers have concretions of calcium carbonate." for faults must be made. These later beds are This same observation can be made of many late separated from the Santa Fe Group on several Tertiary, and also of Pleistocene, deposits in lithologic and other criteria. Deformation of the Arizona, Colorado, Kansas, Nebraska, Cali- beds, although observable, cannot properly be fornia, Texas, and other states. Therefore, the a basis for designation or correlation of a rock- criterion, at best, should be afforded only stratigraphic unit. supplementary consideration in correlations Brvan's third criterion was, "(3) the beds - \, between basins. within any one basin are of diverse lithologic The second criterion stated that "(2) all the types, ranging from coarse fanglomerate to fine deposits are deformed, mostly by normal faults, silt and clay, and abrupt changes in kind and although in the centers of the basins the de- sizes of the contained pebbles are characteris- formation is so slight as to pass unnoticed except tic." No evidence exists to prove that "the di- under intensive search." Deformation of de- verse lithologic types" m;ntioned by Bryan posits can hardly be classed as a valid reason for could qualify under Article 6, Remarks (a) extension of rock-stratigraphic units from one category (ii) of the Code of the American Com- local area to a contiguous one; deformation is mission on Stratigraphic Nomenclature ( 196 1, considerably less valid when applied to deposits p. 650) as "repetitions of two or more lithologic of widely separated basins. Many writers have types," nor would it qualify under category mapped normal faults in and adjacent to the (iii), "extreme heterogeneity of constitution Rio Grande depression; these faults have in- which in itself may constitute a form of unity 42 BULLETIN AMERICAN MUSEUM OF N.ATUR.L\L HISTORY VOL. 1G compared to adjacent rock units." A much that fossils can be a most useful tool if used stronger argument could be presented to show properly. Our original purpose was to classify that the diverse lithologic types cited by Bryan the rocks lithostratigraphically into their proper would serve better to differentiate the various sequence, and this classification, when accom- formations than as a basis for bringing them plished, paved the way for a plausible bio- together. stratigraphic interpretation. The end result is The Rio Grande depression was named by that "diverse lithologic types" are not so Bryan (1938, p. 197), who drew upon the de- diverse when compared with beds of equivalent scriptions of Lee (1907, pp. 12-16). Kelley (1952, age. Only when late beds are compared with p. 92) expanded and refined the concept in his earlier ones are the differences compounded discussion of the tectonics of the depression. above and beyond that inherent in the deposition Essentially, the Rio Grande depression is a of sediments from different source rocks under series of structural basins, apparently arranged varying conditions. We reject the third criterion tn echelon. They are primarily the result of as meaningless and inapplicable to correlation faulting, and each was filled with sediments of beds in the Rio Grande de~ression. during some part or parts of Tertiary or Quater- The fourth criterion seemed to have been nary time, or during both. given particular weight by Bryan, for he follow- Each structural basin is rimmed bv vastlv ed it with a statement that has profoundly differing mountain ranges, uplands, or plat- affected subsequent thought on the extent of the forms. They vary markedly in size and shape, Santa Fe Formation. As cited the criterion is as and the formations that are now ex~osedon the follows: ". . . and (4) these markedly different peripheries of these basins are different in materials attributed to one formation conform lithology and in age. Sediments derived from in their arrangement to a geographic pattern such diverse and deposited in the consistent with the laws of de~ositionin basins. separate basins would necessarily result in litho- The main body of sedimentary deposits of the logic heterogeneity. The ancestral Rio Grande Rio Grande depression, from the north end of was not a factor in the filling of the Rio Grande the San Luis Valley to and beyond El Paso, is L. depression until after the major period of defor- considered to be of the same general age and to mation in late Pliocene, when the various basins belong to the Santa Fe Formation." Even a became linked as drainage basins rather than as cursorv analysis of the various basins of the Rio depositional basins. The deposits of the separate Grande depression shows that great variation basins, before they were integrated by the Rio exists in the pattern of deposition in them. Grande, would have had only grade size of the A paragraph on the ancestral Rio Grande in clastic sediments in common, such as clay, silt, this report (p. 118) deals directly with the prob- sand, cobbles, and boulders (with the possible lem of late deposition in the Rio Grande de- exception of volcanic tuffs derived from volcanic- pression. At noFpointhave the deposits of a large ash falls). Stratigraphic lacunae (Gignoux, 1955, perennial river been recognized in formations p. 15) representing significant periods of non- of the Santa Fe Group as here restricted. The deposition or erosion and recognized as dis- de~ositsassociated with the Rio Grande are conformities unquestionably have had a pro- younger, as pointed out above, and should be found effect on the beds south of the type area, separated from those of the type area. especially those of the southern part of the Spiegel and Baldwin (1963, pp. 38, 39) Albuquerque-Belen basin and farther south. followed and expanded Bryan's concept of the The fossils that have been collected from the Santa Fe Formation, raising the term to group various basins in the Rio Grande depression status and including in it "all the basin fill show that the beds that are now exposed were whether Tertiary or Quaternary . . . including deposited at different times; those south of the sedimentary and volcanic rocks related to the Espanola Valley are significantly younger (with Rio Grande trough, with a range in age from the exceptions noted above under Bryan's middle(?) Miocene to Pleistocene ( ?) ." In our second criterion). Fossils are excluded from con- view this all-inclusive extension of the term sideration in the definition or differentiation of a Santa Fe is unjustified and will lead to a wholly rock-stratigraphic unit under the Code of unworkable concept of the lithology of the Santa Stratigraphic Nomenclature, but we believe Fe. Any advantage that could be gained by 197 1 GALUSHA AND BLICK : SANTA FE GROUP 43 being able to assign beds indiscriminately to the divided into two formations (see fig. 9 and dis- Santa Fe Group in the Rio Grande trough would cussions in this paper, pp. 44, 71). These forma- be more than offset by the loss of precision in the tions have been separated on lithologic charac- attempt to erect a stratigraphic sequence for the ters, stratigraphic sequence, and other rock- beds in the trough. The ultimate aim should be stratigraphic criteria. to elucidate and refine the historical geology of Theoretically, as noted above, rock-strati- the beds in the trough rather than to extend the graphic units should be designated without term Santa Fe, as proposed by Spiegel and regard to the fossil content, but we believe that Baldwin. We believe a better procedure would an extremely valuable tool for the study of the be to restrict the term to those beds that crop out rocks would thereby be disregarded. We have in the type area. Such a procedure would be a used the mammalian fossil remains, laboriously valuable aid to paleontologists also, for the beds collected and documented over the years, to of the type area have produced the Santa Fe help to determine in which parts of the sequence fauna, which has served since Cope's 1874 of the deformed rocks such boundaries reason- report as the basis for the concept of age for the ably could be expected to occur. The boundar- Santa Fe beds. These fossils, and subsequently ies, however, specifically are not differentiated described ones, when tied to the proposed litho- on the basis of the contained fossils, but the two stratigraphic units in the restricted type area, disciplines work as powerful adjuncts to each should provide useful refinements of the con- other toward a clearer understanding of the cepts of historical geology of the area. stratigraphy. In this report we propose to restrict the type The lower formation of the Santa Fe Group area of the Santa Fe Group to the region north in the type area is the Tesuque Formation of Santa Fe, New Mexico, in the Rio Grande (fig. lo), originally named by Spiegel and Bald- Valley in the north-central part of New Mexico win. In the present report the Tesuque is divided (see geologic map, fig. 38). This area is essen- into five members. The two lowermost, the tially that described by Hayden (1869), and by NambC (pronounced Nahm-bav) and the Skull Denny (1940b), with some additional informa- Ridge, are approximately medial to late Mio- tion added to define it further. It occupies parts cene in age or, more specifically, about equiva- of northern Santa Fe County, southeastern Rio lent to the Sheep Creek and Lower Snake Creek Arriba County, and southern Taos County, and beds of the Great Plains. is bounded approximately by parallels 35" 40' The term Pojoaque Member is applied to beds and 36" 50' and by meridians of 105" 45' and that were derived primarily from the Pre- 106" 15'. It occurs in the extreme southern end rocks of the Sangre de Cristo Range of the Rocky Mountain Province as defined by and were deposited through most of Claren- Fenneman (1930), and the type area deposits donian (early Pliocene) time (see discussion in are confined to a part of the structural basin this paper, p. 12). These beds underlie a large described by Bryan (1938, p. 198, fig. 45) as the area in the Espanola Valley. Equivalent in time Rio Grande depression. to a part of the Skull Ridge Member and the The type area, as restricted, in the past has whole of the Pojoaque Member, but of wholly been subdivided by the field collectors of the different lithology, the beds of the Chama-el rito Frick Laboratory. These divisions were mainly Member were derived from volcanic beds of geographical, particularly in the early stages of northern New Mexico and the San Juan region the investigations, and were made as an aid in of southern Colorado. Overlying the Chama-el identifying the localities from which fossil speci- rito are the distinctive beds of the Ojo Caliente mens were obtained. The fossil-collecting locali- Sandstone, predominantly of eolian origin. The ties are shown in figure 2. Some of these locality Tesuque Formation apparently was deposited names were used by Frick (1933, 1937) in through part of Heminpfordian, Barstovian, and reports on mastodonts and horned ruminants, most, if not all, of Clarendonian (early Pliocene) and by Schultz and Falkenbach (1940; 1941, time. pp. 33-36, 44, 49; 1968, pp. 367, 368, 379) on The Chamita Formation comprises the upper- oreodonts, and will surely be an integral part of most, the least extensive, and also the latest beds reports on Santa Fe Group fossils in the future. of the Santa Fe Group in the restricted area. The Santa Fe Group, as here restricted, is The beds are lithologically distinct and contain 44 BULLETIN AMERICAN MUSEUM OF N.4TUR.4L HISTORY VOL. 144 fossils indicating an approximately Hemphillian A new name, the Tesuque Formation, was (medial Pliocene) age for the formation. proposed by Spiegel and Baldwin (1963, p. 39) The general sequence and the relationship of to replace "the term Santa Fe Formation in the the beds of the Santa Fe Group are shown dia- restricted sense." We believe that geology, grammatically in figure 10. In addition, the gen- stratigraphy, and paleontology can be served eral age relations of the various members are better by restricting the use of the term Tesuque shown. It may be appropriate to direct attention Formation to include only those beds in the type to the use in the chart of an unconventional term and contiguous areas of the Santa Fe Group that of North American Land-Mammal Age (see are of dominantly granitic origin. One excep- Savage, 1962). The term Valentinian was pro- tion to this method of categorizing the deposits posed by Schultz and Stout (1961, p. 9) for a of the area is the Chama-el rito Member, which segment of time that they depicted as being is composed primarily of volcanic debris. The represented by the fossils of five local faunas arbitrary type section of the Tesuque Formation collected in the Valentine Formation of the as given by Spiegel and Baldwin (1963, pp. 39- Great Plains. We believe that many comparable 40) was a most unfortunate selection, inasmuch fossil forms occur in the lower part of the Pojo- as it contains only a small part of a single depo- aque Member and the equivalent portions of the sitional cycle and hence is incomplete. Only a Chama-el rito Member. It is not within the small part of the recognized sequence is exposed scope of this report to argue the validity of the at the type section, and, because we have traced use of Valentinian as a term of Land-Mammal it northward to an area where an essentially Age; we use it here to indicate approximate complete section is present, we now find that it equivalence of a portion of the Santa Fe Group is desirable to subdivide the Tesuque. Therefore, with the more familiar Great Plains succession. the beds of the Tesuque Formation are divided in this report into five members, as follows: TESUQUE FORMATION (1) Nambk Member, (2) Skull Ridge Member, Frick Laboratory field parties have used the (3) Pojoaque Member, (4) Chama-el rito term Santa Cruz consistently since 1925 to Member, and (5) the Ojo Caliente Sandstone. identify a collecting locality near Santa Cruz, Other, and quite unrelated, reasons also compel New Mexico. As work progressed in the general the recognition of the five members; these area, other localities were found to contain a reasons are explored in detail under headings similar suite of fossils, and gradually a bio- assigned to each member. The necessity of stratigraphic concept evolved that identified adjusting Frick Laboratory nomenclature to the them as the Santa Cruz fauna, and the beds that concept of Tesuque Formation has presented contained them were considered Santa Cruz unusual but not insuperable problems. equivalents. The specimens from these Santa The Tesuque Formation is the most widely Cruz equivalents were often listed together in exposed formation (fig. 38) of the Santa Fe Frick (1933, 1937) without special attention Group. The beds are more than 3700 feet thick having been directed to the fact that they were in the Espanola Valley. Beds of the NambC from beds that were essentially of the same age. Member, particularly, are superficially difficult In 1940, when we began mapping the geology to distinguish from certain parts of the Pojoaque of the Santa Fe Group, we selected the term Member. The similarities are commonly more Santa Cruz Formation to serve as a rock- apparent than real between the two members, stratigraphic expression of the useful concept of and the two can be se~aratedon several criteria. Santa Cruz equivalent which had been derived In the field the most useful correlation tools have from the careful studv of mammalian remains been the sequence of ash beds, gravel content, from many collecting localities in the general and clast type of certain beds, pos

East

NAMB~MEMBER I West Remnont of qrovel terrace

Conglomeratic sandstones

Recent terraces

6285' Nonconformity

Bosol conglomerale Eost and sond Nonconformity 7500' Belt of hills 6900'- 7000' \ 1 7490' Conqlomerotic sondstone

FIG. 11. Sedimentary contact of Nambt Member of Tesuque Formation with Precambrian crystalline rocks of Sangre de Cristo Range. A. Cross section near mouth of a wash entering Medio (Frijoles) Creek south of Santa Cruz Dam. B. Nonconformity of Nambt Member on Precambrian rocks along east side of Santa Cruz Lake. C. Sketch of a belt of hills of Nambt Member rocks south of NambCCundiyo road, showing relation to crystalline rocks of Sangre de Cristo Range. Length of section, about 4 miIes. 1971 GALUSHPI AND BLICK: SANTA FE GROUP 47 unconformably on a narrow belt of Pennsylvan- R. 10 E., in Santa Fe County, New Mexico. ian rocks of the Magdalena Formation. Along The conglomeratic sandstone and sand phase the base of Pinyon Mountain north of Nambt contains few pure volcanic ash or bentonitic Creek the deposits of the Nambt Member lap strata of the kinds seen in the fossiliferous part of unconformablv across truncated Picuris Tuff the Nambt Member, or in the excellent group deposits containing a weathered lava flow, and of ash beds characteristic of the Skull Ridge lie directly on the crystalline rocks. Fault con- Member. A few ash beds crop out in the con- tacts of the NambC Member with the crystalline glomeratic part of the member; these are mostly rocks are few. The predominantly depositional local and are concentrated east of the NambC contact between beds of the Santa Fe Group and Pueblo where they underlie beds assigned to the the crystalline rocks of the Sangre de Cristo upper or fossiliferous portion of the Nambt Range compels radically different interpreta- Member. tions of the relations of the western border of the Beds of the Tesuque Formation in general and Sangre de Cristo Mountains north of Santa Fe the Nambt Member in particular have a dis- from those presented by Cabot (1938, p. 88). tinctive light pinkish to light reddish color. The These differences are examined in detail in this bulk of the sediments was derived from granitic paper in the section on Structure, but at this rocks, and the unaltered pink microcline was of point it is sufficient to mention that the fault sufficient volume to impart the pinkish color to traces are all observed to pass into the sedimen- the beds. Technically some of the beds might tary sequence, and that the beds on each side of qualify as arkose, but the 25 per cent of feldspar the fault are of the conglomeratic sandstone and might, in some beds, vary significantly, or the 15 sand of the Nambt Member. The faults have per cent matrix might bemuch higher. In general displacements of about 100 to 300 feet and are a more accurate descriwtion of the sediments definitely a part of the post-Santa Fe period of would be arkosic conglomeratic sandstone. deformation. The upper or fossiliferous part of the Nambt NambC Member deposits were derived main- Member is 450 feet thick at the type locality ly, but not wholly, from granitic rocks; their (see fig. 13) and is estimated to be 500 feet thick source was in the Sangre de Cristo Range to the on the NambC Indian Pueblo Grant a few miles east, where granite, granite-gneiss, gneiss, and to the south. East of the Nambt Pueblo, lower other rocks crop out over large areas. Bouldery beds of the fossiliferous portion crop out. They gravel and breccia have been observed on many grade upward from alternating beds of sand and exposures immediately adjacent to the crystal- conglomerate into a fairly uniform group of line rocks, but these boulders are not of the large strata of finer texture. These finer deposits size and magnitude commonly associated with include silt, bentonic and ashy strata, lenses of fanglomerate;; but basinward and away from granitic conglomerate, and a thick series of cliff- the mountains the deposits contain smaller rock forming sandy strata. This group, in turn, grades fragments and a greater proportion of sub- upward into another series of interfingering and angular and rounded pebbles. These observa- alternating lenses of gravel and sand. The tions were made of the same strata and are not a sequence of deposits grading from coarse sand generalized analysis of gross relations of deposi- and conglomerate through finer sediments back tion in the Es~anolaVallev. The effect of to coarse sand and conglomerate is interpreted changes in sedimentation resulting from pro- as indicating shifting back and forth of the de- gressive filling of the Espanola Valley is treated positing channels on the coalescing alluvial fans under the heading Pojoaque Member of the that were building these deposits along the Tesuque Formation. Beds of red, coarse, sandy mountain front. gravel crop out low in the section and can best be A prominent and well-exposed white ash bed observed in exposures around the spur of hills is repeated by faults northeast of the NambC near the Santa Cruz Dam. Farther south the Pueblo. This ash bed is capped laterally by a reddish gravels crop out in a comparatively thin layer of hard sandstone, and this relation is well belt, and one good exposure can be studied con- shown on the southernmost ridge southeast of veniently along the east boundary of the NambC the NambC Day School in sects. 13 and 14, Pueblo Grant northeast of the NambC Pueblo T. 19 N., R. 10 E., Santa Fe County, New about on the line between sects. 6 and 7, T. 19 N., Mexico, where the sandstone lies directly on the 48 BULLETIN AMERICAN MUSE UM OF NATURAL HISTORY VOL. 144 ash. Down the dip of the beds, sand and other numerous in parts of the section. Calcareous sediments crop out between the sandstone and ledges and small calcareous sand concretions the ash, and the thickness of the sand tongue are decidedly more plentiful in the locality north increases with distance. A few miles to the north, of Arroyo Seco than in the East Cuyamunque east of the NambC-Cundiyo road, nearly 20 feet and Tesuque collecting localities (fig. 20), where of the sediments separate the sandstone stratum fossils typical of the member have been collected and the white ash. South of NambC Creek along east of Fault I. In the East Cuyamunque and the west side of Chupadero Creek the white ash Tesuque localities the sand and clays are soft, is mixed with sand, and the bed passes beneath and the sediments are banded; at a few sites red the land surface to the south. The upper 200 to clay and clay-filled sand merge laterally with 300 feet of the fossiliferous part of the NambC channel sand and gravel. The zone of merging is Member in the locality east of the NambC very narrow and shows plainly the relation of Pueblo is not well exposed. From the position of the stream channel to the marginal flood plain the white ash bed mentioned above westward to areas on the NambC alluvial fan. Thin bentonitic the No. 1 White Ash stratum, which crops out or ashy layers occur in the upper part of the on the erosion escarpment at the fork of the member: one of these. about 100 feet below the NambC-Cundiyo road, most of the fossiliferous top of thk member, has been named the NambC part of the member has been eroded or has been White Ash stratum (fig. 13) and has proved to be buried by alluvium; this part of the section, a useful horizon for local correlation. however, is particularly well exposed in the type At the crest of the divide between White section (fig. 13) in White Operation Wash. (See Operation Wash and the drainage basins of the also map of the contact between the Skull Ridge ~antaCruz River, the gravel andsandstones are Member, and the NambC Member, fig. 12). observed to grade laterally to gray sandstones The division between the NambC Member and gray sand. The sediments of the divide area and the overlying Skull Ridge Member has are strongly granitic, conglomeratic, and lentic- received intensive study in an effort to syn- ular in character, and their topographic expres- chronize biostratigraphic and rock-stratigraphic sion resembles that of certain beds of the Pojo- data. The No. 1 White Ash stratum is arbi- aque Member of the Tesuque Formation north trarily selected as the contact between the two of the Santa Cruz River. They are observed, members because it is easily mapped. The base however, to pass beneath Skull Ridge strata in of the White Ash stratum is not a precise bio- an unbroken-section along the ridge To the west. stratigraphic division, because fossils referable Exposures of the upper part of the Nambt to the NambC fauna have been collected a few Member have been very fossiliferous in the feet above it. The No. 1 White Ash stratum Santa Cruz drainage basin south of the river, closely approximates, however, a biostrati- and in White Operation Wash and Arroyo Seco. graphic division and at the same time, owing to Areas of the member in the East Cuyamunque its mappability, fulfills the requirements of a and Tesuque localities, although small, have rock-stratigraphic division. The map of the con- produced diagnostic specimens. tact area between the Skull Ridge Member and North of NambC Creek, particularly in the the Nambk Member (fig. 12) shows the extent vicinity of Pinyon ~ountain;the cong~bmeratic to which the beds have been broken by faults sandstone and sand part of the section underlies and illustrates how this deformation has affected a belt of fairly high but essentially rounded hills. the outcrop pattern of No. 1 White Ash stratum. The westward-dipping conglomeratic sand- This fault pattern is typical of other areas in the stones coupled with a mantle of gravel derived Tesuque Formation. The map also shows how by deflation of the conglomeratic lenses have the beds have been repeated or omitted, depend- served to hold up the hills. Near NambC Creek a ing on the direction of the throw of the normal subsequent drainage pattern has been cut deeply faults. into the deposits by tributaries of NambC Creek. Sediments of the fossiliferous portion of the The result is a bolder topography, for the hills NambC Member are finer-grained than those of appear higher and the slopes steeper. These the conglomeratic portion. Pinkish to buff sand, hills, when viewed from a distance of several silt, or clay-filled sand forms the bulk of the miles across the Espanola Valley, appear as a member, although lenses of conglomerate are regular line along the mountain front and could Y,? (1 I BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY, VOL. 144, ART. 1

. . - r:

,:-q;!.;L FIG. 12.Outcrdp'h3Zip of contact area between NambC Member and Skull Ridge Member of Tesuque Formation, showing area underlying parts of sects. 2, 11, 14, 15, 22, 23, and 27, T. 20 N., R. 9 E., Santa Fe County, New Mexico. Outcrops of volcanic ash beds emphasized. 1971 GALUSHA AND BLICK: SANTA FE GROUP 49 be mistaken for a little-dissected, sedimentary- valleys and low, rounded divides leading down igneous contact line. The high ridges conform to from the high belt of hills. Exposures in this area the general outcrop pattern of the conglomeratic tend to be isolated and of small extent, which is sandstones. Farther north in the Arroyo Seco in marked contrast to the rugged, finely dissected drainage basin the topography has been modi- badlands topography north of Arroyo Seco. fied by long washes, with broad, gently doping The NambC Member has produced a medial

' 5' No. 2 White Ash strotom

~cols:$ inch = I0 feet

'-8' NO. l White Ash stratum

8' Conglomeratic sandstone

Conglomeratic sand wi;h i

kens of clay-filled sand

' ~amb6White Ash stratum

-Light colcore~u~ledge -Colcoreous ledge

FIG. 13. Ideal section along A-B of figure 12, showing type section of fossiliferous portion of NambC Member in sect. 11, T. 20 N., R. 9 E., Santa Fe County, New Mexico. FIG. 14. Fossilifrrous portion of Nambt Mcmbcr of 'r'csuqi~c. Formation, lookinq north across Wliitc Ol>c.ration Wash. 'I'wo 1>11rl1lishlayers in low arca alony right cdye of pl~otograpliarc, c.alled infornially "thr tlouhl(*purl)l(." ant1 arc. a i14('f11lstr-atiqral>hic k(.y liorizon. 131~111;along ~rl,l)('rIcft arc, tlcposits of Sk~~llRiclqc Mcn~berof 'l'c~si~cl~~c.Formation. Note that t onicxl liill on \kylinc. at I(.fi ccantc.r i\ al\o Ski111 Riclgc.. \'ic.w i4 1.044 unbrok(.n fat~ltblock in which contac t 11c.twc.cn Nambt: Mcmbc.r a~~clSki111 Ritlgc, hl(.ml)c.r- is 1,rst \liown. (I'art of this arm n~al,l>c'tlin liy. 12; s(~-also liq. 38.) FIG. 15. A. Contact area of Nambk Mcmber and Skull Riclge Member. High, conical hill on skyline at right center same as that in figure 14. View is to southeast. NambC Mcmber is exposed along base of hills at centcr and in ruggecl arcas at left; Skull Ridge hlembrr crops out along top of hills at center. White as11 layers do not show well in photograph but in the ficld are effective marker beds. Santa Cruz Rivcr is just beyond fringe of trees in foreground. Snow-capped peaks of Sangre de Cristo Range show in left background. B. Thc Red Wall. Dcposits of lower part of Skull Ridge Member, looking north across Arroyo Seco. Prominent clifb are called thc Red Wall. No. 1 White Ash Stratum at far right edge of photograph is faulted down from No. 1 White Ash at base of cliff at uppcr centcr. No. 2 White Ash stratum discernible along top of Rcd Wall. Espanola Formation Esponolo Formation 3

No.4osh

6200'

6100' 6000' 5900'

5800'

A B I Type Block -I : Skull Ridge Member I I FIG. 16. Type section of Skull Ridge Member of Tesuque Formation shown as cross section A-B on the geologic map (fig. 38). The fault block designated as the type has the major ash beds in superposition and is situated in the N. 4 of sect. 2 1, T. 20 N., R. 9 E., Santa Fe County, New Mexico. 1971 GALUSHA AND BLICK: SANTA FE GROUP 53

Miocene suite of fossils or, more specifically, in The Skull Ridge section is 650 to 750 feet terms of North American Land-Mammal Ages, thick, depending on where the section is meas- a Late Hemingfordian fauna (Sheep Creek local ured. The deposits are mainly pinkish, tan, or fauna equivalent; see section on the Age of the gray, fine to medium coarse sand and silt, some Santa Fe Group for extended discussion, p. 106). of which are slightly consolidated, but include The NambC Member thus provides, for the first interstratified beds of clay, conglomerate lenses, time in the hundred-year history of the Santa Fe intraformational conglomerate lenses, and 37 Formation (now Group), the stratigraphic posi- distinct ash beds. The volcanic-ash beds are tion and age of the lowermost member of the usually composed of fine particles or shards, and beds of the type area. commonly are little mixed with other detritus except at points that were near the feeder chan- SKULLRIDGE MEMBER, NEW NAME nels of the depositing alluvial fans. Mixtures of The name Skull Ridge Member is herein pro- ash and sediments are also observed in the upper posed as a new term to be applied to certain part of the thicker ash beds. The ash layers vary distinctive deposits in the Espanola Valley that in color, ranging from pure white to light gray, overlie the Nambt Member and underlie the light blue, blue to dark green, dark gray, or Pojoaque Member. The boundaries of the type black. Occasionally two colors appear in the locality of the Member are outlined approxi- same bed; for instance, a thin white ash streak mately on the west by the road fault just west of may occur at the base of a light blue or gray United States Highways 64 and 285; on the ash bed. More rarely a gray ash may grade east, by the line of cliffs capped by white laterallv to a white ash or to a blue one. Colors volcanic-ash strata that lie west of the NambC- of ash beds, in a series of four or more used as Cundiyo road. The southern boundary of the a unit, have proved extremely useful for corre- type locality can be placed for convenience at lations. Nambt Creek, but areas in the East Cuya- Four of the thicker ash beds of the Skull Ridge munque and Tesuque collecting localities are Member are white ash. At some points thick- correlated as Skull Ridge equivalents by the com- nesses of as much as 10 feet or more can be parison of the sequence of the ash beds, and by observed, but commonly the white ash beds contained mammalian fossils. The northern limit range in thickness from 18 inches to 4 feet. These lies north of the Santa Cruz River in the lower white ash beds are re~eatedin several fault reaches of Third (United States Geological Sur- blocks and are the conspicuous white beds typi- vey: Arroyo dela Morada), Fourth (United States cal of the locality. They may resemble one

Geological Survey : Arroyo de las Martinez), and another on some butcro~s.A, and care must be Fifth (United States Geological Survey: Arroyo taken to insure that a unit series is measured so de la Cuesta de 10s Vaqueros) Washes. that each can be properly identified. The use of A type section of the Skull Ridge Member is a a sequence of ash beds is the only way such composite of two measured sections (fig. 17). identification can be assured at present. The The lower part of the Member represented by ideal section of the Skull Ridge Member (fig. 17 500 feet of deposits between No. 1 White Ash shows such a sequence of ash beds. stratum and No. 4 White Ash stratum is best Skull Ridge deposits in the section above exposed in a fault block south of Arroyo Seco in No. 4 White Ash stratum are not areally exten- the N. & of sect. 21, T. 20 N., R. 9 E., in Santa sive; partly because they are not very thick Fe County, New Mexico (fig. 16). The upper (maximum of 250 feet) ; partly because they are part of the section lies along the divide between not greatly faulted ;and mainly because they have Arroyo Seco and White Operation Wash, yielded readily to erosion, and commonly only approximately paralleling the boundary be- isolated remnants remain. The upper sediments tween sects. 8 and 17, T. 20 N., R. 9 E., in of the Skull Ridge are much softer than those of Santa Fe County. The upper part is composed the main body of the member, which tend to form of 150 to 250 feet of sediments above No. 4 cliffs. The upper beds are mostly fine-grained, White Ash stratum. Contact with the overlying reddish to salmon-pink sand and silt, with some Pojoaque Member of the Tesuque Formation clays, and occasional gravel lenses. Cylindrical can be observed in the SW. 2 of sect. 8, T. 20 N., spindle-shaped concretions commonly less than R. 9 E., in Santa Fe County. 6 inches long are found at several horizons, 54 BULLETIN AMERICAN MUSEUM OF N.ITURAL HISTORY VOL. 144 particularly just above Ash Gamma, but concre- as the lowlands, but, most significantly, the ash tions and concretionary sandstones are not char- would fall on each of the alluvial fans issuing acteristic of the upper part of the Skull Ridge from the Sangre de Cristo Range whether these Member. The upper beds crop out in a narrow fans were widely separated or were arranged as belt from Third JYash (United States Geological coalesced fans. The ash beds would tend to be Survey: Arroyo de la Morada) north ofthe Santa present, therefore, in the same relative series on Cruz River (fig. 38) southwestward to a point contemporaneous parts of the fans. It is axio- north of Pojoaque, New Mexico, where they are matic that ash falling on highlands or exposed covered with alluvium. They crop out again positions would be immediately attacked by south of Pojoaque along the west side of Arroyo wind or water, or both, and would then be con- Ancho, and on the Tesuque Pueblo Grant far- centrated in the lowlands or protected areas, and ther south are covered unconformably by gravel especially in bodies of standing water, whether deposits. ephemeral or relatively permanent. It is impor- The uppermost beds of the Skull Ridge Mem- tant, therefore, to observe that any individual ber can be observed best on either side of the ash stratum may show a variety of characters road that crosses the drainage divide in a notch along the strike, ranging from absence at origin- north of the Three Sisters Buttes (fig. 18). This ally exposed sites through probable normal road is the first one that runs north to the Santa occurrence of pure ash to a variety of mixtures Cruz River east of the junction of Arroyo Seco of ash and sediments; moreover, there may be and United States Highway 64 (fig. 38). At this accumulations of ash showing faint to well- spot the basal sand bed of the Pojoaque Mem- marked lamination as if laid down under water. ber lies disconformably upon a hard, blocky, red In addition, irregular and lenticular masses of sandstone or mudstone that, at this point, is the ash as much as three times the normal thickness uppermost stratum of the reddish or pinkish of the bed have been observed; these are obvi- sediments ofthe Skull Ridge Member. The basal ously the result of concentration, possibly by deposits of the overlying Pojoaque Member are wind currents in protected spots, similar to dunes predominantly gray friable sand, with small or snowdrifts. Differences in thickness, texture, quantities of greenish pebbles that are numerous and lithology of the sediments between the ash enough locally to impart a greenish color to the beds are to be expected, for the different alluvial surface at those points where deflation has fans probably arranged as a bajada or compound caused an erosional concentration of the pebbles. alluvial fans would have been of unequal size, A strong gray conglomeratic sandstone, how- would have had different sediment loads and ever, lies at the contact; from this site the basal transporting power, and may have derived their sandy beds can be traced southwesterly along sediments from dissimilar rocks within the the base of the bluffs until they become covered source area. Another factor influencing the with alluvium or dip below the surface. The general character of the sediments between the contact between the Skull Ridge Member and ash beds was the meandering of the depositing the Pojoaque Member also can be observed on a streams on the fans, thus contributing to the few outcrops south of Arroyo Seco and east of lateral variation of the sediments. Each alluvial the road fault (fig. 38) where remnants of the fan would receive ash from each specific fall. basal Pojoaque sand beds cap some of the ridges Lateral changes of the ash beds would result of Skull Ridge deposits. from action by different geologic agencies or The Skull Ridge Member is distinctive for the combination of agencies, and any program to number and variety of the volcanic ash beds that use ash beds for correlation must recognize and it contains (fig. 17). These ash beds have been use these changes. studied intensively as key markers, for they offer The lower limit of the Skull Ridge Member possibilities of detailed correlation that are in- was placed at the base of the No. 1 White Ash herent in no other member or formation of the stratum for ease of mapping (fig. 12). The No. 1 Santa Fe Group. Selection of ash beds as one of White Ash stratum may be as much as 8 feet the major criteria for correlation is based on the thick, but on most outcrops the thickness is 5 feet hypothesis that the ash from any specific vol- or less. A soapy, gray, impure bentonite occurs canic eruption would fall indiscriminately upon at the base of No. 1 White Ash on nearly all out- the entire area, blanketing the highlands as well crops north of Arroyo Seco. The proportion of BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY, VOL. 144, ART. 1

FEET ;','>',:':(::':', 2, . .,., ,,!::;;:.: .';, . , :;.: .,.,. ,, ;: :.A !.?. + I... ;\ '..'..i., ...,. Scale : I inch = 80 feet ..'. ...?..?: . Stratigraphic Positions of Selected 7 6 0 . 8 .:,';;+:,' . !!'.I, Major Fossil Specimens collected since 1940

Comel, 460-3073

Rhinoceros, 458-3046

Cornel, 459-3062

• Camel, 594-4317; C:ornivora, 521-3589

- - --.-,.. . ---- ...... • Cornel, 431- 1928 00 Carnivore, 513-35183 Rhinoceros, 535-3674; Carnivore, 592-4308

Comel, 517-3549 Horse, 594-4320 White Opsrotlon Ouorry - Horse 633- 4820. Horse 633-4810. Horse 516-3539. Camel 526-3584. Camel 633-4816 Horse,625-4775; ~a~&l,62;-477~~ ~o~re,6~3-4818;~dmel,439-3058; horse, 516-3539; hierycod~nt,511-3502 Lizard, 381-1769 hite Operation Qua Camel, 621-4740 Horse, 591-4296 Rabbit 520-35874 Carnivore 632-4807 ~ornivArs,632-480'6, lnsectiv5re. 459-3061; Horse, 462-3090 Came1,538-3684; Norse, 591-4300 Camel 589-4289 ~ornl:ore, 462-3116 1"4'-~sh 0 Complex Comel, 624-4771; Horse, 638-4819. Comel 494-3314 Camel, 590-4290; IAerycodont, 622-2745; &mel,452-2096; Cornivore1444-2002 Camel, 464-3105; Camel, 509-3472; Camel, 444-1998 ;Msrycodont, 469-3132 Carnlvore, 591- 4297; Comel, 461-3086; Coml,593-4314 Horse 625-4774 ~arne1:618-4665; Rodent,633-4825; Merycodont, 633-4826; Rhinocrroa,462-3089 Worse, 625- 4778 Comet, 617-4664 Horse 622-4744. Horse 591-4301 come;, 586-4261;~oden; and Horre, 622-4723

Horse, 587- 4275 Camel, 454-3022; Carnivore, 536-3679; Dmmomerycid, 454 -3027 Merycodont, 454-3026; Merycodont, 633-4823 Lizard, 513-3519; Carnlvore, 633-4821 Horse,587-4270; Camel, 638-4918 Comel, 633- 4814 Horse, 625-4771 Cornel, 588-4281 Carns1,588-4282; Camel, 633-4817 Oreodont,536-3675 Horse S7-4274;Comal 586-4265- Camel, 586-4259 ~ornef,586-4260; ~amsi,588-428; Cornel, 467-31 19; Comel, 510-3481; Camel, 536-36761 Rhinoceros, 536-36774 Comel, 638-4917 Camel 510-3480;Camel, 510-3483 ~hinoZeros,458-3045 Carnal, 470-31 33 Orsodont, 587-4271 Horse, 587-4269 Rhinoceros, 591-4295; Oraodont, 475-3180; Rhinoceros, 462-3087

Comel, 522-3590 0.0 Camsl, 513-3514; Comel, 513-3515; Camel, 513-3517 0. Comel. 494-3313; Rhinoceros,.540-3700 • Comel, 632-4805 • Rhinoceros, 632-4011

Comel, 519-3581; Horse, 592-4307; Camel, 594- 4318 ... Horse, 468-3123 •

0.0 Cam1,593-4312;Comel, 593-4313; Carnivors, 623-4756

Rhinoceros, 596-4326; Horse, 626- 4782; Camel, 520-3583; Turtle, 625-4779; Comel, 623-4754 Comel, 463-3100 Comel, 624-4770 Camel, 523-3591 Comel, 51 1-3493; Comel, 326-1607 Merycodont, 462-3093 Camel, 559-3985 Comel 326-1604 Horse,'592-4306

Horse 595-4325 ~ame;,468 -3120; CD~QI 559-3987. Camel, 325-1602;Comel, 326-1606; Camel, 526-4605 :....0040.0 Merycodont ,468-3122; &mivore,55~-3999;HorseI559-4001; Horse,328-1611;Come1,329-1612; Camel, 434-1946

Camel, 465-3 117

• Cornel, 434 -1945

Fig. 17. Ideal section of Skull Ridge Member of Tesuque Formation, showing ash-bed sequence and stratigraphic positions of selected major fossil specimens collected since 1940. FIG. 18. View looking north across Joe Rak Wash and tributaries toward Thrcc Sisters Buttes (center of photograph). Arroyo Scco flows along north side of buttes. Bluffs in far distancc are high levels of Pojoaquc Member of Tesuquc Formation. Some of sloping surfaces on right skyline havc been cut on gravels of Picuris rc-entrant fan (see section on Erosion Surfaces). Lowlands in photograph have bccn carved from uppermost 300 feet of Skull Ridge Member. Light-colored bluffs along left edge on skyline are Pojoaque Member beds. Contact area betwccn Pojoaquc Member of Tesuque Formation and underlying Skull Ridzc Member of Tesuque Formation lies in low notch in the dividc, slightly above and less than inch to left of smallcst butte of Three Sisters; contact also exposed along base of distant bluff at far left. 56 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY VOL. 144 bentonite to unaltered white ash increases as suggesting that the East Cuyamunque locality toward the north. Indeed, north of White may have been near, if not actually in, a low Operation Wash, as well as on each side of the interfan area between two alluvia1 fans of a drainage divide between White Operation Wash bajada. and the Santa Cruz River, the No. 1 White Ash Some beds are locally important in correla- is mostly bentonite, with a few isolated patches of tions. One of these is the calcareous ledge (fig. ash and bentonite cropping out on the horizon 17) shown as the base of the Red Wall. This in the Santa Cruz drainage basin. South of ledge may be, locally, as much as 6 inches thick, Arroyo Seco the No. 1 White Ash averages 3 to but more commonly is less than 2 inches thick. 5 feet in thickness, and the bentonite at the base The Red Wall is an informal term applied by becomes very thin or disappears altogether. Frick Laboratory collectors to the predominant- Northeast of the fork of the Nambt-Cundiyo ly cliff-forming reddish sand and silt of the 100 road west of the Nambt Pueblo, No. 1 White feet of sediments underlying No. 2 White Ash Ash caps a cuesta-like erosion escarpment. A stratum. The Red Wall (fig. 15B), with its little farther north on the Nambt Pueblo Grant capping of No. 2 White Ash, is a scenic topo- Ash 1s and Ash 1T crop out as distinctive graphic feature and is relatively easy to identify horizons; two associated thin tuffaceous beds in adjacent fault blocks. Several distinctive ash appear as dark streaks in the section. At the beds (fig. 17) immediately overlie No. 2 White south end of the escarpment, at the road fork Ash stratum; these have been designated Ashes mentioned above, two thin ash beds underlie 2A, 2B, 2C, and 2D and are of unusual impor- No. 1 White Ash. This sequence of ash beds was tance in correlations. No. 3 White Ash stratum is used in correlating the beds of the Skull Ridge less well exposed than No. 2 White Ash and is collecting locality (fig. 2) with those of the East often the most difficult of the major white ashes Cuyamunque collecting locality. The East to map owing to the numerous lenses of granitic Cuyamunque is separated from the Skull Ridge gravel that occur in the section from a point locality by nearly 3 miles of alluvium-mantled about 30 feet below No. 3 White Ash to a few deposits across the valley of Nambt Creek. feet above it. Isolated outcrops occur in linear groups that A channel above Ash F (fig. 17) has been an extend down from the north, where the main important marker horizon and is interpreted as body of the Skull Ridge deposits is exposed, indicating an abrupt change in the sedimenta- almost to the flood plain of the Nambt Creek. tion cycle. Unusual sedimentary structures are South of Nambt Creek, in a wash that heads exposed in this part of the section, and some of against the drainage divide between Nambk the bedding and cross-bedding has been empha- Creek and East Cuyamunque Wash, Ash 1s and sized by the concentration of detrital micas, Ash 1T are well exposed, and southeastward particularly muscovite on certain layers. Fortu- toward the head of the wash where it crosses the nately the outcrop area of the beds between Ash old (now abandoned) Nambt-Santa Fe road, F and No. 4 White Ash (fig. 17) has compara- the No. 1 White Ash crops out. Ash 1S on some tively wide lateral extension, as well as being exposures may be completely eroded, but on repeated by faults in a series of fault blocks, adjacent outcrops it may be several inches thick. which provide a fine opportunity for observa- These ash beds crop out in a variety of combina- tions of changes across the strike. No. 4 White tions south and eastward until they pass under Ash stratum was used as the key stratum, from the pediment gravel in the southeast corner of which measurements were made whenever East Cuyamunque Wash (fig. 19). In general, in possible, and from which the original naming the East Cuyamunque locality the sediments and lettering of the various ash beds progressed between the ash beds are finer-grained, with a as the sequence of the ash beds was established. higher silt and clay content, than in the Skull Those beds below No. 4 White Ash were given Ridge locality. Furthermore, the colors and letters of the English alphabet, or a name, and textures of the outcrops are more suggestive of those above No. 4 were designated by letters of sedimentation in a low and probably muddy the Greek alphabet. Some of the ashes were part of the area of deposition, as contrasted to named to show their proximity to the major the Skull Ridge locality where the sediments are White Ash strata (examples: Ash 32, Ash 2A, coarser-grained on the average-all interpreted and Ash IS). The thicknesses of the intervening BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY, VOL. 144, ART. 1 U

0 20 40 60 IIIIIII Sections, vertical scale in feet

EAST CUYAMUNQUE LOCALITY New Mexico

LEGEND

Pleistocene. Loess-like very fine sand, silt ond clay

Pleistocene. Gravels on erosion surfaces, where mopped

wl Fault. U = upthrom D = downthrown

Approximate surface elevation

Intermittent streoms,dry rashes or arroyos

SCALE: I inch = l Mile 1-1 T,, ,&.,LK Hills, ridges or cliffs, where mapped

Outcrop pattern of volcanic ash beds in the losali ty

FIG. 19. Outcrop map of a part of East Cuyamunque collecting locality and part of Tesuque collecting locality. Base adapted from an aerial photograph. Sections show correlation details. 1971 GALUSHA AND BLICK: SANTA FE GROUP 57 strata between the ash beds, as shown on the with the ash are seen adjacent to the postulated ideal section of the Skull Ridge Member (fig. debouchures. A study of a large group of cross 17), differ enough laterally in the equivalent sections in the Skull Ridge member shows that deposits in East Cuyamunque, and also in the the original surfaces on which the ash falls were equivalent deposits north of the Santa Cruz deposited were remarkably regular. Differences River, to require separate evaluation. The rela- of more than 4 feet in the original surfaces were tionships within the ash bed series in the several rare, and generally that much inequality was localities, however, remain essentially the same. compensated by the thinning or thickening of The ash bed sequence is shown in figures 17 and the immediately overlying sediments. Ponding 20, and this presents an ideal section of the must have been ephemeral, for no lacustrine Skull Ridge Member in which attention is features, such as lake deltaic deposits, wave- directed primarily to the stratigraphic position built cross-bedding, ripple marks, or other simi- of the various ash beds. The measured intervals lar sedimentary structures, either primary or between the ash beds show both the minimum secondary in origin, have been recognized. Fish and maximum observed thicknesses of the inter- remains have not been collected from the Skull vening sediments. A few selected fossil mammal Ridge Member, nor have invertebrates. All specimens are listed on the section to illustrate these facts support a working hypothesis of pond- the method of stratigraphic control used in the ing as opposed to a hypothesis of a lake of field. Many of the taxa are new, hence have not sufficient size or duration to be classed as a been named, but the field numbers can be cross- permanent feature. Fossil specimens are ob- checked with forthcoming reports on the served to be few immediately above the thicker camels, horses, carnivores, rodents, and other ash beds, which is interpreted as support for the groups, and the stratigraphic position of the hypothesis that the returned to the area fossil specimens can be readily determined. This of deposition following the re-establishment of chart (fig. 17) can be regarded as the strati- forage after a period of barrenness caused by the graphic framework for the very large collection ash blanket. A few feet above the ash beds of late Miocene (Barstovian) fossils in the Frick normal numbers of svecimens occur. Some of the Collection from the Espanola area. original ash falls must have been extremely Fossils are extremely rare in the ash beds; this heavy to have produced a bed 8 or 10 feet thick; observation holds true not only for the Skull the degree of compaction caused by several Ridge Member but for the ash beds of the entire hundred feet of sediments on a bed of ash is Santa Fe Group. This fact suggests that the ash difficult to estimate but is undoubtedly great. falls were not of sufficient density at the time of Robert L. Smith (1960, p. 825) showed that eruption to overwhelm and suffocate the animals compactibility is related to bulk porosity, and liviAg in the area. Much support can be adduced that volcanic glass shards or crystals probably for the hypothesis that the animals living in the have a bulk porosity of about 50 per cent. It valley were driven temporarily from the area of seems reasonable to assume, therefore, that the deposition, possibly in several ways, but prob- ash beds of the Santa Fe Group have been com- ably by the temporary accumulation of water pacted to nearly half of their original thickness. over their grazing grounds, from an increase in The Skull Ridge Member is admirably the amount of rainfall coincident with the vol- adapted for detailed study and sectioning. Close canic eruptions. Such ponding of grazing spacing of normal faults, with east side down- grounds, even for a few days, would drive the thrown, has resulted in a repetition of the fault animals to higher grounds or adjacent areas. blocks, which, together with the average regional The approximate position of the standing bodies dip of about 9 degrees west, causes each ash of water at the time of the ash falls can be in- stratum to be exposed in several places both ferred from the study of the ash strata, for vol- across the strike and laterally along it. The canic ash falling into still water tends to settle as pure ash. The location of the various feeder sequence of ash beds between No. 1 and No. 4 streams can be determined by an observation of' White Ash strata is easier to use as a correlation the position of the channel sand, gravel, and unit than is the sequence above No. 4. Ashes intraformational con~lomerate" beds that cut the above No. 4 are not so well exposed, because ash beds. Admixtures of gravel, sand, and mud they are less faulted, more eroded, and the BULLETIN AMERICAN MUSEUM OF NATUIt4L HISTORY VOL. 144

Ash B Complex to Joe Rok Wash Drainoge Basin \ Pleistocene remnant

to ~ornb; Creek Droinoge Basin

Camel skeleton F:A.M. No. 23951 Sandstone Eost __C

FIG. 20. Outcrop map of South Skull Ridge locality, showing location of two camel skeletons, and with associated cross sections illustrating usual method of correlation of field specimens. A-B. Ideal section. C-D. Profile section. 1971 GALUSHA AND BLIC .: SANTA FE GROUP 59 outcrops are arranged in isolated groups, com- contact can be observed in Santa Clara Canyon pared with the section below No. 4. and on a few of the promontories held up by PuyC Conglomerate in the area between Santa Clara Creek and Guaje Creek. The contact of the Pojoaque Member with the A new name, the Pojoaque Member of the underlying Skull Ridge Member is discussed Tesuque Formation, is herewith proposed for above (p. 54), and it is unfortunate that expo- the predominantly pink to buff, or tan to gray, sures are few on which the contact can be soft sandstones of granitic origin that discon- observed. At many places the actual contact was formably overlie the Skull Ridge Member of the buried by the numerous faults or was left in the Tesuque Formation. The name Tesuque Forma- upthrown blocks and eroded. Some of the down- tion of Spiegel and Baldwin (1963) is retained in thrown blocks were displaced only a few feet, a restricted sense for the larger grouping of but generally the amount was sufficient to bury strata, but, as noted in the section on the forma- the critical zone. The road fault (fig. 38) brought tion, several new members must be differenti- the beds of the Pojoaque Member down against ated so that the beds can be recognized in the those of the Skull Ridge, or against lower beds field and used by both geologists and paleontolo- of the Pojoaque Member as exposed in the gists in a meaningful way for future research. splinter blocks. No Skull Ridge strata have been The type area is in the Pojoaque Bluffs2 on the recognized west of the road fault in the Espanola Pojoaque Pueblo Grant. The type section (fig. Valley. 21) is situated just north of the south boundary A columnar ideal section across part of the in the SW. i of SE. i of sect. 36, T. 20 N., Espanola Valley (fig. 23) shows the general R. 8 E., in Santa Fe County, New Mexico. Five stratigraphic relations of the Pojoaque Member. hundred fifty feet of beds are exposed at this This, in particular, shows the stratigraphic posi- point. The lowermost beds of the member are tion of the type section of the Pojoaque Member not exposed in this section. These can be ob- as exposed in the central Pojoaque Bluffs served on the west side of First Wash (United (United States Geological Survey: Los Barran- States Geological Survey: Arroyo del Llano) COS) . near the town of Santa Cruz in the SW. of The type section of the Pojoaque Member is sect. 3 1, T. 2 1 N., R. 9 E., in Rio Arriba County, shown as an ideal section (fig. 2 1).The structural New Mexico, and in Second Wash (United relations in the Central Pojoaque Bluffs are States Geological Survey: Arroyo Quarteles), shown in figure 38. An additional profile section and particularly in Third Wash (United States for correlation is shown of beds in the North Geological Survey: Arroyo de la Morada), north Pojoaque Bluffs (fig. 24) in the NW. ofsect. 25, of the Santa Cruz River in the SW. i of SE. a of T. 20 N., R. 8 E., in Santa Fe County, New sect. 33, T. 21 N., R. 9 E., in Rio Arriba County, Mexico; this is in the southeast corner of the New Mexico. Figure 22A is a photograph of the Santa Clara Pueblo Grant. The relative positions beds in the Santa Cruz locality. The upper part of the Pojoaque White Ash and the Blue-Gray of the section is best exposed in several of the Ash, both of which are key beds in this locality, washes north of the Santa Cruz River where the are shown in these cross sections. A few fossil washes head against the remnant of a great specimens that happened to have been collected alluvial fan (fig. 38). Less well-exposed, but from the line of section are listed to illustrate the nonetheless important, outcrops of the upper method of field correlation of fossil collections made in the locality. The salmon-colored beds 'Pojoaque is the Spanish pronunciation of the Tewa shown above the Pojoaque White Ash are dis- Indian word meaning "drinking water place." Harrington tinctive and are useful for correlation. The 100 (1916), in his monumental work on the ethnogeography of the Tewa Indians, gave more than 40 different spellings feet of beds cropping out above the Pojoaque for the word (p. 334). Pojuaque is the spelling used on White Ash are mostly faintly banded coarse to Lt. G. M. Wheeler's map of north-central New Mexico, fine sand, with a few thin layers of siltstone and issued April 26, 1876, and this spelling was followed by fine sandstone. Some gravel lenses crop out, but Frick Laboratory parties. In order to conform to recent the pebbles in the lenses are small compared practice, however, the form Pojoaque is adopted. ?Shown as Los Barrancos on United States Geological with those of the thick gravel lenses in the Survey Espanola 7.5-minute Quadrangle, 1953. succeeding strata. The color is buff, tan, pinkish, BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY

Type Section of the Pojooque Member of the Tesuque Formation

SW.~of SE.~of Section 36, T. 20 N., R. 8 E.; Santa Fe County, New Mexico

Weathers as gray bond, blue and yellow ashy inclusions

Moy be colcoreous ledge

Pojooque White Ash Crnoy be calcareous oshy sand loterolly toward south) Dork ashy sandstone

Locally colcoreous

White osh or green zone loterolly, rnoy be obsent laterally

White bond-calcoreous,loterolly moy be colcoreous ledge

Dork oshy sand strotum

Light blue or white osh

Dark oshy streok Bentonitic white stratum

FIG. 21. Type section of Pojoaque Member of Tesuque Formation, SW. $ of SE. & of sect. 36, T. 20 N., R. 8 E., Santa Fe County, New Mexico. These beds are exposed in central Pojoaque Bluffs, shown as Los Barrancos on United States Geological Survey, 1953, 7.5-minute series, Espanola, New Mexico, Quad- rangle. FIG. 22. A. First Wash in Santa Cruz collecting locality, view looking northcast across beds of Pojoaque Mcmber of Tesuquc Formation that have been unusually fossilifcrous. First Wash shown as Arroyo del Llano on United States Geological Survey, 1953, 7.5-minute series, San Juan and Espanola, New Mexico, quadrangles. B. Pojoaque Bluffs, type locality of Pojoaque Member of Tesuque Formation, lookinz west from north of Pojoaque, New Mexico. Pojoaque Bluffs shown as Los Barrancos on United States Geological Survey, 1953, Espanola Quadrangle. Alluvial plains in foreground that extend to base of bluff.9 are being dissected by arroyos, which rarely cut deeply cnough to expose the Pojoaque Member. 62 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY VOL. 144

or salmon, and it often depends on the particular munque (fig. 25) and Santa Cruz localities, the bed that is supplying most of the mantle rock. color appears to be largely related to the abun- The same bed may show varying intensities of dance of feldspar in the gravel and in the fine- color on different outcrops; for instance, gentle grained thin sandy strata between the gravel slopes or north-facing slopes may show a lenses. Pink microcline predominates in the marked color difference from those observed on granitic gravels north of Nambt Creek, which steep slopes, cliffs, or on south-facing slopes. In becomes known as Rio Pojoaque below the the succeeding buff to pinkish, relatively thick, mouth of Tesuque Creek. In the higher gravel granitic gravel lenses that crop out in the higher lenses south of Nambt Creek-Rio Pojoaque, par- parts of the Central Pojoaque Bluffs, and in the ticularly in the Arroyo Ancho and \Vest Cuya- stratigraphically high portions of West Cuya- munque Wash (United States Geological Survey :

FIG. 23. Columnar ideal section across part of Espanola Valley, showing stratigraphic position of detailed type section of Pojoaque Member (fig. 21) in the central Pojoaque Bluffs (United States Geological Survey: Los Barrancos) . FIG.24. Profile section in North Pojoaque Bluffs designed to show correlatioi~details. Numbers are field numbers. 64 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY VOL. 144 Arroyo Jacona), the deep reddish microcline of two great systems of alluvial fans in the Santa becomes sufficiently abundant to give a distinc- Fe area, the distal ends ofwhich intertongued, is tive reddish appearance to the outcrops. These fundamental to the interpretation of the strati- reddish rocks are obviously derived from the graphy of the Tesuque Formation. southern part of the Sangre de Cristo Range Fossils were collected at many localities in the and are a part of the alluvial-fan sequence that beds of the Chama-el rito Member (fig. 26). had a in the Precambrian rocks of One of the most prolific of these was the Chama- the range near the city of Santa Fe. el rito collecting locality (fig. 2), which has been In general the Pojoaque Member crops out in selected as the type locality of the Chama-el rito a great semicircular belt or pattern of isolated Member. The type section lies along the east groups of exposures from the vicinity of Chim- border of the Juan J. Lobato Grant, in the two ayo, New Mexico, north of the Santa Cruz easternmost rincons at the head of Caiiada de River, to Santa Cruz, through Espanola, San Tio Alfonso (see United States Geological Sur- Ildefonso, Pojoaque, to the general locality west vey Medanales Quadrangle, 7.5-minute series, of the Tesuque Indian Pueblo. The outcrops are 1953). The area on that map designated as mapped in figure 38. Owing to faulting, several Rincon del Cuervo is underlain by Chama-el of the more fossiliferous horizons in the Pojoaque rito beds and the overlying Ojo Caliente Sand- Member have been repeated, thereby providing stone. The stratigraphic relations between the excellent opportunities for obtaining extensive two members can be seen in the Caiiada Honda mammalian collections from the beds. The total where several faults have been mapped that exposed section in the various fault blocks is bring the Ojo Caliente Sandstone down against much greater than would be expected, because the Chama-el rito as well as displaying the the topographic expression of the area, with its stratigraphic relations of the beds. The type isolated groups of exposures, relatively narrow section would have been in the W. 3 of sect. 23, breadth of outcrop, and large covered areas, has T. 23 N., R. 7 E., Rio Arriba County, New given the illusion that the total exposed section Mexico, had the Juan J. Lobato Grant been is thinner than some of the other formations of surveyed in the General Land Office Surveys of the Santa Fe Group. the area. This method of locating the typeset- The rocks of the Pojoaque Member produced tion is awkward but we hope will prove to be most, but not all, of the fossils described by Cope effective. (1874a, 1874b, 1875a, 187513) and also the bulk Beds of well-rounded-pebble- to cobble-sized ofthe material described by Frick (1926a, 1926b, clasts of volcanic rock, lenticular in outline and 1933, 1937). The fossils have proved to be forms interbedded in buff to pinkish, coarse to fine, currently assigned to approximately Valentine soft sandstones or siltstones, are characteristic of and Clarendon equivalents. The fossil taxa the Chama-el rito Member. The colors of the represented include many forms not commonly volcanic gravel lenses are commonly light included in the Clarendonian, but the "fit" is purplish gray to medium brownish purple; not better with a Valentinian (see above, p. 12) and uncommonly, large areas underlain by the Clarendonian concept of North American member have a somber purplish hue owing to Land-Mammal Ages than with either the pre- the erosional concentration of volcanic clasts on ceding Barstovian or the succeeding Hemphil- slopes, particularly noticeable where the inter- lian. We think it is worth noting that some of the calated buff or pinkish sandstones or siltstones strictly Clarendonian taxa have not been found are thin and the gravel lenses are numerous. in the Pojoaque Member, which does not, how- The volcanic clasts in hand specimens vary ever, prevent an analysis of the forms collected greatly in texture and composition and even in and a subjective assignment of the taxa. color. Some are glassy, some aphanitic, some crystalline, and others porphyritic, and this CHAMA-ELRITO MEMBER,NEW NAME diversity of texture indicates that they were Brief mention of the existence of beds in the derived from several different kinds of rocks. Espanola area that differ lithologically from the The petrography and petrology of the volcanic Pojoaque Member but that were deposited at debris that is characteristic of the Chama-el rito the same time is made above (pp. 7, 43). The Member should provide some future investigator recognition of the contemporaneous deposition with an interesting and tremendously important LETIN AMERICAN MUSEUM OF NATURAL HISTORY, VOL. 144, ART. 1

CUYAMUNQUE LOCALITY New Mexico

I

SCALE: 1.5 inch = I Mile Sect~ons,vertical scale In feet Red groni'te conglomeratic sandstone

Upper Red Bond

Srnoll zone

Red-Green Horizon

ossiliferous horizon

Wh~teashy zone mall concretion zone_ ,' * Yellow ~nclusions

Platy local sandstone Red-Green Horizon

H

FIG.25. Outcrop map of West Cuyamunque collecting locality, with four correlated sections. 1971 GALUSHA AND BLICK: SANTA FE GROUP 65 project, particularly if comparable studies are remnants of an ancient which made of the volcanic rocks of adjacent areas, and dominated the ancestral Valles Mountains." of the general San Juan Mountain or Taos Smith (p. 950) also wrote, "the Abiquiu tuff fan Plateau regions, in an effort to establish firmly appears to have lapped against the Chicoma the provenance of the rocks of the Chama-el rito. volcanic mass after active volcanism had The San Juan Region of Colorado and north- ceased." ern New Mexico is here postulated as the Still another origin for the Santa Fe beds was source, either directly or indirectly by reworking, suggested by Atwood and Mather (1932, pp. 98, of the volcanic pebbles that are characteristic of 99) who correlated the Conejos Formation vol- the gravel lenses of the Chama-el rito Member. canic beds, or material derived from these vol- In this regard, we do not agree with Bryan canic beds, with the Santa Fe Formation "up to (1938, p. 204) who suggested: ". . .the Sierra de the highest beds that contain andesite breccia." 10s Valles area, in the eastern part of the Jemez .They speculated, moreover, that "Probably all Mountains, is similar in many respects to the the sand and gravel near La Madera, Ojo San Juan region except for size. It includes a Caliente, and El Rito is of Conejos age." Several great thickness of older volcanic rocks, which localities were discussed and conclusions drawn. have been much faulted and deformed." He Cross and Larsen (1935) refined the concept of considered the Jemez rocks as pre-Pliocene in the Conejos Formation and correlated many age, and stated, "Many of the thin tuff beds of sets of rocks on petrographic similarity, while at the Santa Fe doubtless had their origin in this the same time stressing that certain rocks chang- volcanic center." Harold T. U. Smith (1938, ed from place to place. By 1956 Larsen and pp. 939, 958) suggested that the Chicoma Vol- Cross had further expanded their subdivision of canic Formation in the Valles Mountains repre- the rocks of the San Juan Region in Colorado, sented 'the much-eroded and partly buried and, although they traced several sets of rocks of 66 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY VOL. 144 Conejos age into northern New Mexico, they did Pinos Gravel as a member of the Hinsdale not postulate that these rocks extended into the Formation and considered both the member and Santa Fe area. They (Larsen and Cross, 1956, the formation to be Pliocene and probably late p. 186) reviewed the stratigraphic position of the Pliocene in age. Bingler (1968, p. 36) estimated Los Pinos Gravel, which previously had been the age of the Los Pinos Formation "as Oligo- considered a member of the Hinsdale volcanic cene to Miocene, based on stratigraphic rela- series, and concluded that the rocks of the Los tionships" and, on a later page (p. 65), assigned Pinos Gravel were correlative with the Fisher a "Late Oligocene-Early Miocene age to the . They quoted Butler as authority Los Pinos." for the Los Pinos age of some of the gravels of We have considered that at least some of the the Tusas-Tres Piedras area, New Mexico, and volcanic rocks in the conglomerate lenses in the they treated in great detail (p. 192) the exten- Chama-el rito were derived from the reworking sions of the into the type of clasts from part of the Abiquiu Tuff (see area of the Santa Fe Group. below, p. 115), but we believe that most of the Recent work by Bingler (1968, p. 35) intro- volcanic rocks had a provenance in the general duced new data concerning the stratigraphic San Juan Region of Colorado and northern New position of the Los Pinos Formation. He stated Mexico. It will be a great advance when all (pp. 36, 37) : "On the basis of this work, it is the these rocks have been dated by radiometric writer's opinion that the lower 300 feet of Pre- methods and the results made available. cambrian clast gravel included in the Abiquiu These introductory paragraphs are written to Tuff are the lateral equivalent of the Ritito provide a brief survey of published opinion Conglomerate and that the upper 1000 feet of regarding the volcanic rocks in the Chama-el conglomerate represent the southwestern exten- rito Member of the Tesuque Formation, and to sion of the volcanic Los Pifios Formation . . . . emphasize our support for the hypothesis that The Santa Fe Formation intertongues with Los the volcanic rocks in the Chama-el rito Member Pifios Formation over a large area from the bad- were derived from the San Juan Region or con- lands east of El Rito Creek through Ojo Cali- tiguous areas to the northeast in the general ente, La Madera, and Servilleta Plaza. In these Taos Plateau area rather than from the Valles areas, the pinkish purple sandstone and con- (Jemez) Mountain region. glomerate beds of the Los Piiios Formation are South of Santa Clara Canyon, and especially prominently intercalated with the buff siltstone east of Battleship Mountain (fig. 38), the Chama- of the Santa Fe. The contact zone represented el rito Member interfingers at the base of, and is by this interfingering appears to rise strati- locally overlain by, part of the Ojo Caliente graphically westward, although the absence of Sandstone. At a few spots between Battleship any key beds makes it very difficult to be certain Mountain and the Sacred Springs (fig. 38) the of this conclusion." We believe that the buff Chama-el rito volcanic-pebble lenses interfinger siltstone that he cited as evidence for inter- with granitic beds of the Pojoaque Member. fingering of the Santa Fe with the Los Pinos Indeed, it can be shown that the top of the Formation is an integral part of his Los Pinos Pojoaque Member at this locality clearly under- sequence and is not a part of the Santa Fe lies part of the Chama-el rito Member which in sequence. It is interesting to note that much of turn underlies part of the Ojo Caliente Sand- the area near El Rito, Ojo Caliente, and La stone, which means not that the entire Chama-el Madera that was mapped as Los Pinos Forma- rito Member is younger than the Pojoaque tion by Bingler (1968, pl. Ib) was mapped by Member but only that a late part of the Chama- Harold T. U. Smith (1938, fig. 4) as part of the el rito is younger. This locality, then, is critical Abiquiu Tuff, and by Atwood and Mather for establishing the stratigraphic sequence of at (1932, p. 95) as the Conejos Formation. These least parts of the various later members of the differences emphasize the importance of a study Tesuque Formation. of the provenance of the deposits of the general Extensive exposures of the Chama-el rito El Rito-Ojo Caliente-La Madera area to obtain Member crop out in the area between Abiquiu an understanding of the stratigraphic position and Rio del Oso near Chili, New Mexico. These of the Chama-el rito Member. deposits lie south and west of the Chama River Cross and Larsen (1935, p. 100) regarded Los in a belt extending to the edge of the high-level 1971 GALUSHA AND BLICK: SANTA FE GROUP 67

Lobato basalt flows. Here, as elsewhere, the Ojo small. A third example of interbedded tuff crops Caliente Sandstone can be observed overlying out on the slopes of a small, unmapped, basalt- the Chama-el rito beds, and the contact displays capped mesa about 3 miles northeast of the town a zone of interfingering. The interfingering of Ojo Caliente. The relations of this tuff are seems to be the result of the overwhelming, by obscure, and the origin of it or its probable ex- eolian sand, of relatively flat broad channels tension is unknown. containing the characteristic volcanic pebbles. A series of multiple working hypotheses were The channels are represented as lenses on most tested in an attempt to decide whether the facies outcrops and in man) places can be seen to have concept should be applied in differentiating the been shifted laterally. An occasional red clay or volcanic sediments of the Chama-el rito Member silt band indicates the presence for a significantly from the granitic sediments of the Pojoaque long time, probably for several years, of broad, Member. Inasmuch as the two groups of sedi- flat, valley-like areas between sand hills. Finally ments are genetically distinct, they are here the volcanic channels or lenses were completely treated as rock-stratigraphic members. Had they cut off, and the eolian sand of the Ojo Caliente shown merely a contrast or change in conditions Sandstone was deposited as a genetically distinct of deposition, they could be called the Pojoaque unit. facies and the Chama-el rito facies of the Concretions in the Chama-el rito do not Tesuque Formation with propriety. The funda- resemble those of the Ojo Caliente Sandstone mental differences are great, however, so they and. furthermore. tend to be confined to certain are separated as formal units. levels. They are small, rarely more than 8 inches in diameter, unless they enclose or partially Ojo CALIENTESANDSTONE, NEW NAME enclose fossil mammalian remains. in which Ojo Caliente Sandstonel is a new member event they commonly are larger. They weather name proposed for the uppermost part of the to a light reddish brown color and typically have Tesuque Formation. The new member is pre- a rough exterior. They disintegrate fairly easily dominantly of eolian origin and is 450 feet thick upon weathering, particularly if they contain at its greatest unbroken section. It is named for fossils. The concretions are not abundant at any the Ojo Caliente River in Rio Arriba County, locality and are composed ordinarily of coarse New Mexico, and the type locality is here desig- sand or granule-size grains. The cement is nated as the triangular area that is bounded on calcium carbonate. the east by the Ojo Caliente River, on the south- Although we recognize the provenance of west by the Chama River, and on the west by most of the volcanic pebbles of the Chama-el rito El Rito Creek (figs. 27B, 27C, 38). The Ojo to be the general San Juan and peripheral Caliente Sandstone overlies beds of both the regions, we are aware of evidence of con- Pojoaque Member and the Chama-el rito temporaneous volcanism in the localities in Member of the Tesuque Formation and inter- which Chama-el rito rocks are exposed. One fingers at the base with each. The upper small, thin, interbedded lava flow crops out in boundary is the unconformity at the base of the the Rio del Oso-Abiquiu collecting locality Chamita Formation (see below, p. 74). It is (figs. 35, 38). This small flow was arched, but exposed in an unbroken section along the south- not breached, by one of the later Rio del Oso west flank of Black Mesa (figs. 28B, 30B) ; also dikes; this occurrence is described in greater in the Dixon sub-basin to the southeast where it detail under the heading Rio del Oso Dikes has been beveled by the Truchas pediment, and (P. 90). where three red clay bands are locally useful for Tuffaceous sediments interbedded in the correlations (fig. 28C; see section on Erosion Chama-el rito Member are exposed along El Surfaces, p. 95). A small area of the sandstone Rito Creek just above the mouth of Cerro de las (fig. 27A) also crops out parallel to the west face Minas Wash (United States Geological Survey: of the Precambrian crystalline rocks of the low Arroyo del Perro). The presence of a nearby vent is indicated by volcanic bombs that lie in lWith equal propriety these beds could have been called the Ojo Caliente Sands owing to the slight amount of the tuff, many of them at the spots where they compaction or consolidation of the sand, but the term originally fell. The volume of tuff contributed to sandstone was used advisedly to imply broader generic the adjacent deposits in the Chama-el rito is relationships. Grovel lenses with intercoloted fine sediments Unconformity \ \ €/ Rilo Creek A Wash I 6580' Abiquiu Tuff Ojo Colienle River

-

Pleistocene remnonts B o Coliente Sondston Sandstone dik

00' H

Block Meso

Pleistocene grovel Chomito Formotion C eistocene grovels 0' Ojo Colionte Sondston J

FIG. 27. Cross sections of deposits of Chama-el rito Member and Ojo Caliente Sandstone of Tesuque Formation north of Black Mesa. A. Geologic section across divide between El Rito Creek and Ojo Caliente River. Length of section, about 8 miles. B. Geologic section from Chama-el rito locality through middle Ojo Caliente locality, showing relation of Ojo Caliente Sandstone to underlying Chama-el rito Member of Tesuque Formation. C. Type section of Ojo Caliente Sandstone in north fork of Middle Ojo Caliente Wash, sects. 28, 34, and Black Mesa Grant, T. 23 N., R. 8 E., Rio Arriba County, New Mexico. Length of section, about 2 miles. 1971 GALUSHA AND BLICK: SANTA FE GROUP 69 mountains immediately west of Ojo Caliente, distribution. They range from very small, indi- New Mexico. West of the Chama River between vidual, ball-like masses to great flattened tubes Kunya Ruins Wash and South Wash (United of sandstone, some of which are more than 40 States Geological Survey: Arroyo de la Presa) in feet in length, 6 to 10 feet wide, and usually not the Rio del Oso-Abiquiu locality (fig. 38) the more than 3 feet thick. The outer shells of the Ojo Caliente Sandstone and the underlying tubelike concretions are only a few inches thick, fossiliferous beds of the Chama-el rito Member homogeneous, and harder than the interiors, are broken by many faults, and excellent ex- which are often friable masses of sandy, ball-like posures are available for study. Some of the high concretions, with loose sand filling the inter- hills that rise as monadnocks above the several stices. The cementing material is calcium car- erosion surfaces of the locality are part of the bonate. Concretionary sandstones may cap Ojo Caliente Sandstone. The Ojo Caliente columns in much-dissected localities, and along Sandstone thins rapidly toward the south, and cliffs may protect the underlying sand so that the exposures in Santa Clara Canyon probably vertical or smooth-walled surfaces as high as represent original thicknesses rather than rem- 30 feet are formed. Large areas underlain by the nants of post-Ojo Caliente erosion. Still farther Ojo Caliente Sandstone have no concretions, or south near Battleship Mountain (fig. 38) the only a few, and some of these areas have a sub- member is only a few feet thick. It is less variable dued, rounded topography modified by loose lithologically than any other member or forma- sand, which is shifted back and forth by the tion of the Santa Fe Group and has been ex- winds. Other areas of soft sand are being strongly tremely useful in the correlation of widely sepa- dissected by small, finely branching gullies rated exposures. which often cause the sandstone to become Several hundred feet of little-consolidated, sculptured into an intricate system of vertical well-sorted, fine- to coarse-grained, pinkish to columns that become pointed and spirelike white quartz sand characterizes the Ojo Caliente toward the top. Sandstone. The individual sand grains are At several horizons, and especially near the commonly well rounded, with a dull, frosted middle of the member, small, round, sand- appearance. Eolian cross-bedding on a large blasted, and light-colored sandstone balls were scale is typical of most, but by no means all, of observed. The origin of these sand-blasted balls the strata and is present over wide areas. A few is not clear, although they appear to have been of the larger observed foresets are more than reworked from Iower beds of the member. 80 feet long; most of them, however, measure Commonly they are between 4 inch and 1 inch less than 25 feet. An easily accessible example of in diameter. eolian cross-bedding is shown in figure 36B, a Fossils are rare in the Ojo Caliente Sand- photograph taken along the highway south of stone; only in the Rio del Oso collecting locality the town of Ojo Caliente. Concretionary sand- (fig. 2) were significant numbers of specimens stones may or may not occur throughout, and found. These fossils came from the lowermost individual concretions may range in length from 200 feet of the member in this localitv. a few inches to many feet and in thickness from a Strong arguments could be presented for few inches to 4 feet. These concretionary sand- separating the Ojo Caliente Sandstone as a new stones are clearly epigenetic and normally occur formation, for it is certainly a distinctive litho- in a horizontal position often incorporating the logic unit, easily recognizable, mappable, and steeply inclined lamina of the cross-bedded with an unmistakable, alth~ughinterfingering, sand. On steep slopes, and when viewed from a lower boundary. We prefer to consider it a distance, the concretionary sandstones com- member of the Tesuque Formation, for the monly cause the outcrops to have a distinctive rocks of which it is composed were obviously ribbed appearance. The ribbed feature is winnowed from the ~ojoaqueand Chama-el rith especially noticeable along the western flanks of members of the Tesuque and were the response Black Mesa. to an environmental change that brought The lower part of the Ojo Caliente Sandstone Tesuque deposition to a close. At many points in the type locality, particularly west of the fault in the areas in which the Chama-el rito Member zone (fig. 38), contains great numbers of con- and the Ojo Caliente Sandstone are in inter- cretions that are very irregular in form and fingering contact, the dune sands of the Ojo 70 BULLETIN AMERIC-W MUSEUM OF N.4TUR.AL HISTORY VOL. 144 Caliente appear to have encroached upon, dis- ci-oss-bedding, the similarity of concretions, the placed, and finally overwhelmed (above, p. 67) weathering characteristics, and the similarity of the broad channels of gravel of volcanic origin topographic expression, these beds are vastly that are characteristic of the Chama-el rito different in age. The Zia Sand Formation is ,Member. Arikareean to Hemingfordian in age, and the Some lithologic similarities exist between the Ojo Caliente Sandstone is Clarendonian. They Ojo Caliente Sandstone and the Zia Sand each represent, obviously, a response to a similar Formation (Galusha, 1966), which is treated set of environmental conditions that occurred briefly in this report in the section on pre-Santa millions of years apart, and these lithologic and Fe Group formations. Despite the general gray other similarities emphasize the danger of rely- or whitish or pinkish color of each, the eolian ing solely on lithology for correlation.

Black Mesa

A

nterbedded flow Chomita Formation

Block Mesa

B Clay or bentonite str

c Truchas pediment

o. I Red stratum .2 Red stratum

FIG. 28. Relations of Ojo Caliente Sandstone at three sites. A. Southwest tip of Black Mesa. B. Unbroken section on wen side of Black Mesa. C. Cross section in Dixon sub-basin on Embudo Creek. 1971 GALUSHA AND BLICK: SANTA FE GROUP 7 1

CH.4hfITA FORMATION, NEW NAME bands of the Upper Tuffaceous zone are com- Strata of the Santa Fe Group in the type area monly several feet thick, but the generally light that are stratigraphically above and are uncon- color of the zone results from the dissemination formably in contact with the Ojo Caliente Sand- throughout the zone of the white pumiceous or stone, which is the uppermost member of the ashy particles. In the lower portion of the Upper Tesuque Formation, are here proposed as a new TufFaceous zone the sands are mostly quartzitic formation. The term Chamita Formation is used and range in size from coarse sand to granules, for these rocks, which are here distinguished and with some fine sand, silt, and reworked tuff described for the first time. The uppermost present. Quartzitic gravels are abundant and boundary of the Chamita Formation commonly are lithologically different from either the vol- is marked by an unconformity, and it is overlain canic gravels of the Chama-el rito Member or the by later formations at several different localities. granitic gravels of the Pojoaque Member of the These later formations include the Puyt Con- Tesuque Formation. Obviously the Chamita glomerate, Los Pinos Gravel, and beds question- Formation marks a profound change in the sedi- ably assigned to the Ancha Formation, to the mentary regimen of the type area of the Santa Servilleta Formation, to unnamed beds of the Fe Group. A few cobble beds and occasional Picuris re-entrant, and to constructional deposits isolated boulders have been observed in the on late erosion surfaces. These occurrences are section. Cross-bedding is neither extensive nor discussed later in this section. The Chamita well developed. The upper portion of the Upper Formation, in addition to being lithologically Tuffaceous zone is fine-grained and may have distinct, has produced an extensive fauna that is many reddish, fine-sand zones and patches. The appreciably different from that previously re- Lower and Upper Tuffaceous zones are sepa- ported from the Santa Fe type area. These rated by about 260 feet of light brown or gray deposits are shown by the fossils to have been bands of fine to coarse sand in which lenses of deposited during a segment of Hemphillian conglomeratic sand and gravel crop out. Thick time. This is discussed in detail in the section on beds of rounded to subangular pebbles of quartz- the age of the Santa Fe Group. ite crop out on the Black Mesa side or base of the The San Juan collecting locality (fig. 2) is triangle, and the beds at that point are different selected as the type locality of the Chamita in appearance from those on the same horizon Formation because it contains a large part of the at the south end of the locality in the apex of the stratigraphic section referred to the formation. triangle. Breadth of outcrop of the two tuffa- The formation takes its name from the nearby ceous zones is vastly different. The lower zone is village of Chamita. The type section is shown as exposed at only a few places, but, on the other an ideal section in figure 29, and is situated in a hand, the Upper Tuffaceous beds crop out in a small, triangular area lying south of Black Mesa broadly saucer-shaped pattern along the north, between the Chama River and the Rio Grand southeast, and south sides of the Chamita (figs. 30A, 38). The apex of the triangle is near Formation type locality, and less distinctly on the mouth of the Chama, and the greater part of the southwest and west. Dips are low except the type section lies within the boundaries of the along the foot of Black Mesa. San Juan Pueblo Grant. The type section is The Upper Tuffaceous beds are moderately further designated as underlying the NW. 4 of resistant and characteristically erode to smoothly sect. 10 and the W. ) of sect. 3, T. 21 N., rounded convex surfaces on which very little R. 8 E., in Rio Arriba County, New Mexico. weathered mantle rock remains. Occasional sand- One of the distinctive features of the type stone or conglomerate lenses form ledges or locality is the presence of two zones of white to benches. These benches and the smoothly pinkish tuffaceous beds (fig. 29). The Lower rounded surfaces combine to give the zone a Tuffaceous zone comprises about 80 feet of distinctive appearance quite apart from the moderately coarse sand and gravelly layers, with four or more white tuff layers and some more obvious one of color. Thin clayey layers dark ashy sand strata interspersed throughout may be present locally, and thin limey or marly the zone. The Upper Tuffaceous zone is com- strata also may crop out. Not uncommonly these posed of 100 feet of white, light-colored or pink- clayey and limey beds have been associated with ish, tuffaceous beds. The white tuff layers or concentrations of fossils. The San Juan Quarry BULLETIN AMERICAN h:IUSEUM OF NATURAL HISTORY VOL. 144

Terrace gravel

Type Section of the CHAMITA FORMATION in NW. I 4 of Sect. 10, and the W. -2 of Sect. 3 T. 21 N., R. 8 E. in Rio Arriba County, New Mexico

Son Juan Quarry Rak Camel quarries

Lower tuffaceous zone

FIG. 29. Type section of Chamita Formation in W. 4 of sect. 10, and W. of sect. 3, T. 21 N., R. 8 E., Rio Arriba County, New Mexico. FIG. 30. A. Type locality of Chamita Formation, showing relationship to southern tip of Black Mcsa, vicw looking northwcst from east of San Juan Pueblo, New Mcxico. 1,inc of trees in middle distance is along Rio Granclc. Chama Ri~~erflows through notch left of top of Rlack R4esa. At left cclgc of photograph, whitc hill in distance is "Conical Hill" in Rio dcl Oso-Abiquiu locality. Dark hills above and bcyond it on skyline arcx remnants of high-level Lobato basalt flows. B. Part of northwcst-facing wall of Rlack Rlcsa taken in castcrly clircction from high cemented zone (Ccrrito de la Baca: Unitcd States Geological Survey, 19.53, 7.5-minute series, San Juan Pucblo, New Mcxico, Quad- rangle) on cast bank of Ojo Calicntc River about 2 milcs above mouth. Chaniita Formation dcl->ositscrop out below basalt near top of steep (-r;l~osuresatriylit ccsntcr. Scveral hunclrccl fcct of Ojo Calicntc Sandstone arc. cxl~osvdon lowcr slopes of Rlack Mcsa and on low hills in foreground. 74 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY VOL. 144 and several small quarries have been worked in thick. The extremely prolific Round Mountain the Upper Tuffaceous zone. Quarry is in the Chamita Formation in a small The topmost tuffaceous stratum in the Upper canyon just north of the road to the PuyC Ruins Tuffaceous zone grades upward into 300 feet of in the NW. a of sect. 20, T. 20 N., R. 8 E., in Rio pinkish, brownish, or gray sand, silt, and con- Arriba County. The quarry is on the Santa glomeratic sand. The general color is light Clara Pueblo Grant. (See photographs showing brown or buff. The sediments are coarse in the early work in the quarry, fig. 8A, B). Chamita lower part of the 300 feet, and conglomeratic beds in Santa Clara Canyon have yielded charac- lenses are numerous. These sediments are much teristic fossils, as have the beds south of Battle- softer than the beds of the underlying Upper ship Mountain on the San Ildefonso Pueblo Tuffaceous zone and are protected from rapid Grant. erosion by remnants of a high, late Pleistocene Beds of several localities were correlated with, or Recent, river-gravel terrace 20 or more feet and included in, the Chamita Formation on thick which cap high points in the Chamita type lithologic similarity, but often it was possible to locality. The light brown strata dip at a lower use both lithology and fossils in making the angle than those of the Upper Tuffaceous zone. determination. In the center of the saucer-shaped basin the dip The contact of the Chamita Formation with is 2 to 3 degrees. The deposits of the Chamita the underlying Ojo Caliente Sandstone is a Formation unconformably overlie the upper- special variety of unconformity in which the most beds of the Ojo Caliente Sandstone of the dune sand of the Ojo Caliente was leveled and Tesuque Formation along the northwest side of reworked over the areas in the type locality of Black Mesa where the 200 to 300 feet of the the Santa Fe Group in which the Chamita Chamita are exposed below the rim. The beds Formation was deposited. At those localities in along the northwest side of Black Mesa are a which the contact can be observed readily, such somewhat different facies from those of the type as the southwest side of Black Mesa, in Santa locality, but the fossils collected from them show Clara Canyon, and in the vicinity of Battleship that they are equivalent. Mountain (fig. 38), the basal beds of the Cham- Additional exposures of the Chamita Forma- ita were heavily overloaded with sand reworked tion crop out as isolated patches along the flanks from the Ojo Caliente. Care must be exercised of Black Mesa from El Guique to the vicinity of in determining the contact, because the re- Velarde. These lie within the Black Mesa Grant worked sand beds above the contact often and closely approximate the southeastern resemble those commonly interpreted as inter- boundary of the grant. West of the Rio Grande fingering. and south of South Wash (United States Geo- Great variation in thickness of the Chamita logical Survey: Arroyo de la Presa) is a much- Formation is commonplace owing to the un- faulted area of scattered and ill-exposed outcrops known, but surely extensive, amount of erosion of the Chamita Formation. The area is known of the upper beds of the Chamita. These thick- as the Hernandez locality, and the topography nesses may range from more than 700 feet at the has been controlled by an erosion surface and the type locality (figs. 29, 30A) to 300 feet along constructional gravels lying thereon. South of Black Mesa (fig. 30B) to a near minimum of Black Mesa the Chamita Formation lies mostly 30 feet at Battleship Mountain (fig. 3 1A). on granitic gravel beds of the Tesuque Forma- The Puyt Conglomerate (Griggs, 1964) over- tion. The Chamita, however, can be observed lies the Chamita in the area west of the Rio overlying a thin wedge of Ojo Caliente Sand- Grande, but along the northwestern side of stone along the lower slopes of the bold promon- Black Mesa the Chamita Formation is uncon- tories west of the Rio Grande from Santa Clara formably overlain by a gravel bed assigned to Canyon south to the Sacred Springs of the Tewa the Los Pinos Gravel by Atwood and Mather Indians near Guaje Canyon (figs. 31B, 38). These deposits are the most fossiliferous, but also (1932, p. 99), which is in turn unconformably the thinnest, part of the Chamita Formation, overlain by Black Mesa basalt, which was for they have been planed off to form the assigned to the Hinsdale Formation by Atwood erosion surface on which the Puyt Conglomerate and Mather (1932, p. 98), Larsen and Cross was deposited and are now no more than 200feet (1956, p. 197), Harold T. U. Smith (1938, FIG.31. A. Contact of Chamita Formation of Santa Fc Group with overlying PuyC Conglomerate at prominent whitc horizontal linc across face of Rattlcship Mountain. Remnant of Randclicr Tuff forms highest point in photograph and wcathcrs with characteristic columnar jointing-. Contact with underlying PuyC Conglomerate lies just below white zone below columns. Low cliifs along base of lcft half of Rattlcship hlountain are Ojo Caliente Sandstone, underlain by thin wedge of Chama-el rito Mcmbcr, in turn underlain here by Pojoaquc Member. H. Contact of Chamita Formation and PuyC Conglomerate, vicw of bold promontories held up by Puyk Con~lomcratcsouth of Rattleship Mountain. Cliffs are Puyi. Conglomerate; slopes, Chamita Formation. Contact hctwrcn the two formation5 is wrll exposed in this locality. Rattleship Mountain, surmountecl hy rcmnant of Randclicr Tuff, at far right. 76 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY VOL. 144 p. 959), and others. These relations are discussed tones of brown or red. The beds are fine-grained, below (p. 87). for the most part, but lenses of conglomeratic A particularly fossiliferous outcrop of the material do occur, and concretions are moder- Chamita Formation occurs near the head of a ately abundant. short steep canyon on the slope of Black Mesa The Osbornoceros fault, which cuts off the near the settlement of Lyden. Some of the upper Osbornoceros fault block on the east, strikes sediments in this canyon suggest those of the N. 15"W., 66"E. It is a high-angle normal fault, Upper Tuffaceous zone in the type locality, but and the amount of throw was not determined. near the main fossiliferous concentration the The beds lying to the east are younger than ~umiceous articles are concentrated in a dis- those of the quarry fault block and are charac- tinct stratum and are not diffused through the teristically cliff forming. Thin and quite diffused section. In this respect the mode of occurrence lenses of sandstone and granitic conglomeratic is very similar to that observed near the Round sandstone grade toward the east to a strong Mountain Quarry. Across the Rio Grande and conglomeratic sandstone ledge, several feet in almost directly opposite the Lyden locality is a thickness, which tends to cap cliffs in the locality. small fault block containing a fossil quarry from The cliffs are brown or buff and may display which was collected the first known remains of dark brown or reddish streaks locally. Osbornoceros osborni Frick (1937, p. 490). The We regard the Chamita Formation as having quarry is associated with a channel deposit, that been deposited as a response to a major geologic is, the channel deposits lie beneath the quarry event in the type area of the Santa Fe. This horizon and are typically greenish or gray. The event brought to an end the deposition of the quarry and channel sand contain concretionary Ojo Caliente Sandstone, which in itself was the lenses locally. Concentrations of pebbles occur final stage of deposition of the Tesuque Forma- in the channel deposits but are not extensive. tion. The contact between the Ojo Caliente The green-colored sand is observed to grade Sandstone and the overlying Chamita Forma- laterally to gray sand. At this spot a direct rela- tion marks the change from eolian deposition of tionship seems to exist between the presence of the Ojo Caliente to one of predominantly the underlying green channel deposits and the fluviatile origin of the Chamita, which culmi- occurrence of fossils. The quarry horizon crops nated in the introduction of a different suite of out onlv a few feet above the level of the wash at rocks from a different source into the type area this point, and it is extremely fortuitous that the of the Santa Fe. These rocks are easily separable quarry concentration was exposed. The sedi- from those of any of the members of the Tesuque ments in the Osbornoceros fault block strati- Formation, and it is on this criterion that the graphically above the quarry horizon have a new term, Chamita Formation, is proposed. banded appearance, with colors that are soft

POST-SANTA FE GROUP FORMATIONS

Post-Santa Fe Group formations discussed in Santa Fe Group, with the remaining formations this report are : (1) PuyC Conglomerate, formerly arbitrarily separated. A few comments on the the Puyt Gravel; (2) Ancha Formation; (3) de- Pleistocene and Recent formations of the type posits on erosion surfaces; (4) Zia Marl; (5) Ser- area of the Santa Fe Group are included in the villeta Formation; (6) Espanola Formation; section on Stratigraphy (above, p. 33). (7) varved or rhythmical sediments; (8) Otowi Lava Flow; (9) Bandelier Tuff; (10) Cerros del PUYQ CONGLOMERATE Rio lava flows; (1 1 ) high level basalts ; (12) vol- The PuyC (pronounced Poo-yay) Gravel was canic rocks; (13) Rio del Oso dikes; and (14) first mapped by Harold T. U. Smith (1938, Round Mountain. Most of the above formations p. 937), and a small area of the formation was were at one time included in the Santa Fe later mapped by Denny ( 1940b, pl. 1). We have Formation; later, as work progressed, they were mapped additional areas (fig. 38). Working in separated as distinct formations. A few of them the Los Alamos area, Griggs (1964, p. 28) in recent years have been reassigned to the described the PuyC Conglomerate as a term to 1971 GALUSHA AND BLICK: SANTA FE GROUP 7 7 replace PuyC Gravel; he recognized two mem- section. About 150 to 175 feet of PuyC is exposed bers: a lower or Totovi Lentil, and an overlying on Battleship Mountain (fig. 31), south of Santa Fanglomerate Member, which represents the Clara Canyon, and is overlain by a remnant main body of Puyt Conglomerate. about 40 feet thick of the Bandelier Tuff. The formation consists mainly of gray sand The PuyC Conglomerate was apparently and smaller pebbles, but cobbles and boulders, named for the Puyi ruins (Tewa Indian: and in a few places large boulders, are conspicu- "Where the cottontail rabbits assemble"), ous sediments. Most of the pebbles are derived which is situated on the (pro- from andesitic, latitic, basaltic, and rhyolitic nounced Pah-hah-reeto) about 10 miles west of rocks. Some of the pebbles near the base of the the village of Espanola, and 30 miles northwest formation are quartzitic and granitic, but these of Santa Fe. The PuyC Conglomerates were form only a small part of the deposits. deposited on an erosion surface originating in the Puyt Conglomerates unconformably and con- Jemez Mountains. The overlying Bandelier Tuff tinuously overlie beds of the Chamita Formation has been stripped from several square miles of of the Santa Fe Group from South Wash in the the gravel, and a long sloping plateau has re- Rio del Oso-Abiquiu locality (fig. 38) southward sulted. The surface of the plateau probably to Guaje and Los Alamos canyons. South of closely approximates the original constructional Guaje Canyon the contact is covered by basaltic surface of the conglomerate. Ancient Indian talus from the overlying Otowi lava flows. The ruins on the ridges and cliffs of Bandelier Tuff PuyC Conglomerate is confined to the west side that lie on the constructional surface have been of the Rio Grande where the deposits form high, an important archeological study region known terrace-like escarpments that are deeply trench- collectively as the Pajarito (Little Bird) Plateau. ed by long, dry washes heading along the base The PuyC Conglomerate was deposited later of the Jemez Mountains. The PuyC Conglomer- than the post-Santa Fe deformation, which ate reaches its maximum exposed thickness brought the deposition of the Santa Fe Group to northwest of Round Mountain in the vicinity of a close. Although three faults are known to cut Santa Clara Canyon. The thickest known sec- Puyt Conglomerates, they are well developed in tion was given by Griggs (1964, p. 28) as 726 feet the Chamita deposits and were traced into the in a test hole in Pueblo Canyon, which is a Puyt just west of Battleship Mountain (fig. 38). northern branch of Los Alamos Canvon,, - which We believe that these faults represent subsequent in turn is a southern tributary of Guaje Canyon. adjustment or, more probably, late stages of At Guaje Canyon and Los Alamos Canyon the adjustment to the regional deformation. Puvt maintains a thickness of 150 to 200 feet, but A thick veneer of volcanic gravel derived from it ;him abruptly toward the east and southkast, the PuyC Conglomerate buries the Chamita and only 60 feet of the gravels are preserved Formation north of Espanola on the west side beneath the northern tip of the Otowi (pro- of the Rio Grande. The gravel veneer lies on nounced Oh-toh-wee) lava flow just west of the erosion surfaces graded to a series of terraces Otowi bridge. Across the Rio Grande to the east along the Rio Grande. The relations to the the PuyC is not present beneath the part of the higher, terrace-like escarpment of PuyC Con- Otowi lava flow known as the Mesa de 10s glomerate can be seen readily, for the long Ortizes, which is surmounted by a dissected washes trenching the escarpment have supplied volcanic cone. the materials as well as provided the agent for The contact between the PuyC Conglomerate lateral corrasion to cut the erosion surfaces. and the Chamita Formation of the Santa Fe Remnants of PuyC Conglomerate occur north of Group is best exposed on promontories south of Rio del Oso, but the main thickness lies south of Santa Clara Canyon. Considerable variation in the igneous spur that extends eastward from the size and texture and lithology of the PuyC along Jemez Mountains on the south side of Rio del the contact makes detailed description beyond Oso. the scope of this report; in general, however, the The age of the PuyC Conglomerate is in doubt. sediments can be said to be gray sand, medium- A thick section of the Chamita Formation, how- sized gravel, or flattened, smoothly rounded to ever, was eroded prior to the deposition of the ovoid cobbles. The large boulders in the Puyt, PuyC, which would place the Puyt as younger for the most part, crop out rather high in the than Hemphillian (mid-Pliocene). A provisional 78 BULLETIX AMERICAN MUSEUM OF NATURAL HISTORY \'OL. 144 assignment of the Puyt Conglomerate as equiv- of the Ancha Formation. They named and dis- alent to the Gila Conglomerate in age seems cussed three of these: (1) the Plains surface, feasible. Regional correlations of thick gravel (2) the Airport surface, and (3) the Divide sur- and conglomerate deposits in Colorado, New face. In our opinion the beds underlying the Mexico, and Arizona have not been made, but Plains surface should be separated at least on the some of these deposits are latest Pliocene or early member level from those underlying the Divide Pleistocene and might well have been laid down surface. The "marls" and sands underlying the during a period of widespread and excessive area described as the Plains surface were part of precipitation, perhaps in conjunction with vol- Hayden's (1869, p. 166) original description of canic activity and regional uplift. the Santa Fe marls. Obviously the beds under- A bed of diatomite in the Puyi Conglomerate lying the Plains surface are younger than those has been prospected commercially in South of the Divide surface; moreover, they are of Wash (United States Geological Survey: Arroyo quite different lithology. de la Presa) south of Rio del Oso (fig. 38). This The relations of the Ancha Formation to the is the only diatomite bed so far reported from the conglomeratic and detrital materials lying on entire region. Farther south, in the region be- the Truchas pediment of the Picuris re-entrant tween Santa Clara Canyon and Los Alamos of Cabot (1938, p. 98) or the Penasco Embay- Canyon, lake deposits were observed at several ment, as mapped by Kelley (1956, p. 1lo), sites in the Puyt Conglomerate. Some of these remain to be worked out. The geomorphology of lake deposits have been called Santa Fe beds the type area of the Santa Fe Group is a major mistakenly, in popular articles on scenic points research project that would add immeasurably of interest that have appeared from time to time to the knowledge of the Santa Fe area and in newspapers and magazines. awaits only the attention of an interested in- vestigator. ANCHA FORMATION The term Ancha Formation was applied by DEPOSITS ON EROSION SURFACES SpiegeI and Baldwin (1963, p. 45) to detrital Remnants of erosion surfaces and the con- materials lying with angular unconformity upon structional deposits preserved thereon are con- the Tesuque Formation (the Pojoaque Member spicuous parts of the geomorphology of the of the Tesuque Formation of the present report). Santa Fe region. The erosion surfaces are all of They pointed out that the rocks of the Ancha post-Santa Fe age, and the interpretation of the Formation lie on an erosion surface (p. 49), but sequence of events during which the various they had difficulty in determining the contact surfaces were cut might well provide future in- between the Ancha and the Tesuque in the vestigators with problems of monumental pro- Santa Fe area. portions and solutions of great significance. We consider the rocks included in the Ancha The deposits lying on the various erosion sur- as Pleistocene, approximately equivalent to or faces are of many kinds. Some are basaltic or slightly post-Bandelier Tuff in age. One outcrop andesitic lava flows and associated tuff deposits. of lithologically similar to that charac- Others, such as the Puyt Conglomerate and the teristic of the Otowi Member of the Bandelier deposits on the Truchas pediment (see discus- Tuff was observed near the base of the Ancha in sions of pediments and erosion surfaces, p. 95), the West Cuyamunque Wash (United States are thick gravel accumulations derived from the Geological Survey: Arroyo Jacona) (fig. 25). mountains. Still others are a thin veneer of The Ancha is readily distinguishable from the gravel partly covered with a coating of caliche. Pojoaque Member in the West Cuyamunque At other places a thin layer of gravel and a general area where it lies with angular uncon- greater or less thickness of buff or yellowish formity on the Pojoaque; this is shown particularly brown or reddish brown fine sand cover the well in the ramifying gullies in the head of surfaces. At some localities onlv buff or brown- West Cuyamunque Wash and in the heads of ish wind-blown sand is present. Other special some of the washes that parallel it on the west. deposits are related to the disruption of adjacent Spiegel and Baldwin (1963, pp. 54, 56) recog- terraces or erosion surfaces. Two such deposits nized three or more graded surfaces as having are: (1) extensive deposits of subangular blocks been developed prior to and during deposition of lava boulders, cobbles, and pebbles derived 197 1 GALUSHA .4ND BLICK: SANTA FE GROUP 79 from the Lobato lava flows that cover many ero- that his Zia Marl was the same as Herrick's sion surfaces in the Rio del Oso-Abiquiu locali- Albuquerque Marl, but used the term Albu- ty ; (2) some gravel deposits derived secondarily querque Marl as follows : "The Pliocene rocks in from the Puyt Conglomerate, or other gravel the Rio Grande embayment which are identical beds, and preserved on lower and later erosion with the Jemez marls, just described, will be surfaces. here called the Albuquerque marls. These marls Pond deposits, on one of the lower erosion sur- are a continuation of the Santa Fe marls of Cope, faces in Kunya Ruins Wash, 2-2 miles southeast a part of which was identified by him when at of Abiquiu, have produced fragments of mam- Algodones in the seventies." moth teeth and other fragmentary late Pleisto- In the interest of stability of stratigraphic cene fossils, and also several kinds of very small nomenclature, we believe that the terms Jemez invertebrates. The pond deposits are greenish or Marl and Zia Marl should be abandoned. brownish in color and are commonly less than Neither of these has been published since origin- 4 feet thick. Similar appearing invertebrates ally proposed (Reagan, 1903), and in each case occur at several sites in the Espanola Formation, the names were applied to beds with prior suggesting contemporaneity of these deposits names. Moreover, the ages allocated by the with the Espanola Formation but not neces- original authors give an erroneous stratigraphic sarily proving it. position to the formations, which probably accounts for the disuse of the terms. ZIA MARL The Pleistocene deposits that lie on the Llano SERVILLETA FORMATION de Albuquerque were named the Zia Marl by The Servilleta Formation was described by Reagan (1903, p. 84) who believed them to be Montgomery (1953, p. 53, pl. 1) as unconform- Eocene in age. He discussed at some length his ably overlying both Picuris Tuff and Santa Fe reason for allocating them to the Eocene, and beds in the Picuris Range and vicinity. He mapped (pl. 4) them as underlying the Zia mapped gravel and basalt flows in the Dixon Mesa (his name for the Llano de Albuquerque). and the Rinconada localities as part of the Earlier Herrick (1898, p. 29, pl. 13) called these Servilleta, and this concept was expanded by deposits the Albuquerque Marl, but his atten- Lambert (1966, p. 45) in his report on the Taos- tion had been directed primarily to the caliche. Questa area. These beds have been regarded as He determined the age of the marl as (?)Pleisto- part of the Hinsdale Formation and the Los cene-a remarkably accurate estimate for his Pinos Gravel (Atwood and Mather, 1932, p. 99; day. Bryan and McCann (1938, pp. 3, 5) des- Harold T. U. Smith, 1938, p. 964) and have cribed the Llano de Albuquerque at length and included also the lava beds of the Taos Plateau cited the "marl" of Herrick (which was also as delineated by Upson (1939). Black Mesa Reagan's Zia Marl) as caliche, and used it to (fig. 28) is a remnant of a lava tongue from the support their conclusion that a great erosion Taos Plateau. Lambert's (1966) study of the surface beveled the Santa Fe beds. This they Servilleta has contributed greatly to the under- (p. 8) identified as a part of the Ortiz surface of standing of the Servilleta and the series of Ogilvie (1905). Pleistocene beds of which it is a part. Much still The Zia Marl was listed by Wilmarth (1938, remains to be done in interregional correlations p. 2394) and by Keroher and others (1966, of the Servilleta units with those of the type area p. 4338) as questionably Eocene. Wilmarth of the Santa Fe farther south, especially correla- further noted that Herrick (1898) called the beds tions with the beds lying on the Truchas erosion Pleistocene. It is clear that the term Zia Marl surface, and with the Ancha Formation. should be abandoned, for it is preoccupied by Miller, Montgomery, and Sutherland (1963, Albuquerque Marl and, furthermore, is not an p. 50) pointed out that the Servilleta is possibly Eocene formation. It should be noted that the equivalent to the Ancha Formation, but, if not term Albuquerque Marl was applied to deposits occurring on several erosion surfaces besides that equivalent to the Ancha, then is younger than of the Llano de Albuquerque. Bryan and the Tesuque but older than the Ancha. They McCann (1938, p. 14) named two such later mapped Black Mesa, Dixon Mesa, and under- surfaces. Reagan (1903, p. 86) did not recognize lying gravels as part of the Servilleta Formation. 80 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY VOL. 144 ESPANOLA FORMATION, NEW NAME scattered over the slope of the hill, with differ- Near the town of Santa Cruz are some ences in altitude of as much as 100 feet. The Pleistocene remnants from which Frick (1926c, strong unconformity at the base shows that the p. 444) reported a fine specimen of Canis dims. area had been well dissected before the Espanola The Pleistocene deposits cap the ridge along the Formation was deposited. west side of First Wash (United States Geo- Fragments of fossils testifying to the presence logical Survey: Arroyo del Llano) for several of Equus, Bison, ?, and other forms in the hundred yards and range from only a few feet to scattered Pleistocene remnants capping some of 30 or 35 feet in thickness. The southernmost edge the hills in the Skull Ridge collecting locality of the Pleistocene remnant (fig. 32) is about (fig. 2) give additional support to the idea that 240 feet north of the General Land Office survey the definitely recognizable Pleistocene deposits stake MC7, SCG; sect. 31, T. 21 N., R. 9 E., in the type area of the Santa Fe Group are ex- Rio Arriba County, New Mexico. This locality tensive enough to warrant being accorded the is here designated as the type locality of the rank of formation. Espanola Formation, a new name proposed for a The Esvanola Formation once must have been series of Pleistocene remnants in the general very extensive and probably formed a mantle of Espanola Valley area. The new formation takes wind-blown sand and loess over the entire area. its name from the town of Espanola near which Eventual correlation of the Esvanola Formation some of the best exposures of the Espanola with the loess and loess-like debosits of the Great Formation crop out. Frick (1926c, p. 444) pub- Plains east of the Sangre de Cristo Range seems lished a photograph which shows a typical out- likely when a thorough study of the subject has crop of the formation. The sediments are wind- been made. Winds strong enough to build the blown sand or silt, with a distinctly brownish great beds and associated eolian deposits of the color. They are easily distinguished from the Great Plains would surelv have carried vast underlying Pojoaque Member of the Tesuque quantities of dust over the Sangre de Cristo Formation, for the Pleistocene sediments lack the Range and would have whipped large quanti- light pink, buff, or flesh color of the beds of the ties of sand and finer particles from the beds of Santa Fe Group. The Pleistocene remnants are the Santa Fe Group. loess-like in that they tend to stand with vertical faces, except where weathering is advanced. VARVED OR Several kinds of small invertebrates have been RHYTHMICAL SEDIMENTS collected in the deposits of the type locality. A small deposit of varved clay or rhythmically Erosion of the beds of the Santa Fe Group deposited sediments crops out on the east side of produced surfaces of considerable relief prior to the Rio Grande in White Rock Canyon just the deposition of the Pleistocene Espanola south of the mouth of Canyada Ancha approxi- Formation. Field relations at the type locality mately on the west boundary of the suggest that the Espanola Formation accumu- Grant about 34 miles southwest of Otowi Bridge. lated in a small valley that had been cut in the The varved clay fills most of the lower part of a Pojoaque Member. Similar deposits occur at small valley that had been cut in the Santa Fe widely separated points from El Rito to Santa beds. The outline of part of the floor of the Fe; they occur at many elevations, and, al- valley and the contact with the underlying though commonly not so thick elsewhere, there Pojoaque Member of the Tesuque Formation is is reason to believe that many of them can be excellently exposed, and several feet of river- considered essentially equivalent to the First channel conglomerate lie at the contact. The Wash (United States Geological Survey: Arroyo varved clays overlie the conglomerate and grade del Llano) remnants. A sketch of the type locali- upward into a fairly thick series of yellowish to ty and the type section is given in figure 32. A cream-colored beds of laminated silt, sand, and few remnants of the Espanola Formation are clay, which typically have small ironstone con- mapped in figure 38. cretions or limonite plates along the bedding A good example of the Espanola Formation planes. crops out on the hill just west of United States Rhythmical sedimentation took place in this Highway 64 about 1 mile southeast of Espanola, small lake for a period of more than 200 years, New Mexico. At this point the remnants are with the eventual dissolution of the glacier Pleistocene remnant, 30 feel thick Gravels,

FIG.32. Type locality of Espanola Formation in sect. 3 1, T. 2 1 N., R. 9 E., Rio Arriba County, New Mexico. 82 BULLETIN AMERICAN MUSEUM OF N.4TURAL HISTORY VOL. 144 supplying the sediments indicated by a gradual Rio Grande the PuyC Conglomerate is not change from varved to laminated deposits. The Dresent beneath the flow on Mesa de 10s Ortizes glacial lake was apparently formed by the (fig. 34B). damming of White Rock Canyon at some point West of the Rio Grande the Bandelier Tuff is downstream, after the Rio Grande had cut the observed to overlie the Otowi lava flow at nearly canyon almost to its present depth, for the bed all exposed contacts; at a few small outcrops of the river is not more than 20 feet below the bluish gray laminated clays and silt were ob- floor of the old varve-filled valley. served to be locally intercalated. One such out- Disruption of the Cerros del Rio flow was crop is at the base of the small, isolated, cone- active prior to the deposition of the varves, shaped hill of Bandelier Tuff resting on the because a large block of lava 4 feet by 3 feet by Otowi flow west of Otowi bridge (fig. 34C). 2 feet was caught along the south side of the Mesa de 10s Ortizes, an extension of the Otowi basin of varve deposition. Two photographs of lava flow, east of the Rio Grande is surmounted the varves appear in figure 33. by a dissected volcanic cone. The cone was prob- A laminated deposit similar in many respects ably the source of the Otowi flow. Thick depos- to that overlying the varves was observed along its of tuff, cinders, agglomerate, basaltic dikes, the west bank of the Rio Grande about half a sills, and irregular intrusive masses have been mile below the Otowi bridge. exposed by the Rio Grande along the west side of the cone, which is shown in the sketch of Mesa OTO'I%'I LAVA FLOW de 10s Ortizes (fig. 34B). The name Otowi lava flow is here applied to a basaltic lava flow that crops out on each side BANDELIER TUFF of the Rio Grande in the vicinity of the Otowi The Bandelier Tuff was mentioned bridge. The type section is at the northern tip of by Harold T. U. Smith (1938, p. 959) in his the flow about half a mile west of the Otowi study of the Abiquiu quadrangle, and several bridge (fig. 34C) and a few hundred yards south isolated outcrops were mapped by him (p. 937, of Guaje Creek. The Otowi flow slopes westward fig. 4). Although the Bandelier Tuff is not ob- and southwestward, and its northern limit is the served to be in contact with beds of the Santa Fe south border of Los Alamos Canyon. At no point Group, yet the Bandelier forms a distinctive and does the Otowi flow cross Los Alamos Canyon, scenic part of the geologic section. Denny but black stratified tuff and laminated, greenish, (1940b, pl. 1) mapped a small area of Bandelier silty clays, fine gravel, and sand occupy its posi- Rhyolite Tuff along the west side of White Rock tion north of the canyon. Canyon but did not discuss the formation other The Otowi flow can be traced continuously to than to include it with Quaternary rocks of the the south past the old Buckman Bridge road to a locality (p. 686). Ross, Smith, and Bailey (196 1, point where it passes beneath the lava of a p. 140) mapped and described the Bandelier higher, later flow. From that point south in Rhyolite Tuff in some detail, and Ross and White Rock Canyon the identity of the Otowi Smith (1961) the same year described in great flow is lost beneath the thick cover of talus detail the lithology of the ash flows of the Jemez formed by the disruption of the very thick upper Mountains and particularly the welded tuffs of flow that forms the rim rock of White Rock the Bandelier. Spiegel and Baldwin (1963, Canyon. The Otowi flow crops out westward p. 64) discussed deposits of pumice in the Santa from the type section for about 2 miles along Fe area that overlie a basalt flow and noted a Guaje and Los Alamos canyons, and a fine sec- similarity to pumice near the junction of the tion of the underlying Puyt Conglomerate can Los Alamos and Bandelier National Monument be studied along most of the distance. Charnita highways. Griggs (1964, p. 46) redescribed and Formation beds are also exposed at a few places along the lower ends of the canyons, and the redefined the formation as the Bandelier Tuff, relation of the three formations to one another is naming three new members: (1) Guaje Mem- well shown. ber, composed mostly of pumice; (2) Otowi The Otowi lava flow laps marginally over the Member, light buff to pinkish pumiceous tuff; southeastern corner of the PuyC Conglomerate and (3) Tshirege Member, ash-flow and ashfall and is later, therefore, than the PuyC. East of the pumice and tuff. This last member apparently Frc. 33. A. View, looking north, of var~~cdor rhythmically clcpositccl secliments on cast sidc of Rio Grandc south of mouth of Canyada Ancha. hfan is standing on lcns of conglomerate that underlies varvcs. B. Close-up of varvcs exposed in cliff wall to right of man in A. North

Red cinders Cone Red cinders North ck cinders ond f---

Block cinder

Intrusive \ Cobble lenses

North Bandelier Tuff

FIG.34. Diagrams of geologic relations at Cerro Azul, Mesa de 10s Ortizes, and Otowi lava flow. A. Cerro Azul, Precambrian inlier com- pletely surrounded by Quaternary alluvium. Small exposure of beds of Santa Fe Group crop out in wash at southeast corner. Basalt is edge of distal end of one of flows of Taos Plateau. B. Mesa de 10s Ortizes, cliff face, showing volcanic cone and Otowi basalt flow and relations to beds of Santa Fe Group. Area shown is 2 to 3 miles long and is east of Rio Grande and south and no more than 4 mile west of Otowi bridge. C. Correlation detail west of Rio Grande, west and south of Otowi bridge, showing cliff-face view of about 2 miles. Otowi basalt is inter- calated between Bandelier Tuff and Puy6 Conglomerate. 1971 GALUSHA AND BLICK: SANTA FE GROUP 85 comprises most, but by no means all, of the were excavated in the cliff walls. Cliffs of some welded tuffs of the area. of the strata of the Bandelier Tuff have a well- The Bandelier Tuff, as now exposed, is a marked joint set; huge blocks break off and form remnant of a thick mantle of hot ash flows that steep talus slopes. Rock falls must have been an welled from vents in the Jemez Mountains. ever-present danger to the Indians of the cliff Some of the pumiceous portions may have villages. originated in explosive eruptions and represent Slopes are smoother and cliffs are commonly true ash falls rather than cascading ash flows, lower on north-facing hillsides, and this feature but the bulk of the formation seems to have been is definitely correlated with the tendency of of ash-flow origin. These distinctive pinkish, snow to accumulate on north slopes in this buff, or whitish tuffs crop out in isolated groups region, and for moisture to remain longer from around the entire Jemez Mountains except the summer rains. The greater moisture content along the northeast corner from Rio del Oso ;o supports a much greater vegetation density, and a point near Caiiones, New Mexico, and, at the the two factors work together to weather the south end of the mountains, in the general bedrock to soil and to retain the soil when it is Borrego Mesa area. These and intervening areas formed. On the south slopes less moisture falls or once may have been covered completely by the is retained, less vegetation grows, and as a result mantle. Renick (1931, p. 69) discussed the erosion is comparatively rapid. Bandelier Tuff as rhyolite and rhyolite tuff, and Phenocrysts of quartz and sanidine are often described a few localities along Jemez Creek and numerous in the ash-flow tuff, and on some its tributaries where he found the rhyolite tuff benches or mesa-like areas hundreds of anthills resting on Poleo Sandstone, Chupadero Forma- made up of piles of predominantly quartz tion, Abo Sandstone, and even on beds of the crystals have been observed. Some of the ant- Magdalena Group. In the type area of the Santa hills are as high as 2 feet. Fe Group, however, the Bandelier Tuff is in Some of the strata of the unwelded ash flow or contact with three formations: (1) the Puyt pumice ash flow have a tendency to weather, Conglomerate, (2) the Otowi lava flow, and with a surface pockmarked with natural holes (3) the Cerros del Rio flows. Several other vol- and caves, and many of these cavities were \, canic rocks of the Jemez Mountains have been utilized as dwellings by the ancient Indians. differentiated, but these are not discussed in Flakes and chips of obsidian and fragments and this report. blocks of fibrous pumice are numerous in some The base of the Bandelier Tuff is mostly, beds. although by no means everywhere, comprised The Bandelier Tuff increases in thickness of beds of white to gray or yellowish ash or toward the south; this general relation is shown pumice. The great bulk of the formation, how- in figure 4. Only isolated mesas of the formation ever, is a fairly compact yellowish, cream- crop out north of Santa Clara Canyon, for colored, pinkish, or brownish tuff. The forma- example, Shupinna Mesa, but south of Santa tion has been incised deeply by streams that Clara Canyon the formation is continuous and have cut across it from the mountains, and the the thickness is as much as 1200 feet. (Griggs, topographic expression commonly is one of deep 1964, p. 47, wrote that 1050 feet of Bandelier canyons with high, narrow, intervening ridges was penetrated in a drill hole in Los Alamos or mesas forming steep escarpments. The south Canyon.) One of the best-exposed and most slopes of the escarpments are usually very preci- accessible sections of the Bandelier is in the can- pitous, and many ancient Indian talus and cliff yon of El Rito de 10s Frijoles in the Bandelier villages were built along them. Large and very National Monument. numerous pueblo ruins occupy the summits of some of the ridges. The rhyolite tuff in many CERROS DEL RIO LAVA FLOWS parts of the area is columnar, particularly the The Cerros del Rio were described by Bryan welded ash-flow portions of the Bandelier. (1938, p. 208) and regarded by him as inter- These were broken and readily shaped by the bedded in the Santa Fe Formation. We have Indians to form building blocks for their pueblos. failed to confirm his correlation, and regard the Tuff that was not welded could be worked easily Cerros del Rio flows as slightly later than the by stone tools, and hundreds of rooms and caves Otowi lava flow and in part contemporaneous BULLETIN AMERIC.I\N MUSEUM OF N.ITUR.IL HISTORY with the Bandelier Tuff. The evidence for this elevation toward the south, rising to the top of a correlation follows: The rim of White Rock ridge of rhyolite tuff on the north rim of Potrillo Canyon, as far south as the Rito de 10s Frijoles, Canyon. The rim rock of lava on the west side of consists of very thick, andesite-basalt flows that White Rock Canyon has maintained a tempo- are stratigraphically higher than the Otowi lava rary base-Ievel for the surface of erosion repre- flow; this relation is well shown in the canyons sented by this plain. west of the site of Buckrnan Bridge. At least four On the east side of White Rock Canyon, less separate flows, including the Otowi flow, are than a mile above the mouth of Pajarito Canyon, exposed in the canyon up which the old Buck- is a group of permanent springs. A white man Bridge road winds. The lowermost flow has efflorescence of salts covers an acre or two of the a general north-south trend and apparently area around the springs, and several small rivu- developed a high wall where it was in contact lets enter the Rio Grande from them. These with sedimentary rocks, for fine-grained sedi- springs are adjacent to the base of a cinder cone ments are plastered on the surface of the lava. on the east rim of the canyon. The sides of the Buff tuffaceous sediments 30 to 35 feet thick cone have been breached by two small ravines. separate the lower flow from the overlying These small ravines have removed large quanti- Otowi flow. These sediments are very tuffaceous ties of red cinders and have formed a secondary and unlike Santa Fe deposits in color, texture, or erosional crater about a quarter of a mile in and weathering characteristics, although some diameter. A conical hill of red cinders remains formation of the Santa Fe Group was probably in the center of the crater. A basalt flow forms a the source of much of the included sand. Above rim around the crater, except on the west where the Otowi flow are several feet of stratified tuff it has been removed by erosion. At the north end and sand, and above this sequence are two or of the cone the lava flowed down the slope of the more lava flows, one of which forms the rim of cone for a short distance. White Rock Canyon. The Cerros del Rio lava flows deserve closer At many points where one lava flow of the study than they have received. Intensive study Cerros del Rio is in contact with another, the of the Cerros del Rio conceivably could provide lava above the contact is often highly frag- important new interpretations of the geologic mented and contains much yellowish or brown- history of the Santa Fe area. It is hoped that ish earthlike material, which may be palagonite. some investigators of the future will give the In a short canyon leading north-northwest from Cerros special attention. the "white-rock" on the Buckman Bridge road a small tongue of the upper flow is interbedded HIGH-LEVEL BASALTS in the white pumiceous tuff as though it had Basaltic lava flows, which were extruded on flowed into a small canyon in the tuff and solidi- erosion surfaces and were originally of greater fied. The tongue is overlain by pink tuff, gray extent, now stand as high, steep-walled mesas in tuff, and columnar tuff, all of which are part of the northern part of the type area of the Santa the Bandelier Tuff. Fe Grou~.The mesas are at different altitudes, South of the Buckman Bridge road, on the and are hifficu~tto correlate because they ard west side of White Rock Canyon, a long narrow isolated. Some evidence of relative age is avail- ridge of Bandelier Tuff extends down to the rim able. however. and such recorded evidence may of the lava. South of this ridge the entire area for eventually be useful in geomorphological studies several miles has been eroded to a much lower of the area. level. The area has been stripped almost to the The high Lobato basaltic were men- underlying lava, which forms the rim of White tioned by Harold T. U. Smith (1938, p. 959, Rock Canyon. Soil and debris from the de- fig. 4) and mapped as high-level basalt. The composition and mechanical disruption of the Lobato flows crop out mainly in the J. J. Lobato Bandelier Tuff have been deposited on the Grant and apparently were named for the grant. truncated beds. The present topography is that The flows are continuous from Rio del Oso of a gently rolling, sloping plain on which the northward to Abiquiu Creek and form a bold streams are not incised, although Pajarito Can- escarpment west of the Chama River. yon has cut a trench into the lava no more than An idea of the stratigraphic position of the 20 feet deep. The plain increases gradually in high-level Lobato flows can be inferred from 1971 GALUSHh AND BLICK: S.\NTA FE GROUP 87 their relations to outcrops of PuyC Conglomerate (1938, pp. 958, 964) discussed the age relations and the Chamita Formation in the Rio del Oso- of the Black Mesa basalt. Larsen and Cross Abiquiu locality (fig. 2). Several remnants of the (1956, p. 193) subdivided the Hinsdale Forma- PuyC Conglomerate occur in the area north of tion into two members on the basis of origin and Rio del Oso. The PuyC remnants are observed to petrographic character of the material. The issue from some canyons cut in the edge of the lower member was called the rhyolite unit; and Lobato flows, and at other places they abut the upper, the latite basalt. They speculated against the steep slopes. A few isolated patches of concerning the extent of both members into beds of the Chamita Formation crop out along New Mexico, and stated (p. 193) regarding the the talus slopes below the Lobato flows. Physi- Hinsdale rhyolite, "Rocks that are almost cally these isolated Chamita exposures are at identical form the regular flows and tuff beds of elevations higher than the PuyC gravel remnants. the 'C'alles Mountains of New Mexico and simi- Stratigraphically the Chamita beds underlie the lar rocks form many of the central Valles PuyC gravels (see Puyt Conglomerate, p. 76). Mountains." The latite basalt of the Hinsdale Cerro de las Minas (United States Geological was recognized as reaching as far south in New Survey: Sierra Negra) is a high, basalt-capped Mexico as "the south end of Black Mesa near mesa of small extent a few miles northeast of the junction of the Chama River and the Rio Abiquiu, New Mexico. The Abiquiu Tuff crops Grande" (p. 196). out very high on the mesa, and the Santa Fe Recent work by Steven, Mehnert, and beds are faulted down against the Abiquiu Tuff Obradovich (1967, p. D50) on the age of the along the south side. volcanic activity in the San Juan Mountains of Cerro Pedernal, another high, basalt-capped Colorado showed that the Hinsdale Formation mesa near Casones, New Mexico, is also a rem- is much older than previously had been sup- nant of a lava flow. A correlation of Cerro posed. Potassium-argon dating of the Hinsdale Pedernal and Cerro de las Minas would be rhyolite gave an age of 22.4 million years. Dates purely conjectural. Harold T. U. Smith (1938, on Hinsdale basalt in the area of Spring Creek p. 954) stated that the structural position of the Pass of the San Juan Mountains ranged from basalt flows on Cerro de las Minas suggests that 12.4 to 15.6 million years. They (p. D55) they are interbedded in the Santa Fe. We inter- questioned whether the dated basalt can be pret the evidence differently and believe the grouped with the other basalts in the San Juan basalt of Cerro de las Minas to be not earlier region into a single formation fitting the concept than that of the Lobato flows and therefore later of the originally proposed Hinsdale Formation. than the Santa Fe Group. Their question raises some doubt concerning the Black Mesa is a canoe-shaped tongue of basalt feasibility of correlating the lava beds of the about 10 miles long and at no point more than Taos Plateau with the Hinsdale. 3fr miles wide. Along most of its length it is more Ozima et al. (1967) dated a series of lava flows than 700 feet high. It lies along the northwest in the Rio Grande Gorge near Taos, New side of the Rio Grande from Embudo to Cham- Mexico; the base of the upper, normal-polarity ita, New Mexico, and is probably best described lava flow gave a potassium-argon date of as a remnant of a valley tongue. Near Embudo 3.7 million years. The exact relation of this part (Spanish: the funnel) erosion has cut through of the Taos Plateau basalt flow is unknown, but the basalt, and Black Mesa is separated for Black Mesa appears to be a valley tongue be- nearly 2 miles from the much larger area of lava longing to the general Taos Plateau sequence. flows, which are apparently a part of the vast This radiometric age assignment for the Taos lava plateau that fills the Rio Grande Valley Plateau would coincide most nearly with that of west of Taos, New Mexico, and extends north- the Blancan North American Land-Mammal ward to the San Luis Valley of Colorado. Age. Velarde Mesa is an isolated part of the flow lying east of the Rio Grande near Embudo and Dixon, Miller, Montgomery, and Sutherland (1963, New Mexico. p. 50) mapped Black Mesa and adjacent rem- Atwood and Mather (1932, pp. 98, 99) were nants of basalt flows as a part of the Servilleta the first to suggest that Black Mesa is capped by Formation, which commonly has been assigned Hinsdale basalt, and later Harold T. U. Smith to late Pliocene or early Pleistocene age. We 88 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY VOL. 144 believe that the basalt lavas of Black Mesa will of fine volcanic ash that crop out in the upper prove to be Pleistocene in age. part of the Nambt Member and in the Skull Ross, Smith, and Bailey (1 961, p. 139) stated: Ridge Member of the Tesuque Formation. "The earliest basaltic lavas of the Jemez Volcanism on a smaller scale is indicated by a Mountains erupted from numerous centers over few ash beds in the Pojoaque Member of the a wide area. They formed a field of low co- Tesuque, and thick zones of pumiceous tuff are alesced shields, the remnants of which now form characteristic of the Chamita Formation and Borrego Mesa in the south and Lobato Mesa and suggest that volcanism in the area had under- Mesa de la Grulla in the north." gone a distinct change of pattern during Cham- It is interesting to note that the Lobato Mesa ita time. The presence of ash beds, even thick basalt overlies the Chama-el rito Member, the ash beds, however, is not proof of proximity to Ojo Caliente Sandstone, and some beds, not the source of the eruption. Martin (1913, well exposed, that are here correlated as Cham- p. 167), describing the eruption of Mt. Katmai ita Formation, indicating at least post-Hemp- in Alaska, reported that ash from the eruption hillian (post-middle Pliocene) age or possibly spread over many thousands of square miles and Blancan (late Pliocene) age for the Lobato ranged in thickness from 44 feet, 15 miles from flows. More significant than the probable age of the crater, to almost 1 foot, 100 miles away, to the Lobato flows is the inference that can be a fraction of an inch, 150 miles away. Too many drawn regarding the source of the well-rounded unknown factors exist to draw even an approxi- volcanic pebbles and cobbles that form the mate comparison between the eruption of the thick lenses that are characteristic of the Chama- Miocene and Pliocene volcanoes and those of el rito Member. Ross, Smith, and Bailey (p. 142) Katmai, Tomboro, Krakatao, or other great pointed out that "nowhere are the older sedi- historic eruptions. The ancient volcanoes could ments of the Santa Fe group known to contain have been smaller, equal, or vastly greater in volcanic rocks of the Jemez Mountains." In a magnitude, violence of eruption, and amount of footnote they added, "Pebbles of volcanic rocks material ejected. The ejected material may have do occur in Santa Fe beds on the east and north been carried great distances, depending on the beneath the basalts of Lobato Mesa and the strength of the winds. PuyC Gravel, but these rocks are unlike those in Late Tertiary volcanic eruptions, some of the Jemez volcanic pile and appear to have which may have spread ash over tens of thou- come from a more distant source." These are the sands of square miles, have great potential rocks that we believe belong in the great possibilities for interregional correlations, not Vallecitos fan, had their source in the San Juan only of the beds of the Rio Grande Valley but of region of Colorado, and are typical of the the Great Plains formations as well. Close Chama-el rito Member of the Tesuque Forma- synchronization of rock-stratigraphic data, par- tion. ticularly of ash beds, with biostratigraphic data, The age of the several occurrences of high- as shown by the study of the very large collec- level basalt is clearly post-Santa Fe Group. tions of mammalian fossils that are available, may lead to correlations quite beyond the expec- VOLCANIC ROCKS tations of geologists and paleontologists working Extrusive rocks are widely distributed around with the disjointed, often fragmentary, and in the outcrop area of the Santa Fe Group. The some cases erroneous information now available greatest outpourings of lava or other volcanic on late Tertiary deposits. Who can say, for rocks in the type area of the Santa Fe Group are example, that the dark ash bed of the Sheep late Pliocene and Pleistocene in age. Volcanic Creek-Snake Creek beds of Nebraska is not rocks of the age of the restricted Santa Fe Group equivalent to Ash D of the Skull Ridge Member are relatively few in number and small in area. of the Tesuque Formation of the Santa Fe Other large areas of volcanic sediments form Group? Who can say that the ash beds of the parts of the Abiquiu Tuff, Picuris Tuff, and Valentine-Burge-Ash Hollow sequence of the Espinaso L'olcanics formations and underlie the Great Plains of Nebraska are not represented Santa Fe Group. by ash beds of the Pojoaque Member? What Direct evidence of volcanic activity during better chance has a geologist to correlate widely Santa Fe time is provided by the numerous beds separated late Tertiary deposits derived from 1971 G.4LUSHA AND BLICK: SANTA FE GROUP 89 dissimilar rocks than to work with large collections hastens the disruption of the mesa borders. of fossils and to tie the time information therebv Steep talus slopes are formed which consist of obtained to the volcanic ash beds in each sec- extensive interlocking masses of lava blocks that tion? Such ash beds are the only late Tertiary move downward as a result of a process akin to stratigraphic layers that conceivably could have deflation. As the underlying soft sands are been contemporaneously deposited over many gradually removed, principally by running thousands of square miles. water, the blocks tend to wedge tightly together Tuffaceous materials. as contrasted to vol- and form a resistant cover on the steep slopes of canic-ash layers, are present in the beds of the the mesas. The talus cover has been cut through Santa Fe Group but are confined mostly to the at some points where a few steep canyons head Chamita Formation. The Chamita Formation against the borders of the mesas. also contains an interbedded lava flow that is The Otowi, Lobato, and Cerros del Rio lava one of the few for which conclusive evidence of flows, the PuyC Conglomerate, and the Bande- Santa Fe age is available. This flow is faulted lier Tuff each has been described as a formation and crops out as low remnants south of Rio del of the post-Santa Fe Group in this report. Oso, and here and there along the south side of Tuffaceous materials of the age of the Chama- South Wash where the dips are about 20 degrees el rito Member crop out along El Rito Creek east. Locally the flow is amygdaloidal and has just above the mouth of Cerros de las Minas burned a fairly thick, red, indurated zone at the Wash (United States Geological Survey: Arroyo base; the maximum thickness of the flow is about del Perro). That a vent was nearby, but not ex- 40 feet, but in most places it is less than half of posed, is proved by the presence of volcanic that thickness. The eastern edge of the dipping bombs that still lie in the tuff at the spots where interbedded flow south of Rio del Oso extends they originally fell. to the west bank of the Chama River about half Two thin beds of coarse-grained tuff crop out a mile south of the settlement of Chili. Terrace in the Pojoaque Member in the North Pojoaque gravels are preserved on the surface of the lava Bluffs. The clasts are commonly smaller than the flow near the river, and these terraces conform lower range (4 mm.) of lapilli, although a few closely to the projected planes of erosion surfaces may be as much as 20 mm. in diameter. The in the Rio del Oso locality. The lava flow range in size of the particles suggests that they deflected the Chama River to the left nearly a came from a vent that was, at most, only a few quarter of a mile. The west abutment of a pro- miles distant. No suggestion of the probable site posed Chamita dam was to be set on the lower of the vent can be deduced owing to the small end of this lava flow. Exploratory holes that area over which the coarse-grained tuff is were drilled in an attempt to reach the lava exposed. where it supposedly had dipped below the sur- The Cerros del Rio lava flows, which were face of the river bed penetrated about 200 feet of considered by Bryan (1938, p. 208) as "probably sediments without striking a trace of the flow. the area of most intense eruption in Santa Fe Probably the end of the flow was originally in time," are regarded by us as post-Puyt Con- the area now a part of the stream bed of the glomerate in time, hence Pleistocene, and Chama River. definitely not a part of the restricted Santa Fe Quaternary basaltic and andesitic flows that Group. The basalt lapilli tuff that underlies the cap many of the mesas and buttes of the area Cerros del Rio basalt flows in Canyada Ancha were extruded on broad erosion surfaces that had northwest of Santa Fe along the old Buckman been cut on Santa Fe or older rocks. The basaltic Bridge road is later than the Pojoaque Member or andesitic-basaltic flows resist erosion, and of the Tesuque Formation. The lapilli tuff also they commonly cap mesas, many of which are is interpreted by us as overlying the Ancha several square miles in extent and several Formation. Spiegel and Baldwin (1963, p. 50) hundred feet high. Even the mesa remnants excluded both the basalt lapilli tuff and the probably long since would have been removed overlying lava flows from the Ancha Formation, by erosion had not their slopes been defended by but stated that the basalt flows interfinger with an armor-like talus of lava blocks. Erosion of the the Ancha Formation, a statement with which soft Santa Fe beds undercuts the flows and we cannot concur. YO BULLETIN AMERICAN MUSEUM OF NATUR.AL HISTORY \'OL. 144

RIO DEL OSODIKES deposits lying on lower and later erosion surfaces Basaltic dikes are numerous in the western in Kunya Ruins Wash, and the relation suggests part of the Rio del Oso-Abiquiu locality where early Pleistocene age for the dikes. they have been injected along fault planes of the South of Dike Wash some of the dikes crop out post-Santa Fe deformation and also into un- in closely spaced groups, particularly in tribu- fractured strata. These relations can be observed taries north of Rio del Oso. At one point a dozen in Dike Wash and also in the second and third parallel dikes were counted in less than half a tributaries on the north side of Rio del Oso (see mile. The arrangement of these dikes, and geologic map, fig. 38). The first basalt dike others in the locality, suggests that they were in- crossed on the way up Dike Wash (United jected into en echelon fault planes. States Geological Survey: Arroyo del Palacio) has Dikes were observed as far north as Kunya a sinuous trend, and the wash has cut a narrow Ruins Wash, but in that locality they are small. gash through it (figs. 35, 36). Many of the dikes They are of the same lithology as those farther form sharp, narrow ridges more than a mile in south in the Rio del Oso-Abiquiu locality, that length; these dike ridges resemble hogbacks and is, predominantly high-density, dark green to are prominent local topographic features at dark greenish brown olivine basalt. those points where the soft Ojo Caliente Sand- stone has been eroded from around them. The ROUNDMOUNTAIN dikes are narrow; few of them exceed a dozen Round Mountain (United States Geological feet in thickness and most of them average 4 to Survey: Black Mesa; fig. 37) is a very prominent 8 feet. Most of the dikes dip to the east, but a few black basaltic mesa situated on the east bank of dip to the west. They always dip at a high angle, the Rio Grande between Espanola, New Mexico conforming in this respect to the regional fault and the San Ildefonso Indian Pueblo. The Tewa pattern. Indians call it Tunyo Pin', which means "very Narrow contact zones of indurated sand, spotted mountain." According to Harrington commonly less than 1 inch wide, occur along the (1916, p. 293) it had many Spanish names, dike walls. The contact zone may be reddened including La Mesa, Mesita, Mesilla, and Hutr- and is much wider where silty clay or clay is fano (orphan). English names have been even mixed with the sand. more diverse, such as Black Mesa, San Ildefonso The second dike at Dike Wash shows clearly Mesa, Mesita, Mesilla, Sacred Fire Mountain, that these dikes have been injected along fault Orphan Mountain, Beach Mesa, Round Mesa, planes; the evidence is shown on the south slope and Round Mountain. Our field parties have of the wash (figs. 35, 36). The sediments east of consistently used the name Round Mountain for the dike have been faulted down into contact, more than 40 years, in order to differentiate the and the dike itself has split into two adjacent mesa from the large Black Mesa mapped by walls. The westernmost of the two is a small Wheeler (1876) along the northwest side of the accessory fault, and the injected material does Rio Grande between Embudo and Chamita, not extend to the surface but pinches out in the New Mexico. We consider it unfortunate that sand. The easternmost wall of the dike is well the United States Geological Survey, on adjoin- exposed up to the base of the small lava flow, ing 7.5-minute quadrangles, used the term but it does not break through it, although it "Black Mesa" for two prominent geographic arches the flow at one place. The lava flow is features no more than 12 miles apart, especially thin and of small extent and cannot be shown to because of the many names that have been be surely equivalent to any other flow in the applied to the mesa that we call Round Moun- locality. The flow is interbedded in the Chama- tain. el rito Member, because a small hill of fossilifer- Round Mountain is a small, gravel-capped, ous sediments rests upon it. The evidence, there- denuded, composite cinder cone and volcanic fore, points to a Santa Fe age for the small lava neck, with a small extrusion of basalt. It rises flow, and a much later age for the dikes. The about 500 feet above the river, and on its flanks dikes are older than the erosion surfaces in the undisturbed Santa Fe beds that vary 2 or 3 locality, because the deposits lying on the sur- degrees from the horizontal are exposed. That faces cross and cover the dikes at many places. beds so close to a conduit are so little disturbed Pleistocene fossils have been collected from is probably owing to the fact that the conduit, FIG.35. A. Breach in Rio clcl Oso Basaltic dike, made by Dikc Wash (United States Gcological Survey: iZrroyo clcl Palacio). This is first dikc crossed as one goes up Dikc Wash from its mouth on Chama River. B. View looking south, showins second dikc crossed as one goes up- stream in Dikc Wash; main part of dike on left (cast). Split or apophysis (scc fig. 36A) in left center pinches out in overlying sediments. Lava flow at right skyline is mapped in figure 38. 92 BULLETIS -4hfERIC.AN IfUSEUM OF N.4TUR.-\L HISTORY FTOL. 1-14

FIG.36. -1.Close-up of apophysis of second Rio del Oso dike (fig. 35B). IZ narrow indurated zone occurs on each side of dike. B. Cross-bedding in Ojo Caliente Sandstone, view taken in road cut on east side of United States Highway 285 about 6 miles south of Ojo Caliente, New Mexico. Several road cuts in \.icinity display comparable gigantic cross-bedding, except where slopes are covered by slump or talus. FIG.37. Prominent landmark known locally as Round Mountain, San Ildefonso Mesa, Black hlcsa, Hucrfano, Mesa Ncgra, ancl, by Tcwa Indians. as Tunyo pi2 (Tewa: very spotted mountain). Vicw looking northcast fi-om north of San Ildcfonso Pueblo and showing contact of Santa Fc Group with basalt. Light spots on slopes and one just under basalt at center of photograph arc Santa Fc sediments. Roundcd surfacc on skyline in notch ncar mitldlc of Round Mountain is thick gravel cover on top of Mesa. This side of Round Mountain has many cindcrs in addition to columnar basalt. 91 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY VOL. 144 initially small, later became enlarged through extinct near Lavic, California. stoping, by the outpouring lava, of the soft A bed as much as 10 feet thick, of river gravel sediments that formed the walls. of cobble size or smaller, caps part of Round The basalt is essentially columnar, and much Mountain. Perched on these gravels is one large of it is vertical, but on the west side of the cone boulder of typical PuyC Conglomerate lithology the columnar part lies almost horizontal and is measuring 3 feet by 3 feet by 2 feet; this is eroding only on the ends of the hexagonal reputedly a sacred fire shrine of the Tewa columns. Such a horizontal position indicates Indians. These gravels attest to the tremendous that this mass of basalt cooled along the wall in erosive power of the Rio Grande and its tribu- the upper part of the conduit. The west side also taries in the Espanola Valley. Round Mountain contains about 50 feet of agglomerate. Cinders is obviously pre-Puyt Conglomerate in age, and and agglomerate are separate from the columnar the gravels on the summit are post-PuyC, with basalt and occur below it, intercalated with it, the large boulder having been reworked from and in a vertical position toward the interior of the Puyt. Round Mountain is probably the the mass. same age as the volcano on the Mesa de 10s The presence of red cinders along the south- Ortizes southeast of Otowi Bridge. These two west side of Round Mountain is further evidence and several other cones in the general Cerros del of local eruptive action. We observed a similar Rio area are arranged in a line along what may red lava to be the last extrusion in the crater of be a deep-seated fissure or line ofweakness in the Mt. Pisgah, a young and almost undissected rocks underlying the Santa Fe deposits. GEOMORPHOLOGY EROSION SURFACES

A COMPLEX SYSTEM of erosion surfaces has been Southwest of the Santa Cruz Dam near cut across the type area of the Santa Fe Group. Chimayo, New Mexico, are remnants of a prom- The erosion surfaces have beveled older rocks as inent, gravel-capped, erosion surface. Cabot well as those of the Santa Fe Group. Tremendous (1938, p. 95) described and figured this surface thicknesses of sediments have been planed away, and others in the vicinity of the Santa Cruz Dam. and the resulting erosion surfaces have had a The deposits of cobbles and boulders on the profound effect on the topography of the Rio erosion surface may be 50 feet thick at some Grande Valley north of Santa Fe. Because of the points, and the remnants end on the high hills extensive planation associated with the forming along the drainage divide of the Santa Cruz of these erosion surfaces, no beds are now pre- River and 1Vhite Operation Wash. Against the served in the type area that can be referred to side of the westernmost of these hills, and at a the absolutely uppermost levels of the original much lower level, another erosion surface can deposits filling the valley. be detected; on this lower surface the buff or The erosion surfaces have been cut across the yellowish brown sand has been deposited, and inclined beds. In many places the surfaces have at some places a thin layer of gravel crops out at remnants of thick gravel preserved on them; at the base of the sand. Sand that is lithologically other places thin gravel beds remain; and still similar to that on the lower surface also lies on others have thin gravel and a few inches to a the bouldery gravel cap of the higher remnants few feet of buff or yellowish brown or reddish south of the Santa Cruz Dam. The field evidence brown, mostly wind-blown sand on them (see indicates that the main erosion remnants are discussion of the Espanola Formation, p. 80). early Pleistocene. The lower remnants, although At some localities only the buff or brownish definitely Pleistocene, must be regarded as sedi- wind-blown sand covers the erosion surfaces. ments deposited during a later stage, because the Some of the upper surfaces of the constructional higher remnants had been dissected extensively gravel deposits that were laid down on the ero- before the lower were laid down. In those sion planes have been neatly beveled, suggesting localities where only the wind-blown sand of the that they, in turn, were subjected to erosional Espanola Formation is preserved, the higher, planation. The cutting of the upper. surfaces gravel-covered erosion surfaces have been appears to have been about parallel to that of eroded strongly, and much of the gravel on the the base of the gravels, but the relation of one to basinward end of the surfaces has been removed the other is becoming increasingly obscure as completely, prior to the deposition of the sand. the gravel deposits are dissected. Technically The buff and light sand deposits of the Espanola the erosion surface lies at the base of the con- Formation were laid down across the uneven structional deposits, but in the field the recog- surfaces and are now ~reservedas scattered nition, projection, and interpretation of the remnants of small area capping many of the surface are greatly simplified by the use of the hills of the Skull Ridge and NambC members of top of the constructional deposits rather than the the Tesuque Formation, and also a few isolated base as the datum plane. exposures in the outcrop belt of the Pojoaque The term erosion surface is used advisedly for Member. the planes of denudation in this area. The evi- A divide separated the drainage system of the dence is not conclusive for the application of the Arroyo Seco and Joe Rak Wash from the Nambt terms piedmont, pediment, or rock pediment to Creek system at the time of the deposition of the all the various types of surfaces in the area, nor Espanola Formation. This relation is illustrated does the term planes of lateral corrasion have by the attitude of the Espanola Formation universal applicability. The use of the term remnant that is preserved a few feet south of the pediment, if used at all, must be in the broadest north boundary of the Pojoaque Pueblo Grant general sense, for few of the surfaces conform to and about a quarter of a mile east of United a restricted definition of a pediment. Most of States Highway 64. The remnant is about 100 them bevel sedimentary rocks and were not cut to 125 feet lower than the present divide, which on crystalline rocks. is a few hundred yards to the south. The 96 BULLETIN .AMERICAN MUSEUM OF NATURAL HISTORY VOL. 144 remnant was deposited on the wide erosion east of the town of Ojo Caliente and extending surface that truncated the beds of the Skull to the base of Black Mesa, is for the most part a Ridge collecting localj ty. series of remnants of at least two gently sloping The name Truchas surface is proposed for the erosion surfaces. During the cutting of these sur- particularly well-exposed and extensively gravel- faces, vast amounts of Santa Fe deposits were capped erosion surface in the valley of Embudo removed. Over most of the locality the Santa Fe Creek, south of the town of Dixon. The Truchas deposits are now covered by alluvium or other surface extends westward from the base of the sediments. The Santa Fe beds have been re- Sangre de Cristo Range in the vicinity of the exposed in the lower reaches of the washes along town of Truchas to a point near the Rio Grande Ojo Caliente River. Cerro Azul, an Ortega southwest of Velarde. The gravels are thick near quartzite inlier of Precambrian rocks (Just, the mountains but thin to less than 100 feet near 1937, p. 43), is being exposed in the locality; its the Rio Grande. The boulders near the moun- relation to the erosion surfaces, to the basalt tains are large; the size of the clasts decreases flows, and to the beds of the Santa Fe Group is rapidly basinward until, near Velarde, pebbles shown in figure 34A. The lower erosion surface and small cobbles are typical. Precambrian in this locality covers most of the area, and in rocks, and limestone from the Magdalena Group addition to its normal gravel mantle it is also of the , have supplied most of the covered by several feet of reddish brown to buff, bouldery material preserved on the Truchas fine, wind-blown sand and soil. Except for the surface. The Truchas surface is younger than the area along Ojo Caliente River, the deposits of deposits of the Picuris re-entrant fan, and the the lower surface have been little dissected. The gravel deposits preserved on the Truchas surface erosion surface slopes gently to about the height and those of the Picuris fan were derived from of the lower of the Ojo Caliente River terrace dissimilar rocks within the range. The relation remnants. This erosion surface has been a prime of the Truchas surface and the deposits thereon factor in the determining of the topographic to the deposits of the Santa Fe Group in the expression of the locality. Dixon sub-basin is shown diagrammatically in A great erosion surface slopes outward from figure 28C. the Ortega Mountains; it once swept around the The Picuris re-entrant was originally des- Precambrian crystalline rocks of Ojo Caliente cribed by Cabot (1938, pp. 91, 92, 98), and the Mountain and can be studied on large numbers deposits of the Dixon sub-basin were treated of isolated remnants in the locality. The surface briefly in the same paper. The great fan filling has a thick gravel cap on many of the remnants this re-entrant is called the Picuris re-entrant fan and narrows greatly between Ojo Caliente in the present report. The Picuris re-entrant Mountain and La Madera Mountain; Ojo fan was formed by the issuance of coalescing Caliente River, or Vallecitos Creek as it is alluvial fans from several mountain vallevs. sometimes known above the town of La Madera, Moreover, good evidence can be adduced that the has cut deeply through it. Tributaries of Ojo sources of various fans could be established by Caliente River are dissecting it strongly but have detailed sedimentation studies, but these would not reached the point at which the continuity of be a major task. The Picuris re-entrant fan is the surface of the remnants is obliterated, and in the process of being dissected from all sides, these, when projected, give an idea of the size and also by long washes that cross it diagonally; and contour of the surface. This surface is here Embudo Creek has carved the Dixon sub-basin named the Vallecitos erosion surface. It can best on the north side, and the Santa Cruz River be observed from the summit of the small, iso- and its tributaries have dissected the southern lated, basalt-capped mesa east of the town of side. Many erosion surfaces are observed in the Ojo Caliente. An exposure of the Vallecitos Picuris re-entrant, and they have affected the erosion surface still remains along the west flank re-entrant fan at many different levels and of that mesa. A large remnant of the surface is obviously reflect a complex series of events. The represented by the heavily gravel-covered table- correlation of erosion surfaces in various parts of lands east of Ojo Caliente. Tentatively correl- the type area should be done with utmost ated remnants of the Vallecitos surface are caution. prominent features along each side of El Rito The area lying east of the Ojo Caliente River, Creek above the town of El Rito. 1971 GALUSHA AND BLICK: SANTA FE GROUP 97

X series of erosion surfaces and terraces are well-marked terrace 60 to 80 feet high. The slope exposed along El Rito Creek. Near the Northern of the terrace ranges from an abrupt escarpment New Mexico Normal School at El Rito an ero- on the upstream side to a gentle slope down- sion surface starts against the distal end of an stream. This surface is about half a mile wide older surface. This later surface is considerably and abuts against another higher terrace rem- lower, but its proximal end merges into the nant or erosion surface. This higher surface has steep face of the cut-off higher terrace. The plain been given a rolling appearance by the washes formed by the lower surface continues for several crossing it, and by the accumulation of alluvium miles to the vicinity of Plaza Media where its that was spread out along the terrace face some- distal border is also marked by a steep terrace. what like the alluvial cones of a bajada. A rem- At this point a still lower plain abuts against the nant of a still higher and much more dissected terrace and can be traced for several miles. terrace is preserved along the base of the very Other erosion surfaces can be observed at pro- prominent PuyC Gravel terrace escarpment. gressively lower levels, each one cutting into the All the erosion surfaces in the type locality of deposits of the higher one, and each leaving a the Santa Fe Group were cut after the post- remnant of the surface and a steep terraced scarp. Santa Fe Group deformation, and many of The erosion of much of the type area of the them, no doubt, record important Pleistocene Santa Fe Group seems to have been a result of a events. Some of the erosion surfaces must have similar series of erosion surfaces, but, instead of lasted for long periods of time to enable the being of small area as are those of El Rito Creek, lateral corrasion of streams to cut broad sloping the surfaces elsewhere may be much larger. In plains. At what points, and in what manner, many respects erosion surfaces are similar to temporary base-levels were established on the abandoned river terraces, and, in fact, many of master and on tributary streams can only be the surfaces along El Rito Creek may be proper- conjectured. The evidence shows only that a ly classed as such. Some of the characteristics of series of such temporary base-levels were estab- rejuvenated streams flowing across alluvial fans lished, and that for each base-level an erosion can be detected. Furthermore, some of the sur- surface was cut. Erosion surfaces also show differ- faces seem definitely to be the result of the ences in size, elevation, and other characteristics lateral corrasion of streams. depending on whether they were cut by the The town of Espanola stands partly on the master stream system or by the tributary sys- flood plain of the Rio Grande and partly on a tem.

DRAINAGE The Rio Grande rises in the San Juan point where the Rio Grande leaves the Rio Mountains of southern Colorado and flows Grande Canyon near Velarde to White Rock southward for more than 400 miles across New Canyon near the San Ildefonso Indian Pueblo. Mexico. Near the southern boundary of New The present flood plain of the Rio Grande is Mexico the river turns southeastward and, after 1 to 3 miles wide for most of its length through leaving the state, forms the boundary between the Espanola Valley. The river bottom lands are Texas and Mexico for nearly 1250 miles to its almost all under irrigation and are surprisingly mouth on the Gulf of Mexico. The Upper Rio fertile, although some of the land has been under Grande Basin includes parts of Colorado, New continuous cultivation for hundreds of years. Mexico, and west Texas. The part of the Upper The first white settlement within the boundaries Rio Grande Basin in which the deposits of the of the United States was established in 1598 on type area of the Santa Fe Group are exposed is the west side of the Rio Grande just above the known as the Espanola Valley, which, in turn, mouth of the Chama River, near what is now is part of the larger Middle Rio Grande Valley. the San Juan Pueblo. The colonists were led by The Middle Rio Grande Valley is about 200 Don Juan de Oiiate who called the settlement miles long and extends from a point near San Gabriel de 10s Espanolas. Before the coming Velarde to San Marcial, near the head of the of the Spaniards, the Indians of the Tewa tribes Elephant Butte Reservoir. The Espanola Valley long had farmed the lands, and before them the is about 25 miles long and extends from the vanished tribes of the Pajarito Plateau had built 98 BULLETIN AMERIC4L?J MUSEUM OF N.4TURAL HISTORY I'OL. 144 their pueblos near the river and irrigated parts diverted for irrigation. Santa Clara Creek joins of the bottom lands. Some of the present irriga- the Rio Grande from the west just below Espan- tion canals are said to follow some of the pre- ola. Most of its water is diverted for use as the historic canals. community water supply of the Santa Clara Near the head of the Espanola Valley the Rio Indian Pueblo; the rest is used for irrigation by Truchas enters the Rio Grande from the east. the Pueblo. All its perennial waters are utilized to irrigate Pojoaque Creek and its tributaries, Nambt between 1250 and 1500 acres of land in the Creek and Tesuque Creek, supply little water to mountain valleys and on the erosion surfaces the Rio Grande, for nearly all its perennial flow along the foot of the mountains. is used by the residents of the valley, particularly The Chama River, a perennial stream drain- by the Nambt, Tesuque, and San Ildefonso ing an area of about 3200 square miles, empties Indian Pueblos. into the Rio Grande from the west just below the The Chama River and Embudo Creek are the San Juan Pueblo. The annual runoff of the only perennial tributaries of the Rio Grande in Chama River has ranged from 977,200 acre-feet the type area of the Santa Fe Group. Very in 1916 to 179,700 acre-feet in the drought year numerous washes, arroyos, and canyadas are of 1934. The Chama, with its tributaries, the tributary to the Rio Grande, but these may run Ojo Caliente River, EI Rito Creek, Abiquiu for only a few hours on a few days during the Creek, and Rio del Oso, drains the part of the year when heavy thunderstorms move down type area of the Santa Fe Group that has been from the mountains and send torrents raging called the Abiquiu re-entrant (Cabot, 1938, down the dry channels. Vast quantities of silt p. 89). and sand are swept into the Rio Grande by the The Santa Cruz River enters the Rio Grande flash floods of the sudden summer storms. from the east at Riverside. Most of its waters are

DEPOSITION OF ALLUVIAL PLAINS IN DRAINAGE VALLEYS

The present channel of the Rio Grande in The interpretation here presented is that the White Rock Canyon below the site of the old Rio Grande at one time cut down much below Buckman Bridge is known to have cut down at its present level. The temporary base-level en- least 55 feet below the present bed of the river. dured for a sufficiently long period to permit In a reconnaissance of the east bank of White several of the tributary streams to entrench Rock Canyon in 1941 we were privileged to themselves and become partly graded to the examine a drill core taken from the bed of the lower (temporary) base-level. At this stage the river by an exploration party for the United Rio Grande apparently was impounded, pos- States Reclamation Service which was testing sibly by a lava flow, the temporary base-level the localitv as a vossible dam site. The drill core was raised abruptly, and a cycle of deposition showed 55 feet of heterogeneous gravel, basalt, started in which the alluvial plains which now sand, and other sediments, and did not contain extend far up the tributaries were formed. After any sediments of the Santa Fe Group. It is these alluvial plains had attained approximately probable that the river-channel deposits in the their present contour, the Rio Grande began river bed extend to a greater depth than the cutting down again. The constructional deposits 55 feet shown by the core. It seems unlikely that were trenched by the tributaries as the tempo- the normal processes of scour and fill in the river rary base-level of the master stream began channel would result in river-laid sediments as moving down. The degradation of these con- deep or deeper than 55 feet; therefore, a special structional plains is going on at the present time, set of hypotheses is required to explain such an and the steep-walled arroyos that incise the occurrence. The fall of the Rio Grande through plains are regarded as an integral part of the White Rock Canyon is about 10 feet per mile adjustment to the lowering of the base-level. (Herron. 1916). 1971 GXLUSH.4 AND BLICK: SANTA FE GROUP 99 SUPERIMPOSED STREAMS Superimposed streams are numerous in the which more than 150 feet of Magdalena beds region. Cabot (1938, p. 96) recognized the have been preserved. The Magdalena rocks, superimposed nature of Embudo Creek and its although areally very small in this particular tributaries, and also of the Santa Cruz River. block, bulk as a rather high hill at the falls. The Ojo Sarco Creek, a tributary of Embudo attitude is N. 10" W., 42" W. The basal portion creek. flows alternatelv across crvstalline and of the exposed Magdalena is composed of 80 to sedimentary rocks at least six times. Each time 100 feet of alternating sandstones, mudstones, that the creek crosses the Dixon granite (Just, and impure in which cherty nodules 1937, p. 24), it could have cut its course in the are abundant. The upper portion is a series of soft sediments of the Santa Fe by a detour of alternating , sandstones, and some highly only a few yards. The Santa Fe beds are banked fossiliferous and crinoidal limestones. NambC against the Dixon granite in this locality and Creek, after leaving the small block of Magda- have been stripped from the contact along many lena rocks, flows for several miles across beds of of the granite hills and spurs. the Santa Fe Group. Finally it joins Tesuque The Rio Pueblo is clearly superimposed. It Creek just below Pojoaque, New Mexico, and rises high in the Sangre de Cristo Range, princi- there becomes known as Pojoaque Creek. pally in areas underlain by beds of the Magda- The streams of the type area showing super- position are the Rio Pueblo, Ojo Sarco Creek, ien; Grou~,. , crosses a small area of ~recambrian crystalline rocks, and then flows again across Embudo Creek, Santa Cruz River, Rio Que- limestone of the Magdalena Group. Near mado, Rio Chiquito, Medio (Frijoles) Creek, Vadito the creek flows across several miles of NambC Creek, and even the Rio Grande. The Picuris Tuff before passing through a notch in a Rio Grande has been let down through the low granite ridge near the Picuris Pueblo. Hinsdale basalt underlying the Taos Plateau Below the town of Rio Lucio the Rio Pueblo (Upson, 1941), and has cut more than a thou- flows through a scenic gorge that has been cut in sand feet below the surface of the lava plains. the Dixon granite to a depth of several hundred Between Pilar and Rinconada, the Rio Grande feet and finally emerges from the gorge a short flows along the contact between the Santa Fe distance above the mouth of Ojo Sarco Creek to and Precambrian rocks. For most of the distance cross beds of the Santa Fe Group. Below the it flows on the Santa Fe beds, but at a few places junction of the Rio Pueblo with Ojo Sarco it has cut through small spurs of the Rinconada Creek, the stream becomes known as Embudo schist phase of the Ortega quartzite (Just, 1937, Creek, which then crosses one more narrow belt see map). The Rio Grande has followed the of Precambrian rocks about a mile below the pattern of some of its tributaries and has cut town of Dixon before entering the Rio Grande through rather than around crystalline rocks. At across a strip of Santa Fe beds. some places a diversion of only a few feet would NambC Creek rises in a lake high in the have carried the river entirely on sedimentary Sangre de Cristo Range, leaves the crystalline rocks. rocks a few miles southeast of the NambC The superimposed streams have been let Pueblo, whereupon it flows for less than a mile down through a thick cover of Santa Fe Group across a belt of sedimentary rocks of the Picuris deposits. Erosion surfaces, rather than the differ- Tuff, and the Nambt Member of the Tesuque ential hardness of the rocks, have controlled the Formation. At the NambC Falls the creek position of most of the streams. plunges over a small inlier of crystalline rocks on STRUCTURE

STRUCTURALRELATIONS of parts of the Rio (1952, p. 93) emphasized the necessity ofinclud- Grande depression have been described by ing the borders or rims in the consideration of Renick (1931, p. 74), Bryan and McCann the depression and stated, "In consequence, the (1937, p. 818), Bryan (1938, p. 199), Cabot width of the total structure, including the (1938, p. 97), Harold T. U. Smith (1938, bordering uplifts, is often twice that of the inter- p. 959), Denny (1940a, p. 99; 1940b, p. 683), vening depression." In 1956 (p. 109) he further Stearns (1943, p. 317), Wright (1946, p. 414), stated, "The deformations throughout the Kelley (1952, p. 93; 1956, p. log), Ross, Smith, length of the intermontane depressions do not and Bailey (1961, p. 142), and Spiegel and appear to have been synchronous." With the Baldwin (1963, p. 68). Some of the features last statement we are in general accord, al- described by these writers, and by others not though the post-Santa Fe deformation that out- listed above, were noted as structural relations lines the Rio Grande depression in the Espanola of the Santa Fe Formation, and indeed many of basin and the Albuquerque-Belen basin appears them are identical. No clear distinctions have to be synchronous throughout both basins. been attempted, with one or two exceptions- The discussion of structure herein is confined namely, Wright (1946) and Stearns (1953b)-to mostly to the Espanola basin and to the parts of interpret the sequence of events from the incep- the Albuquerque-Belen basin in which Santa tion of the initial basins through the deposition Fe Group beds, as restricted in this report, are of the various formations filling them, eventually exposed. culminating in the post-Santa Fe Group de- The western border of the Sangre de Cristo formation and subsequent erosional history. Range north of Santa Fe commonly has been Bryan and McCann (1937, p. 818) first used regarded as a post-Santa Fe fault-line scarp. We the term Rio Grande depression for the series of present evidence to show that the fault border is structural basins or troughs in the Rio Grande pre-Santa Fe Group in age (figs. 11, 38; see also Valley in New Mexico, and the term appears p. 104). Moreover, we show that the Santa Fe several times in their report on the stratigraphy beds are in sedimentary contact with the crystal- and structure of the Ceja del Rio Puerco. Later line rocks of the range (p. 45). A few small Bryan (1938, pp. 197, 199) further expanded the post-Santa Fe faults are at the contact locally concept of structural basins by describing several between NambC Member beds and the crystal- of them and relating them to the broader fea- line rocks, but they pass into, and die out in, the tures of the Rio Grande Valley. In this respect, NambC Member (fig. 38). The post-Santa Fe understandably, he followed Lee (1907, p. 12) in faults do not follow the contact and cannot be emphasizing the erosional character of most of considered as marking a fault border of the the inner valleys. That the term Rio Grande Sangre de Cristo Range. depression was in use, if not in print, prior to Postulated gradual subsidence associated 1937 is implied by the use of the term by with downfaulting or downwarp during the Bryan's students or associates [Cabot (1938, deposition of the Santa Fe beds lacks field evi- p. 88), Harold T. U. Smith (1938, p, 933), and dence. Indeed, no simple hypothesis will suffice Denny (1940a, p. 73; 1940b, p. 680)], whose to explain the accumulation of the thick Santa field work in New Mexico antedated their Fe Group deposits. It is not enough to interpret published reports by several years. the original extent of the Santa Fe Basin, in Tectonic studies of the Rio Grande depression which the beds of the type area were deposited, were published by Kelley (1952, 1954, 1956), by the outlines of the post-Santa Fe Group whose work greatly expanded knowledge con- deformation, which is now considered to mark cerning the structural troughs comprising the the Rio Grande depression. An attempt must be depression. His description of embayments, made to separate the concepts of pre-Santa Fe salients, constrictions, and uplifts, in addition and post-Santa Fe deformations; this is incor- to those described by Bryan (1938, p. 198) and porated in the succeeding pages. Lee (1907, p. 12), should greatly facilitate future The faults of the type area of the Santa Fe work on the tectonics of the region. Kelley Group must be sharply discriminated as to their 1971 GALUSHA AND BLICK: SANTA FE GROUP 101 age relations. An Oligocene period of deforma- Cristo and northern areas." We emphasize and tion can be regarded as the pre-Santa Fe Group reiterate our opinion that the beds formerly deformation (this paper, p. 104). The post-Santa included in Bryan's Upper Buff, Spiegel's two Fe Group deformation is the primary factor in unnamed formations, various axial river gravels, outlining the recent Rio Grande depression. and other late gravel and associated deposits, as This post-Santa Fe deformation probably started well as late volcanic deposits, should be ex- in the late Pliocene and may have continued cluded from the Santa Fe Group. into early Pleistocene time. The recognized late Ross, Smith, and Bailey (1961, p. 140), on a Pleistocene formations are not involved in the generalized geologic map, show a small wedge major post-Santa Fe deformations. of Tertiary rocks along the southern end of the Beds of the Santa Fe Group, as restricted to Pajarito fault zone.1 These Tertiary rocks in- the type area, dip westerly, and, although the clude a surprisingly diverse lithologic sequence dip is not so great near the Rio Grande as in which rocks suggestive of the Galisteo Forma- farther east, we have failed to confirm reports tion, El Rito Formation, Espinaso Volcanics, of low easterly dips which have been inter- and the Pojoaque Member of the Tesuque preted as part of a broad synclinal structure Formation are exposed. Fragments of Ramoceros across the basin (Kelley, 1956, p. 111). Such horns and mastodont tooth fragments were col- dips may be typical of beds in the Santo Domin- lected in the Santa Fe beds in this fault block. go Basin farther south along the Jemez uplift These beds lie outside the map area covered in that are not included in the Santa Fe Group of the present report, but they are extremely im- the type area but are lithologically and tem- portant because they form the only tangible link porally compatible with the Upper Buff of between the beds of the type area and the beds of Bryan, which, as indicated elsewhere in this Jemez Creek and Ceja del Rio Puerco. On these report, should be rock-stratigraphically and rests the evidence for continuity of the Pojoaque biostratigraphically separated from the Santa Member of the Tesuque Formation to the Fe Group. Spiegel (1961, p. 133) suggested that Albuquerque-Belen basin, and not on the beds two unnamed formations are exposed in the cited by Bryan (1937, p. 810) in the Santo Lower Jemez River area and that these also Domingo Valley and in the vicinity of Bernalillo appear to represent facies of the Upper Buff. (see discussion, this paper, p. 39). Moreover, apparently they are part of the beds 'The Pajarito fault zone was mapped and named by in which Kelley (1956, p. 11 1) detected "an Griggs (1964, p. 73). Unfortunately the critical area con- abundance of rock fragments of Jemez proven- taining the Tertiary rocks occurs in the part of the map ance, and little material from the Sangre de occupied by the map legend.

FAULT SYSTEM The fault system in the type area of the Santa ous, but those with west side down are usually Fe Group is series of high-angle, normal, strike larger. Faults within the type locality of the faults, with their strikes about parallel to the Santa Fe Group commonly have net dip-slips of trend of the Rio Grande Valley. In the Espanola less than 300 feet, but the greater number of Valley the strike of many of the faults is nearly them have dip-slips of only a few feet, yet the true north, varying at most only a few degrees sum of the displacements of the small faults is (figs. 12, 20, 25, 38). A few faults in the type large. The average angle of dip of the faults area strike northeasterlv., - but these are exposed throughout the Santa Fe Group is about 70 principally along the northwestern edge of the degrees. Fault dips of less than 45 degrees are rare area in the Abiquiu re-entrant north of Black and, where observed, are commonly in short Mesa. The fault traces may show a marked local branch faults bounding small, wedge-shaped sinuosity (fig. 38), but normally they are blocks. straight or gently curving. The direction of dip The geologic map (fig. 38) showing the faults of the fault planes may be either easterly or of the type area of the Santa Fe Group empha- westerly, resulting in closely spaced fault blocks sizes the point that the faults seem to be arranged with downthrown blocks on the east or west. in clusters. Such apparent clustering results from The faults with east side down are more numer- our having mapped observed fadt traces, for BULLETIN XMERIC.&V MUSEUM OF NATURAL HISTORY rarely were inferred faults plotted. The clusters, fault results in omission rather than repetition of therefore, are controlled primarily by the the beds. The mere mention of the combination arrangement of the outcrops of Santa Fe Group of dip of beds with fault dips makes the problem beds, which afforded us an opportunity to of correlation within the Santa Fe Group sound observe the faults, rather than by any lack of deceptively simple. It is, in reality, only one of a faults in the intervening areas. ~heseintervening series of necessary observations required to make areas are commonly effectively masked by late a stratigraphic correlation of each fault block. deposits lying on erosion surfaces that occupy Fault traces throughout the Santa Fe Group parts of local-drainage basins between the areas vary greatly along the strike. Sandstone and of outcrops. conglomeratic sandstone dikes often occur in the Small branch faults locally complicate the fault traces and range from a fraction of an inch general fault pattern by forming acute-angled to more than 10 feet in thickness. Thin crystal- splinter blocks. Branching, however, is not line calcitic dikes were observed in the fault characteristic of the fault pattern in the Espanola planes at many places, and, rarely, as at the base Valley, but several fine examples occur-in the of the North Pojoaque Bluffs, pseudo- eastern part of White Operation Wash, in the morphs after aragonite occur. One fault ob- North Pojoaque Bluffs, and west of Black Mesa served in the eastern part of White Operation between Ojo Caliente River and El Rito Creek. Wash, and also in its probable extension to the In White Operation Wash some faults, especi- south on the Nambt Grant, has brecciated ally those with the downthrown block on the material along the trace and also crystalline west, have been observed to split, hinge-out, or calcite, and both ofthese have been encrusted by to dovetail with east-side-down faults. The east- botryoidal chalcedony. These, and somewhat side-down faults commonly intersect at a slight similar occurrences in which hyaline opal is the angle, resulting in minor warping and torsion. encrusting material, will commonly fluoresce A small degree of differential rotation, particu- and, in addition, are weakly radioactive. larly of the acute-angled blocks, has locally Fault traces in the more consolidated sedi- complicated the interpretation of the strati- ments of the Santa Fe Group are usually well graphy. defined, although the fault traces may narrow The fault Dattern and the attitude of the markedly where the two fault walls are tightly strata of the &nta Fe Group are closely related appressed. Faults with a vertical displacement of and, therefore, can be discussed together con- more than 100 feet have at many places a fault veniently and advantageously. he prevailing trace that is less than 1 inch wide. Slight bends dip of the beds in the Espanola Valley is west- or undulations in the fault planes apparently ward. The angle of dip of the individual fault caused open spaces that were later filled with blocks is low, normally about 9 degrees, but dips sediments, which upon consolidation formed as high as 30 degrees are present locally, notably dikes. Just how these spaces were filled is not

in the North Pojoaque-. Bluffs. At various locali- known, but it may have been by injection of ties elsewhere in the region the beds may dip in mixtures of sand and water, or sand, water, and various directions; for instance, immediately conglomerate under pressure coincident with west of the Ojo Caliente River the prevailing movement of the fault blocks. Rarely, if ever, dip is northeast or east. Beds around the periph- were planes of stratification noted in these dikes. ery of the type area of the Santa Fe Group may Several of the faults that deformed the eolian dip in any direction, but commonly the dip is to sand that comprises the bulk of the Ojo Caliente the west. Sandstone instead of shearing cleanly, crushed In the Espanola Valley, as stated above, the and crumpled the soft sandstone and formed a prevailing dip of the beds is to the west. When great series of interlocking cracks that produced these westward-dipping beds are deformed by a wide fault zone. These cracks formed a distinc- faults, with fault dips to the east, the result is tive dike system where percolating waters have that the same beds mav be re~eatedin a series formed concretions or have caused cementation. of fault blocks. ~herekerthe' pattern is inter- The dikes are composed mostly of calcareous rupted by westward-dipping faults, the con- sandstone; a few have siliceous cement; a few tinuity is broken, and the westward dip of the are composed of sandstone concretions, which beds combined with the westward dip of the probably are epigenetic; and the smaller cracks 1971 G.ILUSH.I .LSD BLICK: S.-\ST.\ FE GROUP 103 commonly contain thin, soft, kshite, potvdery Kunya (Tewa Indian : turquoise) Indian ruins calcareous material. A large fault zonk with about 2 miles below Abiquiu and curves toward comples dike system forms high, resistant cliffs the east and passes along the south end of Cerro or pinnacles in the apex of the triangle (fig. 38) de las Xiinas. The Santa Fe beds are thrown bounded by the Chama River and the Ojo down against the Abiquiu Tuff by this fault in Caliente River. which is a tributarv of the the vicinity of Cerro de las hiinas. The Abiquiu Chama. On the' high pinnacles the ceientation Tuff is also broken by several other faults in the was observed to become less downward except general Abiquiu area. in the fault plane itself. Cross-bedding of some The fault pattern that is observable in the of the cemented sandstones is brought into sharp type locality of the Santa Fe Group is clearly relief bv wind erosion, which has sandblasted that of the post-Santa Fe deformation. Cross the surface; some of the laminae were softer than sections (fig. 38) across the Espanola \'alley others and were filed down, leaving the hard show the general fault relations. The cross sec- laminae to stand out as ribs. inexplicably, and tion of the Skull Ridge Member of the Tesuque unfortunately, this particular set of cemented Formation displays some of the structural de- zones, and two othdrs southeast of hledanales, tails, and many of the areal maps and cross were mapped on the geologic map of New sections covering the outcrops of volcanic ash Mexico (Dane and Bachman. 1965) as intrusive beds of particularly significant localities, such rocks, apparently in the mistaken belief that they as Skull Ridge, Pojoaque Bluffs, East Cuya- were of igneous origin. munque, and Itrest Cuyamunque, illustrate the cemented zones-occur at several points in a close relation between outcrop patterns of the large fault near the town of Abiquiu; one of ash beds and of the fault pattern. Obviously it is these was known to the early Spanish settlers as unrealistic to attempt extremely detailed map- El Cuchillo (Spanish: The Knife). This same ping of the entire Santa Fe Group, but we be- cemented zone was called "Battleship Rock" by lieve the examples given will present a frame- Harold T. U. Smith (1938, p. 960) and is work for better understanding of the strati- mapped on the United States Geological Survey graphy and structure of the type area of the Abiquiu Quadrangle (1953) as Cerrito Blanco. Santa Fe Group. This large fault brings the Santa Fe beds down The post-Santa Fe faults of the Espanola into contact with the Abiauiu Tuff. \'alley are interpreted as the result of tension of .A small cemented zone lies between Black the beds. The observed facts that support this Mesa and the east bank of the Ojo Caliente view are: (1) all the Santa Fe group beds dip to River about 2 miles above its mouth. Cemented the west, even in closely spaced fault blocks, zones also occur as dikes in several faults in the (2) the faults are normal faults and dip at high Rio del Oso-Abiquiu locality (figs. 2, 38), and angles either to the east or west, (3) reverse in these, as in most other places in the general faults are absent, and (4) the contact with the area, the cemented zones commonly occur in the crystalline rocks of the Sangre de Cristo Range downthrown blocks along the fault planes. is an unconformable sedimentary contact and A swarm of basaltic dikes in the Rio del Oso- not a fault contact. -4biquiu locality (see geologic map, fig. 38) have Uplift of the Sangre de Cristo Range probably been injected into fault planes, and these igneous provided the tensional forces needed to account intrusions have been described briefly in the for the lengthening of the beds, as shown by the section on Rio del Oso dikes (above, p. 90). 4 cross sections (fig. 38). If the fault system had major fault with east-side-down brings the Ojo been controlled primarily by compression or Caliente Sandstone down into contact with the even downwarping of the ~antaFe beds against fossiliferous beds of the Chama-el rito Member the pre-Tertiary rocks, the effect should have of the Tesuque Formation in the western part of been shortening of the beds instead of lengthen- the Rio del Oso-Abiquiu locality (fig. 38). The ing. The horizontal compression resulting from dip-slip of this fault is estimated as about 600 such a downwarp should have caused buckling feet. The Ojo Caliente Sandstone also crops out of some of the fault blocks, probably large num- west of this fault along the high Lobato lava bers of reverse faults, and other complications flow escarpment. Another fault with a compar- that do not exist. The large number of normal able slip crosses the Chama River near -the faults in the Espanola Valley, although of the BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY VOL. 144 high-angle variety, actually represent a signifi- which would be substantial. cant extension of the beds when estimates are Faults that involve beds of the Santa Fe made of the horizontal separation. Only a few of Group along the western border of the Sangre de the total number of faults can be measured Cristo Range are few in number and small in accurately, and a tabulation of these would, at size (either in length of trace or amount of dis- best, produce an inadequate picture of the total placement), and all die out in the Santa Fe beds horizontal separation. It should suffice merely without causing major dislocations. In our opin- to point out that the faults all show horizontal ion the faults mapped by Cabot (1938, p. 92) separation. The hundreds of small fractures that and Spiegel and Baldwin (1963) along the are unmeasured or are unmeasurable in the mountain front from the vicinity of Bishop's fault blocks, that is, faults with 2 or 3 inches up Lodge south to Santa Fe and beyond are pre- to 6, 8, or 10 feet, or even more, of vertical slip, Santa Fe Group in age because they cut older all show some horizontal separation the sum of rocks and do not involve Santa Fe beds directly.

AGE OF THE PRE-SANTA FE GROUP DEFORMATION

The age of the pre-Santa Fe Group deforma- deposition of the Galisteo beds in Duchesnean tion must be inferred from the results of observa- time. tions of widely separated exposures. Beds at the south end of the Sierra Naci- Beds along the Chama River had been de- miento, and in Canyada Piedra Parada, which formed by the subsidence of the original depres- is a tributary of Jemez Creek, were assigned by sion in which Tertiary beds were deposited. This Renick (1931, pp. 57-58) to the lower Wasatch; can be seen by the manner in which the edge of by Bryan and McCann (1937, p. 808) to Cre- the Mesozoic platform has been successively taceous or older beds; and by the senior author faulted down on the south and east in the vici- (Galusha, 1966, p. 4) to the Galisteo Formation. nity of Cerro Pedernal, the Abiquiu Dam, and The field evidence indicates that the age of the Abiquiu, New Mexico. The first formation laid pre-Santa Fe Group deformation at this point down along the edge of the depression at this was post-Galisteo. The Galisteo Formation was point was the El Rito Formation (Harold T. U. the last formation laid down preceding deforma- Smith, 1938, p. 940). Stearns (1943, p. 315) dis- tion by the Sierrita fault, and the Zia Sand cussed the pre-Galisteo unconformlty in the Formation (Galusha, 1966) was the first to be Galisteo-Tonque area. He also pointed out deposited across its trace. The age of the Sierrita (p. 301): ". . . the igneous rocks of the Ortiz fault, which Renick (1931, p. 74) considered Mountains and the Cerrillos Hills intrude the part of the Nacimiento overthrust, thus can be Galisteo formation and the Espinaso volcanics. assigned to some part of the Oligocene. At this These formations were deformed and eroded stage of the investigation it is not possible to before deposition of the late Tertiary Santa Fe allocate the deformation to Chadronian, Orel- formation. The Rio Grande depression was not Ian, or Whitneyan time (Wood et al., 1941) with outlined until late Tertiary time." He also con- precision. cluded that warping had occurred during the

AGE OF THE POST-SANTA FE GROUP DEFORMATION

The age of the post-Santa Fe Group deforma- the Ojo Chamisa fault. Borrego Mesa is broken tion never has been established accurately. by several faults, and Santa Ana Mesa is also Renick (1 93 1, p. 77) noted that the beds of the faulted. All these lava flows are later than the Santa Fe Formation were involved in the de- (?)Gila Conglomerate equivalent (the Upper formation of the and San Buff Member of Bryan and McCann) and hence Pedro Mountain. He did not, however, recog- are of early Pleistocene age. nize that numerous faults deform the basalt Bryan and McCann (1937, p. 827) described mesas north of Jemez Creek. Chamisa Mesa is a three distinct fault systems in the Ceja del Rio remnant of a downthrown fault block west of Puerco area. They stated that "the Ceja faults 1971 G-ALUSHA AND BLICK: SANTA FE GROUP 105 are post-Santa Fe and thus not earlier than late Formation" (see Bryan and McCann, 1937, Pliocene or perhaps the beginning of the p. 815). The post-Santa Fe faults cut and dis- Pleistocene." Denny (1940a, p. 101) postulated placed the "Upper Buff." Fossils collected from several periods of Tertiary deformation in the this member (?Gila Conglomerate equivalent) San Acacia area. He mentioned three pre-Santa will ultimately provide the solution as to whether Fe deformations: one during the Santa Fe, and the deformation was Pliocene, ended in the two post-Santa Fe deformations. Denny con- Pliocene, or was of early Pleistocene age. We sidered the "Santa Fen beds in the San Acacia collected fragments of horse bones of appropriate area to be upper Pliocene in age, although the size for Equus at several points in the "Upper fossils he listed are probably more characteristic Buff" along the Ceja del Rio Puerco. A section of the early Pleistocene. The difference in funda- of a mastodont tusk was observed in the member mental interpretation of the age of fossils pro- in the Sand Hill fault-zone locality (Wright, foundly affects the dating of the post-Santa Fe 1946, pl. 8). A small collection of fossils was Group deformation. obtained from the "Upper Buff" along the Ceja Harold T. U. Smith (1938, p. 964) stated, del Rio Puerco at the north end of the Isleta ". . . it seems probable that the deformation Indian Pueblo Grant. A larger and more com- must have taken place well before the close of plete fauna is needed before the age of the the Pliocene period." Denny (1940b, p. 684) member (?Gila Conglomerate equivalent of the described faults in the Espanola Valley but did writers) can be definitely established, but if, as not speculate concerning their age. In his con- we believe, the "Upper Buff" of Bryan and clusions Denny (p. 691) stated, however, "Since McCann is an equivalent of the fine-grained the Pliocene the formation has been tilted west- phase of the Gila Conglomerate the age of the ward and broken along many normal faults." deformation is considerably later than previ- Wright (1946, p. 415), in speaking of the ously supposed. Albuquerque-Belen basin, postulated that the The Ortiz erosion surface was cut following "subsidence of the depression continued apace the post-Santa Fe deformation, and the deposits with deposition during the late Tertiary." He lying on the Ortiz surface have not been de- also stated, "In the late Tertiary downwarping formed by the post-Santa Fe faults. Pleistocene and downfaulting formed the Albuquerque- fossils collected from deposits on later erosion Belen basin, in which the Santa Fe formation surfaces and from the Espanola Formation was deposited." Wright regarded the post- (above, p. 80) suggest an early Pleistocene age Santa Fe deformation as a period of accelerated for the Ortiz surface. The post-Santa Fe defor- subsidence of the depression. mation is interpreted on the basis of the fore- The age of the post-Santa Fe deformation is going evidence to have taken place not at the inalienably involved in the problem of the so- very start of Pleistocene time, but somewhat called "Upper Buff Member of the Santa Fe later in early Pleistocene time. AGE OF THE SANTA FE GROUP

DEPOSITSNORTH OF Santa Fe, New Mexico, that discussion of the Tesuque Formation (p. 44). have been described by various writers during The restricted Santa Fe Group comprises two the past 100 years, first as the Santa Fe Marl, formations: (1) the Tesuque Formation, with then as the Santa Fe Formation, and in recent five members, namely, the NambC Member, the years as the Santa Fe Group, in this report have Skull Ridge Member, the Pojoaque Member, been redescribed. subdivided. and restricted to the Chama-el rito Member, and the Ojo Cali- the type area. These rocks provide an essential ente Sandstone; and (2) the ChamitaFormation. lithogenetic unity in the geologic history of this We believe that these subdivisions are a practical part of New Mexico. Beds in other parts of New solution to the stratigraphy of the Santa Fe Mexico that are not represented in the type area Group, for they present a rock framework are excluded from the Santa Fe Group. established primarily on a lithologic sequence, A recognizable rock sequence in the type area on which the biostratigraphy can be superposed that can be given reasonably accurate age and interpreted. When the local biostratigraphic assignments should enable both paleontologists ranges are known in a controlled area, such as and geologists to provide a basis for separating the restricted type area, then the data thus lithogenetically distinct beds in other parts of the obtained can be confidently applied to the solu- Rio Grande depression in New Mexico. Fossils tion of other problems. Any meaningful dis- that were collected in the various units have cussion of the age of the Santa Fe Group must provided controls for the age assignments, but necessarily deal with fossils; consequently in this even these fossils are subject to different inter- section we comment briefly on our general inter- pretations by paleontolo~sts. pretations of the ages of the fossils that we have Over the years the concepts of the age of the collected in the group. Santa Fe beds have gradually evolved from Much of the confusion and uncertainty con- Miocene to the more inclusive Mio-Pliocene; cerning the age of the Santa Fe can be traced to finally to ( ?)middle Miocene to ( ?)Pleistocene imprecise stratigraphic allocation of the original (Keroher et al., 1966, p. 3463). A review of the fossil collections from the Santa Fe area. Klett literature on the ~antaFe Formation (see collected fossils north of San Ildefonso in 1873; Historical Sketch, p. 16) shows general un- Cope and Shedd in 1874 worked in the same certainty among paleontologists and geologists locality and also obtained some material north regarding the time-stratigraphic boundaries to of Pojoaque and some south of NambC. The two be used in the area. Attempts to apply the usual latter localities introduced a few late Miocene geologic-time (geochronologic) units and North forms into Cope's predominantly early Pliocene American Land-Mammal ages to the beds can fauna and resulted in a mixed faunal list, which be, and have been, criticized, but the applica- for nearly 100 years has formed the basis for dis- tion of these terms at least serves as a ~ointof cussion of the age of the Santa Fe Formation. reference for the particular beds. By 1909 Osborn and Matthew (1909, p. 79) Radiometric (absolute) dating ultimately listed "the Santa Fe marls of Cope, New may provide a precise scale for measuring the Mexico," as Upper Miocene and correlated range zone of any particular taxon, or, better them with the Ogalalla [sic] Formation in part. still, the concurrent-range zones of specified In a faunal list in the same paper, Matthew taxa. Until these refinements are available. how- (p. 115) listed the fossils then known from the ever, and regardless of eventual changes in usage Santa Fe and placed them under Upper Mio- of the time-concepts here discussed, we present cene and (?) Lower Pliocene headings without the information in this report in a manner that further comment. Frick (1933, pp. 549, 571) we hope will be intelligible and useful to future reported the existence of mid-Miocene to Pleisto- investigators. cene deposits in the type area and discussed ~eaionsfor restricting the term Santa Fe possible time equivalents of the beds in terms of Group to the beds in the type locality are given the mastodonts and horses that he had collected. in the Introduction (p. 9), in the general state- The Pleistocene deposits he mentioned are here- ment on the Santa Fe Group (p. 40), and in the in described as the Espanola Formation. The 1971 GALUSHA AND BLICK: SANTA FE GROUP 107

Uppermost Pliocene that he mentioned (p. 549) An effort has been made to correlate the field proved to represent a part of the Hemphillian. and laboratory evidence of the Santa Fe Group Latest Hemphillian and Blancan faunas so far with the provincial time scale proposed by the have not been recognized in the type area, al- Committee on Nomenclature and Correlation though Morris Skinner (personal communica- of the North American Tertiary (Wood et al., tion) detects horses in the collections from Lyden 1941). The conclusion that has been reached is Quarry and the San Juan locality that he re- that the provincial terms can be applied in a gards as late Hemphillian forms. Osborn (1936, general way to the beds of the Santa Fe Group, p. 320), in his monograph on the Proboscidea, but the use of the terms implies an arbitrary called the Santa Fe beds "the Mio-Pliocene division of the faunas of the Santa Fe Group at Santa Fe Marls." All subsequent workers, with a point supposed to mark the boundary between one notable exception,l either directly or in- the Barstovian and the Clarendonian. These directly have quoted Cope, Matthew, Osborn, provincial time terms were erected bv the and Frick as authorities for age determinations. committee avowedly to circumvent the question Parts of the very large collection of mammal- of the Miocene-Pliocene boundary, yet a com- ian fossils from the beds of the Santa Fe Group parable problem is created in deciding where in the Frick Collection of the American Museum the Barstovian ends and the Clarendonian of Natural History are being studied, but much begins. The difficulties encountered in making a time may elapse before an evaluation can be decision involving these particular time terms made of the complete fauna. Preliminary analy- can be better understood when it is pointed out ses by our colleagues of portions of the collection that Hemicyon, one of the five index fossils for the of carnivores, horses, mastodonts, camels, mery- ~arstovianas determined by the committee, is codonts, oreodonts, rhinoceroses, rodents, lago- more characteristic of later beds and more often morphs, and insectivores from these deposits found in association with Valentinian (p. 12) show that the fossils are broadly equivalent to and Clarendonian fossils than with those listed those ranging from late Hemingfordian (late for the Barstovian. medial Miocene) to Hemphillian (medial Plio- Two species of Hemicyon from the Barstow cene) in age as compared with assemblages from area, California (Hemicyon barstowemis Frick and the Great Plains sequence. The oldest fossils col- Hemicyon californicus Frick) are from the Hemi- lected from the type area (Nambt Member) cyon stratum, a bed in the uppermost ?pre- compare closely with those obtained in the Valentinian (p. 12) portion of the Barstow sec- Sheep Creek quarries of western Nebraska and tion. Hemiyon (Canis) ursinus (Cope) Frick was their equivalents. collected from Clarendonian (early Pliocene) Deposits containing early Miocene (Galusha, beds of the Pojoaque Member of the Tesuque 1966) and very late Pliocene or Pleistocene Formation of the Santa Fe Group. Hemicyon fossils (Needham, 1936) have been assigned to barbouri Colbert from the Ainsworth area, the Santa Fe Formation in the past, but these Nebraska, is also from beds in the Pliocene deposits crop out in sedimentary basins in section.2 An undescribed Hemicyon specimen in localities outside the type area, in some areas the Frick Collection from the Skull Ridge even 100 or 200 miles or more away, and more Member of the Tesuque Formation, one from properly should have been named as distinct Steep Side Quarry, and one from Turbin formations. They are not genetically, lithologic- Quarry of the Barstow area are the only Hemi- ally, or faunally like beds of the Santa Fe type yon specimens known to us that are unreservedly locality. referable to the Barstovian.

'Schultz and Falkenbach (1940, p. 254; 1941, pp. 15, 33, 34, 43, 44, 48; 1947, p. 245; 1949, pp. 80-82; 1968, 2Morris F. Skinner (personal communication) was pp. 367, 368, 379) recognized Brachycrus and present when the type specimen was collected and says (Metoreadon) as indicating a Miocene age for a portion of that it came from a site 70 feet above the base of the Cap the sediments. They listed four species of L7statachoerus from Rock Member of the Ash Hollow Formation. (The strati- the area and designated the beds that contained them graphic section ofthe site is shown in Skinner's section book, simply as "the Pliocene deposits north of Santa Fe, New vol. 1, p. 145, now in the Frick Collection, Department of Mexico." Their conclusions were based on their studies of Vertebrate Paleontology, the American Museum of the oreodonts. Natural History). Faunal List of the Santa Fe Group Tesuque Formation

Testudo undata Cope, 1875a Testudininac, Williams, 1950'1 Testudo klettiana Cope, 1875a Testudininae, Williams, 1950 Cathartes umbrosus Cope, 1874a Palaeoborus unzbrosus (Cope), Brodkorb, 1964 Panolax sanctaqfidei Cope, 1874a Panolax sanctaejdei Cope, Dawson, 1958 SteneoJber pansus Cope, 1874a Monosaulax panrus (Cope), Stirton, 1935 Hesperontys loxodon Cope, 1874a Copemys loxodoiz (Cope), Albert E. Wood, 1936 Canis wheelerianus Cope, 1877 Aelurodon wheelerianus (Cope), Matthew in Osborn and Matthew, 1909 Canis ursinus Cope, 1875a Hemicyon ursinus (Cope), Frick, 1926a Marles na~nbianusCope, 1874a Martinogale nanzbiana (Cope), Hall, 1930 Alastodon productus Cope, 1874a Serridentinw flroductus (Cope), Osborn, 1936 Trilophodon pojoaquensis Osborn, 1936 Megabelodon cruziewis (Frick), Osborn, 1936 Ocalientinus ojocaliensis Frick, 1933 Trobelodon taoensis Frick, 1933 Trilophodon (Tatabelodon) riograndensis (Frick), Osborn, 1936 Mega6elodon.joraki (Frick), Osborn, 1936~ Cf. Aphelops meridianus Leidy, Cope, 1875a Cf. Aphelops meridianus Leidy, Cope, 1875a Apllelops jemezanw Cope, 1875b Aphelops jenlezanus Cope, Matthew, 1932 Hiplotherium calamarium Cope, 1875b Merychippus calamarius (Cope), Osborn, 19 18 Hipbotherium speciosum (Leidy), figured and Hipparion sanfondetuis Frick, 1933d referred by Cope, 1877 Cf. Procamelus occidentalis Leidy, Cope, 1875b Cf. Procamelus occidentalis L.eidy, Cope, 187513 Pliauchenia humphresiana Cope, 1875b Pliauchenia humphresiana Cope, Matthew in Osborn and Matthew, 1909 Pliauchenia vulcaizorunt Cope, 1875b Pliauchenia vulcanorum Cope, 1875b Cosoryx ramosus Cope, 1874a Ramoceros ramosus (Cope), Frick, 1937 Dicrocertu necatus, Cope, 187513 A4eryceros (Submeryceros) crucianus Frick, 1937 Cosoryx teres Cope, 1874a Cranioceras teres (Cope), Frick, 1937 Dicrocerus trilateralis Cope, 1877 Cameliclae, indet. Frick, 1937e Dicrocerus tehuanus Cope, 1877f ? TABLE 3--((;bt~Linued) Faunal List of thc Santa Fc Group Tcs~~qi~c.Formation

Dicrocerus gemmifey Cope, 187413 ( ?) Longiroslromeryx blicki Frick, 1937 Lotzgirostronzeryx novotnexicanus Frick, 1937 Blastotneryx fratzcesca Frick, 1937 Blastotneryx francescila Frick, 1937 Ranzoceros ranzosus quadralus Frick, 1937 Ranzoceros (Paramoceros) tnarlltae Frick, 1937 Ramoceros (Paratnoceros) fialtnatus Frick, 1937 Cosoryx (Subcosoryx) cerroetlsis Frick, 1937 Cosoryx i@o~zsettsisFrick, 1937 Meyceros major Frick, 1937 Meryceros crucensis Frick, 1937 Osbornoceros osborni Frick, I937 Plioceros blicki Frick, 1937 Pseudoceras klausi Frick, 1937 Rakonylus raki Frick, 1!)37 Uslatoc/roertrs skitazcri santacrrr,-et1si.r Schul tz ancl Falkenbach, 1941 Uraclycrtrs rusticus riograt1detl.si.r Schultz ant1 Falkcnbach, 1968 Braclycrtts vai~gllrlirioosoalsis Schultz ant1 Falkenbach, 1!)G8 Ustatoc/ioerus ccllifornictc.~raki Srhultz ant1 Falkcnbach, 1!)41 Us~nioclroer.lcrnler1iu.r nol~omc.viccn~zt.r(I:ric.k), Schi~ltz and Falkcnbach, 1941 Ustatochoe~.usprofcctus cs~1rrtco1etrsi.rSt:hullz ant1 Falkcnbach, 1941

-- -- (&Authorityfor current identification is given in each example, but it lnay ~lotrepresent the latest consensus. 'I'll~p~~rpc~s[. 111'this ti~l~leis to tlirtsrt iltt~t~tio~~to ~IN. various taxa described Dom the type locality of the Santa Fe Group; it is not withi11 tl~cscope of this paper to pass 011 tltc \.ali(lity of any ofthe taxn citt.tl. 'I'hc strati- graphic positions of Cope's specimens are shown as interpreted kom a personal knowlcclgc of the stratigraphy of thr I)c.cls in wllicl~(:ope was collr.c,tir~g,as rccorrlrtl in the daily entry in his 1874 field notcl~ook,further supported IJ~the tnatcl~ingof many of tl~cCope spccitner~sill tllc. str:ltigr:ipl~ic.;~llyc.or~trollt.tl Itrick collrc~tion. oWilliams (1950, p. 30) listed both Tesltido rolda[a and Tcslttdo kletliar~awith an asterisk in his chcck list cjf Necv M'nrld tvstutlincs ailti sti])l~~~sc~tltc*stutli~lc.s to i~ltlicatc- that the material was so fragmentary as pro11al)ly to I)e indetertninal)lc. rosborn (1936, p. 738). dFrick (1933, p. 549) cited the maxilla figured and clescribrtl by Colic (1877, pl. 75) as the type of I-li/)/~nrio~r.~o~!lb~r~/err.\i.\. sFrick (1937, p. 315), "Dicrocerus Lrilalcralis Copt*, in the ramel fragment at Irasl, is pro11al)ly of the C:atnc~litlac." /I:rick (1937, 11. 315), "Thc actual affinity is yrt to 11c determined in: M. f~lrrrn~l~r.r(C:opca), 11177, fro111NI-~q M(.xico, t)'~)(.rcalrlr.s(.ll(illg itti ~IIIIII~~III.~.i~~

THEGEOLOGIC HISTORY of the Santa Fe Basin is the Otowi and Cerros del Rio lava flows in a record of a complex series of lithic and faunal Quaternary time. events. The Santa Fe area may be one of the few Several temporary base-levels were estab- places where sedimentation was continuous lished for the ancestral Rio Grande by lava during the transition from Miocene to Pliocene flows, and extensive erosion surfaces were cut in time, as North American Miocene and Pliocene the area. but were it not for the intricate ~ost- are currently understood.1 A sharp faunal break Santa Fe deformation the exposures in the type is difficult to recognize at any horizon, although area would be inadequate to give an integrated the study of certain groups of animals, notably concept of the stratigraphy. horses and merycodonts, suggests that such The study of the geologic history of the Santa faunal breaks may actually exist at one or more Fe Basin must be approached from several points in the section. The base of the Pojoaque angles. Of primary importance is the necessity Member of the Tesuaue Formation can be of determining, as nearly as possible, the series stated to be the horizon below which the fossils of events that resulted in the forming of the are mostly Miocene in aspect and are essentially original Santa Fe Basin. A distinction should be equivalent to, or older than, those of the Lower drawn between the Rio Grande depression and Snake Creek quarries of western Nebraska, the original Santa Fe Basin. The concept of the those of the Barstow, California, Green Hills and Rio Grande depression is currently that of a Second Division, and above which the fossils are structural basin outlined bv features mostlv mostly Pliocene in the sense of being equivalent associated with the post-Santa Fe deformation. to fossils from the Valentine and Ash Hollow Actually the major features of the Rio Grande formations of the Great Plains. depression were outlined in at least two ~eriods Lee (1907) and, later, Bryan (1938, p. 197) of 'deformation, and the post-Santa Fe deforma- described a series of structural basins extending" tion merely followed closely that of the initial along the Rio Grande from the point where it faulted basin. Depositional limits of the original enters the San Luis Valley near Monte Vista, Santa Fe Basin were much broader, however, Colorado, to Fort Quitman, Texas. To this than the more recently deformed and down- group of basins Bryan applied the excellent faulted Rio Grande structural depression. descriptive term Rio Grande depression. Not all Kelley (1956, p. 110) has subdivided and re- structural basins of the Rio Grande de~ression defined a part ofthe Rio Grande depression, and afford good opportunities for study of the sedi- his designation of the salient features of the type ments filling them-many of them because they and adjacent areas should be helpful for future are covered mostlv with later detrital sediments. research. The wider lateral extent of the deposits and others because they have not been subjected of the Santa Fe group is indicated by several to extensive and rapid erosion. Fortunately, the hundred feet of Santa Fe sediments that are best-exposed and thickest section of the ~antaFe preserved in the downthrown blocks that form Group crops out in the type area north of Santa the footwalls of some of the faults bounding the Fe, New Mexico. The magnificent badlands of Rio Grande depression. Erosion has stripped the that area have resulted from an interaction of Santa Fe beds from the upthrown blocks. In the many geologic agencies over a long period of Abiquiu area Santa Fe beds are preserved in time, but probably the most significant events footwall blocks, and along the Lobato flows in that shaped the pattern of the present topo- the Rio del Oso-Abiquiu locality (fig. 2) deposits graphy were the post-Santa Fe deformation and of the Santa Fe Group have been preserved from the successive damming of the Rio Grande by erosion by high-altitude basalt flows. South of Los Alamos, part of the Pojoaque Member is exposed west of the Pajarito fault, which drops 'On page 9 of this report, and in figure 10, an attempt is made to clarify our use of various time terms. Our intent the Bandelier Tuff down along the east base of is to use terms that are amenable to adjustments regardless the Jemez Mountains. The clearest examples of of future shifts in concepts of age boundaries. these relations can be seen along the Canyada de 1971 GALUSHA AND BLICK: S.4NTA FE GROUP 113 las Milpas fault at the south end of the Sierra the Baca Formation (Wilpolt et al., 1946). The Nacimiento, and along the faults forming the Baca Formation has not been identified outside western border of the Albuquerque-Belen basin, the Socorro region, and Wilpolt et al. (1946) which is a part of the depression. Projection of noted the lithologic similarity of the Baca to the the surfaces of the great alluvial fans that once Galisteo Formation and suggested that the two filled the Espanola Valley would extend far to formations may be correlative. If the identifica- the east of any known exposures of the deposits tion of the brontothere tooth is correct, the Baca of the Santa Fe Group. Formation conceivably may contain a medial Rocks of Precambrian age crop out in the core Eocene fauna. of the Sangre de Cristo Range, and along the Renick (1931, p. 57) referred beds at the east periphery of the type area of the Santa Fe south end of the Sierra Nacimiento to the lower Group. Just (1937) described several Pre- Wasatch, but Frick Laboratory field parties cambrian formations in the Picuris, Ojo Caliente, recovered Duchesnean fossils from the supposed and Petaca mining districts. Montgomery lower Wasatch beds, and therefore the deposits (1953), in his report on the Precambrian geology are now correlated with the Galisteo Formation. of the Picuris Range, expanded some of Just's At the south end of the Sierra Nacimiento the formations and redefined others. These rocks Galisteo rocks are exposed only between the underlie the Picuris and Ortega Mountains, and Jemez fault on the east and the Sierrita fault a fragments derived from them can be recognized mile or two to the west. They lie unconformably readily in deposits of the Santa Fe Group, on rocks referred by Renich (1931, p. 53) to the which commonly contain a high proportion of Puerco-Torrejon (=Nacimiento) formations.1 Precambrian quartzite. The Sangre de Cristo The Sierrita fault, according to Renick (p. 74), Range has supplied most of the sediments mak- is a part of the Sierra Nacimiento overthrust ing up the Santa Fe Group south of Black Mesa zone. The age relations of the formations in- to Santa Fe Creek. Granitic rocks at the south volved at the south end of the Sierrita fault may end of the Sangre de Cristo Range near Santa prove to be important in dating the Sierra Fe contain much red feldspar in contrast to the Nacimiento overthrust. The drab "Puerco- light, flesh-colored feldspar of the rocks farther Torrejon" beds were deformed by the Sierrita north in the range. Lenses of gravel composed fault, and the Galisteo equivalent was apparent- primarily of red granite that have been observed ly the last formation deposited in the locality in the Pojoaque Member in the West Cuya- preceding the deformation, tending to date the munque and Tesuque collecting localities indi- movement as occurring in some part of the cate that parts of the sediments in those local- Oligocene. Deposits in this locality at the top of ities were derived from fans built along the south the Galisteo Formation equivalent consisting of end of the range. Interfan areas can be recogniz- greenish clay, sand, silt, and some bentonite ed, and intensive sedimentation studies might may conceivably represent the so-far unrecog- explain some of the anomalies of lithology that nized New Mexico equivalent of the Oligocene haveled previous investigators to state that Santa formations of the Great Plains. The Zia Sand Fe beds are discontinuous and that key strata do Formation (Galusha, 1966), with its faunal not exist in the area. equivalent of the Harrison Formation of late The early Tertiary geologic history of the Rio Arikareean to late Hemingfordian age, lies un- Grande depression is based on fragmentary conformably on the deposits at the top of the records. No formations have been Galisteo equivalent and extends without inter- recognized definitely in the depression, with the ruption across the trace of Sierrita fault as far possible exception of the upper part of the west as the Canyada de las Milpas fault. McRae Formation (Kelley and Silver, 1952, The Canyada de las Milpas fault was a part p. 1 19), despite the fact that beds of that epoch not of the Nacimiento overthrust, but of the were extensively deposited in the San Juan post-Santa Fe deformation. Beds of the "Puerco- Basin in northwestern New Mexico. No deposits Torrejon" were deformed by the Canyada de of early Eocene ( or Bridgerian) age las Milpas fault, but a Galisteo Formation have been described in the Rio Grande depres- 'Additional work in these sediments has produced sion, although Gardner collected a mammal hadrosaurian ossified tendons that suggest Cretaceous age tooth that Gidley identified as Palaeosyops from for part or perhaps all of these deposits. 114 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY L'OL. 144 equivalent does not crop out along the fault, and (Harrison Formation equivalent) to late Hem- hence probably was absent from the vicinity. In ingfordian (Sheep Creek equivalent). Fossils the downthrown block along the east side of the from the Kiva Quarry, which occurs in an iso- fault about 1000 feet of sediments are preserved lated, local, valley fill south of Jemez Creek, that are referable to the following three forma- indicate that sediments equivalent to the Sheep tions: (1) a part of the Zia Sand Formation, Creek Formation may be present. South of (2) an equivalent of part of the Pojoaque Mem- Jemez Creek the Tesuque Formation uncon- ber of the Tesuque Formation, and (3) a thin formably overlies the Zia Sand Formation. Here wedge of the Upper Buff of Bryan and McCann. it should be emphasized again that no beds in None of these formations crops out west of the the type locality of the Santa Fe Group have Canyada de las Milpas fault, yet it is obvious produced fossils equivalent in age to those from that the original thickness of the Zia Sand and the Zia Sand. beds of the Santa Fe Group that extended west Analysis of the stratigraphy of the formations of the fault must have exceeded 1000 feet. The in the type area of the Santa Fe Group clearly approximate thickness and extent, however, can points to the inadequacy of the known deposits only be inferred. Mesa Prieta, 15 miles to the to provide a basis for systematic interpretation west, is capped by Quaternary basalt that lies of the earlier part of the geologic history of the directly on Cretaceous rocks, and, if the Santa Santa Fe Basin. For example, formations laid Fe ~rdu~ever extended so far west, no evidence down during the later part of the late Cre- can be adduced to prove it. taceous, the Paleocene, and early to medial The Zia Sand Formation comprises about Eocene times are inadequately known or have 1000 feet of predominantly quartz sand. The not been identified positively in the Rio Grande formation accumulated along the southeast end depression. In the and other of the Sierra Nacimiento; equivalent deposits adjacent areas these formations may be thick have not been recognized elsewhere in the Santa and extensive. Fe region or reported from New Mexico. The Stearns (1943, p. 315) discussed the pre- Zia Sand originated as dominantly eolian Galisteo unconformity and the general geologic deposits, as shown by eolian cross-bedding, and history of the Galisteo Formation. The deposi- bythe frosted, rounded, sand grains comprising tion of the Galisteo Formation was terminated most of the deposits. A few thin, fresh-water, by regional volcanism. During the period of limestone layers occur in the section, and these volcanism several formations were deposited; crop out in discontinuous belts, commonly in their relations are discussed at length below. conjunction with sand and silt strata showing The accumulation of the Abiquiu Tuff, the few eolian characteristics. These features are Picuris Tuff, and the Espinaso Volcanics marked interpreted as indicative of local leveling among a time ofwidespread volcanic activity in the type low dunes. The low dune areas did not receive area of the Santa Fe Group. Only three possibly direct sedimentation from alluvial fans, as shown earlier occurrences of Tertiary volcanic rocks by the absence of channels containing gravels have been reported from the Rio Grande and by the absence of original structures com- depression. Stearns (1943, p. 307) cited a few monly regarded as of alluvial-fan derivation. localities in which thin beds of water-laid tuff The limestone and other noneolian strata might crop out in the upper part of the Galisteo Forma- well have accumulated in shallow interdune tion. The other formations were reported from valleys similar to those in some areas of the Sand the Socorro area, which is about 150 miles south Hills of Nebraska. Worm borings, casts, and of the type area. Winchester (1920, p. 9) des- trails have been noted on many of these lime- cribed the Datil Formation. Later, Wilpolt et al. stones. The sandy strata immediately underlying (1946) restricted the Datil to the upper part of the limestones are commonly green in color. Winchester's section, named the lower part the Toward the top of the Zia Sand are bands of Baca Formation, and suggested that the Baca yellowish sand and silt or reddish sand and silt Formation may be equivalent to the Galisteo. If which alternate with the pinkish gray eolian so, then the Datil Formation may be correlative sand. Fossils from horizons high in the section also with the Abiquiu Tuff, Picuris Tuff, and indicate that the time period covered by the Zia Espinaso Volcanics. We believe that the Abiquiu Sand Formation extends from late Arikareean Tuff was derived from volcanic centers north or 15171 G.ILUSH.3 .ISD BLICK: S.lNT.3 FE GROCP 115 northeast of the type area, probably in the San easily eroded slopes to distances far beyond that Juan region of Colorado. The other formations reached by the flows of lava or the unwashed are believed to be accumulations from local ejecta . . . The finer gravel and sand were vents. washed scores of miles southward into the region Denny (1940a, p. 77) described the Popotosa adjoining Santa Fe and Espanola, where they Formation in the San Acacia area, which lies at form the lower part of the Santa Fe Formation." the north end of the larger, more inclusive, The beds that they cite as lower Santa Fe, how- Socorro basin. The Popotosa, according to ever, belong to both the Chama-el rito Member Denny, consists of debris eroded from volcanic of the Tesuque Formation and to the Abiquiu rocks, and a small amount of tuff. He stated that Tuff-two formations separated by a hiatus the Popotosa Formations rests unconformably covering a period of several million years. The on volcanic rocks of Miocene(?) age, and fur- possibility is good that both the Conejos Forma- ther stated that locally the two formations are tion and the Abiquiu Tuff will prove to be of conformable. In view of the general uncertainty Oligocene age. The lenses of volcanic pebbles in of the age of the Popotosa Formation, subsequent the Chama-el rito Member were obviously re- work might well investigate a hypothesis that worked from the Abiauiu Tuff or were derived the Popotosa may belong in the general Abiquiu or reworked from volcanic beds northeast and Tuff-Picuris Tuff-Espinaso Volcanic period of north of the area. Many of the volcanic pebble volcanism. Denny (1940a, p. 81) tentatively lenses are directly associated with early Pliocene ascribed a late Miocene age to the Popotosa. fossils in the Ojo Caliente, Chama-el rito, and The formation is more likely to be correlative Rio del Oso-Abiquiu collecting localities (fig. 2), with Oligocene deposits than with the late Mio- and consequently the implications are that the cene, although it must be admitted that, as yet, historv of the sedimentation is much more com- no deposits have been found in New Mexico that plex than the mere identification of Conejos contain a fauna that represents a time-unit rocks in the Santa Fe Group would indicate. equivalent to that assigned to the Gering and The start of de~ositionof the formations that Monroe Creek formations (Arikareean) of the comprise the Santa Fe Group, as restricted in Great Plains section. The Popotosa is composed this report, marks a change in the record of the mainly of debris from volcanic rocks and is not geologic history of the Rio Grande depression likely to have been formed contemporaneously in the type area of the Santa Fe Group. Sedi- with the Zia Sand Formation or with the NambC mentation was favorable for the fossilization of Member of the Tesuque Formation. A fossil mammalian remains for the first time on a scale collection is needed from the Popotosa and other sufficient to permit extensive collections to be formations of doubtful correlation in the Rio made. Also for the first time large areas of Grande depression. Absolute dating by radio- fossiliferous strata were preserved to be later metric methods should be made of these forma- exposed as the major collecting areas. tions, and a careful petrographic, petrologic, It is clear that many of the beds in the type stratigraphic, and paleontologic study of the area east of the Rio Grande were built by allu- Abiquiu Tuff-Picuris Tuff-Espinaso Volcanics, vial fans issuing from the Sangre de Cristo and the Popotosa Formation would be a highly Range, but it is equally clear from faunal and desirable contribution to the geology of the lithologic studies of the beds west and north of general area. the Rio Grande in the same area that volcanic Atwood and Mather (1932, p. 98) traced sand rocks supplied much of the sediments. These and gravel derived from andesite flows and relations are discussed at length in this report breccia of the Conejos Formation, which is ex- particularly in the section on the Chama-el rito posed principally in the San Juan Mountains of Member of the Tesuque Formation. Colorado, southward to the type area of the Any correlations of the beds of the Santa Fe Santa Fe Group [some of the beds correlated by Group based on the presence of tuffaceous sedi- them with the Conejos Formation were included ments, or beds of ash, or bentonite, or eruptive by Harold T. U. Smith (1938, p. 958) in his rocks, must take into consideration the fact that Abiquiu Tuff]. They stated (1932, p. 19): volcanism in the area was not confined to any "Streams descending the flanks of the Conejos one or ti on of the section. but occurred in all volcanoes washed debris derived from their members and formations from late Eocene to 116 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY VOL. 144 and including part of the Pleistocene. The con- an opportunity for correlations of the fault clusion is inescapable that these correlations blocks both along and across the strike and there- must be made cautiously and be fully supported fore are admirably adapted to sedimentation by paleontologic evidence or by stratigraphic studies. Field evidence suggests that, by the start relationships to beds that have been dated by of Skull Ridge time, the sediments had built up fossils, or by radiometric methods, or by both. sufficiently so that they eventually buried the The stratigraphy of the Nambt Member of front range of crystalline hills. the Tesuque Formation is discussed in this paper, The deposits of the Red Wall (fig. 15B), in the and the nature of the contacts of the Nambt lower part of the Skull Ridge Member, are Member with the crystalline rocks of the Sangre somewhat more homogeneous and finer-grained de Cristo Range, and with the Picuris Tuff, is than is usual in the rest of the member; only a described. For the most part, the conglomeratic few gravel lenses crop out, and these are north sandstone and sand portion of the Nambt was of White Operation Wash. A distinct change in deposited on piedmont alluvial fans on which sedimentation takes place at the horizon of the the gradient was not unusually steep; in fact, No. 2 White Ash, which caps the Red Wall much of the Nambt as exposed appears to have cliffs, and this change continues to the horizon developed on lateral distributaries ofalluvial fans about 40 feet above No. 3 White Ash stratum. and in interfan basins. Some of the crystalline Several channel-like deposits occur in the hills north of Nambt Creek are high and con- Tesuque Formation, and several different hypo- tinuous, and the sediments of the Nambt Mem- theses could be explored to explain them. These ber banked against them are best explained by channel-like deposits appear to have had their the hypothesis of deposition from alluvial fans origin as distributaries of alluvial fans; the that swept around the ends of the crystalline abrupt changes in lithology at some horizons hills on the north; or crossed them in valleys can be interpreted as the result of breaches in toward the south, and then sent distributaries the natural levees on the larger alluvial fans. laterally parallel to the range of hills into the Braiding, filling, and damming of the main basins between the fans, here called interfan streams on the fan could cause diversion and basins. start local trenching of the levees and parts of The fossiliferous portion of the Nambt Mem- the main fan. The extraordinary supply of sedi- ber indicates a period of deposition on slopes of ments therebv obtained would differ in texture lower gradient than that of the conglomeratic from those deposited under more normal cir- sandstone and sand portion. The relatively fine cumstances. These postulates permit an explana- sediments of the fossiliferous part of the section tion of local of low relief that are occur marginally along lenses of conglomeratic observed at the base of some of the channel-like sandstone and conglomerate. Beds of bentonitic deposits. The intraformational breccia in some clay of considerable lateral extent show that a of the channels consists of angular blocks of fine- relatively smooth depositional surface had been grained silt or silty sand that could not have built in the area southwest of Chimayo. The been transported more than a few hundred bentonite and ashy strata testify to volcanism yards at most before redeposition. Each of these during the period of accumulation of the Nambt, channel-like beds is overlain by deposits that but no direct evidence of proximity of the erup- gradually attain sedimentation characteristics tive center is available. A petrologic comparison that are similar to those underlying the channel. of volcanic ashes of the Nambt Member with Perhaps the best example of this type of deposit those preserved in the Sheep Creek Formation is the channel above Ash F in the Skull Ridge of the Great Plains would be of great value. The Member (fig. 17). NambC and Skull Ridge members of the Tesuque During Valentinian time the Pojoaque Mem- Formation may contain ash strata correlative ber of the Tesuque Formation began to receive with those of the Sheep Creek-Snake Creek beds coarser sediments from the granitic rocks of the of Nebraska. Sangre de Cristo Range, and a thick section of Evidence of the presence and significance of a irregular lenses of gravel in coarse sand or con- series of ash beds in the Tesuque Formation is glomeratic sand was built up. These deposits are presented in the discussion of the stratigraphy of of alluvial fan origin and comprise: (1) a large the Skull Ridge Member. These ash beds afford part of the great Picuris re-entrant fan north of 1971 GALUSH.1 4ND BLICK: SANTA FE GROUP 117 the Santa Cruz River; (2) a few hundred feet of Caliente collecting localities (fig. 2) to and the gravels that form the higher parts of the across the Rio Grande near Embudo into the Pojoaque Bluffs; and (3) deposits west of West Dixon sub-basin south of the westward end of Cuyamunque Wash (United States Geological the Picuris Prong. Samples of sand collected Survey: Arroyo Jacona), south of Pojoaque from the Ojo Caliente Sandstone in the above Creek, where another large area of gravel lenses localities show very little variation in the size of in sand occurs (but these were formed mostly by the grains. It is difficult to correlate these ob- fans with sources farther south in the range). servations with the explanation given by Bryan The cause of the increase in competency of the (1938, p. 207) that a large river was being streams on the alluvial fans is unknown, but that approached and the wind-blown sand indicated increase may have resulted from a marked in- the probable border of a river flat. Particularly crease in the rainfall of the time; it may have are the facts out of adjustment with Bryan's accompanied differential uplift of the source postulate that a large Pliocene perennial river areas of the range; it may have resulted from occupied the position of what is now Chicoma downwarp of the basin area; or the alluvial fans Peak (altitude 11,507 feet) and Cerro Pedernal may have simply built up their lower ends and (altitude 9867 feet). then were able to carry larger particles farther The Ojo Caliente Sandstone was obviously basinward. The hypothesis of downwarp has deposited in response to special environmental been explored by several investigators, but con- conditions. Local aridity that continued for a clusive evidence for downwarp during the depo- long period of time, perhaps thousands or even sition of the Santa Fe beds has never been hundreds of thousands of years, would seem to presented. The hypothesis of increased rainfall be a logical prerequisite for the accumulation of has little support when consideration is given to several hundred feet of essentially eolian sedi- the 450 feet of Ojo Caliente Sandstone that ments. Strong and special wind conditions, per- formed mainly by eolian action in the upper haps directly associated with the size and shape part of the Tesuque Formation. These eolian of adjacent mountain areas during a particular deposits apparently overrode and overwhelmed part of the Tertiary, must be another require- the alluvial fans issuing from the volcanic high- ment. Still other unrecognized conditions must lands to the north. The alluvial fans were di- have existed to cause such a profound change in verted to other regions, for no outcrops of vol- the sedimentary environment. canic pebbles characteristic of the Chama-el rito Coincident with volcanic disturbances of Member have been observed in the type area of Hemphillian time, deposition was resumed in the the Santa Fe Group in beds later than the lower center of the depression in the type area of the part of the Ojo Caliente Sandstone, indicating Santa Fe Group. The Chamita Formation was that the Ojo Caliente represents a time of laid down, of which a maximum of about 750 change in the major sources of the sediments feet of deposits have been preserved from later deposited in the type area; the San Juan Moun- erosion. On the north side of Black Mesa tain region was no longer a provenance. (fig. 27C) the Chamita Formation overlies the The widespread and thick Ojo Caliente Sand- Ojo Caliente Sandstone. Wherever it can be stone probably was an isolated dune-sand area observed, the contact at the base of the Chamita similar to that of the Great Sand Dune National Formation with the upper beds of the Ojo Monument in the San Luis Valley of Colorado. Caliente Sandstone is interpreted as the result of We question the interpretation of Bryan (1938, leveling among the dunes or sandy areas at the p. 207), and of Harold T. U. Smith (1938, top of the Ojo Caliente, heralding the start of p. 959), that the eolian sand of the Santa Fe new and vigorous deposition that resulted ulti- beds (Ojo Caliente Sandstone) were of flood- mately in the accumulation of the Chamita plain dune or river-side dune origin. It is diffi- Formation. cult to reconcile their hypothesis with the fact Eventually the deposition of the Chamita that deposits of the Ojo Caliente Sandstone can Formation ended, possibly as a result of the be traced for many miles from the Three Sand post-Santa Fe deformation. Basins that had Hills Wash (United States Geological Survey: been separated and probably filling independ- Canon la Madera) in the Rio del Oso-Abiquiu ently with sediments were at last integrated by a collecting locality northeastward across the Ojo through drainage system. The ancestral Rio 118 BULLETIN AMER1C.W MUSEUM OF NATUR.4L HISTORY VOL. 144 Grande thus formed had tremendous erosive Mexico, remains to be determined, but Black power and removed several cubic miles of sedi- Mesa appears to be a valley tongue belonging ments in the Espanola Valley and adjacent to the general Taos Plateau sequence. This areas. Remnants of erosion surfaces cut on rock would indicate at least a Blancan (Evernden platforms along the mountain fronts or preserved et al., 1964, p. 164) age for the Taos lava and, by beneath high-altitude basalt flows (fig. 30), such correlation, at least a Blancan age for the Black as Black Mesa, Lobato flows, and Cerro de las Mesa lava and the cobbles that underlie it. Minas (United States Geological Survey: Sierra Magnetic reversal studies coupled with potas- Negra), when projected attest to a probable sium-argon dating of Black Mesa, and other thickness for the original deposits in the area. high level basalts, such as the Lobato flows, Even such a projection may not be a maximum Cerros de las Minas, and Cerro Pedernal, would approximation, because each of these erosion provide a valuable contribution to the geologic surfaces represents a temporary base-level of and geomorphic history of the Santa Fe Basin. unknown duration during which sediments were If such studies were extended to include the being removed. Cerros del Rio, Otowi lava flows, Mesa de 10s No deposits of perennial rivers have been Ortizes, and Round Mountain ( Tunyo pin"),even observed either in the Tesuque Formation or in greater results could be expected. the Chamita Formation; therefore the ancestral The present Rio Grande has cut a gorge about Rio Grande is post-Santa Fe Group in age. 1000 feet deep (Lambert, 1966, p. 43) in the Bryan (1938, p. 207) reported the occurrence of southern end of the Taos Plateau; the river perennial river gravels interbedded in the Santa leaves the Rio Grande Canyon near the town of Fe Formation at the north end of White Rock Velarde, New Mexico, and flows along the Canyon. Denny (1940b, p. 682) figured an southeastern flank of Black Mesa for a distance exposure west of the old Buckman Bridge site. of about 10 miles. Here, also, more than 1000 These are regarded by us as associated with the feet of sediments have been eroded. and an erosion period immediately antedating the extremely complex series of erosion surfaces and deposition of the Puyt Conglomerate and the terraces have been cut in the type area of the Otowi lava flows. Santa Fe Group and some constructional The history of the Santa Fe region following deposits preserved thereon (the effects on the the post-Santa Fe deformation is extremely geomorphology and the geology are discussed in difficult to decipher, and bits and pieces of this report under the heading Erosion Surfaces). information must be fitted together from many All these erosion surfaces were cut following the sources to attempt an explanation. The high- post-Santa Fe deformation, and probably many altitude basalts provide evidence that volcanism of them can be correlated with important was an important factor in events that brought Pleistocene events. deposition to an end in the type area of the A volcanic pile had been building in the Santa Fe Group. The 15- to 30-foot-thick bed of general area of the present Jemez (Valles) cleanly washed, well-sorted, mainly ovoid- Mountains since the post-Santa Fe deformation, shaped pebbles and cobbles that underlies the but apparently this did not interfere greatly basalt capping Black Mesa (fig. 38) shows that a with the removal of a large volume of sediments large perennial river had been established at of the Santa Fe Group from the Espanola Valley that point and that a probable lava tongue by the time the Puyt Conglomerate was de- followed its course. posited. Perennial gravels observed at the base Ozima etal. (1967, pp. 2618,2619) have dated of the Puyt at several sites between Santa Clara by potassium-argon methods a series of succes- Canyon and Guaje Canyon indicate that a large sive lava flows exposed in the Rio Grande gorge river was involved in excavating the valley into near Taos, New Mexico. The dating was a part which the Puyt was deposited. of their study of the paleomagnetism of the area ; Increased volcanic activity in the Jemez area it showed that the base of the upper normal caused impounding of the drainage system along polarity sequence is about 3.7 million years old. the edge of the rapidly building alluvial fan of The exact relation of this part of the lava PuyP gravel, thus forming long narrow sequence to the lava capping Black Mesa from into which some sediments from the adjacent .8 .8 Embudo to the vicinity of Chamita, New Santa Fe beds were reworked. These and other 1971 GALUSHA AND BLICK: SANTA FE GROUP 119 reworked sediments from the Santa Fe Group known as Valle Grande. The deposition easily can be mistaken for Santa Fe beds because of the Bandelier Tuff appears to have been the they are similar in appearance. This similarity culmination of volcanic activity in the Jemez has led to a variety of interpretations of inter- Mountains, for younger volcanic rocks by com- tonguing and interfingering, by Griggs (1964, parison are small in area and in volume. Co- p. 27) of Santa Fe beds and Puyt Conglomerate, incident with the collapse of the caldera, the and by Spiegel and Baldwin (1963, pp. 47, 50, Pajarito fault along the east shoulder of the 53, 59) of the Tesuque Formation, Ancha For- Jemez Mountains dropped the east side down, mation, basalt tuffs, and Puyt Conglomerate. displacing the Bandelier Tuff. Lava flows eventually blocked these lakes, and The history of the post-Bandelier Tuff of the one unit of these flows was observed intercalated Santa Fe Basin continued to be primarily one of between Puyt Conglomerate and the thick over- degradation, in which successive erosion sur- lying Bandelier Tuff. faces were cut. Some of these erosion surfaces are The Bandelier Tuff represents a period of surmounted by remnants of constructional intense volcanic activity in the Jemez Moun- deposits that testify to intermittent periods of tains in which hot turbulent ash flows (Ross, aggradation during the Pleistocene. Smith, and Bailey, 1961, p. 141) erupted along A surface of relief almost as intricate as that of the crest of the Valles (Jemez) Range and spread today had been eroded in the Espanola Valley as coalescing fans on surrounding slopes. These in late Pleistocene time, and on this was de- ash-flow tuffs occur as welded tuffs, nonwelded posited the loess-like Espanola Formation. Evi- tuffs, and pumice units. Extrusion of great dence for de~ositionin the Santa Fe Basin since volumes of free-fall pumice and volcanic ash that time has been negligible, consisting mostly must have accompanied these ash-flow erup- of terraces or alluvial plains along drainage tions, which immediately preceded the collapse basins that reflect relatively long stands at tem- of the roof of the chamber to form the porary base-levels.

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western Sandoval County, New Mexico. 1968. The phylogeny of the oreodonts. Ibid., vol. U. S. Geol. Surv. Water-Supply Paper 620, 139, pp. 1498, figs. 1-56, tables 1-19, vi+ 117 pp., figs. 1-3, pls. 1-10, 1 map. charts 1-23. ROBINSON,PETER SCHULTZ,C. BERTRAND,AND THOMPSONM. STOUT 1957. Age of Galisteo Formation, Santa Fe 196 1. Field conference on the Tertiary and Pleis- County, New Mexico. Bull. her. Assoc. tocene of western Nebraska. In Guide Book Petrol. Geol., vol. 41, no. 4, p. 757. for the Ninth Field Conference of the Ross, CLARENCES. Society of Vertebrate Paleontology. Special 1925. Beds of volcanic material as key horizons. Publ. Univ. Nebraska State Mus., no. 2, Bull. Amer. Assoc. Petrol. Geol., vol. 9, pp. 1-55, figs. 147. no. 2, pp. 341-343. SIEMS,PETER L. 1931. The Valles Mountains volcanic center of 1964. Correlation of Tertiary strata in mountain New Mexico. [Abstract.] Trans. Amer. basins, southern Colorado and northern Geophys. Union, 12th Ann. Meeting, vol. New Mexico. Mountain Geol., vol. 1, no. 3, 12-13, pp. 185-186. pp. 161-180, fig. 1, tables 1-5. Ross, CLARENCES., AND STERLINGB. HENDRICKS SIMPSON,GEORGE G. 1945. Minerals of the montmorillonite group. 1925. Reconnaissance of part of the Santa Fe Their origin and relation to soils and clay. Formation. [Abstract.] Bull. Geol. Soc. U. S. Geol. SUN. Prof. Paper 205-B, pp. 23- her., vol. 36, p. 230. 79, figs. 5-9, pls. 1-8, tables 1-20. 1933. Glossary and correlation charts of the North American Tertiary mammal-bearing Ross, CLARENCES., AND ROBERTL. SMITH formations. Bull. her. Mus. Nat. Hist., 1961. Ash-flow tuffs: their origin, geologic rela- vol. 67, pp. 79-12 I, figs. 1-8. tions, and identification. U.S. Geol. Surv. 1948. The Eocene of the San Juan Basin, New Prof. Paper 366, vi+81 pp., figs. 1-98. Mexico. Amer. Jour. Sci., vol. 246, pp. 257- Ross, CLARENCES., ROBERTL. SMITH,AND ROYA. 282, figs. 1-2. BAILEY SKINNER,MORRIS F., SHIRLEYM. SKINNER,AND 196 1. Outline of the geology of the Jemez Moun- RAYMONDJ. GOORIS tains, New Mexico. Guidebook of the Albu- 1968. Cenozoic rocks and faunas of Turtle Butte, querque country, New Mexico, 12th Field south-central . Bull. Amer. Conf., New Mexico Geol. Soc., pp. 139- Mus. Nat. Hist., vol. 138, pp. 379436, 143, figs. 1-2. figs. 1-16, pls. 20-25, tables 1-7. SAVAGE,DONALD E. SLICHTER,CHARLES S. 1955. Nonmarine lower Pliocene sediments in 1905. Observations on the ground waters of the California, a geochronologic-stratigraphic Rio Grande Valley. U. S. Geol. Surv. classification. Univ. California Publ. Geol. Water-Supply Paper 141, pp. 1-83, figs. 1- Sci., vol. 3 1, no. 1, pp. 1-26, figs. 1-13. 32, pls. 1-5. 1962. Cenozoic of the fossil mam- SMITH,HAROLD T. U. mals of the Western Hemisphere. Rev. Mus. 1938. Tertiary geology of the Abiquiu Quad- Argentino Cien. Nat., cien. zool., vol. 8, rangle, New Mexico. Jour. Geol., vol. 46, no. 4, pp. 53-67. no. 7, pp. 933-965, figs. 1-12. SAYRE,ALBERT N., AND PENNLIVINGSTON SMITH,ROBERT L. 1945. Ground-water resources of the El Paso area, 1960. Ash flows. Bull. Geol. Soc. Amer., vol. 71, Texas. U. S. Geol. Surv. Water-Supply pp. 795-842, figs. 1-6, pls. 1-2. Paper 919, pp.1-190, figs. 1-11, pls. 1-16. SMITH,ROBERT L., AND ROYA. BAILEY SCHULTZ,C., BERTRAND,AND CHARLESH. FALKEN- 1968. Stratigraphy, structure, and volcanic evolu- BACH tion of the Jemez Mountains, New Mexico. 1940. Merycochoerinae, a new subfamily of oreo- [Abstract.] In Epis, Rudy C., Cenozoic donts. Bull. Amer. Mus. Nat. Hist., vol. 77, volcanism in the southern Rocky Moun- pp. 213-306, figs. 1-18. tains. Quart. Colorado School of Mines, 1941. Ticholeptinae, a new subfamily of oreo- vol. 63, no. 3, pp. 259-260. donts. Ibid., vol. 79, pp. 1-105, figs. 1-17. SMITH,ROBERT L., ROYA. BAILEY,AND CLARENCE 1947. Merychyinae, a subfamily of oreodonts. S. Ross Ibid., vol. 88, pp. 159-286, figs. 1-17, tables 196 1. Structural evolution of the , 1-6, charts 1-4. New Mexico, and its bearing on the em- 1949. Promerycochoerinae, a new subfamily of placement of ring dikes. U. S. Geol. SUN. oreodonts. Ibid., vol. 93, pp. 69-198, figs. 1- Prof. Paper 424-D, pp. D145-D149, figs. 26, tables 1-8, charts 1-6. 1-3. 126 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY \'OL. 144

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