1. Field Surveys, Lithology armen, and Age 97 405 8 Lom о и, S he ا Ban‏ MCZ LIBRARY HARVARD UNIVERSITY 7 The Paleontological Research Institution acknowledges with special thanks the contributions of the following individuals and institutions PATRONS ($1000 or more at the discretion of the contributor) JAMES E. ALLEN (1967) RICHARD I. JOHNSON (1967) AMERICAN Оп, COMPANY (1976) J. M. McDonALD FOUNDATION (1972, 1978) ATLANTIC RICHFIELD COMPANY (1978) Мови, OIL CORPORATION (1977 to date) CHRISTINA L. BALK (1970, 1982, 1983) SAMUEL T. Pees (1981) Hans M. Bo ti (1984) RICHARD E. Petit (1983) Mn. & Mns. KENNETH E. CASTER (1967) ROBERT A. PoHowsky (1982) CHEVRON Оп, COMPANY (1978, 1982) TEXACO, Inc. (1978, 1982) Exxon COMPANY (1977 to date) UNION Orr OF CALIFORNIA (1982 to date) Lois S. FOGELSANGER (1966) UNITED STATES STEEL FOUNDATION (1976) GULF Оп, CORPORATION (1978) CHARLES G. VENTRESS (1983 to date) MERRILL W. Haas (1975) CHRISTINE C. WAKELEY (1976-1984) ROBERT C. 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Hoover Director Paleontological Research Institution 1259 Trumansburg Road Ithaca, New York 14850, U.S.A. 607-273-6623 VOLUME 89, NUMBER 323 MARCH 25, 1986 Neogene Paleontology in the Northern Dominican Republic 1. Field Surveys, Lithology, Environment, and Age John B. Saunders, Peter Jung, and Bernard Biju-Duval by Paleontological Research Institution 1259 Trumansburg Road Ithaca, New York, 14850 U.S.A. Library of Congress Card Number: 85-63715 Printed in the United States of America Allen Press, Inc. Lawrence, KS 66044 U.S.A. CONTENTS Río Mao GED STARR E a a 30 TEiihaloay wen A en 31 ЕУЕН ЕСРИ о 32 Anc em e i ess 32 Río Amina Generale ы ud up иаша иы E. 32 КАШЫН М sa ds Rer e A AA 32 TIN ROOTING ta 33 NS A MAL NK OS EEE 33 Arroyo Zalaya CA PEA A НЕДА OA 33 POVOD MENE ое LR 34 AUCI LR A ME ai RAN 34 AWrovoPBunale o A E E сае 34 Pos Verde o S d eU DD MM M LR LL 34 Conclusions Late Tertiary Geography of the Cibao Valley ........... 34 Generalized Geologic History (MT AL Lu en 37 Middle Part of te MIOCENE sola ater dde ear 37 TESTE аселе Ta e LM ME d Ld 37 ESTA ac Lo e RP чанлык 38 ТИ ЕУ OCENG ES ik е 38 Appendix 1. The Use of Formation Names ............... 39 Appendix 2. Natural History Museum of Basel (NMB) INiierotossu LOCALES E о очар 41 Appendix 3. Natural History Museum of Basel (NMB) IMA ое А ae 33 Appendix 4. Tulane University (TU) Macrofossil Localities .. 64 Appendix 5. U.S. Geological Survey (USGS) a NE D... d нн 68 ааа оа NOT n E LL cu qme Ma t uu ыы 69 IDs T UM eem A RON SEM 71 LIST OF ILLUSTRATIONS Page ASAS A tee EIA C EE 5 A CESS AR есес и 5 MSOC ue. E M mU 8 "cknowledgmentsSesc u карш er RUM et 9 Earlier Paleontologic and Stratigraphic Studies ............ 10 The River Sections Río Gurabo спета а ема: 11 Lithology LADA re 11 T:abera/@e1cado-@onlactr te ee ae 11 (sercadoasbopmationé ol E EGE 11 ¡GUADA a este 12 E cei anal 13 Environment CGercadosBonmationg es Coe аза аса ыл a 15 GuüraborBormauoha a ee ale 15 Man korma л аллы OE ы EL E 16 A eT RN BG NR T LEE 17 Rio Cana (INIA IO AD E ы UA LE 19 IA ERR AUT аы нр HM pens 20 JM ro а pA DUI XAR IU qM LEE TU DC MIS DE 22 Río Yaque del Norte Generale een ee a ad e 23 Lithology Beds below the Miocene unconformity at López ... 24 Beds above the Miocene unconformity at López ... 24 Stratigraphic sequence between López and Santiago 26 Environment Beds below the Miocene unconformity at López ... 28 Beds above the Miocene unconformity at López ... 29 Stratigraphic sequence between López and Santiago 29 GOs ere E D ETE 29 Text-figure Page 1. Map of the Caribbean area, showing some of the more important Neogene molluscan localities .............. 6 2. Geological sketch map of the Dominican Republic .... 7 3. Geological sketch map of the Cibao Valley, northern Do- minican Republic, showing areas from which samples for this projestswerescolleetede ne OR 7 4. Map and columnar section of Río Gurabo, showing geo- graphic and stratigraphic positions of NMB collecting LOCALES аа ce xo bones ta adc in pocket 5. Map of Río Gurabo, showing geographic positions of se- lected TU and USGS collecting localities......... in pocket 6. Columnar section for Río Gurabo, showing lithologies and авео, tte Mee no vio ete dore koe Nc in pocket 7. Three sections from Río Gurabo showing the nature of the contact between the Cercado Formation and the underlying Taber Formanon enn etn ded oom ae Red Dp taa 12 8. Five sections in the lower part of the Cercado Formation on Río Gurabo, showing details of sands and interbedded a E IC: 12 9. Three sections illustrating the unconformable overstep of the basal conglomerate of the Gurabo Formation on Río Gurabo across the coral beds and sands of the underlying CrO EOE a pu LIEN ee Us 13 10. Section in the Gurabo Formation on Rio Gurabo, showing details of coral-rich horizons exposed in a steep ravine in the ciis ОНОЛСО DANE оао: 13 11. Section at the base of the Mao Formation on Río Gurabo close to NMB collecting localities 15994 to 15999 ..... 13 12. Section in the Mao Formation on Río Gurabo, showing fossiliferous silts with interbedded conglomerates and coral асва зва SUR Rd A A 14 13. Four exposures observed between NMB localities 16119 and 16122 in the Mao Formation on Río Gurabo, showing channeling, cross-bedding and slumping characteristic of the yoünger portions-of thatunit Wr... 14 14. Stratigraphic positions of NMB collecting localities across the Miocene-Pliocene boundary on Río Gurabo ....... 17 15. Map and columnar section of Río Cana, showing geograph- ic and stratigraphic positions of NMB localities, and geo- graphic positions of TU localities................ in pocket 16. Columnarsection for Río Cana, showinglithologies and ages NU I M MD LU M Le in pocket Text-figure 17. Sections in four cliff exposures of the Cercado Formation on Río Cana, showing the relationship of the Arca patricia beds to the surrounding sediment types 18. Section exposed in cliff near NMB locality 17000 in the Cercado Formation on Río Cana, showing the position of the Arca beds 19. Exposure in the lower part of the Mao Formation, below the Mao Adentro Limestone, on Río Cana, showing high- angled foreset beds in coarse sands and conglomerates . . 20. Section through the base of the Mao Adentro Limestone on Río Cana 21. Map of Río Yaque del Norte, showing geographic positions of NMB, TU, and USGS collecting localities 22. Map of the city of Santiago, showing geographic positions of NMB microfossil collecting localities 23. Map showing geographic positions of NMB microfossil collecting localities along the road between Santiago and Baitoa and on Río Bao 24. Schematic column for Río Yaque del Norte showing rel- ative stratigraphic positions of localities and estimated thickness of strata 25. Columnar section ofcliffexposures on Río Yaque del Norte north of Baitoa, showing lithologies and stratigraphic po- sitions of NMB collecting localities .............. 26. Section at Arroyo López on Río Yaque del Norte, showing detail of exposures of highly fossiliferous conglomerate 27. Composite section based on exposures at the south end of a conspicuous limestone gorge (“Angostura Gorge") be- tween López and Angostura on Río Yaque del Norte 28. Photograph of cliff exposure on Río Yaque del Norte north Page 21 in pocket 24 in pocket 26 211 29. 30. 3E 32, Soy 34. 35. 36. 3 38. 39 of Baitoa, showing the discordant contact between the Bai- toa Formation and the underlying Tabera Group Map of Rio Mao, showing geographic positions of NMB, TU, and USGS collecting localities .............. in pocket Map of Rio Mao, showing geographic positions of NMB collecting localities from Maury's Bluff 2 and the right bank cliff at the mouth of Arroyo Bajón Section exposed in Maury's Bluff 2 on Río Mao, showing lithological details and stratigraphic positions of NMB col- lecting localities Section exposed at the mouth of Arroyo Bajón on Río Mao, showing lithological details and stratigraphic positions of NMB collecting localities Section exposed at the downstream end of Maury’s Bluff 3 on Rio Mao, showing lithological details and stratigraph- ic positions of NMB collecting localities Map of the central portion of Rio Amina, showing geo- graphic positions of NMB, TU, and USGS collecting oc la T nr cdo tue in pocket Schematic column for the central portion of Río Amina, showing relative stratigraphic positions of NMB and TU collecting localities Map of Cañada Zalaya, showing geographic positions of NMB and TU collecting localities ................... 33 Map of Arroyo Puñal, showing geographic position of TU locality 1353 Map of Río Verde, showing geographic positions of TU localities 1250 and 1251 Block diagram showing the relationship between Neogene sections on Río Gurabo and Río Cana LIST OF TABLES Table 1. Stratigraphy of the Cibao Valley, northern Dominican Re- public, as interpreted by authors of pertinent papers .... 2. Ostracode datum points for the Río Gurabo and Río Cana sections, supplied by Dr. W. A. van den Bold Page 10 3. Stratigraphic sections from six of the river valleys studied 4. for this project, showing approximate correlations Planktic foraminiferal and nannofossil zones, and absolute ages of Neogene strata in the Río Gurabo and Río Yaque del Norte sections NEOGENE PALEONTOLOGY IN THE NORTHERN DOMINICAN REPUBLIC 1. FIELD SURVEYS, LITHOLOGY, ENVIRONMENT, AND ÁGE By JOHN B. SAUNDERS,! PETER JUNG,! AND BERNARD BIJU-DUVAL” ABSTRACT This is the first in a series of papers on the Neogene fossiliferous sediments exposed along the south flank of the Cibao Valley west of the city of Santiago, Dominican Republic. Part One provides field data and stratigraphic and environmental conclusions as a framework for subsequent, detailed faunal and floral studies. Later refinement and alteration in the conclusions is to be expected. Field work carried out in 1978, 1979 and 1980 concentrated on the Río Gurabo and Río Cana sections while other rivers as far east as the Río Yaque del Norte were studied in less detail. The work has provided a number of parallel transects through sediments ranging in age from Miocene to middle Pliocene, giving an insight into the development of the south flank of the Cibao trough. The 887 samples collected in the field have been sorted and distributed for macrofossil and microfossil analysis. The classical subdivision into formations has been found to be difficult to use in the field, because each unit can be reliably differentiated only in its type area. We have stabilized the fourfold subdivision of the Miocene and Pliocene rocks as far as possible in an appendix. The stratigraphy of this time interval is as follows: Mao Formation: maximum thickness exposed, 625 m Age: late early Pliocene to middle Pliocene. Upper part of Globorotalia margaritae Zone to upper part of Globorotalia miocenica Zone (based on planktic foraminifera) and NN14 Zone to NN15 Zone or above (based on calcareous nannofossils). Gurabo Formation: maximum thickness, 420 m Age: late late Miocene to early Pliocene. ?Globorotalia humerosa Zone to upper part of Globorotalia margaritae Zone (based on planktic foraminifera) and NN11 Zone to NN13 Zone (based on calcareous nannofossils). Cercado Formation: maximum thickness, 275 m Age: late Miocene. NN11 Zone (based on calcareous nannofossils). Baitoa Formation (recognized only in the type area): thickness measured, 75 m Age: in the interval from late early to early middle Miocene (based on ostracode and molluscan evidence). In both Río Cana and Río Gurabo, the sediment sequences start with shallow-water conglomerates, sands and silts and progress to highly calcareous silts in which beds of coral are frequent but in most instances suggest transport on an unstable slope. The Río Gurabo has a deeper-water, more open-marine facies than is seen in the Río Cana. In the Río Cana is found a thick sequence (340 m) of coral-rich limestone. This facies is not seen in the Río Gurabo, where the time equivalents seem to be silts interbedded with much thinner coral debris beds, conglomerates and pebbly sands. In both sections the highest outcrops are of sands and conglomerates, with conspicuous channeling in those of the Río Gurabo. The general tendency is for deeper-water environments to occur upsection in both rivers, but this has to be seen in the context of increasing distance into the trough. The marked instability of the north flank of the Cordillera Central in the Neogene is evident from the sedimentation patterns in the two river sections. In the Río Yaque del Norte, fossiliferous silts (Baitoa Formation) overlying a thick sequence of conglomerates of the Tabera Group are believed to represent a time interval not seen in the Río Gurabo and Río Cana. A thick limestone interval occurs higher in the sequence, but this appears to be of latest Miocene age, unlike that seen in the Río Cana. In the Río Mao, Maury's Bluffs 1, 2 and 3 were re-collected. RESUMEN Este es el primero de una serie de artículos sobre los sedimentos fosilíferos del Neógeno expuestos a lo largo del flanco sur del Valle de Cibao, al oeste de la ciudad de Santiago, en la Repüblica Dominicana. El suministra datos de campo y conclusiones estratigráficas y ambientales, como un cuadro general para subsecuentes estudios detallados de la fauna y la flora. Posteriores precisiones y algunas alteraciones en las conclusiones, pueden ser esperadas. Los trabajos de campo, llevados a cabo en 1978, 1979 y 1980, se concentraron sobre los perfiles expuestos en los ríos Gurabo y Cana, mientras otros ríos, tan lejanos al este como el río Yaque del Norte, fueron estudiados con menos detalle. El trabajo ha proporcionado un nümero de transectos paralelos a través de sedimentos que varían en edad, desde el Mioceno al Plioceno medio. Ellos ofrecen una visión del desarrollo del flanco sur del graben de Cibao. Las 887 muestras colectadas en el campo, han sido clasificadas y distribuídas para estudios macro- y microfósiles. La clasica subdivisión en formaciones se ha encontrado que es difícil de usar en el campo, porque cada unidad puede ser seguramente diferenciada sólo en su área tipo. Los autores han establecido, tanto como ha sido posible, la cuádruple subdivisión de las rocas del Mioceno y del Plioceno en un apéndice. La estratigrafía de este intervalo de tiempo es como sigue: ' Naturhistorisches Museum Basel, Basel, Switzerland. stitut Francais de Recherche pour l'Exploitation de la Mer, Paris, ? Institut Frangais du Pétrole, Rueil-Malmaison, France, and In- France. BULLETIN 323 Formación Mao: espesor máximo expuesto, 625 m Edad: Plioceno temprano tardío a Plioceno medio. Parte superior de la Zona Globorotalia margaritae a la parte superior de la Zona Globorotalia miocenica, sobre la base de foraminíferos planctónicos, y Zona NN14 a Zona NN15, o más arriba, sobre la base de nannofósiles calcáreos. Formación Gurabo: Espesor máximo, 420 m Edad: Mioceno tardío tardío a Plioceno temprano. Zona Globorotalia humerosa (?) a la parte superior de la Zona Globorotalia margaritae, sobre la base de foraminíferos planctónicos, y Zona NN11 a Zona NN13, sobre la base de nannofósiles calcáreos. Formación Cercado: Espesor máximo, 275 m Edad: Mioceno tardío. Zona NN11, sobre la base de nannofósiles calcáreos. Formación Baitoa (reconocida solamente en la región tipo): Espesor medido, 75 m Edad: en el intervalo Mioceno temprano tardío a Mioceno medio temprano, sobre la base de moluscos y ostrácodos. Las secuencias de sedimentos expuestas en los ríos Cana y Gurabo comienzan con conglomerados, arenas y limos suavemente cementados de aguas poco profundas, y progresan a limos altamente calcáreos poco cementados, en los cuales son frecuentes capas de corales, pero en la mayoría de los casos sugieren transporte en un declive inestable. La secuencia del río Gurabo se depositó en aguas más profundas; presenta una facies marina más abierta que la que se observa en el río Cana. En el río Cana hay una potente secuencia (340 m) de caliza rica en corales. Esta facies no ha sido encontrada en el río Gurabo, donde el tiempo equivalente parece estar representado por capas de limos poco cementados, intercalados con capas mucho más delgadas de detritos coralinos, conglomerados y areniscas guijarrosas friables. En ambos perfiles los afloramientos superiores son de arenas poco cementadas y conglomerados, con facies de canales en los del río Gurabo. La tendencia general es que los ambientes de aguas más profundas se encuentren en las secciones superiores de ambos ríos; pero esto tiene que ser visto en el contexto del incremento de la distancia dentro del graben. La marcada inestabilidad del flanco norte de la Cordillera Central en el Neógeno, es evidente en los patrones de sedimentación de las secciones de ambos ríos. En el río Yaque del Norte, los limos fosilíferos poco cementados de la Formación Baitoa, los cuales sobreyacen a la potente secuencia de conglomerados del Grupo Tabera, se cree representan un intervalo de tiempo que no se reconoce en los perfiles de los ríos Gurabo y Cana. En la parte superior de la secuencia se halla una potente caliza, pero esta parece ser de edad Mioceno más tardío y es diferente de esa encontrada en el río Cana, la cual es de edad Plioceno. En el río Mao, las escarpas 1, 2, y 3 de la Dra. Maury fueron nuevamente colectadas. H 250 b 159 850 750 70° 65° 60° DOMINICAN REPUBLIC i PUERTO RICO JAMAICA S. I Baar + Bowden EN y BARBADOS ۵ y 2 eu актай ой unta Gavilan argarita Ф Rockly Ba Cubagua e Melajo 4 Cabo Blanco Springvale COLOMBIA VENEZUELA TRINIDAD & TOBAGO Text-figure 1.— Map of the Caribbean area, showing some of the more important Neogene molluscan localities. DOMINICAN REPUBLIC NEOGENE: SAUNDERS ET AL. ү: MONTE CRISTO — ub Exe PUERTO PLATA Republic of Haiti SANTO DOMINGO 2 NN 0 50 100 km П ] Mesozoic Cenozoic С Quaternary Text-figure 2.—Geological sketch map of the Dominican Republic. ۹ 10 20km 1 Rio Cana 2 Rio Gurabo à 3 Rio Mao GUAYUBIN = Upper Cenozoic 4 Rio Amina [7] Oligocene - Early Miocene ? 5 Cañada Zalaya Rio Y del t MEO 6 Rio Yaque Norte 7 City of Santiago 8 Arroyo Puñal 9 Rio Verde ACP BAITOA Text-figure 3.— Geological sketch map of the Cibao Valley, northern Dominican Republic, showing areas from which samples for this project were collected. More detailed maps of areas 1 (Text-fig. 15), 2 (Text-figs. 4, 5), 3 (Text-figs. 29, 30), 4 (Text-fig. 34), 5 (Text-fig. 36), 6 (Text- fig. 21), 7 (Text-fig. 22), 8 (Text-fig. 37), and 9 (Text-fig. 38) show geographic positions of most NMB, and some TU, USGS, and other collecting localities. 8 BULLETIN 323 INTRODUCTION The richness of Cenozoic faunas in the Dominican Republic has attracted attention since the first collec- tions were made more than a century ago. Our group has become particularly interested in the Neogene sed- iments exposed in the Cibao Valley, situated in the northwest of the Dominican Republic (Text-figs. 1-3). There are few places in the Caribbean Region where macrofaunas of this age are so diverse and also so well exposed in continuous sequences, allowing close ex- amination of total assemblages and their relation to paleoenvironment and to time. Though much earlier work has been published, these rich faunas have yet to be placed in a modern time and environmental framework. If this can be done, the results should then be usable elsewhere in the region, to assist in an un- derstanding of its more recent geologic history. With this in mind, a group of us planned to apply the highly successful, multi-disciplinary approach of the Deep Sea Drilling Project, and out of this was born the present study. A small field party was formed to measure sections and collect samples. The material, amounting in total to about five tons, was shipped back to the Natural History Museum in Basel where it was processed, sort- ed and shipped to interested specialists in many insti- tutions. Their results will be submitted for publication in the Bulletins of American Paleontology. This first paper in the series gives as much back- ground data as possible at this stage, to act as a frame- work for the detailed faunal studies. Though it would obviously be wiser to wait until more results have been produced before making too many statements, itis now that preliminary findings are required. The interpre- tations and inferences given in the present paper must be viewed in this light. At a later stage it is hoped to summarize and draw conclusions from the detailed studies. We planned our approach using the unpublished geological maps of the Dominican Seaboard Oil Com- pany produced in 1943 on a scale of 1:40,000. Recon- naissance of the area was carried out in 1977, at which time contact was made with Ing. Nelson Gil Gil, di- rector of the Department of Geology and Mines in the Universidad Católica Madre y Maestra in Santiago, Dominican Republic, and all later work was done in close cooperation with that institution. Our field work was done in 1978, 1979 and 1980 during a total period of three months. Finance was provided by a grant from the Swiss National Science Foundation with vital ad- ditional support coming from the Institut Frangais du Pétrole (IFP) in Rueil-Malmaison. This support in- cluded the provision of a survey team that made it possible to map the Gurabo and Cana rivers (Text- figs. 4, 5, 15), to locate accurately the positions of sam- ples collected, and to obtain the elevations necessary for the construction of the stratigraphic columns (Text- figs. 6, 16). Of the left bank tributaries of the Río Yaque del Norte that provide good dip traverses across the Neo- gene succession (Text-fig. 3), the Río Gurabo consti- tutes the best standard. We spent our 1978 field season in this river. In 1979, we worked laterally from our reference sec- tion in the Río Gurabo spending most of the time in the Río Cana 10 km to the west, but also working eastward to sample in the Río Mao, Río Amina and in the Río Yaque itself. While working the Río Mao we were able to re-collect Bluffs 1, 2 and 3 made famous by Carlotta Maury. Time restrictions allowed a com- prehensive study of only the Río Cana. In 1980, our final year of field work, we used our small amount of time to complete some survey work in the Río Mao and to make further collections at Baitoa on the Río Yaque, and along this river north- ward to Santiago. The present paper makes 1t apparent how difficult it is to correlate laterally using the established forma- tions. Each can be recognized in its type area, as one might expect, but lateral facies changes make corre- lation of formational tops and bottoms from one river to the next hazardous. The names Mao, Gurabo and Cercado formations can be used in the Río Gurabo, with less certainty in the Río Cana and possibly as far east as the Río Mao. Outside that area we feel that subdivision at this stage is conjectural. When planning our study we tried to estimate thick- nesses for the formations from the Dominican Sea- board maps and came up with values ofthe same order as had been used by other workers (Butterlin, Ramírez, and Hoffstetter, 1956). Thus we had maxima of: Mao Formation, 500 m; Gurabo Formation, 1000 m; and Cercado Formation, 1000 m. The value of the survey work carried out by IFP is now apparent as we have measured a total section of only 900 m exposed in the Río Gurabo and 1200 m in the Río Cana. In these sections the maxima would be: Mao Formation, 625 m (Río Cana until the section 1s covered by alluvium in the lower part of the river)— including 340 m of Mao Adentro Limestone in the Río Cana; Gurabo Formation, 420 m (Río Gurabo); Cer- cado Formation, 275 m (Río Cana). On the Río Yaque del Norte south of López we measured 55 m of section that we place in the Baitoa Formation, but this represents a minimum thickness for this unit. The following methods were used to plot samples in the field. DOMINICAN REPUBLIC NEOGENE: SAUNDERS ET AL. 9 Before leaving Basel, the 1:50,000 topographic sheets were photographed as color transparencies and en- larged to a scale of 1:5000. The relevant river sections were then traced off, copies were made and these were used as our field sheets. Wherever possible, these were later replaced by surveyed sheets produced by IFP, also at a scale of 1:5000. The accuracy of the more impor- tant maps and columns is as follows. Río Gurabo. —Map (Text-fig. 4) constructed by re- duction to 1:10,000 of the IFP theodolite survey. The samples collected in the field could be placed accurately by this means on both map and column and the thick- ness of the total section calculated (Text-fig. 6). Rio Сапа. —Map (Text-fig. 15) downstream from the horseshoe bend at NMB locality 16984 surveyed by IFP as in the Río Gurabo. Upstream from this point, the map was taken from the 1:50,000 topographic sheets. The measurement of thicknesses for the column (Text-fig. 16) are from the survey down to the level of the Arca beds. Below that, some estimations had to be made. Río Yaque del Norte. —Maps (Text-figs. 21, 22) were enlarged from the 1:50,000 topographic sheets. The column for the whole river (Text-fig. 24) was calculated using dips and strikes measured in the field plotted over distances calculated from the 1:50,000 map. The column at López (Text-fig. 25) was measured using compass, tape and measuring rod. Río Mao. —Map (Text-fig. 29) was enlarged from the 1:50,000 topographic sheets. The maps and columns of Text-figures 30, 31, and 32 were measured using compass, tape and rod. Río Amina. —Map (Text-fig. 34) was enlarged from the 1:50,000 topographic sheets. Some isolated sam- ples on this river are not accurately located. We shipped back to Basel a total of approximately 300 samples for macrofossil study (see Appendix 3) and 500 for microfossil study (see Appendix 2). Wher- ever possible, the two sets are from the same horizons to allow complete faunal analysis of contemporaneous populations which, in turn, are linked to varying li- thologies. A list of paleontologists involved in the proj- ect at the time was given in Saunders et al. (1982); there have been some changes since then with the num- ber now standing at around 50 individuals. The make-up of the field parties was as follows: 1977. Reconnaissance by J. Saunders in cooperation with Prof. John Weaver of Puerto Rico. 1978. B. Biju-Duval, W. van den Bold, A. Chartier, P. Jung, C. Meynot, J. Saunders. 1979. B. Biju-Duval, W. van den Bold, A. Chartier, A. Eva, J. Geister, P. Jung, A. Mascle, J. Saun- ders. 1980. A. Chartier, J. Geister, P. Jung, A. Mascle, J. Saunders. Field Excursion for the Ninth Caribbean Geological Conference led by J. Geister, P. Jung, J. Saunders (see Biju-Duval, Jung, and Saunders, 1980). The main responsibilities within the Project are as follows. Bernard Biju-Duval has produced the sur- veyed maps and columns at IFP. Macrofossil studies are being coordinated by Peter Jung, who has sorted and classified the various fossil groups and distributed them to specialists for study. John Saunders is coor- dinating microfossil studies, and has produced the dat- ing on planktic foraminifera while Carla Müller has provided nannofossil dating, Willem van den Bold the ostracode results, and Jacques Butterlin the dating of the Tabera limestones, based on larger foraminifera. The responsibility for the text of the present paper has largely fallen to John Saunders but the three authors would like to mention again their gratitude to all those listed in the Acknowledgments for theirimportant con- tributions. It is normal practice in Bulletins of American Pa- leontology to give author and date for all taxa. In the present paper we are using many of the taxa in a rather broad way, particularly at the generic level. For this reason, we feel that it would be misplaced accuracy to give a citation in many instances. Therefore, such ref- erences are confined to the few species that we use in a definitive fashion. A specific example of this broad usage is the expression *menardiform Globorotalias". Further work will be done on this plexus of forms but, at present, they have been found useful as a group, particularly in respect to the ratio of right-coiled to left-coiled individuals. ACKNOWLEDGMENTS In the Dominican Republic we would like to ac- knowledge the support received from Monsignor Agri- pino Núñez C., and Ing. Nelson Gil Gil of the Uni- versidad Católica Madre y Maestra. Falconbridge Dominicana, under its manager Mr. Bill Dales, pro- vided generous assistance with transport while Ing. Romeo Llinas of the Ministry of Mines was most help- ful. Ing. José Hungria, director of the Instituto Geogra- fico Universitaria made it possible for us to purchase topographic maps. Important contributions to the present paper have come from Dr. Carla Müller (calcareous nannofossils), Dr. Jórn Geister (corals), Dr. Willem van den Bold (ostracodes), Dr. Jacques Butterlin (larger foraminif- era), and Dr. Enrique Gonzalez (palynology). 10 BULLETIN 323 Table 1.—Stratigraphy of the Cibao Valley, northern Dominican Republic, as interpreted by authors of pertinent papers. limestone Gurabo limestone Gurabo Gurabo | !imestone | Gurabo Gurabo Miocene laevigata | Gurabo authors| Maury Maury | Cooke |Vaughan | Maury Weyl |Bermudez|Butterlin| Ramirez Weyl | van den | van den | van den | Bowin Seiglie | Dorreen | Vokes present 1917 b 1919 1920 et al. 1929 1940 1949 1954 1956 1966 Bold Bold Bold 1975 1978 1979 1979 paper ap 1921 1921 1931 1968 1969 1972 Pleistocene Ф Мао late " O De a e УЕА ЕВЕ РАВЕН EL SI eee Ч] р, c 8 Mao I Mao ОЛ; тшде 8 & Gurabo vag Mao ER & L Gurabo EM y Gurabo yy ی‎ urabo Y Ж Mao Gurabo 5 Caimito Mao Mao Mao Mao Ж Gurabo pp Cercado cado E Sconsia E e Yj CH ? ? — É Cercado ? f = laevigata Mao clay Mao clay Мао Cercado Cercado 8 ? Z 5 Gurabo MaoAdentro اس‎ 8 7 2 = Z 4 E ô Gurabo Gurabo | Gurabo (Baitoa) Cercado Baitoa Cercado Cercado | Cercado Baitoa Bulla Baitoa early .Aphera. | Aphera islacolonis | islacolonis Cercado Cercado Cercado | Cercado uo Cercado | Cercado Bulla Baitoa ? Tabera WE ? 5 early | middle | late Miocene Cercado Tabera Cevicos- Trinchera limestone Kalk Sombre- rito limestone Tabera | Tabera Tabera Oligocene Tabera | Tabera Villa Tabera 20 Tabera Trina | Tabera Tabera Oligocene Tabera Aid has also been sought from Dr. Hans Bolli and Dr. Anthony Eva (foraminifera), Dr. Katharina Perch- Nielsen (calcareous nannofossils), and Dr. William Macdonald and Dr. William Lowry (paleomagnetics). Dr. Macdonald has collected his own samples along the Río Gurabo for paleomagnetic studies and it is expected that he will continue this work and publish the results separately. Drafting of the foldouts was undertaken by the In- stitut Francais du Pétrole in Rueil-Malmaison, who also paid half the cost of their printing. In Basel we have been fortunate to have the facilities ofthe Natural History Museum, including aid in preparation of the manuscript and figures by Messrs. Urs Marrer, René Panchaud and Wolf Suter. We repeat our gratitude to the Swiss National Sci- ence Foundation for their grant No. 2.646-0.76, and to the Institut Francais du Pétrole for their great con- tribution of both expertise and finance. EARLIER PALEONTOLOGIC AND STRATIGRAPHIC STUDIES In the following paragraphs we refer to the majority of paleontologic and stratigraphic papers that have been written on the Neogene of the Cibao Valley. The text discusses those papers that give new information based on material collected, while Table 1 gives the strati- graphic conclusions of most of these authors and also of others, a number of whom only made compilations of earlier work. All are included on the table to show the development of thinking from 1917 to the present day. The earliest authors reporting on fossils from the Neogene of the Northern Dominican Republic include G. B. Sowerby II (1850) in Moore (1850), Moore (1853) and Lonsdale (1853), both in Heneken (1853), who discussed a number of localities. Some of the molluscs described by G. B. Sowerby II (1850) were later revised by Pflug (1961). In 1873 Gabb described a large num- ber of molluscan species, but he gave neither illustra- tions nor locality information. This gap was partly filled by Pilsbry (1922), who revised the species described by Gabb (1873), and also those described but not fig- ured by Pilsbry and Johnson (1917). Maury (1917a, 1917b, 1919, 1929, 1931) added a great deal to the knowledge of the Neogene molluscs and their strati- graphic occurrence. The aims of her expedition to the Dominican Republic in 1916 read very much like those of our own project. Her low-key account of the diffi- culties and dangers of the trip is a classic of under- statement and well worth reading (Maury, 19172). It may be noted at this point that Maury (1931) assigned a late Miocene age to her Caimito Formation. This assignment infers that her Caimito beds by ne- cessity overlie her Cercado and Gurabo formations (Maury, 1929). However, there is some confusion here as her measured sections in the 1917b paper make it fairly clear that she would place the Arca beds, which she later included in her Caimito Formation, low in the Gurabo Formation and perhaps also including some of her original Cercado Formation concept. This is logical as the Caimito outcrops are well down in the overall Río Cana Section (Text-fig. 15 of the present paper). The most important stratigraphic work on the Cibao Valley formed a part of the study undertaken by T. W. Vaughan and his associates of the U.S. Geological Sur- vey in 1917 which is published in detail in Vaughan et al. (1921). Particularly relevant is the chapter on stratigraphy and geologic history by W. Cooke and on Tertiary and Quaternary stratigraphic paleontology by T. W. Vaughan and W. P. Woodring. The latter con- tains the first comprehensive lists not only of molluscs but also of corals and foraminifera, the last of which were taken from the work of Cushman (1919). This stratigraphic work formed the basis for all later studies. DOMINICAN REPUBLIC NEOGENE: SAUNDERS ET AL. 11 The USGS collecting stations are, wherever possible, plotted on the maps provided with the present paper (see also Appendix 5). An important field study was undertaken by Do- minican Seaboard Oil Company leading to the pro- duction in 1943 of the 1:40,000 manuscript maps that we used in our planning. Samples collected by oil com- pany geologists, particularly C. F. Dohm, formed the basis for a monograph on smaller foraminifera by Ber- mudez (1949) and on ostracodes by Bold (1968). The papers by Ramírez (1950, 1956) merely list and figure some of the species already described from the Cibao Valley. A series of eight colored geologic maps at a scale of 1:250,000 was published as an atlas (Zoppis, 1969). This compilation contains the work of many earlier geologists and, with its pages ofexplanatory notes, forms a useful basis for later work. Our own collecting was preceded by and partly over- lapped the collecting activities of Emily and Harold Vokes of Tulane University, New Orleans, Louisiana, U.S.A. The Vokes” collecting stations are plotted as TU localities on our maps (see also Appendix 4). Some age assignments based on their collections were given by Vokes (1979). THE RIVER SECTIONS Río Gurabo General We started our field work in the Río Gurabo, because previous information suggested that this river would provide the best reference section. As a matter of lo- gistic convenience, the survey and sampling was begun ata central access point (Los Quemados). The numbers generally run from that point down river to the top of the section and then up river to the lowest part of the section, including the Río Gurabito tributary. For the section down river from Los Quemados, it was possible to use a 4-wheel-drive vehicle along a difficult track that crosses and recrosses the river and finally joins the road from Mao to Guayubín. During or after heavy rain, this track is likely to be impassable. The southern part is reached from footpaths, and fi- nally from a track running from the Mao to Monción road to the river at Monte Higuero. To examine the section in its entirety, long stretches can only be reached on foot, making it difficult to bring out large volumes of samples. The work took three weeks, during which time ap- proximately 348 samples were collected for microfos- Sils and for lithologic study, and 137 samples were collected for macrofossils. Lithology Tabera Formation. —This unit was not studied or sampled in detail. The upper part of the exposed sec- tion is predominantly limestone, with an average dip of 40? towards the east. Interbedded subordinate con- glomerates, coral rubble beds and shell beds were not- ed. The limestones often have abundant larger fora- minifera and miliolids. They are certainly rich in coral and algal colonies, but these are not always easy to identify due to heavy recrystallization of the whole rock. Palmer (1979) has erected the name Monción Limestone as a formation within the Tabera Group. Below more than 200 m of predominant limestones and calcarenites, the section becomes much more con- glomeratic, with only subordinate coralliferous lime- stones. Beds which are thought to be stratigraphically lower are exposed in the Río Gurabito and higher up- stream in the Río Gurabo, where thick, massive, poly- mictic conglomerates rest directly on green schists of the Cordillera Central (NMB loc. 16254), or perhaps are faulted against them. The predominant red color of the basal conglomerates is noticeable and suggests that they would be placed by Palmer in his Inoa Con- glomerate. Tabera/Cercado contact (Text-fig. 7).— The actual contact between the Cercado Formation and the un- derlying Tabera Formation is rarely exposed. Where an eroded Tabera surface is seen, it shows considerable relief and is almost certainly karstic, sometimes ex- hibiting autobrecciation (NMB loc. 16239). The sur- face is here penetrated by pebbly shell beds occupying solution hollows, some of which are coated with clay. The marked difference in dip at the unconformity shows that the older beds were faulted and folded, or at least tilted, before being eroded. This episode of active tectonics must have been important in the his- tory of development of the Cibao trough. Cercado Formation. —The lower part of the for- mation consists of sands with interbedded conglom- erates and subordinate silts and clays (Text-figs. 7, 8). The dip is less than 10? towards the north. Sorting is generally poor and pebbles occur frequently in the sands and silts. The clays are often rich in plant debris and may pass laterally or vertically into lignites. Cross- bedding is very common in the sands. The beds are basically noncalcareous except around scattered shell fragments and where secondary redeposition of cal- cium carbonate has formed concretionary layers. Upwards, sands and silty sands strongly predomi- nate with minor pebbly layers and lenses. The sands are often coarse-grained and show scour structures and planar cross-bedding. Tests of Amphistegina are ex- ceedingly common and are often concentrated along the crossbeds where they stand out conspicuously as 12 BULLETIN 323 C Pebbly sandy silt B Lignitic clay A Pebbly silty clay with lenses of conglomerate. Pebbles up to 6 cm m 16236 " 16234 16233 Highly irregular limestone surface coated & penetrated by pebbly shell beds with variable matrix of sand or clay C Cross-bedded, very poorly sorted, pebbly sand with lignitic & silty clay layers B Hard pebbly sandstone A Clay with scattered plant debris fue a ey eee. 18240 + =" 0000000 Tabera Fm. Interbedded conglomerates, sandstones & coral & foraminiferal limestones Text-figure 7.—Three sections from the southern end of the study area on Rio Gurabo, showing the nature of the contact between the Cercado Formation and the underlying Tabera Formation (see Text-fig. 4, bottom). Black squares represent NMB localities collected for microfossils and lithologic analyses. lines (PL 1, fig. 4). Bioturbation is intense at many levels with Callianassa-sized burrows and smaller ones; these are often packed with shell fragments and Am- phistegina. The highest level seen in the Cercado Formation is a silt packed with coral and algal debris. This may be up to nine m thick, but can also be completely cut out by overstepping of the basal Gurabo conglomerate (Text-fig. 9; Pl. 1, fig. 1). Gurabo Formation. —The basal conglomerate when seen at river level is less than two m thick, but when seen capping cliffs upstream, where it has cut out the underlying coralliferous silt, it is at least seven m thick (PI. 1, fig. 1). The base is irregular and shows clay-lined scours filled with finer conglomerate overlain by coarser spreads of pebbles and cobbles. The components are well-rounded but poorly-sorted up to 15 cm in di- ameter (Pl. 1, fig. 2). The material is polymictic and apparently derived from the Cordillera Central. No examples of Tabera Limestone were seen. Poorly-pre- served, scattered molluscs and coral heads are found throughout but are more common towards the top. Above the conglomerate follow calcareous, fossilif- erous silts with bedding picked out by lines of calcar- eous concretions. Molluscs and solitary corals are scat- tered throughout. The silts pass up into cross-bedded, burrowed sands similar to those seen in the Cercado Formation (Pl. 2, fig. 5). The calcareous silts and sandy silts that follow are characterized by their richness in corals, which occur in beds and as separate, scattered heads. Some corals are in position of growth while others have been trans- ported (Text-fig. 10; Pl. 2, figs. 3, 4). At the top of the RIO GURABITO il C Sand with large vertical burrows, underlain by shell conglomerate & cross-bedded sands B Lignitic silty clay A Cross-bedded sands Cross-bedded sands & sands with silt laminations Lignites occur laterally ® 15922/16213 m Massive silty sand Text-figure 8.—Five sections in the lower part of the Cercado Formation on Rio Gurabo (see Text-fig. 4, bottom), showing details of sands and interbedded lignitic clays. Black squares represent NMB localities collected for microfossils and lithologic analyses; black circles represent NMB localities collected for macrofossils. DOMINICAN REPUBLIC NEOGENE: SAUNDERS ET AL. 13 Silt & sandy silt with abundant ке molluscs, algae & solitary corals. Age Hard & soft layers formed by е secondary calcification ved clay Uneven base of conglomerate has pebbly clay coating hollows Coral debris thickly and thinly distributed in silt and sandy silt. Branching corals pre- dominate with occasional large & small heads Conglomerate of poorly sorted, well-rounded pebbles & cobbles. Worn coral heads & molluscs more common towards the top Base of conglomerate is seen to cut out the underlying coral debris bed & to lie directly on the sand member P dd 255 Planar & cross-bedded fine to very fine sands. Bedding surfaces picked out by Amphistegina & shell debris which also fill burrows Text-figure 9. — Three sections illustrating the unconformable overstep of the basal conglomerate of the Gurabo Formation on Río Gurabo across the coral beds and sands of the underlying Cercado Formation. Figures 1 and 2 of Plate 1 illustrate this contact. 16141m Silt & sandy silt rich in branching corals & coral heads. Molluscs & solitary corals scattered throughout. Hard and soft layers more sandy with small scale cross-bedding Ledge of calcified silt rich in branching corals & coral heads. E One colony 45 x 35 x 25 cm in position of growth m Ao л а XL E pn Well-laminated silt & fine sand becoming more silty upwards Жыр. with increase in scattered corals 16139m Silty sand Text-figure 10.—Section in the Gurabo Formation on Río Gurabo (see Text-fig. 4, middle), showing details of coral-rich horizons ex- Posed in a steep ravine in the cliffs on the left bank. Black squares represent NMB localities collected for microfossils and lithologic analyses; black circles represent NMB localities collected for mac- rofossils. coral-rich sequence occur interbedded biostromal cor- als and coralliferous silts (Pl. 2, fig. 2). Downstream from the road bridge at Los Quemados, there follows a thick section predominantly of massive, calcareous silts rich in microfossils and with molluscs scattered and in lenses. Some levels are also rich in coral debris and solitary corals. Mao Formation. —The base of the formation is tak- m Bedded sands with subordinate silts Poorly-sorted sand containing rounded & angular pebbles up to 4 cm. The base is picked out by loading & flame structures Medium.: to coarse-grained sands with numerous balls of finer sand up to 60 cm in largest diameter. Passes up into well-bedded silty sands Clayey silts & channeled pebbly silty sands with pockets of conglomerate. Abundant shell debris & Amphistegina. Text-figure 11. —Section at the base of the Mao Formation on Río Gurabo close to NMB collecting localities 15994 to 15999. 14 BULLETIN 323 Calcareous silts with foraminifera & scattered corals & molluscs. Intermittent influxes of coarse material are represented by beds & lenses,some of which show small-scale channeling EIN xe SWS} |15824 e 15825 A B e E] | a a a a 16039 15826/16041 16042 16043 16044 16047 16048 Text-figure 12.—Section in the Mao Formation on Río Gurabo (see Text-fig. 4, top), showing fossiliferous silts with interbedded conglomerates and coral debris beds. Black squares represent NMB samples collected for microfossils and lithologic analyses; black circles represent NMB localities collected for macrofossils; black triangles represent exact horizons collected for microfossils. See also Plate 3, figure 3. en where predominantly sandy silts are overlain by Bed thicknesses alter rapidly laterally (Pl. 3, figs. 4, 5). channeled, medium- to coarse-grained sands and con- Burrowing is not a feature at this level. The conglom- glomerates showing loading and the development of erate components are less polymictic than those at the flame structures; one sand bed is conspicuous for hav- base of the Gurabo Formation. ing many enclosed balls of finer sand (Text-fig. 11). Calcareous, clayey silts follow the basal beds. After E‏ ر و en‏ 8 — xm —— — Lithologies varying from silts through sands to conglomerates 0 with different degrees of sorting. Shell & plant fragments scattered throuthout. Bedding may be either planar or in large cross-bedded packages. 9068900 — — A — Text-figure 13.— Four exposures observed between NMB localities 16119 and 16122 in the Mao Formation on Río Gurabo (see Text-fig. 4, top), showing channeling, cross-bedding and slumping characteristic of the younger portions of that unit (see also Pl. 3, fig. 1). DOMINICAN REPUBLIC NEOGENE: SAUNDERS ET AL. 15 acovered interval, calcareous silts and sandy silts occur interbedded with thin (decimetric) beds and lenses of coarser material including coral debris and pebbles (Text-fig. 12; Pl. 3, fig. 3). Some of the conglomerates show erosional bases. Pebble beds become less important upwards where interbedded, harder and softer calcareous silts form high cliffs (Pl. 3, fig. 2). The harder layers are usually packed with coral debris while the softer layers contain a rich microfauna; molluscs are scattered throughout. True limestone (“Мао Adentro Limestone") is poor- ly developed in the Río Gurabo. Shelly and pebbly limestones with corals occur as blocks in the river and in small outcrops on the slopes above, but it is difficult to know how continuous this near-reef facies was. One possibility is that this part of the section is cut out by a fault. After an interval with almost no outcrops, a series of low cliffs expose sands, pebbly sands and conglom- erates that show both large and small scale channeling (Text-fig. 13; Pl. 3, fig. 1). Higher parts of the section are hidden under a cover of young terrace sands and gravels of the Río Yaque del Norte. Environment Cercado Formation. —The environment of the basal beds is shallow-marine to brackish with molluscs oc- curring on the karstic surface of the underlying Tabera Limestone. This is in contrast to the situation in the Río Cana where the base of the section could be non- marine, though not necessarily of exactly the same age. The sorting is poor, suggesting varying energy levels, the higher ones being indicated by pebble layers and crossbeds (Text-fig. 8; Pl. 1, fig. 5) and the lower ones by carbonaceous clays. An internal report by G. Deroo of IFP indicates that the carbonaceous component is made up of a mixture of terrestrial vegetable matter and marine material. The presence of calcareous con- cretionary layers suggests that some of the shells may have been lost by solution and this is a feature through- out the whole Río Gurabo section. As pointed out by Saunders et al. (1982) the lower part of the Cercado Formation is characterized by a Larkinia -Mytilus -Melongena mollusc assemblage, which indicates a brackish-water environment (Rutsch, 1942; Clench and Turner, 1956). The upper half of the formation is dominated by sands, often cross-bedded (Pl. 1, fig. 4) with huge num- bers of tests of Amphistegina along the crossbeds and infilled burrows, many of which are 3.5 to 4 cm wide and suggest those of the arthropod Callianassa. Mol- luscs as whole shells and as broken debris occur scat- tered and in the burrows. Many, or perhaps all of the Amphistegina tests have been concentrated by water movements but the preservation of many suggests that no great transport was involved. Shallow-water sand shoals are indicated, with thickets of Thalassia (eel- grass) probably originally present on the sea bottom. No trace ofthese now remain but the richness of soritid foraminifera in some samples suggests their presence at the time of deposition, as these organisms prefer to live as epizoans on eelgrass blades. The rest of the foraminiferal fauna and the molluscan assemblages (Pachycrommium-Stigmaulax assemblage and Ana- dara willardaustena-Tellina-Strombina assemblage of Saunders et al., 1982) would agree with an environ- ment of shallow-marine sand flats with patches of eel- grass interspersed with more active regions of sand waves. The top of the Cercado Formation as seen in the river is marked by a coral-packed bed that is discor- dantly cut by the overlying conglomerate at the base of the Gurabo Formation. This bed may lens strongly or it may have been completely removed laterally as at NMB locality 15910 where the conglomerate rests directly on the underlying sands (Text-fig. 9; Pl. 1, fig. 1). The coral bed at some localities (e.g., NMB loc. 16184; Pl. 1, fig. 3) shows colonies of (?) poritids almost in position of growth with breakage only due to com- paction in situ. A coral thicket of poritids with some more massive heads and with common algal balls seems to have been the environment here. Gurabo Formation. —The basal conglomerate has well-rounded but poorly-sorted polymictic compo- nents (Pl. 1, fig. 2). The igneous material is mainly melanocratic and may suggest a source not far away. This and the conformity of dip does not indicate any great deformational event at this level. There is no evidence for shallower water above the conglomerate; in fact, the influx of material does not seem to disturb the general trend of deepening. However, it must be remembered that as we go upsection we also go steadily further northward and, presumably, progressively fur- ther offshore as is illustrated in Text-figure 39. The mollusc assemblages occurring in the lowest part of the Gurabo Formation (small Anodontia-Turbo as- semblage and Pachycrommium-Stigmaulax assem- blage) both point to a shallow-marine environment, whereas the assemblages characterizing higher parts of the Gurabo Formation indicate an increase in water depth. The calcareous silts above the basal conglomerate become steadily richer upwards in microfauna with a more diverse foraminiferal assemblage rich in benthic species, and with planktic species beginning to appear. At first the latter are only represented by taxa, such as Globigerinoides, which are known to come further in- 16 BULLETIN 323 shore than the keeled species of Globorotalia, though these begin to appear in small numbers towards the top of the interval. Ostracodes are common and more diverse but still dominated by shallow-water forms. Molluscs are abundant, as are solitary corals and cal- careous algal masses. If a water depth of about 12 m is taken as the lower limit of rich Thalassia growth (Eva, 1980), such an environment is excluded from the section here and above. Cross-bedded sands follow. They show strong bio- turbation with large and small burrows filled with shells (PL 2, fig. 5). Though lithologically similar to the sands in the upper part ofthe Cercado Formation, these higher ones carry a deeper-water, more open-marine fora- miniferal fauna. The instability of the bottom here, as in many other parts of the section, is borne out by the presence of solitary corals such as Antillia, Antillo- phyllia, and Dominicotrochus. By analogy with similar Recent genera, these seem to have been mobile forms, able to right themselves and even to migrate back to the surface if covered by sediment. Outcrops of nearly 100 m of calcareous silts rich in both macrofauna and microfossils follow, and this in- terval, including stretches with poor outcrops, may total almost 200 m. Secondary calcareous cementation is common, forming harder layers and lines of flattened concretions; these probably reflect greater original po- rosity due to more coral debris at these levels (Text- fig. 10).The main feature of the interval is its richness in corals. Though some colonies could have been in position of growth, the great majority show evidence of movement on a slope. One of the best examples of this is at NMB locality 16933, where a chaotic mass of large coral heads has been tumbled, broken, and often inverted (Pl. 2, fig. 3). Corals include such reef- forming species as Goniopora jacobiana Vaughan, 1919 and Montastrea sp. Associated with the massive heads are branched corals (for example, branching poritids and a branching species of Goniopora) and these, though moved and fractured, are not completely disarticulated (Pl. 2, fig. 4). The evidence points towards mass move- ment of sediment downslope with coral colonies en- closed in sediment. Above and below the slump the bedding is more continuous but still suggests debris slides on a slope. The reason for such slides is uncertain but Stoddart (1972) has given convincing evidence for the effects of earthquakes on coral communities. The Cibao graben could well have been tectonically active at the time under review, making this mechanism im- portant for some of the larger slides. Depth of deposition is uncertain but very shallow- water corals that one would expect to find in reefs at less than 20 m water depth are conspicuously absent. The greater diversity of the benthic foraminiferal fauna and appearance of keeled planktic species suggests a depth probably greater than 40 m and open ocean cir- culation. At 380 m on the column (Text-fig. 6) well-bedded alternating harder and softer layers are shown (NMB loc. 15837; Pl. 2, fig. 2). No biohermal coral masses occur but the beds could represent biostromal coral growth in patches, with development of major reef mounds prevented by scarcity of hard substrate and perhaps stress conditions due to high levels of fine sed- iment influx. Foraminiferal faunas again show access to the open ocean and a slowly increasing water depth. Ostracodes also show the first indication of deeper- water species at this level, while a general deepening of the water around this level is also suggested by the Glycymeris—Polystira mollusc assemblage. A relatively rapid deepening takes place just below 400 m on the column (at the location of the bridge at Los Quemados; Pl. 2, fig. 1). Massive silts at first have coral debris beds and lenses of molluscan debris and packed shells of Amphistegina but they soon become more uniform. The ostracodes suggest a water depth greater than 200 m and the high ratio of planktic to benthic foraminifera also supports a depth of that or- der. Macrofossils are scarce in this environment. Mao Formation. —The base of the formation is tak- en at a sudden influx of coarse terrigenous material, the basal conglomerate showing channeling, load fea- tures, flame structures and silt clasts. The badly-sorted material was swept into a relatively deep-water envi- ronment, probably by turbidity flows (Text-fig. 11; Pl. 3, figs. 4, 5). Between 600 and 700 m on the column (Text-fig. 6) good outcrops show repeated influxes of pebbles, silt clasts and coral debris into the calcareous silt envi- ronment (Text-fig. 12; Pl. 3, fig. 3). Some of the coarser beds have erosional bases and load structures suggest- ing sudden turbidity inflow. Upslope from the site of deposition, conditions were intermittently unstable, perhaps due to shifting sources of supply of detritus, or perhaps reflecting increased wave action due to fre- quent storms. At approximately 700 m on the column a tall cliff (Pl. 3, fig. 1) exposes alternating hard and soft beds. The latter are calcareous silts interspersed with cal- carenites composed of coral debris, sand and pebbles that have become secondarily calcified. The silts may be somewhat shallower than below but still suggest a water depth greater than 100 m, into which the coarse debris has been swept. Discontinuous outcrops show this environment ,to continue at least as high as 770 m on the column. From about 650 to 750 m on the column a Limopsis- Pteropoda mollusc assemblage predominates. This as- DOMINICAN REPUBLIC NEOGENE: SAUNDERS ET AL. 19 semblage also includes Propeamussium, terebratulid brachiopods, and small solitary corals, and thus points to considerable water depths. Just above 800 m on the column “limestone” is found in minor outcrops on the valley slope and as blocks in the river. This lithology is a pebbly calca- renite with corals not in position of growth and an Ostrea-Lithophaga assemblage that also includes Pli- catula and rare large echinoids. The highest outcrops in the section, at around 900 m on the column, consist of channeled sands, grits and conglomerates (Text-fig. 13; Pl. 3, fig. 1). Distorted pebbly, clayey silt clasts are common. Plant fragments are particularly common in the sands along with scat- tered shell fragments. The silt clasts produce forami- niferal faunas that are environmentally heterogeneous but have a reasonable planktic component suggesting relatively deep water. The evidence points to turbitity and slump influxes into an environment of indeter- minate water depth. A large suite of samples has been studied for pollen and spores by Dr. E. Gonzalez, who has plotted fre- quency diagrams giving the quantitative distributions of major floral groups. 15964 9 15933 15963 Ф 15932 15951 Ф | 1 y | $ өм КҮ age ey agua шыс 5962 15960 15961 $ 15930 O 15959 15934 y @ 15958 е 15938 al =— سے ے‎ اس س ہکن‎ | ee 7: ud | 15929 N | en SES | N@ 15935 l 2 | ба My N _0 15939 15936 Ї 1 15937 | iiit alie Des س‎ жа» x 15940 15948 C 1594 5m 15942 15943 15945 sa ыы шн н лс ер 1 б 15947 Text-figure 14.—Stratigraphic positions of NMB collecting local- ities (circles) across the Miocene-Pliocene boundary on the Río Gu- rabo (see Text-fig. 4, lower middle). The boundary is indicated by the dashed line. The vertical lines represent single outcrops. Black circles indicate the presence of Globorotalia margaritae. Throughout the section the flora is dominated by pteridophytes (mainly ferns). There is a gradual up- section increase of angiosperms, mostly represented by savanna and coastal plain elements, with palms being important. There is also an increase of gymnosperms (particularly the conifer Podocarpus) and of temperate angiosperms towards the top of the section. No forest development is seen. Mangrove pollen occurs in only a few samples and then only as a few grains. Abrupt floral changes are absent except between 300 and 400 m on the column where the change to a deeper- water environment apparently affected the input of fine, land-derived material of which the pollen and spores would have formed a part. The gradual upward increase of plants requiring a cooler climate is perhaps mainly due to uplift of the hinterland but may also reflect the beginning of a regional temperature drop, which could be expected in the Pliocene. The earlier appearance of temperate forms such as A/nus (alder) and Quercus (oak) in this area, relative to northern South America and some other parts of the Caribbean, may reflect the considerable topographic expression of the Cordillera Central, which still today has the highest elevation in the Caribbean (3087 m). Age The larger foraminifera from thin sections of the limestones in the Tabera Formation (the Monción Limestone of Palmer, 1979) have been studied by Dr. J. Butterlin. The majority of samples fall in the range P18 Zone to N5 Zone (that is, Cassigerinella chipolen- sis/ Pseudohastigerina micra Zone to Catapsydrax dis- similis Zone); they are thus in the range from middle Oligocene to early part early Miocene. The age of sam- ple NMB 16220 is given more precisely by Dr. But- terlin as P19 or P20, which would make it equivalent to the Globigerina ampliapertura Zone of the middle Oligocene. As considerable section seems to be present above this sample, it is possible that the top of the limestone could be as young as Miocene. The bottom of the Cercado Formation has been dat- ed as NN11 Zone on the basis of calcareous nanno- fossils, making it late Miocene. The first occurrence of the ostracode genus Radimella at the top of the Cer- cado Formation would support a late Miocene age throughout this formation. The Miocene-Pliocene boundary is placed on the first occurrence of the foraminiferal species Globoro- talia margaritae Bolli and Bermudez, 1965, and thus is the base of the zone of the same name. The detailed plot of samples at this level is given in Text-figure 14. As the NN11-NN12 zonal boundary occurs at ap- proximately sample NMB 15941 only about five m below the incoming of G. margaritae, this nannofossil Conglomerate, up to 30 cm, lensing. Shells including Arca. Pebbles 18 BULLETIN 323 J 17a I H J Conglomerate 23550 59 | Sand орд оо, 3 G Zen H Silt with pebbles ee G Conglomerate, lensing 22. 168380 F Conglomeratic pebbly silt with scattered shells MA E Conglomerate Nope D Shelly silt C 168396 16986m up to 12cm Arca B Shelly silt richer towards top 168400 16987m A Packed Arca horizon at top of silt ss e? 16841e 1m 17b G Bedded pebbly sand F Conglomerate, appears to fine upwards E Shelly silt passing up into sand D Very pebbly silt C Shelly, silty clay B Silt with scattered Arca passing down into A A Lignitic silty clay with minor cross-bedding 16990m "T 16991m 1m 17c H Sand & silt G Cross-bedded sand F Conglomeratic sand, lensing E Silty sand D 5 cm conglomerate SS... C Pebbly shelly silt 1 km B Base of silt rich in Arca A Festoon bedded sand with top heavily burrowed. Branching ?callianassid tubes up to 5 cm diameter (Plate 5, fig. 6) E Im 17d 1 | — H ° San Terrace gravel ==32> G | ==) 168470 F i r Along strike Arca becomes less frequent & oysters more H Arca 168480 common to be replaced by a thin (10 cm) conglomerate Е F = 168490 . Along strike Arca is largely replaced by oysters ES DD Arca 16850 0 D 169928 с ie B A cm A Fig 17a * Fig 17b Fig 18 Brown clay & silt Shell bed of Arca & other molluscs, lensing 40-70 cm Lignitic silty clay Brown silt packed with shell fragments, mainly Mytilus Arca bed with other shells including Melongena, lensing Lignitic silty clay Sandy silt Lignitic silt Silt 2 DOMINICAN REPUBLIC NEOGENE: SAUNDERS ET AL. 19 Text-figure 17.—Sections in four cliff exposures (Text-figs. 17a- d) of the Cercado Formation on Río Cana, showing the relationship of the Arca patricia beds to the surrounding sediment types. Geo- graphic locations ofexposures are shown in Text-figure 17e (see Text- fig. 15 for more detail). Black squares represent localities collected for microfossils and lithologic analyses; black circles represent lo- calities collected for macrofossils. For more details on Text-figure 17a, see Plate 4, figure 3; for more details of Text-figure 17c, see Plate 5, figure 6; for more details on Text-figure 17d, see Plate 4, figure 4. datum level is also taken to represent the epoch bound- ary. Comparative zonal charts usually show the NN12 Zone extending down slightly into the Miocene (Table 4) but in the Gurabo section the two horizons are seen to be very close indeed. The plot of the position of the micropaleontological samples (Text-figs. 4, 14) shows that due to the very low dip and the large meanders A = Arca bed A above lignite A dispersed in sand A + oysters 5 pen = lignite aS A at top of green clay m ái lignites 0 — Text-figure 18.—Section exposed їп cliffnear NMB locality 17000 in the Cercado Formation on Río Cana, showing the position of the Arca beds (“A”). The geographic position of this section is shown in Text-figure 17e (see Text-fig. 15 for more detail). See also Plate 4, figure 1. in the river, the boundary is crossed several times, and this adds credence to its mapping. The water was deep- ening rapidly at about this time but because of the presence of considerable numbers of menardiform Globorotalias already in samples below the boundary, 1t is not thought that the first occurrence of G. mar- garitae is facies controlled. Also, the swing in coiling direction of the menardiform Globorotalias from pre- dominantly sinistral, through random, to almost en- tirely dextral at the boundary strongly supports its placement. Vail, Mitchum, and Thompson (1977) have proposed a series of global eustatic sea level changes through time based on seismic stratigraphy. At the Miocene-Pliocene boundary an abrupt relative rise of sea level amounting to about 140 m is illustrated by them. In relation to the increase in water depth near the boundary as suggested in the Río Gurabo section this fits very nicely, though one cannot see a sea level change of comparative magnitude in the Rio Cana section only 10 km to the west. From 400 to 700 m on the column (Text-fig. 6) planktic foraminiferal faunas are usually good and a determination of Globorotalia margaritae Zone, Plio- cene is possible, though the two subzones that are known in richer assemblages are not used here (see explanation of Table 4). The foraminiferal findings agree with the nannofossil dating of zones NN12 to NN15. The upper part of the column above about 710 m is dated as Globorotalia miocenica Zone, middle Plio- cene. The base of the zone is above the fault shown on the column (Text-fig. 6) and the structural break may not have any great significance. Sample NMB 16094 above the fault is still within the G. margaritae Zone. Division of the G. miocenica Zone into its two subzones (see explanation of Table 4) has not been attempted due to the poor and scattered faunas in the uppermost outcrops. However, the section is still in the lower subzone (Globigerinoides trilobus fistulosus Subzone) at least as high as 770 m, based on the pres- ence of Globoquadrina altispira sensu lato in sample NMB 16108. The highest outcrop contains a sample dated as high NN15 Zone, based on nannofossils. This does not entirely agree with the correlation between nannofossils and foraminifera given in Table 4, as it would suggest that the section is still high in the G. margaritae Zone, whereas on foraminifera it is prob- ably already within, and perhaps towards the top of, the Globorotalia exilis Subzone. Río Cana General The central part of the Río Cana section was tackled by using a track leading from the road south of the village of Zamba. Long stretches can only be reached 20 BULLETIN 323 on foot and the limestone gorge is difficult of access and impassable at above average water levels. Access to the gorge from the north requires a long walk from Cana Chapetón on the road connecting Guayubín and Mao. The upper reaches of the Cana are equally difficult to reach with a vehicle but it is possible to drive to Cementerio (Dominican Republic Grid ref. BM508633) which is close to the contact between the Cercado For- mation and the underlying rocks of the Cordillera Cen- tral. In the Río Cana and Cañada de Zamba approxi- mately 75 samples were taken for microfossils and lithologic study and 71 for macrofossils over a period of 11 days. Lithology In the Río Gurabo, the lithologic sequence was dis- cussed under the headings of the formation names that have been used in the past. This is possible in that river section because the Gurabo Formation in its type area separates the underlying Cercado Formation from the overlying Mao Formation. However, when one goes 10 km to the west to a parallel section exposed in the Río Cana, itis apparent that lateral changes make it impossible to correlate lithologic units except in a broad way. On the column (Text-fig. 16), a tentative subdivision into formations has been included and this breakdown is defined in Appendix 1, but no great em- phasis is placed on the formational subdivision in this part of the text. The section begins with 75 to 100 m of conglom- erates and cross-bedded sands that follow unconform- ably immediately above steeply-dipping, hard shales and sandstones of the Cordillera Central. Above an unexposed interval follow channeled and cross-bedded sands, often pebbly and with interbedded conglomerates. Silts and lignitic silts are also frequently associated with minor lenses that are rich in molluscan debris and, occasionally, coral debris. Higher in the section, sands and sandy silts predom- (5) Conglomerates with pebbles up to 5 cm inate with conglomerates and occasional shell beds. Particularly distinctive are a number of levels rich in large specimens of the bivalve Arca patricia G. B. Sow- erby, II, 1850, which also dominate the river float downstream. Details of these occurrences are given in Text-figures 17 and 18 and in the Explanation of Plate 4. In a single cliff face (Pl. 4, fig. 1), five Arca levels can be traced, and downstream some or all of these can be seen at river level. Correlating a particular shell level from one outcrop to another is not easy as single localities show how discontinuous the Arca beds can be and how they may change laterally within a few meters into oyster beds or into conglomerate lenses. Text-figures 17a to 17d exhibit details of the types of sediment in which the Arca beds occur. Two of the beds (see Text-fig. 17d; Pl. 4, fig. 4) occur in rhythmic series where they are preceded by a highly lignitic bed and followed by a clayey silt packed with shell frag- ments (in one case, Mytilus). In other localities the Arca horizons are associated with sands and shelly silts, sometimes with large-sized Callianassa-type burrows (Pl. 5, fig. 6). The Arca beds were grouped by Maury (1931) in her Caimito Formation but this unit has not been found to have any lateral correlative value. The base of the Gurabo Formation in the Río Cana has been tentatively placed at the bottom of a series of pebbly sands and a conglomerate with components up to 10 cm in diameter. Channeling is common and the base is erosional. The next 300 m of section are dominated by cal- careous silts and silty sands and these are considered to be the equivalent of the Gurabo Formation. Minor conglomerates and pebbly layers occur sparsely except in what is still considered to be the upper part of the Gurabo Formation, where channeled sands and con- glomerates with load structures at the bases are con- siderably more frequent. The basic lithology is highly calcareous silt or sandy silt with abundant secondary concretions (Pl. 5, fig. 4). Corals are common throughout in the form of heads and of branching colonies (Pl. 5, fig. 3). At some levels, Fine to very coarse or pebbly sands with lenses & pockets of conglomerate. Structures include scouring & burrows Text-figure 19. — Exposure in the lower part of the Mao Formation, below the Mao Adentro Limestone, on Río Cana, showing high-angled foreset beds in coarse sands and conglomerates. This sequence appears at 630 m above the base of the section on Río Cana (see Text-fig. 16). Fine to medium sands, cross-bedded to laminated. Scattered oysters. Conglomerates & coarse sands Coarse to pebbly sand DOMINICAN REPUBLIC NEOGENE: SAUNDERS ET AL. 21 particularly in the Cañada de Zamba, they indicate true reef structures. In many other places they are in the form of debris that could often indicate reef talus. Mol- luscs are frequent either scattered through the silts or as shell horizons. Particularly in the lower part of the interval, spherical shells of the foraminifer Sphaero- gypsina are thickly distributed and easily visible. Bur- rowing is common at many horizons. The base of the Mao Formation has been drawn where calcareous silts are replaced by conglomerates, pebbly grits and sands. A spectacular outcrop of con- glomerates and coarse grits prograding towards the northeast (Text-fig. 19; Pl. 5, fig. 1) is followed by a poorly exposed interval, probably mainly of sands. Unlike the situation in the Río Gurabo section, lime- stones are well developed in the Río Cana within the Mao Formation (“Mao Adentro Limestone"). The riv- er has cut a deep, narrow gorge through an estimated thickness of 340 m of limestone (Pl. 6, fig. 3). Below the limestone are cross-bedded, heavily bur- rowed, pebbly sands and thin conglomerates. These pass abruptly into pebbly, sandy limestone that ap- pears to be somewhat discordant locally (Text-fig. 20; Pl. 6, fig. 2). The major part of the limestone is massive. Coral heads and branching colonies are visible but not tightly packed except as debris beds in a calcarenitic matrix. 16876 0 Coral rubble limestone Coral rubble limestone Sandy limestone with concretions passing up into coral limestone Coral rubble Massive coral limestone with Ms a scattered heads & debris Interbedded limestones & softer calcareous sandy silt. Corals & small gastropods Coral debris packed in a sandy matrix Pebbly sandy limestone e, (4 16873170218 h 7 Base of pebbly limestone somewhat discordant SS 5 i over channeled, cross-bedded pebbly sand & D i d— e , A > 16475 conglomerate and sand with concretionary burrows [| — 44 — — 17020 0 Silty sand, less calcareous Conglomerate layers in sand 1m | Text-figure 20.—Section through the base of the Mao Adentro Limestone on Río Cana. See Text-figure 15 for geographic and strati- graphic positions of localities. See also Plate 6, figure 2. Black squares represent NMB localities collected for microfossils and lithologic analyses; black circles represent NMB localities collected for mac- rofossils. At the top, the bedding is much more pronounced, with thin calcareous siltstones alternating with coral- rich, flaggy limestones (Pl. 6, fig. 1). A long, covered interval occurs downstream from the limestone gorge and, as the country is relatively flat, this probably represents the clays that follow the limestones in the Mao Formation in the type section. Asin the Río Gurabo, the highest beds seen are sands with minor conglomerates. The bedding here is more uniform than in the Río Gurabo while shells and coral debris are commoner, together with frequent plant de- bris. Environment Unfossiliferous, poorly-sorted conglomerates rest on steeply-dipping shales and sandstones. The base of the series here could be fluviatile with material dumped under rapidly-fluctuating energy conditions. Á super- jacent covered interval is in turn overlain by channeled sands and carbonaceous clays. Shell debris shows the environment to have been shallow marine and the character ofthe beds suggests basically low energy con- ditions with frequent floods of coarser material. Up- wards, cross-bedded, pebbly sands and conglomerates suggest similar conditions but with a slightly increased marine microfauna found in lenses and comprising molluscs, coral fragments and echinoid debris. The interval including the Arca patricia and oyster beds, characterized by the Larkinia—Mytilus—Melon- gena mollusc assemblage of Saunders et al. (1982), reflects brackish water conditions. A. patricia is closely related to the Recent Eastern Pacific species A. grandis (Broderip and Sowerby, 1829). Woodring (1973, p. 512) even considered it as a subspecies of the living form, citing it as Anadara (Grandiarca) grandis patri- cia. According to Maury (1922, p. 194), A. grandis lives in mud between tides, and it is restricted to a mangrove swamp habitat (Olsson, 1932, p. 62). Olsson (1961, p. 94) stated that “its usual habitat is lying deeply buried in soft mud banks which border mangrove swamps; hence, its distribution coincides with that of the man- grove". If A. patricia had a habitat similar to that of A. grandis, pollen samples from that interval should yield abundant mangrove pollen. Unfortunately the relevant samples of the Río Cana section have not yet been studied, but palynological examination of Río Gurabo samples has shown mangrove pollen to be almost absent (see p. 17). The A. patricia beds not only contain A. patricia but are characterized by an oligotypic fauna consisting of varying combinations of species of the genera Bulla, Melongena, Anadara, Mytilus, few large oysters, and Corbula. Even where A. patricia 1s replaced to a great extent by large oysters (see Text-fig. 17d), the oligotypic 22 BULLETIN 323 assemblage still exists but now contains only small numbers of A. patricia, Mytilus, and Corbula. A minimum of five discrete Arca horizons span a thickness of section of at least 10 m (Text-fig. 18). The sketch sections in Text-figure 17 show that these occur in different lithologic sequences at various localities. The most brackish would be the two beds both pre- ceded by highly carbonaceous clays and separated by a silt packed with Mytilus (Text-fig. 17d; Pl. 4, fig. 4). The most northerly occurrences of Arca beds, on the other hand, are associated with sands rich in Calli- anassa-sized burrows and with shelly silts rich in shal- low marine molluscs, bryozoans and Amphistegina (Text-figs. 17a, b, c; Pl. 4, figs. 2, 3; Pl. 5, fig. 6). The environment continues to be shallow-marine upwards with an influx of sands and pebble beds sug- gesting relatively high energy until a minor uncon- formity is seen at the base of a polymictic conglomerate rich in well-rounded, melanocratic pebbles. Burrowing is common but the macrofauna is not rich. Some of the finer-grained layers are rich in Amphistegina, Cu- neolina and small molluscs. The shells of Amphistegina in particular may show considerable wear. The conglomerate cited above is taken as the base of the Gurabo Formation in the Río Cana. Ostracode results give the best clues to correlation and these are considered in the section dealing with age. Above the conglomerate there is a change in style of sedimentation with a long sequence of calcareous silts with frequent horizons rich in corals. Compared with the Río Gurabo section, potentially frame-build- ing corals are much better represented, though only at one locality (NMB loc. 16813) at the mouth of the Cafiada de Zamba is there an association of platy reef corals with common Agaricia, comparable to that found on the outer slopes of present-day Caribbean reefs be- low 20 or 30 m water depth. Water depths were prob- ably less than 30 m. Shallow benthic foraminiferal fau- nas are, as usual, rich in Amphistegina but also are peppered with large, spherical Sphaerogypsina easily visible to the eye (Pl. 5, fig. 5). These, together with Planorbulina and frequent miliolids, attest to the shal- low-marine, clear-water environment and suggest rel- atively low energy levels. The very low percentages of planktic species could reflect restricted oceanic circu- lation but are probably merely a result of the shallow- ness of the water. Molluscs are frequent throughout and discrete shell beds occur as, for example, one rich in the large bivalve Anodontia, which usually has both valves still present. Lines of secondary concretions are a feature of the silts showing that the original sediment was extremely calcareous (Pl. 5, fig. 4). Within the upper part ofthe calcareous silts, at around 500 m on the column (Text-fig. 16), an influx of coarser material in the form of cross-bedded sands and pebble beds requires higher energy, erosional bottom currents (PI. 5, fig. 2). Further influxes of terrigenous material, including spectacular foresets in conglomerates and grits (Text- fig. 19; Pl. 5, fig. 1), are taken to represent the lower part of the Mao Formation. There is probably a shal- lowing at this level as suggested perhaps by these sed- imentary features and, more particularly, by the Os- trea-Lithophaga molluscan assemblage (Saunders et al., 1982). Shallow, inshore conditions persisted to the base of the limestones that are taken to represent the Mao Adentro Member. Pebbly, sandy limestone begins to build on an uneven surface of cross-bedded, heavily burrowed sands that contain a very shallow-water fo- raminiferal fauna (Text-fig. 20; Pl. 6, fig. 2). The paleoenvironment represented by the 340 m of limestone as exposed in the river gorge is not yet fully understood. At the top (Pl. 6, fig. 1) and bottom (Pl. 6, fig. 3), bedding is well marked but the rock is more massive towards the center. Where examined, it is seen to contain abundant massive and branching corals but many of these are fragmented and not in growth po- sition. Also, the colonies are not sufficiently densely packed to form a true reef framework. Repeated surges of coral debris downslope seem to be the most logical explanation of cause based on our present knowledge. A sample taken in softer clays between the coral rubble beds in the youngest limestones (NMB loc. 17023) produced a surprisingly rich foraminiferal fauna with a high ratio of planktic to benthic species and was rich in keeled Globorotalias, suggesting a water depth of at least 100 m at this point. The topmost series of beds exposed in the river sec- tion includes relatively flat-lying sands, pebbly sands and minor conglomerates that contain coral debris and scattered molluscs and are rich in plant fragments. The environment is difficult to judge because it is possible that everything is introduced. However, the forami- niferal fauna is relatively rich, considering the lithology and, though the benthics could represent more than one environment, there is a strong planktic component somewhat different from that known below. It would again suggest a water depth of more than 100 m. Age The shallower water environment of the Río Cana section as compared with that ofthe Río Gurabo makes dating by planktic microfossils less certain. The bottom of the section has so far proved to be undatable based on planktic foraminifera and calcar- eous nannofossils. Planktics begin to appear around 300 m on the column and, on a poor sample giving a DOMINICAN REPUBLIC NEOGENE: SAUNDERS ET AL. 25 Table 2.—Ostracode datum points for the Río Gurabo and Río Cana sections (see Text-figs. 4 and 15, respectively), supplied by Dr. W. A. van den Bold. Rio Gurabo Rio Cana Ostracadesdatuin gan NMB sample Height in NMB sample Height in number column (m) number column (m) Base Munseyella sp. 2 15982 17010 430 q 527 Top Munseyella sp. 1 15982 16964 { ©з. текте Top Coquimba congestocostata 15933 410 16964 Top Radimella sp. 1 15958 398 17006 852 Base Gangamocerithidea ? plicata + Cythereila А 16178 160 16978 282 Base Radimella genus 16186 146 17004 165 predominance of dextrally- over sinistrally-coiled menardiform Globorotalias, the base of the Pliocene is thought to be at least as low as about 315 m. This seems to agree with a determination of 2NN12 Zone based on nannofossils at 345 m (in the Cafiada de Zamba). If the situation here is as in the Río Gurabo, the NN12 Zone can be expected to be quite thin, which would fit the placing of the base of the Pliocene around 300 m, with a change to NN13-NN14 Zone by 370 m. Between this level of the column and the top of the Mao Adentro Limestone, faunas are poor though a Pliocene age is always suggested by the coiling ratios of menardiform Globorotalias. A surprisingly rich planktic component of the foraminiferal fauna in sam- ple NMB 17023, about 40 m below the top of the limestone, is considered to represent the topmost Glo- borotalia margaritae Zone or the basal Globorotalia miocenica Zone. When Text-figure 16 was printed, we had a determination of NN16-NN18 Zone, based on nannofossils, but this has since been revised to upper NN15 Zone, giving better agreement between the two fossil groups. Considering the coarse lithology of the highest out- crops, the planktic fauna is better than might be ex- pected. It gives an age still within the middle Pliocene and not above the middle of the Globorotalia exilis Subzone of the Globorotalia miocenica Zone. Some interesting tie-points between the Río Gurabo and Río Cana sections are suggested using ostracode datum levels supplied by Dr. W. A. van den Bold. Information from him has been used to construct Table 2. The first occurrence of the genus Radimella seems proven as being below the base of the Pliocene on the evidence of the Río Gurabo section. Its equivalent position in the Río Cana section, where the location of the base of the Pliocene is much less certain, is an important factor. Río Yaque del Norte General The part of the river included in the present study stretches from Baitoa in the south, past the confluence with the Río Bao, and northwards for 13 km to the city of Santiago (Text-fig. 22). This represents a dis- tance of 20 km along the river and therefore time only permitted visits to some of the major outcrops along this length. The intention was to try to make a general comparison between this section and those seen to the west with the hope of recognizing lateral facies changes. A reconnaissance survey was carried out to the south of Baitoa by geologists of the Institut Francais du Pét- role, who mapped a thickness of more than 1000 m of conglomerates, shales and silts below our section. These 24 BULLETIN 323 beds have been grouped as the Represa Conglomerate Formation of the Tabera Group by Palmer (1979). A few spot samples were also taken along the old road from Santiago to Baitoa and on the Río Bao: these are plotted on Text-figure 23. Fifty-eight samples were taken in the area for microfossils and lithologic study and 36 for macrofossils. Lithology Beds below the Miocene unconformity at López (Text- figs. 24, 25). — The section including the unconformity was particularly well exposed in the river in 1980, as the extra water flow resulting from a hurricane that year had cleaned away much of the vegetation that had masked the bottom of the cliffs on earlier visits. A very clear angular discordance makes the unconformity eas- ily visible. The dip is 10? above and 20? below with a change of approximately 10? in strike direction. Twen- ty m of section was closely examined below the un- conformity (Text-fig. 25). It consists of conglomerates to coarse, pebbly sands, all poorly sorted and some- times indistinctly graded. Components are well round- ed and consist of dark igenous rocks, dark limestones and hard siltstone clasts that have been used for dating. Broken molluscs and coral heads occur sparsely throughout and more commonly at a few horizons. Up the river the section was seen to continue downwards in a predominantly conglomeratic facies. The river cliffs just north of Baitoa expose somewhat lower beds that are also truncated by the unconformity (see photograph in Text-fig. 28). Calcareous silts are separated by occasional thin, sandy conglomerates. Text-figure 22. — Map of the city of Santiago (area 7 on Text-fig. 3), showing geographic positions of NMB microfossil collecting lo- calities (black squares). La b vem Barranca Palo Amarillo NX ЕА ыг ( Angostura! Los Ciruelos Text-figure 23.—Map showing geographic positions of NMB mi- crofossil collecting localities (black squares) along the road between Santiago and Baitoa and on Río Bao. These would fall in the Janico Formation of Palmer (1979). Upriver from the new bridge at Baitoa, con- glomerates become more dominant again and in- terbedded conglomerates and pebbly sands with oc- casional thin shales are at least 1000 m thick. These comprise the Represa Formation of Palmer (1979). Both Janico and Represa formations are part of the Tabera Group. It is possible that Palmer did not see the river section used for the construction of our Text- figure 25 as he makes no mention of the strongly con- glomeratic facies below the unconformity at that point. Beds above the Miocene unconformity at López (Text- fig. 25; Pl. 9, figs. 1, 2).— Fifty-five m of beds were examined closely and sampled extensively. Pebbly, well-bedded, fossiliferous silts predominate with many Text-figure 24.—Schematic column for Río Yaque del Norte, showing relative stratigraphic positions of localities and estimated thickness of strata. Black squares represent NMB localities collected for microfossils and lithologic analyses; black circles represent NMB localities collected for macrofossils. The coverage of other Text- figures herein is shown. DOMINICAN REPUBLIC NEOGENE: SAUNDERS ET AL. 25 conglomeratic and coarse sandy layers. Where the beds Text-fig 206 Mam = taa can be followed along strike for some meters, the len- | Silts and clays siform nature of individual layers is very evident. This 17315 M — — was made apparent by comparing exposures before and ES А after the hurricane of 1980 during which there was As Mom Ed MCA en active lateral erosion. Sorting in the coarser grades is БРГ. poor; the clay and fine-silt fractions have been win- кол ша тш. nowed out. Secondary calcification is common, form- | ing bands of irregularly oval concretions in the direc- | ARROYO HONDO tion of bedding; hard calcarenite beds are the final stage 17300 B en ect Sit Witheoral debris at some levels. Shell-filled burrows and lenses of shells and shell debris are common (Pl. 8, figs. 3,4). Plant fioe | fragments, up to more than опе m in long dimension, LIEN EE E B | occur at many horizons. Lensing conglomerates con- o UL LA BARRANCA tain boulders up to 35 cm in diameter and coral heads 17267 € —9»! 7303 8 PT. Shelly silts up to 50 cm. Some corals were growing attached to 1730287//| boulders. Components in the conglomerates are gen- 17266 92538 TUE erally well rounded and mostly of igneous origin with, overall, melanocratic types exceeding leucocratic. The Cretaceous Duarte Formation now exposed in the Cor- dillera Central to the south of the Baitoa area may 17297 LA BOCA i side have provided much of the more basic material while 17296 rei 4—— PLIOCENE the lighter-colored intrusive tonalites could have given pnan rise to the leucocratic pebbles. Tabera conglomerates were exposed on the unconformity before deposition ner of the beds above, making it likely that much material Ec is at least second generation. CE The name Baitoa Formation was defined by W. E Mainly limestone Cooke (in Vaughan et al., 1921) as comprising the beds at the top of the cliffs downstream from Baitoa (“Baitoa Ane Zr Cliff t of Text-fig. 28). This location was made the type LS locality but it was stated that collecting from the cliffs is not easy and that the old trail from Baitoa to Santiago i * provides better accessibility. Vokes (1979) gave a good ARROYO LOPEZ photograph of these cliffs but also did most of her Text-fig 26 E ed Shelly conglomerate collecting on the track where weathering has led to poorer preservation of the fossils. Only Ramírez (1956) LÓPEZ SECTION mentions a locality in cliffs below the confluence of the Río Bao with the Río Yaque and this must surely be our López section (see Text-figs. 21, 23). Predominantly Some authors have considered the Baitoa beds to be nguoi within the base of the Cercado Formation (e.g., Cooke, 1920, 1921; Bermudez, 1949) while others (Cooke in BAITOA CLIFF Vaughan et al., 1921; Vokes, 1979) have given it for- mational rank. We would agree with the latter for two Predominantly reasons: 1) both lithofacies and biofacies are very dif- conglomerates with ferent from what is seen in basal Cercado beds to the silts + thin conglomerates west, as the environment is fully marine at Baitoa; 2) ne bin present evidence shows the beds to be considerably older than the basal Cercado Formation in the Río Gurabo (see Table 4). We here designate the river sec- tion south of López where the Arroyo Hondo joins the main river (Text-figs. 21, 25; Pl. 8) as a hypostratotype 0 because of the quality of the outcrop (see Hedberg, 1976, pp. 26, 38). This locality is approximately 400 Text-fig 25 Shelly silts etc. E a 16909, 17168 ~ 17169 m 17170 в 17328 Ш 1004 m 17161 to О, 17165 и E 26 BULLETIN 323 m north of the original type locality cliff. Formal def- initions are given in Appendix 1. In contrast to the use of the term “Baitoa Forma- tion", the basal beds above the unconformity along the river have been placed in the Bulla Conglomeratic Member at the base of the Cercado Formation by Palmer (1979, folded map). In road and river sections to the west, particularly at Bulla on the Río Mao, the basal beds are variably conglomeratic. Usually the con- glomerates are nonfossiliferous and probably nonma- rine but Palmer does say that the Bulla shows “local presence of marine fossils". The use of the term “Bulla Conglomeratic Member" for the Baitoa facies seems questionable. Stratigraphic sequence between López and Santia- go. — Outcrops are discontinuous over this long stretch of the river and, due to lack of time, we were able to do only reconnaissance sampling of the most likely localities (Text-fig. 21). It was found that dips and strikes remained very constant at an average of 10? to the north and, using these, an attempt has been made to give the thickness of the section and the positions Te, Ge Ж Silty sand of our samples on the resulting column (Text-fig. 24). This calculation supposes that no significant faulting disturbs the sequence. Small normal faults with down- throw to the north are seen in some outcrops (for ex- ample, at Arroyo López and at La Barranca) but some antithetic faulting is also visible; these effects have been discounted in the calculation. Between the northern Arroyo Hondo (NMB loc. 17300) and Santiago the thickness of section is too doubtful to plot, as the geo- graphical terrain suggests less constant dips and strikes. This is borne out by the measurements taken for three samples within the bounds of the city of Santiago where the dip is to the east (Text-fig. 22). If the calculation is correct, at least 1300 m of section is seen above the unconformity at López with another 200 m of section in Santiago itself. At a point where Arroyo López joins the main river, two distinctive conglomerates separated by two m of clayey silt are seen, the lower one forming a prominent tilted island in the river (Text-fig. 26; Pl. 8, fig. 5). The surface of the island shows the bed to be a biogenic rubblemass with corals, echinoids and large molluscs Conglomerate, relatively well sorted Silty sand with lignitic silt at top Hard rubbly limestone interbedded with softer silts с m Interbedded silty clays & sands Conglomeratic grit rich in molluscs, corals and echinoids o Silt. Upper 40 cm has infilled burrows, some from paleosurface at top of bed; filled with Amphistegina & shell debris o Rubble bed, very poorly sorted. Large fossils, partly broken, sometimes well preserved — corals up to 25 cm, echinoids up to 15 cm, large oysters, Pecten, etc.in a sandy matrix composed largely of Amphistegina & Sphaerogypsina. The lower part of the bed is much richer in igneous pebbles & cobbles A Sand, burrowed throughout but more heavily in upper 1 m. 17276 9 Scattered coral heads & stringers of pebbles up to 2 cm 172740 lime 17316 8 17272 9 A SL : =: „| 172739 ESAMI з E в 220975 TESS e Text-figure 26.—Section at Arroyo López on Río Yaque del Norte, showing detail of exposures of highly fossiliferous conglomerate. Black squares represent NMB localities collected for microfossils and lithologic analyses; black circles represent NMB localities collected for mac- rofossils (see Text-fig. 21 for geographic positions of these localities). See also Plate 8, figure 5. DOMINICAN REPUBLIC NEOGENE: SAUNDERS ET AL. such as oysters and Pecten in a gritty matrix largely composed of the foraminifer Amphistegina and Sphaerogypsina. The lower part ofthe 1.5 m conglom- erate contains igneous cobbles and pebbles while the sand below is strongly burrowed from its upper con- tact. This locality is incorrectly given as ‘type loc Bai- toa’ by Bold (1968, text-fig. 6). What we have called the “Angostura Gorge" is a well-marked feature on the topographic map and turns out to be so on the ground. We take it to be composed entirely of limestone, with perhaps very subordinate calcareous silts or sands, but we had time only to ex- amine the base of the limestone at the upstream end Rubbly limestone ledge 17319m Clay 172780 Hadr tob 8m 172770 AE ——..! (A iE m ———— + 27 and its top at the downstream end. Its thickness could be at least 300 m as calculated for Text-figure 24. Text-figure 27 shows the situation at the upper end of the gorge and is interesting as it affords one of the few places known to us where the corals are almost all in position of growth and represent actual reef con- ditions. The corals appear to have grown on a paleo- surface of silty sand. A few calcareous sands and clays some cross-bedded, can be seen above the basal lime- stone. Above these are limestone beds that are pebbly and have erosive bases. Downstream from these out- crops the river enters the main gorge. The top of the limestone gorge is seen at the down- Hard brown sand, concretionary Sandy limestone with massive coral heads in living position. Concretionary layers near top Dense coral carpet of thinlysbranched poritids near top. Massive coral heads below (Siderastrea, Porites and large Coscinaraea up to 60 cm diam) with large branching Montastrea. Most corals in living position Pockets of clay in base of limestone Erosional base of limestone cuts across top of silty sand Hard silty sand 5-8? /0109 Conglomerate of small pebbles Rubbly limestone Text-figure 27. — Composite section based on three exposures at the south end ofa conspicuous limestone gorge (“Angostura Gorge") between López and Angostura on Río Yaque del Norte. Black squares represent NMB localities collected for microfossils and lithologic analyses; black circles represent NMB localities collected for macrofossils (see Text-fig. 21 for geographic positions of these localities). 28 BULLETIN 323 stream end, at La Boca, where coral debris layers are interbedded with Amphistegina-rich silty sand with coral debris and casts of large gastropods and bivalves. The dip is locally as steep as 20? at this point, but this seems to be only a local steepening. Immediately to the north the valley widens in more uniform clayey silts rich in foraminifera and with scattered small mol- luscs and plant debris. At La Barranca, cliffs on both sides of the river give good exposures in rather uniform silts with subordi- nate interbeds of silty sand and with discontinuous layers and minor lenses richer in shells. The dip re- mains at 10? just east of north. A number of small faults are visible with downthrows to the north. A single sample (NMB 17300) was taken on the old valley slope further to the north (Text-fig. 23). It con- sists of weathered silt with scattered, rotted coral de- bris. In Santiago, three samples were taken. The lowest (NMB 17293) is a uniform, massive, clayey silt rich in foraminifera and pteropods. The middle sample (NMB 17315) is in bedded, clayey and sandy siltstones while the highest one (NMB 17196) is a uniform silty clay. Taking a uniform easterly dip of 10°, the Santiago section amounts to a little more than 200 m of sedi- ments. Environment Beds below the Miocene unconformity at López. — The conglomerates and sands exposed along the river, w Baitoa Ta bera though poorly sorted, show repeated incomplete grad- ing. Close to the unconformity the bedding is better developed and load casts are common. Frequent grav- ity inflow of shallow-water material (including coral heads) took place on a slope. Silt clasts containing rel- atively deep-water faunas were torn up and carried in with the shallow material. Some of the clasts show distorted bedding, suggesting that they were only semi- lithified when eroded and were therefore penecontem- poraneous. This is important as the sequence has had to be dated on planktic foraminifera from the clasts. Sampling in the cliffs at Baitoa (NMB locs. 17168— 17170) is from somewhat lower in the section, as cal- culations suggest that the unconformable surface is cut- ting deeper in this direction. Here, finer-grained silts are interbedded with conglomerates, and these also suggest a water depth certainly greater than 100 m and probably considerably more. One incongruity is the finding of a single specimen of a land gastropod at NMB locality 16909 on the cliffs. Perhaps this was a living specimen that was rafted in. The coarse beds below the unconformity represent the top ofa sequence, predominantly of conglomerates, that is known to be at least 1700 m thick, according to measurements by IFP. This is in line with a cal- culation by Palmer (1979) of 2400 m. The major part of it may have been deposited during a time span not longer than two million years, probably with many periods of nondeposition. Considerable uplift of the Cordillera Central is suggested, providing a copious Text-figure 28.— Photograph of cliff exposure on Río Yaque del Norte north of Baitoa, showing the discordant contact (black triangle) between the Baitoa Formation and the underlying Tabera Group. The inaccessible upper part of the cliff was designated as the type locality of the Baitoa Formation (Cooke, 1920). See Text-figure 21 for geographic position of this exposure. DOMINICAN REPUBLIC NEOGENE: SAUNDERS ET AL. 29 supply of well-rounded, hard rocks that include pre- dominant melanocratic igneous rocks, but also some leucocratic rocks and, at least at the top of the section, dark limestone boulders up to one m in long dimen- sion. Although the major part of the section could have been deposited in two million years, as suggested above, the total time span for the complete conglomerate se- ries in the Baitoa area could be as long as six million years, which is considerable when taking account of the whole known time span of the Cercado, Gurabo and Mao formations in the Río Gurabo and Río Cana (see Table 4). Beds above the Miocene unconformity at López. — The first 14 m of badly-sorted, pebbly sands and con- glomerates have abundant shallow-marine molluscs and hemispheric and encrusting coral heads, some of which were certainly growing in situ on the gravel flats in an environment that, when it remained stable, could provide clear, shallow-water conditions favorable to them. The following six m of silt, richer in molluscs and bryozoans and with more foraminifera, again repre- sents very shallow water as is borne out by the complete absence of planktic foraminifera and calcareous nan- nofossils. The numbers of miliolids suggest that the environment could have been lagoonal. The remaining 34 m of the measured section are finer grained, but with varying energy levels as sug- gested by frequent influxes of pebbles and cobbles. The instability of the environment was noted by Dr. Geis- ter, who recorded layers of cobbles overgrown by coral heads (mostly Siderastrea and Coscinaraea and some Montastrea) up to 0.5 m across. These beds were them- selves covered by conglomerates that included rolled and broken, massive corals of the same species, with some debris of branching corals (Stylophora sp.). The silts are heavily burrowed and rich in smaller molluscs and also in soritid foraminifera. The latter are thought to have lived on the fronds of sea grasses such as Thalassia, which almost certainly covered the sandy bottom much of the time. Lignites are not seen but woody fragments, including several pieces of tree branches, are common. Planktic foraminifera and cal- careous nannofossils are still excluded from this very Shallow-water marine environment. Stratigraphic sequence between López and Santia- go. — The sequence of beds at Arroyo López (Text-fig. 26) indicates conditions rather similar to those dis- cussed above in the López section. The silts carry an Ammonia/Elphidium foraminiferal fauna, showing a brackish influence. The rubble bed that forms the is- land suggests clear, shallow water with enough move- ment to winnow out all the fines. The richness of large irregular echinoids is unusual. At the south end of the “Angostura Gorge," the base of the limestone section was visited (Text-fig. 27). Its main interest lies in the environmental information given by the corals about which Dr. Geister (written commun., 1984) has provided the following notes: At the entrance of the Angostura gorge a true coral framework of about 3 m thickness has been recognized [NMB locality 17277]. Dense stands of an unusually branching species of Monastrea along with numerous branching poritids, massive Siderastrea, Porites and ? Coscinaraea (up to 60 cm across) are comparable to well developed coral formations found today in many thriving Caribbean fringing and patch reefs. Since most of the corals are encountered in situ this is certainly the best example of a true reef formation found up to now in the Neogene of the Gurabo, Cana and Yaque del Norte river sections. Due to the limited outcrop area examined, it cannot be decided if it is a patch reef or just an extensive coral carpet. The systematic composition of the coral fauna does not provide good bathymetric criteria. However, the general appearance of the densely packed corals with several massive species that do not show a flat- tened growth habit suggests a depth shallower than 20 m. Several of the massive species would be expected to have developed a flat- tened growth habit when found below this depth on living reefs. Unfortunately, we had no time to study the lime- stones that form the gorge itself. At La Boca, the top limestones are followed immediately by clayey silts with rich foraminiferal fauna showing a high ratio of planktic to benthic species indicative of deeper water, probably greater than 100 m. The outcrops at La Barranca, between La Boca and Santiago, are of silts that again have a rich foraminif- eral fauna with a strong planktic component, suggesting a continuation of water depths greater than 100 m. The three samples taken in Santiago (Text-figs. 22, 24) are all deep water with rich planktic foraminiferal faunas; the lowest one (NMB loc. 17293) is a clay that is also rich in pteropods. Age The great thickness of conglomerates exposed up- stream from Baitoa has been dated at several levels by Dr. Carla Miiller. All samples are of NP24 Zone, middle Oligocene age. The cliffs at Baitoa (NMB samples 17168-17170) contain a flora of NP24 Zone, middle Oligocene. Planktic foraminifera agree with a late middle Oligo- cene or late Oligocene age. Rare specimens of Globig- erinoides primordius Blow and Banner, 1962, are pres- ent. Immediately under the unconformity in the Lépez section (labelled “horizon A” on Text-fig. 25), NMB samples 17320, 17321, and 17193 from silty clay clasts within the conglomerates have yielded planktic fora- minifera. Globigerinoides primordius is commoner here and the fauna places the clasts at approximately the Oligocene-Miocene boundary. This is supported by the nannofossils in NMB sample 17321, which give a date probably near the top of the NN25 Zone. It must 30 BULLETIN 323 be remembered that this dating is on resedimented clasts that might represent a somewhat older age than the matrix. The section at López above the unconformity, des- ignated as a hypostratotype for the Baitoa Formation, has not been dated by planktic foraminifera or nan- nofossils but Dr. W. A. van den Bold reports that NMB samples 17186 to 17190 belong to his Aurila amygdala Subzone on ostracodes, the range of which would be from Globigerinatella insueta Zone to Globorotalia fohsi Zone, based on planktic foraminifera, and therefore of late early to early middle Miocene. This is an important finding as the base of the Cercado Formation on the unconformity in the Río Gurabo, where it can be dated on nannofossils is NN11 Zone, late Miocene. The results on ostracodes are in good agreement with Vokes (1979), who dated the Baitoa Formation as late early Miocene (Burdigalian) by using the concurrent ranges of several species of gastropods. The section downstream on the Río Yaque continues to have been deposited under inshore conditions and has not been dated on foraminifera or nannofossils between López and the north end of the “Angostura Gorge". However, NMB samples 17316 and 17317 at Arroyo López are thought to be late Miocene by Dr. van den Bold. Text-figure 24 places the various outcrop sections in their correct positions if no significant fault- ing has taken place. This shows that the thickness of section between the López section and Arroyo López is not great, though a concealed unconformity between the two cannot be ruled out. It must also be mentioned that Dr. J. Geister has identified the coral genus Coscinaraea in samples at López (NMB loc. 16943), Arroyo López (NMB loc. 17274) and at the base of the limestones that form the *Angostura Gorge" (NMB loc. 17277). The range of this genus in the Caribbean region as determined in Chiapas (Frost and Langenheim, 1974; Frost, 1977) is from the base of the Miocene to the early part of the middle Miocene. This would agree with evidence given above for the age of the Baitoa Formation but would conflict with the presumed age of the section between López and La Boca. This question remains unresolved at the moment. At the top of the limestone section at La Boca, the silts are of Globorotalia margaritae Zone age with one sample (NMB loc. 17295) containing dextrally-coiled G. margaritae. Such a level is known elsewhere in the Caribbean close to the base of the zone (Bolli and Saunders, 1985) and thus we draw the Miocene/Plio- cene boundary at about the top of the limestones. De- termination of the upper part of the NN11 Zone, based on nannofossils from the same samples, gives reason- able support to this conclusion. Samples higher in the section, at La Barranca, Ar- royo Hondo and in Santiago itself, mostly give good determinations of the upper part of the Globorotalia margaritae Zone (i.e., equivalent to the С. margaritae evoluta Subzone) and would be classed as late early Pliocene according to our classification (Table 4). De- terminations of NN13 to NN15 zones, based on nan- nofossils, are in agreement. We see from the above that the Río Yaque section does not reach stratigraphically as high as the sections seen in the Río Cana and Río Gurabo. Río Mao General It was realized that we should not be able to do any 4? 10159 to 025° NM а = = I ar ar hl М P Las 16930 , = S NU 17329, 16914 16931 16932, 17176 x 16929 , 17179 » 39/2035 ХА ч % J 4°/2000° 16916 = % 16919 NN 16918 16924 17177 * 16922 Text-figure 30.—Map of Rio Mao (based on tape and compass survey), showing geographic positions of NMB collecting localities from Maury’s Bluff 2 and the right bank cliffat the mouth of Arroyo Bajön. DOMINICAN REPUBLIC NEOGENE: SAUNDERS ET AL. 31 extensive sampling in the Río Mao, as this is a river section of great length with formidable cliffs showing negligible dip (Pl. 8, fig. 1), separated by long stretches with no outcrops. To construct a meaningful strati- graphic column under such circumstances is not pos- sible. We therefore concentrated on re-examining Maury's Bluffs 1, 2 and 3 in an attempt to date them and to collect discrete levels within them. Seven sam- ples were taken for microfossils, 25 for macrofossils. The lower part of Text-figure 29 shows the area on which we concentrated and the map is extended north- wards to document the position of U.S. Geological Survey (USGS) and Tulane (TU) localities. Bluffs 2 and 3 are illustrated in Text-figures 30 to 33, of which Text-figure 30 is a map drawn on a tape Young gravel terrace Silt with few shell stringers 16930 € Shell bed with most shells at base but Amphistegina throughout assive silt with burrows filled with shells Lensing shell bed packed with Amphistegina 17329 Massive silt 17176 ш Crushed clay with silt partings. Average thickness 10 cm e - 16932 @ Silt, minor cross-bedding, concretions & minor shell lenses. Amphistegina very common in bottom 50 cm 169290 17179 Concretionary bed of packed Amphistegina with shells Sandy silt with minor cross-bedding. Amphistegina common along laminations 90 |? —> ==>» — Probable correlation ^" ES 12 on 40 cm shell bed { === Shell bed, lensing Silt with ?calli id burrows. Cross-bedding visible in lower part A 1m Text-figure 31.—Section exposed in Maury's Bluff 2 on Río Mao. Inset section at lower left represents section exposed across the river at Arroyo Bajón (see Text-fig. 32), and shows the probable corre- lation of the two sections, based on a 40 cm shell bed. Black squares represent NMB localities collected for microfossils and lithologic analyses; black circles represent NMB localities collected for mac- rofossils. See Text-figure 29 for geographic position of this section. See also Plate 7. P Silt O Shell bed N Unfossiliferous silt M Shell bed L Poorly fossiliferous sandy silt K Lensing shell bed, 15-30 cm 169280 J Silt, more massive | Well-bedded sands & silts in channels =| ——— 16918 e 169240 169250 =| —— 16926 @ 17177 m 17178m Н Bedded silts & sands, rather unfossiliferous but shells scattered & on some bedding planes G Cross-bedded shelly silt F Cross-bedded sandy silt E Shell lens D Silt with ?callianassid burrows C Silt, partly covered == B Hard concretionary silt A Ledge of greensand capped with 5 cm shell bed 169220 Text-figure 32.—Section exposed at the mouth of Arroyo Bajón on Río Mao, showing lithological details and stratigraphic positions of NMB collecting localities. Black squares represent NMB localities collected for microfossils and lithologic analyses; black circles rep- resent NMB localities collected for macrofossils. The shell bed on which correlation across the river to Maury's Bluff 2 was based (see Text-fig. 31) is here indicated by “С”. See Text-figure 29 for geo- graphic position of this section. and compass survey of Bluff 2 and its continuation on the right bank at the mouth of the Arroyo Bajón. Lithology Bluff 3 is the furthest upstream. Only the eastern end of this huge, curving cliff was studied (Pl. 7, fig. 3; Text-fig. 33). This is in the strike of the beds at ap- proximately 280? (magnetic); the dip is only a few de- grees to the north and so it would appear that there is a partial stratigraphic overlap with Bluff 2 and its con- tinuation at the mouth of Arroyo Bajón. Silty sands 16912 @ is fallen rubble thought to be Seen from below there is little change. Mostly silty from this bed sand. Shells & concretions not conspicuous Sands & silty sands with minor cross-bedding & scattered concretions. Shells very apparent on bedding surfaces in bottom 2 m Threads of shells broadening into packed lenses | 160190172600) 4—17307m Shell-packed bedding plane (lensing) Silty sand. Low angle cross-bedding outlined by Amphistegina & small shells E Text-figure 33. —Section exposed at the downstream (eastern) end of Maury's Bluff 3 on Río Mao, showing lithological details and stratigraphic positions of NMB collecting localities. Black squares represent NMB localities collected for microfossils and lithologic analyses; black circles represent NMB localities collected for mac- rofossils. See Text-figure 29 for geographic position of this section. See also Plate 7. 32 BULLETIN 323 have cross-bedding that is prominent at some horizons where it is picked out by lines of pink shells of Am- phistegina and molluscan debris (Pl. 7, fig. 4). Though the sands are relatively massive, bedding is obvious from a distance being accentuated by wisps, lines and lenses of shells and by secondary concretions. The section in the cliffs on the right bank at Arroyo Bajón (Text-fig. 32) can be continued across the river in Bluff 2 (Text-fig. 31) as the 3-4? dip allows slow progress upsection. The lithology of these differs slight- ly from what is seen along the base of Bluff 3. In Bluff 2/Arroyo Bajón, there is somewhat more variation in lithology from sands to occasional thin clays with bed- ding more prominent but cross-bedding less well-de- veloped (PI. 7, fig. 1). The fauna is richer with beds up to 50 cm thick packed with well-preserved molluscs and shells of Amphistegina. One such secondarily cal- cified layer is illustrated in Plate 7, figure 2. Shell-filled burrows are frequently visible. Bluff 1 (Pl. 8, figs. 1, 2) consists of uniform silts in the lower part with lines of concretions. Fossils were found scattered throughout and in lenses but the latter did not prove to be as rich as those of Bluffs 2 and 3. Between Bluffs 1 and 2 the track along the right bank passes at the foot of a steep slope overgrown with trees and capped by a cliff from which blocks of limestone had fallen. These were principally of interest for their corals (NMB loc. 16911). Environment The silts and silty sands with shell lenses seem to be of very shallow-water origin at Bluff 3 and Bluff 2. Going upsection, Bluff 1 suggests more open marine conditions with planktic foraminifera and calcareous nannofossils beginning to make their appearance. The isolated sample at the Mao Clay type locality (TU loc. 1337) is deeper water with a rich planktic component. Age Bluff 3 and the Arroyo Bajón bluff have so far pro- duced no dates based on calcareous nannofossils and planktic foraminifera. Bluff 2 has given a weak determination of late Mio- cene, NN11 Zone, based on nannofossils (NMB sam- ple 17329). Bluff 1 (NMB sample 17175) is late Miocene, NN11 Zone, based on nannofossils and this is supported by the coiling ratio of menardiform Globorotalias. A sample from the Mao Clay type locality supplied by Dr. Emily Vokes (TU loc. 1337) is NN16 Zone, based on nannofossils and has a rich planktic fora- miniferal fauna of Globorotalia exilis Subzone of the Globorotalia miocenica Zone, late middle Pliocene. These two determinations agree well. Río Amina General We had intended to sample extensively in the Río Amina but, after a reconnaissance of the river above the Potrero Dam, it was apparent that the logistic prob- lems would not allow us to do any meaningful work in the time available. One disadvantage is access in this part of the river and also the distance that has to be covered to gain any appreciable thickness of section, as the dip is negligible. We sampled a few localities in the middle reaches of the river and these are plotted on Text-figure 34. The individual measured sections are separated on the column (Text-fig. 35). Though they are thought to be stacked in the right order strati- graphically, the amount of section between each out- crop area is uncertain. Only 10 samples were collected for microfossils and four for macrofossils. Lithology The general trend is for the section to become more clayey upwards, beginning at the Potrero Dam where a sandy silt is packed with shells of Amphistegina and rich in small molluscs. Solitary corals were noted in the Cañada de Mera where the overall lithology is still the same. Downriver, silty clays contain a more varied foraminiferal fauna with planktic species becoming common. An isolated sample (NMB loc. 16958) was collected 16957 B к=! Silty clay TU 1248 168070 16956 ш |= clayey silt TU1219 |= ?TU 1220 a 16805, TU 1217@ 16952 ш [.— lr ЫШ, CAÑADA DE MERA 16955m ' 169548 | Sandy silt 16806 © 16953шШ POTRERO DAM 16949 m TU | 16804 6 16950 M 10 Sandy silt 1218 169518 == Text-figure 35. — Schematic column for the central portion of Río Amina, showing relative stratigraphic positions of NMB and TU collecting localities. Black squares represent NMB localities collected for microfossils and lithologic analyses; black circles represent NMB localities collected for macrofossils. DOMINICAN REPUBLIC NEOGENE: SAUNDERS ET AL. 33 on the road from Mao to Santiago south of the Río Yaque at its junction with the road to Potrero Dam; this is 5.5 km northeast of the dam and 1 km west of Guatapanal (Dominican Republic Grid ref. BM 577973). The lithology is a subconchoidally-fracturing clayey silt with microfauna and scattered stick corals. This seems to be equivalent to TU locality 1216. Environment The samples taken in the Río Amina were all fine grained. Those at Potrero Dam suggest open marine but inshore conditions, the weak planktic foraminiferal component comprising those species normally found closest to the coast (e.g., Globigerinoides spp.). The evidence suggests slow deepening upwards. At NMB locality 16956, 25% of the foraminiferal fauna is plank- tic, but species of Globorotalia are virtually absent. By NMB locality 16957, a deeper assemblage has 90% planktics with species of Globorotalia well in evidence. The isolated younger sample at NMB locality 16958 carries a good, deep-water, open-marine assemblage of planktic foraminifera. Age The series of samples at Potrero Dam has given no positive result on foraminifera, but the highest locality (NMB sample 16949) has a poor flora of possible NN12 Zone age. Most other samples taken downriver and considered to be upsection give almost no age results on planktic forms except for NMB sample 16952, which is again 2INN12 Zone. The highest sample (NMB loc. 16957), in an isolated outcrop on the river, has a rich NN12 Zone flora and a rich Globorotalia margaritae Zone fauna. The dom- inance of sinistrally-coiling menardiform Globorota- lias would place the sample almost at the base of the zone and, therefore, at the base of the Pliocene; the determination of NN12 would support this. The isolated NMB sample 16958 taken at the road junction is either from the upper part of the Globo- rotalia margaritae Zone or the lower part of the Glo- borotalia miocenica Zone, and a revised estimate of approximately NN15 Zone, based on nannofossils would agree with this determination. Arroyo Zalaya General The road from Santiago to Janico crosses the Arroyo Zalaya about 9 km south of the city. We collected 0 500m Кт N A =| La Cruz тше 1731 17515 17314 tre" occi TU 1227A 17270 Wi ee 0 КУ A سے‎ сб = / TU 1381 N La Barranca S (4 Rio yaa” ЭИ UC La Boca Text-figure 36.—Map of Cañada Zalaya (area 5 of Text-fig. 3), showing geographic positions of NMB and TU collecting localities. Open Squares represent NMB localities collected for microfossils and lithologic analyses. 34 BULLETIN 323 samples and made a rough survey of a stretch of the stream course above and below the bridge (Text-fig. 36). Above the bridge, some of the strikes are rather irregular but the overall trend is 10—15° due north, which fits the regional pattern seen in the Río Yaque 4 km to the east. The overall lithology is a silt with minor shell beds, minor conglomeratic lenses and, at the eastern end of the traverse (upper part of section), more strongly lignitic silts and sands. Environment The relatively rich foraminiferal faunas suggest open marine conditions with moderate water depths. Rel- atively low energy levels allowed the deposition of lig- nitic silts and sands near the top of the section. Age Rather sparse results on nannofossils suggest a prob- able early Pliocene age. NMB sample 17312 has a good planktic foraminiferal fauna of Globorotalia marga- ritae Zone, early Pliocene age, and is probably from the upper part of the zone. Arroyo Puñal The Arroyo Pufial area is situated approximately 12 km southeast of the city of Santiago (Text-fig. 3). We have not visited these outcrops and Text-figure 37 is given here exclusively to document the location of TU locality 1353. Río Verde The fossil localities on Río Verde are situated ap- proximately 21 km southeast of the city of Santiago (Text-fig. 3). Text-figure 38 is included here to docu- ment the location of TU localities 1250 and 1251. Our field party did not visit these localities. CONCLUSIONS LATE TERTIARY GEOGRAPHY OF THE CIBAO VALLEY During the geological time interval under discussion the Cibao Valley was apparently occupied by a sea- filled graben backed to the south by the Cordillera Central and perhaps closed or partially closed to the north by land across the area now occupied by the Cordillera Septentrional. The southern edge of the trough was steepened by down-to-the-basin faulting that was probably active during deposition. In fact, the tectonic activity of the region is reflected in some of the structures seen in the sediments, especially the large amount of redeposited sediment. The trough lies within the deformed belt that marks the northern limit of the Caribbean Plate and is still S \ = puño! Tu 1353 Yl arr) d ( 1 » Los Indios f \ Text-figure 37.— Мар of Arroyo Puñal (area 8 of Text-fig. 3), showing geographic position of TU locality 1353. today within an area of shallow earthquake activity (Case and Holcombe, 1980). The Cordillera Central provided a plentiful supply of clastic material, much of the coarser perhaps being second generation components that were derived from earlier conglomerates and thus were already rounded. The sparsity of mangrove pollen in Río Gurabo sam- ples suggests an absence of brackish water swamps along the coast though the dominance of ferns with palms could result from freshwater swamps backed by quick- ly rising ground, covered by savanna vegetation and not heavily forest-covered. The main suggestion is of great instability along the southern margin of the trough, with sediments being periodically moved into deeper water down an appre- ciable slope. A stable shelfis missing and, though water clarity favored coral growth, instability of the bottom prevented luxuriant reef development. И \ | . gue eg x „ S © ш ш E El 5 —- (16958) 8 = 5 аня Tales sis E ==| clayey silt F едае 2. | coral 2 5 " fr Ists АК $ NN 141.3 as = ЧЕ о o a = weedy $ у lign &s " س‎ m E > i mu El E $ E " SEE i o " Six. Е HM Arroyo E NN13 else - 2 “~al sits Hondo E EIS EL S| ~~ e : $ Ese t. | slits = pe s JE 5 si coral Ed m ~7~|slts Barranca 3 Eti onn 216 : NN12| 8 22. ~ ? also © Й SIE 8 о |22 > Asus (16957) анаа |2: Es ү, Potrero Eu E gr aeri AE > congls nA) Bluff 1 zr] sits Dam д org А — dt فل‎ uM ® NN11 3 Ra XD 8 E23 us Ze sits ne. $ ш 8 Arca | 5 26] : en 1. А 35 Ф|: beds | 3 [-— ziz) congl. rroyo > 2 OF Сар Iren | ee E co Sar ao ern tolam A ae ir & sit López "n ш > e o Se > [sit 3 o = д & López = = ? ES pebbly ge ¡EN sits SC t = 2 Ш m— Ist |congls > Qu RS & Baitoa Qu oz congls SESS gue al SS Al © © si congls o Oo Ea me le WEST EAST There is no clear proof of a shallowing or infilling Of the trough at least as late as middle Pliocence; the reverse may be the case. Evidence is in favor of the major source of supply being from the Cordillera Central to the south, but some influx of material from the north or even along the trough axis cannot be ruled out. The importance of the Cordillera Central as a source of supply is also seen on its southern side, in the En- riquillo Trough, where a turbiditic sequence more than 3000 m thick is found in the late Miocene and probably continuing into the early Pliocene (Biju-Duval et al., 1982). Tables 3 and 4 and Text-figure 39 attempt to sum- Marize what is known at this stage of the project. Table 3 relates the three major river sections studied, and the more scattered localities in the other rivers, against a time framework which must be considered as ap- proximate only. The zonation used is given in Table 4, which is drawn to a linear time scale to show better the relationship of the various lithologic units. Text- figure 39 draws attention to the situation of two of the important river sections in relation to the geography of the southern flank of the trough through time. It has been included because the vertical stratigraphic col- umns of Text-figures 6 and 16 give a false impression ofthe upward change in facies, ignoring the large north- ward shift in location. The separate slice shows some of the lateral facies changes between the two sections. Although the sequence in the Río Cana containing the Arca beds is shown on the slice, it is likely that it would not have extended that far into the trough. Oversim- plification seems inevitable in this figure. 36 BULLETIN 323 MA NN/NP| FORAMINIFERAL ZONES Hio Epod AOS ZONES section section mo NN20 1 |PLEIST! NN19 Globorotalia t. truncatulinoides [7NN18—] ; Е £ lu РМА Globorotalía tosaensis tosaensis 3|uz- ммте Globorotalia miocenica === 4|9 [-NN14—] ME Map ZZ ч WI .NNI3_| G/oborotalia margaritae ^ Gurabo Г 51° INN12 Г rn Г 6 Y 7 Globorotalia humerosa Y aaa Y Apos 12 " Y 8| S|NN11 4 9 10 Globorotalia acostaensis " NN10 ? — | ммо L—G/oborotalia menardii 12 Globorotalia mayeri ? ш w| NN8 |. SM wb 13123 NN7 K=Globigerinoides ruber ш 5 |. Globorotalia fohsi robusta ? 14| O S | Globorotalia fohsi lobata 15 | 2 | NN6 | Gioborotalia fohsi fohsi 7 I od pM E [ — Globorotalía fohsi peripheroronda 27 E £ E 16 NN5 Praeorbulina glomerosa Y gle 17 ыд] Globigerinatella insueta 1 5: È 18 NN3 Catapsydrax stainforthi 19 > = d Cat drax dissimili. atapsydrax dissimilis 21 NN2 ia М 22 | 2:5 NNI Globigerinoides primordius | 24 Globorotalia kugleri Y R 25 | m Y £ _ 26 pong T. Y 5536 S| NP25 | Globigerina c. ciperoensis 2 Y 3859 S ? 4 Y $254 28 EZ и ш — = £ 29| 2 | 8 Ж ш 30) 0 „ NP24 ! | | 5 О 5 Globorotalia opima opima | z 32| 33 m Y о 33 NP23 — ; 7 5 Globigerina ampliapertura Г > Fides cio Ж 35 ZLNP22 | Cassigerinella chipolensis/ | 36 Ш | NP21 Pseudohastigerina micra 37 NP20 DOMINICAN REPUBLIC NEOGENE: SAUNDERS ET AL. 37 Table 4.—Planktic foraminiferal (NP) and nannofossil (NN) zones, and absolute ages of Neogene strata in the Rio Gurabo and Rio Yaque del Norte sections. The equivalence of the NP and NN zones is largely after Bolli, Saunders, and Perch-Nielsen (1985). The juxtaposition ofthese zonations with the linear time scale (in millions of years B.P.) is calculated from Berggren et al. (in press). This use of a linear time scale shows the time ranges of the sediments seen in the field, and particularly emphasizes the magnitude of the major unconformities. Space does not allow the subdivision ofthe Globorotalia miocenica Zone into an upper Globorotalia exilis Subzone and a lower Globig- erinoides trilobus fistulosus Subzone. The Globorotalia margaritae Zone is also subdivided into an upper Globorotalia margaritae evo- luta Subzone and a lower Globorotalia margaritae margaritae Sub- zone, but this subdivision has not been made here. GENERALIZED GEOLOGIC HISTORY Oligocene The Oligocene rocks are rather loosely grouped to- gether in the Tabera Group. Various lithologies are involved, from limestones to suites of conglomerates. Varying degrees of folding and planation followed their deposition but these movements should be seen in the context of the long time interval represented every- where that we have seen the unconformity below the Miocene and younger series. In the Río Cana, the ‘base- ment' rocks are of unknown age. In the Río Gurabo, Rio Gurabo (900 m vertical section over 14 km lateral distance) the limestones are of probable Oligocene age though they could reach as high as early Miocene. This gives a minimum time represented by the karst surface of 12 million years and, more probably, as much as 20 million years. In the Río Yaque del Norte, an inter- mediate series of rocks (the Baitoa Formation) is found between the conglomerates of the Janico Formation and the late Miocene age equivalents of the basal Cer- cado beds in the western river sections. There is still room for a time gap of several million years as rep- resented by the erosional surface that is well displayed in the cliffs at Baitoa (Text-fig. 28). Middle Part of the Miocene The sediments of the Baitoa Formation on the Río Yaque del Norte are considered to occupy part of the time interval between basal Miocene and late Miocene that is represented by unconformities in the Río Cana and Río Gurabo. Either this was a low area in the tectonically active southern edge of the trough, or equivalent deposits were laid down but later removed from other segments of the margin. Late Miocene The beds above the basal unconformity in the Río Cana are unfossiliferous and may even have been non- E Cordillera Central 10 km Time: Pliocene TRUE 1 = ERES _ MO : SR ў М Mao Formation ? — Shoreline Miocene « Rio Cana —— (1200 m vertical section over 15 km lateral distance) Fri Mao Formation Gurabo Formation fex Arca beds Cercado Formation Text-figure 39.—Block diagram showing the relationship between Neogene sections on Río Gurabo and Río Cana. The sedimentary record reflects a deepening that is partly due to increasing distance from the shoreline as one proceeds downriver. The lithologic differences between the two columns (only 10 km apart along strike) are apparent. Some aspects of this variation are shown on the block slice, where the disappearance of the thick limestone mass seen in Río Cana is shown as a possible wedge-out, with new minor limestones coming in at a slightly higher stratigraphic level in Río Gurabo. A possible wedge-out of the section containing the Arca beds is shown on the block slice, though this lithology may not have extended as far north into the trough as is suggested. Showing the position of the shoreline through time is hypothetical, as its repeated oscillations due to regressions and transgressions in the framework of a subsiding trough are difficult to forecast from the information at hand. A rapidly-rising sea level at the Miocene-Pliocene boundary seems very likely, and this is reflected particularly in the deeper-water facies of the Río Gurabo section at this time. This is why we show the shoreline further south at the east edge of the block. A comparative amount of deepening is not seen in the Río Cana; perhaps this reflects variable subsidence along the length of the trough. 38 BULLETIN 323 marine in origin. The earliest beds in the Río Gurabo are, in contrast, already shallow marine with some possible brackish influence. Moving upwards in the Río Cana very shallow marine deposits have occa- sional shell and coral debris and are succeeded by a series of sands and silts containing a number of Arca beds arranged partly in rhythmic sequences. This in- terval is largely represented by the cross-bedded Am- phistegina sands of the Río Gurabo. An interesting possibility suggested by preliminary ostracode datum points supplied by Dr. van den Bold and plotted here in Table 2 is that the part ofthe section containing the Arca beds themselves in the Río Cana is missing in the Río Gurabo because it has been cut out by erosional overstep of the basal conglomerate of the Gurabo Formation. Such a possibility 1s indicated in Table 3 and on the block diagram (Text-fig. 39). In the Río Cana the distance between the first occurrence of Gangamocerithidea? plicata + Cytherella A and the first occurrence of Radimella is 117 m whereas in the Río Gurabo the distance has shrunk to 14 m, occupied predominantly by the basal conglomerate of the Gu- rabo Formation. The position of the shallow-marine silts and sands of Maury's Bluffs 2 and 3 in the Río Mao is uncertain, but they could be equivalent to the Amphistegina sands of the upper Cercado Formation or of those in the lower Gurabo Formation. The Arroyo López rubble bed on the Río Yaque del Norte is also not well tied down within the late Miocene, where it is placed at the moment on rather doubtful evidence. Thelatest Miocene in the Río Cana seems condensed in comparison with other sections. It remains very shallow and certainly has a number of hiatuses within it. In the Río Gurabo the interval is represented by a sequence of fossiliferous silts with frequent interbeds that are particularly rich in corals, most of which show signs of displacement, probably on a slope. In the Río Yaque del Norte, the top of the Miocene has a con- siderable sequence of limestones at least the bottom of which appear to be truly reefal. Early Pliocene The coral-rich silts and the occasional sands of the Río Cana continue to indicate deposition in shallow water and these are then followed by the thickest se- quence of limestone seen in the region. Our knowledge of the environment of these beds is, unfortunately, incomplete. Though some levels may suggest reef framework, much would seem to be debris derived from the reef. The Río Gurabo section shows a much greater in- crease in water depth at the base of the Pliocene than is seen in the Río Cana. A deep-water silt environment has only a small amount of allochthonous material being introduced at first, but, higher in the sequence, repeated influxes of terrigenous and shallow-marine debris are seen. A possible rise in sea level linked to a worldwide eustatic change is referred to in the section on the age of the Río Gurabo beds. Little is known of the early Pliocene further east except for a number of outcrops along the Río Yaque del Norte that again suggest relatively deep water with the change taking place rather suddenly near the base of the Pliocene. Middle Pliocene Outcrops are, on the whole, sparse in this youngest interval seen. Sands and grits in the Cana and Gurabo sections could still have come downslope into deep water while, in the Río Mao, the type locality of the Mao Clay carries a deep-water foraminiferal fauna. In the Río Gurabo occurs a pebbly limestone level that is younger than the thick limestones seen in the Río Cana. If the latter are considered to be Mao Ad- entro Limestone, it is difficult to place the Río Gurabo occurrence under the same name. The Mao Adentro Limestone at its type locality (USGS locs. 8532, 8533 on Text-fig. 29) was described by T. W. Vaughan (Vaughan et al., 1921, p. 73) as 21 m of conglomeratic limestone interbedded with bluish shale and underlain by 3.8 m of laminated sands and silts. The precise age of this horizon is not known by us. The relation of these various limestones one to another has yet to be resolved. The highest level seen in the whole area is the Tulane locality 1337 (Text-fig. 29) from the type locality of the Mao Clay on the Río Mao. Our measured sections in the Río Cana and Río Gurabo represent, at most, a time span of five million years. This gives a maximum deposition rate of 24 cm/ 1000 years for the Río Cana and 18 cm/1000 years for the Río Gurabo. A considerable proportion of the time span is, however, probably represented by the many hiatuses associated with minor conglomerates as well as with several more major ones. Also, the overall accumulation rates do not show the considerable vari- ations that occur within each section. DOMINICAN REPUBLIC NEOGENE: SAUNDERS ET AL. 39 APPENDIX 1 THE Use OF FORMATION NAMES The difficulty of applying formation names outside their immediate type areas will be apparent from the content of the present paper. However, for commu- nication between workers a minimum ofnomenclature 1s needed. For this reason, we here define those names that we use. They can only be considered as mappable units in the field in the broadest sense. Where no names are used as, for example, above the Baitoa Formation in the Río Yaque del Norte section, it is because we feel that to do so can only add confusion at this stage. The definitions of terms follow those published in Hedberg (1976): Lectostratotype: a stratotype selected later in the ab- sence of an adequately designated original strato- type. Hypostratotype: a stratotype designated to extend knowledge of the unit or boundary established by a stratotype to other geographical areas or to other facies. It is always subordinate to the holostratotype. Baitoa Formation Author. — C. W. Cooke, 1920. Type locality. — Right bank cliff downstream from Baitoa on the Río Yaque del Norte. The difficulty of collecting from this near-vertical cliff face (Text-fig. 28) led Cooke to say that fossils could be found on the trail leading from Baitoa to Santiago, though the exposures are poor and fossils not abundant. The type locality is incorrectly placed too far downstream by Bold (1968, Text-fig. 6). Hypostratotype. — Erected in the present work on the right bank of the Río Yaque del Norte below its con- fluence with the Río Bao and up- and downstream from the small gorge caused by the entry of the Arroyo Hon- do (Text-fig. 21). As the type locality was clearly stated geographically, we do not take our section to be a lec- tostratotype and as it is about 400 m away from the original we consider it to be a hypostratotype in the sense given above. Photographic views of the section looking upstream and downstream are given on Plate 9. Base of formation. — At the unconformable contact With the underlying Tabera Group (Represa Formation ы Palmer, 1979) given as Horizon А on Text-figure 5. Top of formation. — Not seen. Thickness.—55 m were measured at the hypostra- totype with a further 20 m (approximate) visible higher in the cliff. Northwards, towards the village of López, It is concealed below low ground. К Аре.— Оп ostracode апа molluscan evidence the age 15 taken as late early to early middle Miocene. Cercado Formation Author. —C. J. Maury, 1919. This was a new for- mational name replacing her Aphera islacolonis For- mation (Maury, 1917b). Type locality. —No single type locality was given. Instead, Maury included her Bluffs 2 and 3 on the Río Mao near Cercado, Zone G at Los Quemados on the Río Gurabo, and Zones I and H around Caimito on the Río Cana. The name indicates that she considered the Río Mao localities as constituting the type area. However, these outcrops are of limited vertical extent and show no contacts with formations above and be- low. Lectostratotype on the Río Gurabo. —Both the Río Gurabo and the Río Cana possess relatively uninter- rupted sections through beds originally designated as Cercado Formation by Maury. As the lectostratotype, we choose the section in the Río Gurabo because it has a clear top marked by the unconformity at the base of our designated Gurabo Formation, its lower part is more continuously exposed and more certainly mea- sured, and it does not have the complication of the Arca beds that Maury later moved into her Caimito Formation. Base of formation. — The unconformable contact of fossiliferous sands and pebble beds on the probable karstic surface of the Tabera limestones (Moncion Limestone of Palmer, 1979) at Monte Higuero. Top of formation. — The unconformable overstep of the basal conglomerate of the Gurabo Formation at 145 m above the base of the stratigraphic column of Text-figure 6. This is approximately 4.25 km south of the old bridge at Los Quemados. Thickness.— 145 m. Age.— Late Miocene, NN11 Zone, based on calcar- eous nannofossils. Hypostratotype on the Río Cana. —We would take the bottom 275 m of the Río Cana section as Cercado Formation. This would include the section at Caimito listed by Maury (1917b, pp. 25, 26) and would include the Arca beds. This section she later designated as the Caimito Formation (Maury, 1931), butas there is some confusion about her actual meaning (see p. 10) and as the beds have not been found elsewhere, we do not continue to use the name. Base of formation. — The unconformity with folded sandstones and shales of the Cordillera Central at the village of Cementerio. Top of formation. — The base ofa conglomerate (des- ignated as the base of the Gurabo Formation for this section) at which level the lithology changes from pre- 40 BULLETIN 323 dominantly silts and sands below to predominantly calcareous silts above. Gurabo Formation Author.—C. J. Maury, 1919. This was a new for- mational name replacing her Sconsia laevigata For- mation (Maury, 1917b). Type locality. —No single type locality was given. Instead, Maury included Zones F to A on the Río Gurabo around Los Quemados, and Bluff 1 on the Río Mao. Lectostratotype. — We here designate the middle part of the Río Gurabo section, which includes within it Maury's Zones F to A, as the lectostratotype. It extends from a point approximately 4.25 km (measured in a straight line) upstream from the old bridge at Los Que- mados, to a point 3.0 km downstream from the same bridge (see Text-figs. 4, 6). Base of formation.— The unconformable base of a major conglomerate at 145 m on the stratigraphic col- umn. This bed oversteps the Cercado Formation be- low. Top of formation.— The erosional base of a series of channeled sands and conglomerates at 570 m on the stratigraphic column. Thickness. —425 m. Age.—Late Miocene and early Pliocene, NN11 to NN13 Zones, based on calcareous nannofossils, and ?Globorotalia humerosa Zone to Globorotalia marga- ritae Zone, based on planktic foraminifera. Hypostratotype on the Río Cana. — We would take the base of the formation at the base of a conglomerate at 275 m above the base of the stratigraphic column of Text-figure 16. The top of the formation is taken at 575 m at the base of channeled sands and conglom- erates overlying calcareous silts. Mao Formation Author. —P. J. Bermudez, 1949, p. 15. He included the Mao Adentro Limestone and Mao (=Valverde) Clay of Cooke (1920) together with “a thick section of silts, sands and conglomerates overlying these clays and limestones”. He made two members, the lower comprising the Mao Adentro Limestone and, where limestone lenses are not present, clays and minor sand- stones and limestones (presumably Cooke’s Mao Clay). He gives the type locality of the Mao Adentro Lime- stone as being on the Río Gurabo, but this is incorrect, as it was described by Vaughan (in Vaughan et al., 1921) from Mao Adentro on the Río Mao. The upper member of sandstones and conglomerates is said to have its type locality “on the lower course of Río Cana and Río Gurabo” (Bermudez, 1949, p. 15). Hypostratotype on the Río Cana. — This seems to be one of the best reference sections for the formation. Base of formation.— At 575 m on the stratigraphic column (Text-fig. 16) below a series of sands and con- glomerates that overlie calcareous silts of the Gurabo Formation but underlie the limestone. This follows the concept of Bermudez (1949) who considered that such beds defined the base of the formation. In the Río Cana the Mao Adentro Limestone has been measured as 340 m thick. Above it, outcrops are nonexistent across low land that probably conceals Mao Clay. The section finishes in sands and conglomerates that must be those referred to by Bermudez (1949) as constituting his up- per member. Thickness.— From the base to the highest outcrop the thickness is thought to be 600 m though measure- ments are problematic between the highest outcrops. Hypostratotype on the Río Gurabo. — The base of the formation is taken at 570 m on the stratigraphic col- umn (Text-fig. 6), where channeled sands and con- glomerates overlie calcareous silts. The section of 340 m between this point and the highest outcrops is dif- ficult to subdivide, as a limestone mass equivalent to that seen in the Río Cana is not evident. Age of formation. —In both Río Cana and Río Gu- rabo sections, the formation begins in the early Plio- cene and continues into the middle Pliocene— that is, from approximately NN14 Zone to NN15 Zone or above, based on calcareous nannofossils and from the upper part of the Globorotalia margaritae Zone to the Globorotalia miocenica Zone, based on planktic fora- minifera. The Mao Adentro Limestone in the Río Cana is considered to represent the upper part of the Glo- borotalia margaritae Zone. The age of the type locality of the Mao Clay on the Río Mao is NN16 Zone, based on calcareous nanno- fossils, and Globorotalia exilis Subzone, based on planktic foraminifera. DOMINICAN REPUBLIC NEOGENE: SAUNDERS ET AL. 41 APPENDIX 2 REGISTER OF NMB MICROFOSSIL COLLECTING LOCALITIES (s = same spot; G = geochemical analysis; M = paleomagnetic analysis; T = thin-section analysis) JS [John B. Equiv- Saun- alent NMB ders] macro- Other studies locality field fossil (see Intro- number number localities duction) Lithology and faunal remarks Río Gurabo (1978 field season) 15929 3412 15803 G hard massive silt with few whole molluscs and many fragments, some fora- minifera 15930 3413 G M T hard massive silt 1.8 m above 15929 15931 3414 G hard massive silt 2.3 m above 15930 15932 3415 G hard massive silt 2.6 m above 15931 15933 3416 G hard massive silt 2.6 m above 15932 15934 3417 15804 s G hard silt with lenses and infilled borings of very fine sand packed with 4m- phistegina, small molluscs, and bryozoa 15935 3418 15805 hard silt weakly bedded, with molluscs mostly as small fragments forming part of the matrix, 2 m below 15934 15936 3419 G hard massive silt rich in molluscs and foraminifera, poorly sorted, 1.8 m below 15935 15937 3420 G hard silt with diverse fauna scattered throughout and concentrated in lenses and burrows 15938 3421 G massive weathered silt rich in Amphistegina with molluscs and rotted corals 15939 3422 G variable silt to silty sand, fauna as for 15938 15940 3423 G massive silt rich in Amphistegina, molluscs, echinoid impression, rotted corals 15941 3424 15806 s G hard massive silt with diverse fauna scattered and in pockets 15942 3425 G hard massive silt with common Amphistegina showing no orientation, coral fragments conspicuous, minute lignitic fragments common 15943 3426 15807 G M hard silt with bedding suggested by orientation of Amphistegina and lignite fragments 15944 3427 G mm as for 15943 15945 3428 G silt and very fine sand, as for 15943 15946 3429 G as for 15945 15947 3430 hard silt very rich in Amphistegina 15948 3431 (a) silt and (b) coral debris bed 75 cm above (a) 15949 3432 silt 15950 3433 silt 15951 3434 silt 15952 3435 silt 15953 3436 | 15809 12-15 cm bed of harder silt packed with Amphistegina 15954 3437 fine sand with molluscs and Amphistegina 15955 3438 thin layer particularly rich in Amphistegina 15956 3439 4—5 cm dark organic silty clay immediately above 15955 15957 3440 fine sand immediately above 15956 15958 3441 15810 sandy silt with sparse fauna 15959 3442 2 cm weathered grey to olive-green clay 15960 3443 15811 cubical weathering sandy silt 1.4 m above 15959 15961 3444 silt 15962 3445 15812 s 5 cm (maximum) thick lens of shell debris, foraminifera, bryozoa, corals, trace- able for 4 m 15963 3446 15813 silt 15964 3447 15814 10-15 cm shell bed 15965 3448 15815 G hard lens traceable for 20-30 m of shells, shell fragments and corals 15966 3449 15816 G M on strike with end of 15965; less hard and with fauna more scattered 15967 3450 15817 G sandy silt; poor fauna but with scattered molluscs 42 BULLETIN 323 APPENDIX 2 Continued JS [John B. Equiv- Saun- alent NMB ders] macro- Other studies locality field fossil (see Intro- number number localities duction) Lithology and faunal remarks Río Gurabo (1978 field season) 15968 3451 G silt 4.5 m above 15967 15969 3452 15818 M G shelly silt passing down into poorly fossiliferous sands 15970 3453 G better clay above 15969 separated by distinct bedding plane break 15971 3454 15819 17 cm sand in silt; contains silt balls up to 7 cm, shell debris, echinoid spines, etc. 15972 3455 G silt 15973 3456 G silt 3.5 m above 15972 15974 3457 G hard silt 15975 3458 15820 G about 1.8 m above 15975 in same silt 15976 3459 G 50 cm above 15975 in same silt 15977 3460 G blocky silt, slightly weathered 15978 3461 as for 15977 15979 3462 G M silt with foraminifera visible 15980 3463 G silt 15981 3464 G blocky silt as before 15982 3465 G silt with sparse molluscs; probable good microfauna 15983 3466 G silt showing ellipsoidal weathering 15984 3467 G silt probably good for microfauna 15985 3468 G silt 4 m above 15984 15986 3469 G uniform silt 15987 3470 G as for 15986 but more weathered 15988 3471 G sli uniform clayey silt 15989 3472 G as for 15988 15990 3473 G as for 15988 but slightly more micaceous and fissile 15991 3474 G as for 15988 but slightly richer in fauna 15992 3475 T poorly sorted silty sand with shell debris, Amphistegina, etc. 15993 3476 T poorly sorted sand, less rich than 15992 15994 3477 G poorly sorted sandy silt with shell debris, Amphistegina, etc. 15995 3478 G M clayey silt with mollusc fragments, etc. 15996 3479 T coarse, badly sorted sand 15997 3480 pebbly sand with clayey silt clasts up to 7 cm from base of bed 15998 3481 G clayey silt mass, 20 cm ovoid, from poorly sorted sand matrix 15999 3482 G very poorly sorted medium to coarse sand near base of bed 16000 3483 D poorly sorted medium sand higher in bed than 15999 16001 3484 clayey silt from top of a sand bed; lignitic fragments common and shell debris 16002 3485 clayey silt with scattered larger grains; lignitic fragments, etc., as for 16001 16003 3486 hand specimen of concretionary flame structure 16004 3487 d sand associated with flame structure 16005 3488 T fine to medium sand 16006 3489 very fine sand with infrequent burrows filled with coarser sand 16007 3490 G clayey silt with mollusc debris and foraminifera 16008 3491 G silty clay with lignite fragments and visible fauna 16009 3492 ^ sandy clayey silt with scattered coarser grains; foraminifera and mollusc debris 16010 3493 clayey silt rich in small molluscs, shell debris and foraminifera 16011 3494 very poorly sorted pebbly sand 16012 3495 very poorly sorted coarse to medium sand 16013 3496 bedded sandy silt 16014 3497 T pebbly sand with silt clasts and wood fragments 16015 3498 G clayey silt with mollusc fragments and foraminifera concentrated in burrows 16016 3499 massive silt rich in molluscs, foraminifera and lignite fragments DOMINICAN REPUBLIC NEOGENE: SAUNDERS ET AL. 43 APPENDIX 2 Continued JS [John B. Equiv- Saun- alent NMB ders] macro- Other studies locality field fossil (see Intro- number number localities duction) Lithology and faunal remarks 16017 3500 G shattered clay with foraminifera and small Pinna 16018 3501 G silty clay very rich in small molluscs (scaphopods) and foraminifera 16019 3502 G slightly silty clay less rich in fossils than 16018 16020 3503 G silty clay with molluscs as fragments and casts 16021 3504 as for 16020 16022 3505 | 15821 silt and silty clay with fauna mainly in sand pockets = 16023 3506 silty clay with more silty pockets; molluscs and foraminifera 16024 3507 uniform silty clay; foraminifera visible 16025 3508 T very poorly sorted pebbly sand with worn Amphistegina 16026 3509 G silt 16027 3510 G silt 1.5 m above 16026 16028 3511 G silt with discontinuous lenses of coral debris 16029 3512 20 cm thick clay 16030 3513 G M coral debris bed with some heads up to 30 cm 16031 3514 G dark colored silt with foraminifera visible 16032 3515 lensing sand in the silts of 16031 and 16033 16033 3516 G silt with foraminifera visible; 80 cm above 16031 16034 5017, G silt with scattered molluscs and corals 16035 3518 G silt less rich in macrofauna than 16034 16036 3519 G silt as for 16034 16037 3520 G silt as for 16034 16038 3321 G silt as for 16034 16039 3922 G near base of 3.8 m silt rich in foraminifera 16040 3523 G top of silt of 16039 16041 3524 15826 s G M 30 cm thick clay with scattered pebbles 16042 3525 10-40 cm sand with pebbles up to 10 cm; coral debris 16043 3526 G 2.5 m bed of silt with scattered shells and coral fragments 16044 3527 G 40 cm bed of coral debris packed in silt matrix 16045 3528 G 1.2 m bed of silt 16046 3529 a) 50 cm sand with clay balls and pebbles passing laterally into b) silt 16047 3530 50 cm conglomerate with erosive base and transitional top 16048 3531 G M center of 2 m silt 16049 3532 G more clayey top of 2 m silt of 16048 16050 3533 15825 s G 40 cm coral debris bed 16051 3534 G 1.5 m silt with scattered molluscs and few coral fragments 16052 3535 G 50 cm coral debris bed as 16050 16053 3536 15824 s G 50 cm lensing conglomerate and silt with molluscs and corals 16054 3537 : G M near bottom of 2.7 m silt with pockets of small shells 16055 3538 G near top of silt of 16054 16056 3539 15823 G 2 m silt separated from 16055 by a fault 16057 3540 15822 s G 45 cm packed coral debris and molluscs in silt 16058 3541 G 1.6 m silt 16059 3542 30 cm lensing coral bed 16060 3543 10 cm shattered tectonized dark clay 16061 3544 G from middle of 2.4 m silt 16062 3545 G near bottom of 1.3 m silt 16063 3546 50 cm conglomerate 16064 3547 G 20 cm silty clay between conglomerates 16063 and 16065 16065 3548 thin sandy conglomerate 16066 3549 thin conglomerate rich in corals 16067 3550 G 4 m silt with minor lenses of corals; sample 1.5 m above conglomerate of 16066 16068 3551 G top of 4 m silt immediately below sand/silt of 16069 16069 3552 G finely interbedded sand and silt LA BULLETIN 323 APPENDIX 2 Continued NMB locality number number localities JS [John B. Equiv- Saun- alent ders] macro- field fossil Other studies (see Intro- duction) Lithology and faunal remarks 16070 16071 16072 16073 16074 16075 16076 16077 16078 16079 16080 16081 16082 16083 16084 16085 16086 16087 16088 16089 16090 16091 16092 16093 16094 16095 16096 16097 16098 16099 16100 16101 16102 16103 16104 16105 16106 16107 16108 16109 16110 16111 16112 3567 15827 3578 15828 3587 15829 3095 15831 s 10 100 Се Фос OO Сое ZA aoo qc Q —_ «ы Río Gurabo (1978 field season) = 2.5 m silt; sample taken 2 m above 16069 near top of silt with sandy nodules pockets of sand (sampled) in 40 cm silt with pebbles and corals 50 cm conglomerate with corals sampled at bottom (16073) and top (16075) with 10 cm slightly pebbly silt 20 cm above base (16074) 3 m silt with pebble and shell pockets and irregular thin layers of corals sampled at top immediately below lensing pebble bed in middle of 80 cm silty sand 1 m from top of 4.5 m uniform silt 1 m from base of 3 m clayey silt with shell fragments; sampled immediately below 2 cm undulating pebbly sand layer 60 cm below top of silt 16079 thin conglomerate with corals; load structures at base near base of 2.5 m silt rich in shell fragments; immediately above 16081 40 cm coral debris bed; possible correlation with 16050 in middle of 1.4 m silt rich in foraminifera 30 cm coral debris bed; possible correlation with 16052 silt rich in foraminifera 2.5 m above bed 16085 silt approximately 7 m above 16086 silt approximately 2 m above 16087 and just below conglomerate with corals silt 1.5 m below hard bed 16090 40 cm calcareous sandstone with harder and softer parts silt 1 m above 16090 1.2 m highly fossiliferous hard silt with pockets of fine conglomerate blocky silty clay 20 cm above top of 16092 shelly silt rich in foraminifera lens of coral fragments with nests of delicate terebratulid brachiopods hard lens 9 cm (maximum) thickness 1.8 m above 16095 near base of more than 8 m silt rich in foraminifera near top of silt 16097 thin bed of corals and shell debris packed in silt at top of 1.2 m silt hard coral-rich bed up to 30 cm several meters of silt with isolated coral heads and lenses of coral debris; sampled 2 m above 16101 silt very rich in foraminifera 2.5 m above 16102 silt with scattered coral heads 1 m above 16103 and 2.25 m below a 15 cm coral rubble bed silt with foraminifera and ostracodes visible 40 cm above 15 cm bed silt with pockets of shell debris 5 m above 16105; very rich in foraminifera variable thickness pebble bed with shell fragments and whole shells silt 1.6 m above 16107 isolated outcrop of very hard conglomeratic shelly calcareous sandstone. Varied fauna of foraminifera, corals, echinoid spines, and molluscs 1.5 m cross-bedded conglomerate of well-rounded pebbles in a coarse sand matrix; sorting appears bimodal pebbly sandy clay with grains of 0.1 to 2 cm in a clay matrix with shell fragments siltstone with bedding picked out by common lignite fragments; mollusc frag- ments and casts DOMINICAN REPUBLIC NEOGENE: SAUNDERS ET AL. 45 APPENDIX 2 Continued JS [John B. Saun- Equivalent NMB ders] macro- Other studies locality field fossil (see Intro- number number localities duction) Lithology and faunal remarks 16113 3596 T pebbly sandy claystone with shell fragments 16114 3597 ap bedded poorly sorted sandstone with silt partings; lignite fragments 16115 3598 sandy silt 16116 3599 T sandy clayey silt with lignite fragments 16117 3600 15832 clayey sandy silt with pebbles up to 1.75 cm; shell fragments and foraminifera; this is perhaps a transported mass 16118 3601 calcareous cemented sands and pebbly sand layers near 16117 16119 3602 silt from a series of cross-bedded silts, sands and conglomerates 16120 3603 15833 G pebbly silt with molluscs and foraminifera from cross-bedded silts, sands, and conglomerates 16121 3604 interbedded silt and sand with fine lignitic material on partings 16122 3605 G pebbly silt very rich in shells 16123 3606 15835 G shelly silt 16124 3607 15836 G silt with molluscs, corals, bryozoa, and foraminifera 16125 3608 G interbedded softer and harder silt with rich coral debris in the latter 16126 3609 G M 1.5 m below 16125 and also in the softer silts 16127 3610 15837 G hard silt between cemented layers; 4 m below 16126 16128 3611 G cemented layer with softer pockets 20 m laterally from 16127 16129 3612 15841 G silt with coral debris 16130 3613 15840 G silt with coral debris 2.5 m below 16129 16131 3614 15839 s G silt with coral debris 3 m below 16130 16132 3615 G silt with coral debris 3.3 m below 16131 16133 3616 M silt 16134 3617 15842 G 15 cm discontinuous concretionary siltstone 1.2 m below 16133 16135 3618 15843 G sand rich in Amphistegina 16136 3619 15844 G sandy silt with some harder layers; rich in Amphistegina and soritids 16137 3620 | 1-5% G taken over 1 m of hard silt rich in small coral debris 16138 3621 G as for 16137 and 5 m below 16139 3622 G sand 16140 3623 G silt rich in miliolids; less corals than above and below 16141 3624 G silt rich in corals including Porites and small Siderastrea 16142 3625 G weathered silt with carbonaceous material (1 piece 30 cm); 2.3 m below 16141 16143 3626 silt with more varied corals including Porites and Siderastrea; 1.5 m below 16142 16144 3627 15853 s G silt below concretionary ledge; 2 m below 16143 16145 3628 15851 s G silt 1 m below 16144 16146 3629 soft and hard silt above ledge with 45 cm coral head in position of growth 16147 3630 | G silty sand 5 cm below 16146 and probably same horizon as 16140 16148 3631 15860 G silt rich in foraminifera including large soritids and Amphistegina 16149 3632 G 3-4 cm layer of silt and clay with carbonaceous material and gypsum 16150 3633 G base of a coral debris bed with foraminifera visible 16151 3634 G M silt as for 16148 16152 3635 15863 G soft silt interbedded with hard; rich in macrofauna; 65 m on strike and 4.5 m below 16151 16153 3636 G silt rich in molluscs and solitary corals; richer coral levels above 16154 3637 15864 G silt 4.5 m below 16153 and less rich 16155 3638 15865 G shelly silt rich in vermetids 16156 3639 15866 s G silt with molluscs including oysters, solitary corals and foraminifera 16157 3640 15867 G silt with molluscs and foraminifera 16158 3641 15868 G silt as for 16157; a 20 cm fine sand layer close by 16159 3642 15869 G weathered sandy silt 16160 3643 15870 s G silt with molluscs and solitary corals 46 BULLETIN 323 APPENDIX 2 Continued JS [John B. Saun- Equivalent NMB ders] macro- Other studies locality field fossil (see Intro- number number localities duction) Lithology and faunal remarks Río Gurabo (1978 field season) 16161 3644 15872 G sandy silt with pockets of Amphistegina; solitary corals; sampled over 80 cm 16162 3645 15873 G M 8-10 cm packed shells and Amphistegina; more scattered above 16163 3646 G laminated top of sand bed passing down into 16164 16164 3647 15875 G massive fine sand; solitary corals seen towards base 16165 3648 15876 s silty fine sand with Amphistegina, Oliva, etc. 16166 3649 G silty fine sand with Amphistegina 16167 3650 15878 s shell bed, partly concretionary 16168 3651 15880 G silty sand packed with Amphistegina, many in burrows 16169 3092 15881 G M cross-bedded sand with Amphistegina; rotted carbonaceous material 16170 3653 G M silt with Callianassa-size borings filled with shells and Amphistegina 16171 3654 G silt with shell debris 16172 3655 15884 G sandy silt with harder concretions, some containing algae 16173 3656 15886 G sandy silt about equivalent to 16172 16174 3657 silt with harder lenses containing algae and corals 16175 3658 15888 G silt with harder and softer parts; molluscs and solitary corals 16176 3659 bedded hard and soft silty sand 16177 3660 G silt 75 cm below 16176; algae and solitary corals common 16178 3661 G 15 cm almost pure clay with distinct cleavage; 75 cm below 16177 16179 3662 conglomerate of metamorphic pebbles, algae, gastropods, corals; approximately 30 cm below 16178 16180 3663 15889 G silt rich in macrofossils; infilled borings up to 1.5 cm diameter 16181 3664 15891 hard conglomerate from 1.8 m thick bed 16182 3665 15892 coral debris bed below conglomerate (16181); hard and softer pockets, algal balls 16183 3666 piece of Recent-looking wood from conglomerate 16184 3667 G pebbly coral rubble bed 16185 3668 15893 G silt with corals 16186 3669 15894 G M silt with solitary corals, molluscs and worn Amphistegina shells; approximately 1.5 m below 16185 and 10 cm below hard bed, on which the paleomagnetic analysis was performed; matrix noncalcareous in this sample and in the fol- lowing sands. 16187 3670 G very fine silty sand with mollusc fragments and Amphistegina 16188 3671 G T very fine sand; borings up to 4 cm diameter with 7 mm wall more clayey and better cemented with concentration of Amphistegina shells 16189 3672 G 40 cm interbedded silt and very fine sand; much lignite in silts; Amphistegina richer in sands 16190 3673 15899 G clayey silt; molluscs, soritids and lignitic fragments common 16191 3674 G silt richer than 16190; soritids up to 1.4 cm in diameter 16192 3675 G M d silt, sandy in parts; cross-bedding picked out by pink Amphistegina shells and mollusc fragments; soritids present 16193 3676 15911 well-sorted very fine sand rich in molluscs, Amphistegina and soritids 16194 3677 G T very fine sand with shells scattered and in pockets; conglomeratic lenses 16195 3678 15912 fine sand packed with shells, shell fragments and foraminifera 16196 3679 hand specimen of bedded sand with coquina forming the top surface 16197 3680 15917 fine to medium cross-bedded sand; some small pebbles and shells 16198 3681 G laminated silt to very fine sand; few shell fragments 16199 3682 conglomerate of well-rounded pebbles with mean size 1-2 cm, maximum 9.5 cm 16200 3683 G M T very fine grained laminated sandstone with calcareous cement 16201 3684 G poorly sorted pebbly sand DOMINICAN REPUBLIC NEOGENE: SAUNDERS ET AL. 47 APPENDIX 2 Continued JS [John B. Saun- Equivalent NMB ders] macro- Other studies locality field fossil (see Intro- number number localities duction) Lithology and faunal remarks 16202 3685 G T poorly sorted, fine to medium grained, pebbly sand with wood fragments 16203 3686 M calcareous sandstone 16204 3687 15919 G silty sand very rich in whole and fragmented bivalves including Anadara 16205 3688 15920 G shell bed rich in Anadara 16206 3689 G variable lithology of sandy clay, silty clay and carbonaceous clay 16207 3690 G silty clay and fine sand; carbonized wood layer 1 cm thick 16208 3691 T medium to fine grained friable sand 16209 3692 G claystone with lignitic silty clay interbeds 16210 3693 G T friable sand with enclosures of lignitic clay and fragments of carbonized wood 16211 3694 M ap 2-3 cm clayey silt with calcareous cement; pockets of fine to medium sand; very fine lignite-coal fragments 16212 3695 G T calcified siltstone and shell coquina with impressions of plant leaves and com- mon plant fragments 16213 3696 15922 G shelly silty clay packed with mainly broken “Modiola” and other bivalves 16214 3697 G silty claystone interbedded with lignitic silt; well-bedded to laminated 16215 3698 15923 angular to subrounded, fine to very fine sand; few shell fragments 16216 3699 siltstone with very fine sand partings; shell fragments 16217 3700 15924 M concretionary sandstone rich in Anadara 16218 3701 medium grained sand with scattered pebbles; few shell fragments 16219 3702 M dense limestone often with larger foraminifera visible 16220 3703 Т as for 16219 16221 3704 T as for 16219 16222 3705 T as for 16219 16223 3706 T corals and algal balls loose on track; limestone fragments also sampled 16224 3707 T dense limestone on hillside 16225 3708 M concretionary sandstone with Anadara 16226 3709 20 cm long piece of grey clay in float 16227 3710 pieces of conglomerate and sandstone 16228 3711 lignitic and limonitic claystone; bedding picked out by plant fragments 16229 3712 clayey lignitic siltstone and bedded lignitic silty clays; 1 m above 16230 16230 3713 alternation of lighter colored claystone with darker, highly lignitic claystone 16231 3714 claystone with occasional large quartz grains; lignitic and coaly fragments 16232 3715 sandy conglomerate with pebbles up to 5 cm; some frosted quartz; lignitic specks 16233 3716 hard very poorly sorted conglomerate with well rounded dark igneous and chert pebbles up to 3 cm; partly recrystallized coral colonies embedded 16234 3717 corals from a coralliferous limestone 16235 3718 T 2 m red sandstone from below limestone 16236 3719 T G 3 m recrystallized algal limestone 16237 3720 15 very hard conglomeratic sandstone with shell beds, mainly Anadara 16238 3721 ЯЕ Anadara beds in sands with festoon bedding 16239 3722 T G limestone with autobrecciated surface picked out by iron cement 16240 3723 T algal limestone with pebbly silty pockets; all very hard 16241 3724 claystone with scattered larger grains and pockets of sand; lignitic, weathered 16242 3725 T variable claystone to siltstone; occasional well-rounded frosted quartz grains 16243 3726 T limestone rich in larger foraminifera sampled with calcarenite 1 m below 16244 3727 T calcarenite rich in small algal colonies and echinoid plates 16245 3728 T porcellanous limestone with algae, larger foraminifera and miliolids 16246 3729 limestone, as for 16245 16247 3730 piece of recrystallized coral colony from limestone 16248 3731 T cemented boulder bed of coral colonies with some igneous pebbles 16249 3732 G finer grained limestone of small fossil debris 16250 3733 recrystallized coral colonies and echinoid spines in limestone 48 BULLETIN 323 APPENDIX 2 Continued JS [John B. Saun- Equivalent NMB ders] macro- Other studies locality field fossil (see Intro- number number localities duction) Lithology and faunal remarks Río Gurabo (1978 field season) 16251 3734 conglomerate with large ?Ostrea and some corals 16252 3735 T conglomerate with dark igneous cobbles up to 8 cm 16253 3736 shattered silty clay interbedded in conglomerate and sand 16254 SIE T green schistose metamorphic rock 16255 3738 hard red-brown conglomeratic grit, very poorly sorted with flattened rounded pebbles up to 5 cm; black and green igneous components and algal colonies (? growing in situ) Río Gurabito (1978 field season) 16256 3739 dense algal limestone 16257 3740 dense limestone with larger foraminifera 16258 3741 foraminiferal calcarenite 16259 3742 siltstone with thin beds of very fine sand; wood-lignite fragments 16260 3743 coquina of mollusc debris in silty clay; some whole shells 16261 3744 T dense limestone with algae and miliolids 16262 3745 slickensided silty lignitic clay 16263 3746 T sandy pebbly silt; some frosted quartz 16264 3747 20 cm pebbly silty sand with Anadara, etc.; this is relatively unconsolidated 16265 3748 T porcellanous limestone 16266 3749 pebbly calcarenite 16267 3750 T conglomerate with interbedded sand lenses 16268 3751 G d calcarenite below conglomerate 16269 3752 F limestone with recrystallized coral heads up to 60 cm 16270 3753 pebbly sandstone associated with hard conglomerate 16271 3754 T algal and shelly limestone 16272 3755 pebble bed plastered onto limestone surface 16273 3756 rather soft, very badly sorted conglomerate with rounded components up to 4 cm; mainly dark igneous rocks Río Amina (1979 field season) 16949 3889 sandy silt rich in Amphistegina; lenses and beds of Amphistegina and shells 16950 3890 as for 16949 16951 3891 as for 16949 16952 3892 16805 sandy clayey silt with solitary corals and some Amphistegina 16953 3893 16806 sandy silt with Amphistegina, solitary corals and some molluscs 16954 3894 as for 16953 16955 3895 as for 16953 but slightly more sandy 16956 3896 16807 clayey silt richer in foraminifera and with good solitary corals 16957 3897 silty clay rich in foraminifera 16958 3898 clayey silt with subconchoidal fracture Río Cana (1979 field season) 16959 3899 sandy silt with molluscs and foraminifera 16960 3900 as for 16959; rich in Sphaerogypsina 16961 3901 partly cemented silt rich in Anodontia 16962 3902 16858 concretionary siltstone 16963 3903 16860 silt packed with flat coral fragments (Helioseris or Leptoseris) 16964 3904 16862 sandy silt rich in coral debris and with molluscs 16965 3905 sand with concretions; softer parts sampled 16966 3906 silt with foraminifera visible DOMINICAN REPUBLIC NEOGENE: SAUNDERS ET AL. 49 APPENDIX 2 Continued JS [John B. Saun- Equivalent NMB ders] macro- Other studies locality field fossil (see Intro- number number localities duction) Lithology and faunal remarks 16967 3907 16817 silt rich in foraminifera including Sphaerogypsina 16968 3908 shelly sandy silt from between concretions 16969 3909 as for 16968; very rich in molluscs and Sphaerogypsina 16970 3910 as for 16969 16971 3911 as for 16969 16972 3912 as for 16969 with varied foraminiferal fauna visible 16973 3913 16824 from 8 m silt with concretions 16974 3914 16840 silt 16975 3915 silt with beds and lenses very rich in Sphaerogypsina and molluscs 16976 3916 from silt with layers of concretions 16977 3917 16829 silt with molluscs and foraminifera from below a well-burrowed bed 16978 3918 from 1 m silt with scattered pebbles 16979 3919 silt with carbonaceous material from within a pebble bed 16980 3920 1 m silt and sand with shells below a conglomerate and above a lignitic sandy clay 16981 3921 silt 16982 3922 carbonaceous silty clay 16983 3923 16835 shelly sand with pebbles up to 10 cm 16984 3924 16836 shell coquina from top of a silt 16985 3925 16819 shelly silt 16986 3926 16839 shelly silt overlying conglomerate with large Arca 16987 3927 16840 same bed as 16986 16988 3928 16843 sandy silt with scattered Arca; shells strongly concentrated at top of silt 16989 3929 16844 shelly silt rich in molluscs including scattered Arca 16990 3930 from 1 m silty clay with molluscs above an Arca bed 16991 3931 silt with scattered Arca from below Arca bed of 16990; silt passes down into lignitic silty clay with small-scale cross-bedding 16992 3932 jarositic lignitic silty clay below oyster/Arca bed 16993 3933 16852 shelly silt 50 cm above an Arca bed 16994 3934 carbonaceous clay with shell fragments below Arca bed of 16993 16995 3935 shelly fine sand with Tellina and scarce Arca 16996 3936 silty clay 16997 3937 silt with small and fragmented molluscs and ostracodes; 1.5 m below an Arca bed 16998 3938 carbonaceous clayey sands and silts sampled 1 m below an Arca bed 16999 3939 sandy clayey silt with shell fragments 17000 3940 sand with silt pockets, sand-filled borings and lignitic films 17001 3941 : clay with molluscs from below lowest Arca bed of main cliff 17002 3942 16853 conglomerate with pebbles up to 15 cm and coral heads 17003 3943 16854 s lens a few cm by 60 cm, rich in Tellina and other small molluscs 17004 3944 16856 lenses of molluscs, small corals and calcareous sponges in silty sand 17005 3945 shelly silt with lenses very rich in molluscs and large soritids 17006 3946 fine sand with molluscs and foraminifera 17007 3947 pockets of softer silt with foraminifera and rotted coral debris from between concretions 17008 3948 | silt with concretions including hardened burrows up to 5 cm in diameter 17009 3949 ipeum silt without concretions above 17008 17010 3950 16866 silty sand with molluscs; probably about 3 m below 17009 17011 3951 16868 silt probably about 5 m above 17008 17012 3952 bedded fine sands and thin silts 17013 3953 silty fine sand about 3 m above 17012 17014 3954 hard silts with clayey sands between; channeled base, pebbly sands above 50 BULLETIN 323 APPENDIX 2 Continued JS [John B. Saun- Equivalent NMB ders] macro- Other studies locality field fossil (see Intro- number number localities duction) Lithology and faunal remarks Río Cana (1979 field season) 17015 3955 clayey silt with spatangoid echinoid 17016 3956 16869 silt sampled between concretionary layers 17017 3957 16871 on strike with 17016 17018 3958 1 m sand with convoluted sand and silt balls—?thixotropic 17019 3959 gritty silt with foraminifera and poor molluscs above a 1 m conglomerate 17020 3960 silty sand below base of main limestone 17021 3961 16873 pocket of shelly pebbly sand within pebbly limestone 3.5 m above base 17022 3962 large clypeasteroid echinoid from limestone gorge 17023 3963 silt with scattered coral heads interbedded with harder coral debris layers 17024 3964 16885 shelly sand with Conus 17025 3965 pebbly clayey silt 17026 3966 50 cm carbonaceous clay, almost a lignite at base; 4 m above silt of 17005 17027 3967 clay passing down into lignite 17028 3968 shelly silt 17029 3969 carbonaceous clay 17030 3970 shelly silt 1 m below 17029 17031 3971 lignitic clay 50 cm below 17030 17032 3972 shelly silty sand equivalent to 17030 17033 3973 carbonaceous clay below 3 m pebbly sand 17034 3974 1.5 m silt below a carbonaceous silty clay Santiago-Baitoa road (1979 field season) 17158 4098 weathered silt with mollusc fragments and casts 17159 4099 weathered silt 17160 4100 as for 17159 Rio Yaque del Norte (1979 field season) 17161 4101 T hard grit with Lepidocyclina, algal colonies, echinoid debris and corals 17162 4102 hard silty shale 17163 4103 shale and 10 cm grit with Lepidocyclina 17164 4104 hard silt 17165 4105 hard silt 17166 4106 compact clayey silt 17167 4107 hard silt 17168 4108 sandy silt half way up high cliff 17169 4109 as for 17168, about a quarter of way up high cliff 17170 4110 as for 17168, near base of high cliff at level of tree tops Río Bao (1979 field season) 17171 4111 above river and road; cliff of hard splintery silty shale with one or two hard concretionary layers per m : 17172 4112 interbedded clayey silts with silts and pebbly sandstones; grading, shale slabs 17173 4113 as for 17172 and 35 m below 17174 4114 as for 17173 and 18 m below Rio Mao (1979 field season) 17173 4115 16910 silts with scattered molluscs and foraminifera 17176 4116 16914 9 cm crushed clay with silt films 17177 4117 16924 s partly cemented shell lens in silts DOMINICAN REPUBLIC NEOGENE: SAUNDERS ET AL. 51 APPENDIX 2 Continued JS [John B. Equiv- Saun- alent NMB ders] macro- Other studies locality field fossil (see Intro- number number localities duction) Lithology and faunal remarks 17178 4118 16926 s 45 cm cross-bedded shell bed with soritids common 17179 4119 hand specimen of concretionary layer packed with Amphistegina Río Gurabo (1979 field season) 17180 4120 shell-filled burrows in sandy silt immediately below hard ledge of 15973 17181 4121 silt almost free of corals between grain-supported coral layers at 16137 17182 4122 40 cm lens of silt with scattered molluscs in coral bed at 16150 17183 4123 16934 relatively coral-free silt between large coral heads at macro locality 15855 (716934) Río Yaque del Norte (1979 field season) 17184 4124 50 cm silt packed with small molluscs and soritids 17185 4125 concretionary shelly silt 17186 4126 small lens of highly lignitic sand 17187 4127 irregular concretionary shell beds 17188 4128 | 16938 soritids from shelly silt of 17189 17189 4129 silt with shells scattered and concentrated in burrows 17190 4130 16942 20 cm silt packed with ‘Turritella 17191 4131 1 m long slumped silt ball out of pebbly sand matrix 17192 4132 limestone cobble from conglomerate 1.5 m below 17191 17193 4133 silty clay near base of 5.5 m of sands, silts and fine conglomerates immediately below unconformity and approximately 4 m stratigraphically above 17191 Santiago-Baitoa Road (1979 field season) 17194 4134 blocky silty clay 17195 4135 blocky silty clay with squeezed clay partings 17196 4136 silty clay above river in Santiago Río Yaque del Norte (1980 field season) 17293 4190 blocky clayey silt with pteropods and planktic foraminifera; left bank in Santiago 17294 4191 silty sand rich in Amphistegina, coral debris and casts of molluscs interbedded with more indurated beds richer in corals 17295 4192 foraminiferal clayey silt 17296 4193 foraminiferal clayey silt with leaf impressions and Dentalium approximately 15 m above 17295 17297 4194 г foraminiferal clayey silt 7-8 m above 17296 17298 4195 17266 uniform sandy silt 17299 4196 as for 17298 17300 4197 weathered silt with 5 cm layer of rotted corals 17301 4198 uniform sandy silt with foraminifera visible 17302 4199 as for 17301 17303 4200 as for 17301 and approximately 5 m above 17302 17304 4201 as for 17301 and approximately 5 m above 17303 17305 4202 sandy silt approximately 19 m above 17304 and 50 cm below a shell debris bed 17306 4203 silt with scattered shells approximately 6 m above 17305 Río Mao (1980 field season) 17307 4204 17269 silty sand collected over a 1-2 m interval 52 BULLETIN 323 APPENDIX 2 Continued JS [John B. Equiv- Saun- alent NMB ders] macro- locality field fossil number number localities Lithology and faunal remarks 17308 17309 17310 17311 17312 17313 17314 17315 17316 Str 17318 17319 17320 17321 11322 17323 17324 17325 17326 17327 17328 17329 4205 4206 4207 4208 4209 4210 4211 17270 al 17271 4212 4213 4214 4215 4216 4217 4218 4219 4220 17287 4221 17288 4222 4223 4224 4225 4226 Arroyo Zalaya (1980 field season) clayey silt with miliolids uniform clayey silt with scattered molluscs and lenses of shells and Amphistegina very uniform blocky clayey silt silt with thin conglomerate beds above uniform silt with foraminifera visible uniform blocky silt as for 17313, slightly weathered Río Yaque del Norte (1980 field season) rather indurated bedded, sandy, and clayey siltstones in Santiago low in 2 m silty clay interbedded with silty sand 60 cm above top of 2 m pebbly grit clayey silt 2 m above top of fossiliferous rubble bed of macro locality 17274 pockets of clay at base of a coral reef limestone silty clay below a coral rubble bed 1 m x 30 cm bedded silt clast in grit matrix silty clay ball immediately below unconformity concretionary rubbly silt rich in molluscs; softer parts sampled; miliolids visible burrowed sandy silt with shells and Amphistegina 1 m x 30 cm lignitic sandy silt lens burrowed silt with scattered molluscs and pebbles and lenses of Turritella; large oysters strongly burrowed interval of 20 cm with Amphistegina and soritids shelly silt with scattered pebbles; 90 cm above 17325 laminated siltstones interbedded with sands and fine conglomerates showing grading and load structures; shell fragments in coarser beds Río Bao (1980 field season) clayey silt a few cm above marker clay bed DOMINICAN REPUBLIC NEOGENE: SAUNDERS ET AL. 53 APPENDIX 3 REGISTER OF NMB MACROFOSSIL COLLECTING LOCALITIES PJ [Peter 5 : Equivalent micro- Jung] Ld lossit NMB field ossil localities locality num- same same number ber spot horizon Mode of occurrence of fossils Remarks Río Gurabo (1978 field season) 15803 1429 15929 scattered in silts collected thickness 2 m over a distance of 120 m 15804 1430 15934 in 15 cm thick sand overlies 15803 directly; Amphistegina predom- inant; bulk sample (5 liters) 15805 1431 15935 scattered in silts collected thickness 2 m over a distance of 80 m; bulk sample (5 liters) 15806 1432 15941 scattered in silts alternating with indurated some corals layers 15807 1433 15942, scattered in indurated silts corals and few molluscs 15943 15808 1434 scattered in indurated 2 m thick bed full of massive corals apparently in place, branching coral rubble; base channeled corals fragmented; coral deposit forms a flat lens up to 4 m thick and 100 m long; collected over the whole coral deposit (716921) 15809 1435 15952, scattered in silts some corals 15953, 15954 15810 1436 15958 scattered in silts collected thickness 1.5 m over a distance of 60m 15811 1437 15960 scattered in silts collected thickness 3-4 m; silt softer than at 15810; overlies 15810 directly 15812 1438 15962 in 5 cm thick sand Glycymeris predominant 15813 1439 15963 scattered in silts collected thickness 2 m over a distance of 150 m 15814 1440 15964 in 10-15 cm thick sand bed 30 m long, then wedging out at both ends 15815 1441 15965 in up to 60 cm thick sand bulk sample (5 liters) 15816 1442 15966 scattered in silts above and below 15815; collected distance: 250m 15817 1443 15967 scattered in silts collected over a distance of 100 m 15818 1444 15969 scattered in silts few molluscs; collected over a distance of 60 m 15819 1445 15971 scattered in silts overlies 15818 directly; collected over a dis- tance of 90 m 15820 1446 15974, scattered in silts collected thickness 2 m over a distance of 15975, 40m 15976 15821 1447 16022, scattered in silts few molluscs and corals 16023 15822 1448 16057 60 cm thick bed of coral rubble overlying mostly branching corals; few coral heads; in silts with undulating surface silty matrix of rubble bed some pteropods (Diacria) 15823 1449 16056 scattered in silts underlies 15822 directly; pteropods (Diacria, Cavolinia), Propeamussium and other thin- shelled bivalves; bulk sample (5 liters) 15824 1450 16053 80 cm thick bed with coral rubble 15825 1451 16050 70 cm thick rubble bed corals and few molluscs (Spondylus); under- lies 15824 15826 1452 16041 scattered in silts collected thickness 1 m; some corals and few molluscs in upper part 15827 1453 16084 scattered in silts overlying 50 cm thick bed pteropods and Propeamussium with coral rubble 15828 1454 16095 scattered in silts pteropods, small solitary corals; terebratulid brachiopods predominant 15829 1455 16104 scattered in silts pteropods; silts alternating with conglomer- ates and beds with coral rubble 54 BULLETIN 323 APPENDIX 3 Continued PJ [Peter Р i Equivalent micro- Jung] fossil totalit NMB field ossil localities locality num- same same number ber spot horizon Mode of occurrence of fossils Remarks Río Gurabo (1978 field season) 15830 1456 large blocks of coral limestone large oysters, Plicatula, boring bivalves, rare large echinoids 15831 1457 16112 scattered in 60 cm thick silt overlying 30 few molluscs; bedding planes full of plant de- cm thick conglomerate bris 15832 1458 16117 scattered in sands with some pebbles (di- bulk sample (5 liters) for small fossils; col- ameter up to 4 cm) underlying a con- lected over a distance of 70 m glomeratic layer 15833 1459 16120 scattered in sands with pebbles (diameter few corals; molluscs quite frequent; bulk up to 5 cm) underlying conglomerates sample (5 liters); collected over a distance of 80m 15834 1460 in 15 to 20 m thick limestone locality 15830 is stratigraphically equivalent; few corals 15835 1461 16123 scattered in silts few molluscs; few bryozoans; Amphistegina predominant; bulk sample (5 liters) (716812) 15836 1462 16124 scattered in silts molluscs, corals and Amphistegina; collected thickness 1.5 m over a distance of 20 m; bulk sample (5 liters) 15837 1463 16127 alternation of silts with few corals and in- durated layers full of corals partly in liv- ing position and few molluscs 15838 1464 silts full of coral rubble and few molluscs overlies 15837; solitary corals, branching cor- als, and coral heads 15839 1465 16131 silts full of coral rubble and few molluscs collected thickness 7 m 15840 1466 16130 in 10 cm thick band full of vermetids overlies 15839 directly 15841 1467 16129 coral rubble with few molluscs (mainly collected thickness 4 m; overlies 15840 di- large cerithids) rectly 15842 1468 16134 scattered in silts collected over a distance of 50 m; bulk sam- ple (5 liters) 15843 1469 16135 scattered in fine sands collected over a distance of 30 m 15844 1470 16136 scattered in sands molluscs and corals; collected over a distance of 50 m 15845 1471 silts with molluscs and corals 15846 1472 16137, scattered in sands with indurated lenses of collected over a distance of 70 m; bulk sam- 16138 coral rubble; irregular surfaces; no bed- ple (10 liters) ding 15847 1473 scattered in silts with coral rubble 15848 1474 scattered in silts with coral rubble 15849 1475 silts with coral rubble bulk sample (5 liters) 15850 1476 silts with coral rubble alternating with in- collected thickness 8 m (=16882) durated layers 15851 1477 16145 soft silts with coral rubble situated within 15850; bulk sample (5 liters) 15852 1478 shells packed in 25 cm thick indurated situated within 15850; overlies 15851 direct- layer ly; bulk sample (5 liters) 15853 1479 16144 soft silts with coral rubble situated within 15850; overlies 15852 direct- ly; bulk sample (5 liters) 15854 1480 scattered in 60-80 cm thick bed of silts bulk sample (5 liters) (=16811, 16883) within coral rubble 15855 1481 scattered in silts and coral rubble around (=16934) huge, partly inverted coral heads 15856 1482 scattered in silts with coral rubble DOMINICAN REPUBLIC NEOGENE: SAUNDERS ET AL. 55 APPENDIX 3 Continued PJ [Peter Т | Jung] Equivalent micro- NMB feld fossil localities locality num- same same number ber spot horizon Mode of occurrence of fossils Remarks 15857 1483 scattered in silts with coral rubble alternat- ing with indurated layers 15858 1484 scattered in silts with coral rubble stratigraphically under 15857; collected over a distance of 60 m 15859 1485 scattered in silts with coral rubble collected over a distance of 20 m 15860 1486 16148 scattered in silts few solitary corals; bulk sample (5 liters); col- lected over a distance of 20 m 15861 1487 scattered in silts with coral rubble stratigraphically about 3 m above 15860 15862 1488 scattered in silts with coral rubble collected over a distance of 50 m 15863 1489 16152 scattered in silts collected over a distance of 50 m; few soli- tary corals; bulk sample (5 liters) 15864 1490 16154 scattered in somewhat indurated silts solitary corals ; 15865 1491 16155 scattered in silts solitary corals; collected over a distance of 40 m; bulk sample (10 liters) (716810) 15866 1492 16156 scattered in silts few corals 15867 1493 16157 scattered in silts (716808) 15868 1494 16158 scattered in silts solitary corals; large Spondylus 15869 1495 16159 scattered in silts; occasional layers and solitary corals; bulk sample (5 liters) lenses full of thin vermetids 15870 1496 16160 scattered in silts solitary corals 15871 1497 scattered in silts (716809) 15872 1498 16161 scattered in silts solitary corals; 4musium 15873 1499 16162 5 cm thick bed full of molluscs; silty ma- Oliva predominant trix 15874 1500 10 cm thick silty bed full of molluscs Oliva predominant; bulk sample (2 liters) 15875 1501 16164 scattered in silts collected thickness 2 m; solitary corals; few molluscs; underlies 15874 directly 15876 1502 16165 silty band bulk sample (2 liters) 15877 1503 scattered in silts overlies 15876; solitary corals; few molluscs 15878 1504 16167 10 cm thick, silty bed full of molluscs bulk sample (10 liters) 15879 1505 pectinids on surface of 20 cm thick, indu- rated layer 15880 1506 16168 silts with band full of molluscs Oliva predominant 15881 1507 16169 silts with thin band of molluscs at one spot parallel specimens of Dentalium: current direction east-west or west—east; bulk sample (5 liters) 15882 1508 silts with burrows filled with small mol- bulk sample (2 liters) luscs 15883 1509 scattered in silts collected over a distance of 20 m 15884 1510 16172 few molluscs scattered in sandstone; sand- collected over a distance of 40 m stone with irregular, indurated layers 15885 1511 silts with irregular, indurated layers; nu- numerous specimens of Turbo and their iso- merous lucinids in living position lated opercula; shell material leached; col- lected over a distance of 120 m 15886 1512 16173 scattered in silts with some indurated lay- corals; few molluscs; collected over a distance ers of 40m 15887 1513 scattered in silts; few lucinids in living po- few corals; Turbo and their isolated opercula; sition shell material leached; collected over a dis- tance of 60 m 15888 1514 16175 scattered in silts; lucinids in living position few corals; Turbo and their isolated opercula; collected thickness 5 m over a distance of 80 m 15889 1515 16180 lucinids scattered in indurated silts 56 BULLETIN 323 APPENDIX 3 Continued PJ [Peter : ; Equivalent micro- Jung] fossil localiti NMB feld ossil localities locality num- same same number ber spot horizon Mode of occurrence of fossils Remarks Río Gurabo (1978 field season) 15890 1516 thin band with pectinids in silts some calcareous lenses with pectinids and large foraminifera (diameter up to 3 cm) 15891 1517 16181 conglomerates with a few corals 15892 1518 16182 coral rubble underlies 15891 directly 15893 1519 16185 coral rubble with silty lenses few badly preserved corals; large internal mould of a Strombus 15894 1520 16186 scattered in silts solitary corals; underlies 15893; collected over a distance of 60 m 15895 1521 silts with thin band full of molluscs collected over a distance of 40 m; bulk sam- ple (5 liters) 15896 1522 silts with thin bands full of molluscs bulk sample (5 liters) 15897 1523 silts with thin layers of molluscs bulk sample (2 liters) 15898 1524 scattered in silts collected over a distance of 70 m 15899 1525 16190 scattered in silts few solitary corals; collected over a distance of 80 m 15900 1526 silts with bands full of molluscs bulk sample (5 liters) 15901 1527 scattered in silts 15902 1528 scattered in silts overlies 15901 15903 1529 20 cm thick, silty band extremely rich in bulk sample (60 liters) molluscs 15904 1530 several bands extremely rich in molluscs bulk sample (30 liters) interbedded in silts 15905 1531 scattered molluscs and few solitary corals overlies 15904 in silts 15906 1532 silts with band full of molluscs bulk sample (20 liters) 15907 1533 silty band full of molluscs bulk sample (40 liters) 15908 1534 scattered in silts collected over a distance of 50 m 15909 1535 scattered in silts collected thickness 1 m over a distance of 300 m (716920) 15910 1536 20-25 cm thick, silty band full of molluscs bulk sample (20 liters) 15911 1537 16193 20 cm thick band full of molluscs in silts bulk sample (20 liters); collected over a dis- tance of 50 m 15912 1538 16195 conglomeratic shell bed; few Oliva, many bulk sample (20 liters) fragile bivalves; pebbles with diameter up to 10 cm 15913 1539 conglomeratic shell bed collected over a distance of 60 m 15914 1540 layer full of molluscs in silts bulk sample (10 liters) 15915 1541 conglomeratic layer with molluscs in silts bulk sample (10 liters) 15916 1542 15 cm thick, conglomeratic layer with mol- bulk sample (2 liters) luscs in silts 15917 1543 16197 conglomeratic layer with molluscs tellinids predominant; less venerids; few gas- tropods; collected over a distance of 30 m 15918 1544 scattered in silts bivalves predominant; bulk sample (10 liters) 15919 1545 * 16204 20 cm thick shell bed in silts Anadara predominant; lucinids, Bulla, Me- longena 15920 1546 16205 scattered in silts; few concretions Anadara predominant; collected thickness 1 m over a distance of 40 m; bulk sample (2 liters) 15921 1547 indurated silts full of molluscs Anadara predominant; collected over a dis- tance of 40 m 15922 1548 16213 10 cm thick, conglomeratic layer full of overlies 10 cm thick clay mytilids and some small Melongena DOMINICAN REPUBLIC NEOGENE: SAUNDERS ET AL. 57 APPENDIX 3 Continued PJ [Peter E : Equivalent micro- Jung] fossil localities NMB feld locality num- same same number ber spot horizon Mode of occurrence of fossils Remarks 15923 1549 16215 sands, partly conglomeratic with few mol- Anadara and Mytilus predominant luscs 15924 1550 16217 conglomeratic layer with fine sandy matrix Anadara, Mytilus and Melongena predomi- nant; collected over a distance of 50 m 15925 1551 few molluscs scattered in sands Anadara and Corbula predominant; collected over a distance of 30 m 15926 1552 scattered in partly indurated silts Anadara, Melongena and mytilids predomi- nant; collected over a distance of 40 m 15927 1553 16264 shell bed in sands Anadara predominant; collected over a dis- tance of 15 m; Rio Gurabito 15928 1554 corals in hard, silty matrix Rio Gurabito Rio Mao (1979 field season) 16801 1555 few fossils scattered in silts collected thickness 2 m over a distance of 300 m 16802 1556 10 cm thick band with molluscs and Am- bulk sample (2 liters) phistegina 16803 1557 scattered in silts numerous solitary corals and molluscs; in- cludes short, thin lens with Dentalium; col- lected thickness 4 m over a distance of 100 m Río Amina (1979 field season) 16804 1558 16950 scattered in silts Amphistegina predominant; pectinids, Amu- sium, few corals; collected thickness 2 m over a distance of 200 m 16805 1559 16952 scattered in silts solitary corals; few pectinids; collected over a distance of 50 m 16806 1560 16953 scattered in silts Cañada de Mera; solitary corals; few Amu- sium; collected thickness 2 m over a dis- tance of 200 m 16807 1561 16956 scattered in silts solitary corals; few molluscs: Cypraea Río Gurabo (1979 field season) 16808 1562 16157 gastropods and solitary corals scattered in (715867) silts 16809 1563 gastropods and solitary corals scattered in (715871) | silts 16810 1564 16155 gastropods and solitary corals scattered in collected over a distance of 20 m and a silts, but also concentrated in certain ho- thickness of 2 m (=15865) rizons 16811 1565 coral rubble in silts concentrated in certain (=15854, 16883) horizons; mostly solitary and platy corals 16812 1566 16123 scattered in silts large oysters (=15835) Rio Cana (1979 field season) 16813 1567 alternation of silts and indurated beds rela- Cafiada de Zamba; frequent Kuphus perpen- tively poor in fossils dicular to bedding plane; collected thick- ness 2.5 m over a distance of 30 m 16814 1568 scattered in silts with some 5-10 cm thick, Cañada de Zamba; overlies 16813 directly; irregularly indurated lenses collected thickness 1.5 m over a distance of 40 m 58 BULLETIN 323 APPENDIX 3 Continued PJ [Peter 2 ; Jung] Equivalent micro- NME беа fossil localities locality num- same same number ber spot horizon Mode of occurrence of fossils Remarks Río Cana (1979 field season) 16815 1569 coral rubble in silty matrix; unclear bed- Cañada de Zamba; collected thickness ca. 2 ding indicated by platy corals m from base of coral rock; platy and branching corals 16816 1570 partly indurated silts with Kuphus Cañada de Zamba; collected over a distance of 30 m 16817 1571 16967 scattered in silts and concentrated in cer- Cañada de Zamba; Anodontia, lucinids, and tain beds, not in situ; sediments appear strombids predominant; corals locally to have slumped abundant; collected over a distance of 70 m; bulk sample (10 liters) 16818 1572 16968, scattered in silts but mainly concentrated Cafiada de Zamba; large strombids, lucinids 16969, within certain horizons, with indurated (not in living position), and turbinids pre- 16970 layers dominant; corals: Montastrea, Stylophora, Goniopora, Siderastraea, burrows of ? crus- taceans abundant; collected thickness ca. 4 m over a distance of 100 m; bulk sample (10 liters) 16819 1573 16985 scattered in silts with indurated layers Cañada de Zamba; lucinids and turbinids predominant, mostly solitary corals; col- lected thickness 2 m over a distance of 100 m 16820 1574 1 m thick silty bed full of burrows; few Kuphus frequent, not perpendicular to bed- molluscs ding plane 16821 1575 1.5 m thick silts with scattered molluscs overlies 16820 directly; collected over a dis- tance of 50 m 16822 1576 indurated beds in silts with hydrozoans (?); few corals (branching Porites, Antillia) and burrows bivalves 16823 1377 1.5 m thick bed of coral rubble with partly overlies 16822 directly recrystallized corals and hydrozoans 16824 1578 16973 molluscs and solitary corals scattered in collected thickness 1 m over a distance of silts, locally with burrows 20m 16825 1579 scattered in silts with indurated layers overlies 16824 directly; collected thickness 2 m over a distance of 30 m 16826 1580 coral rubble (platy and branching corals); collected from blocks; outcrop stratigraph- corals apparently in situ ically about 15 m above 16825 16827 1581 scattered in silts corals; few molluscs 16828 1582 2.5 m thick silts with some indurated, thin Gypsina predominant; collected over a dis- layers full of molluscs and locally coral tance of 100 m; bulk sample (5 liters) debris 16829 1583 16977 silts with Kuphus 16830 1584 silts with molluscs occurring in layers Kuphus and Astraea predominant; large crab; collected thickness 1.5 m over a distance of 50m 16831 1585 scattered in silts; lucinids partly in living frequent Turbo, their opercula isolated; col- position; Kuphus mostly perpendicular to lected thickness 1 m bedding plane 16832 1586 50 cm thick bed with small molluscs frequent Astraea; bulk sample (5 liters) 16833 1587 silts with small molluscs frequent Astraea and Tegula, bulk sample (5 liters); collected thickness 1 m 16834 1588 silts with small lenses with molluscs bulk sample (2 liters) DOMINICAN REPUBLIC NEOGENE: SAUNDERS ET AL. 59 APPENDIX 3 Continued PJ [Peter ү . Jung] Equivalent micro- NMB feld fossil localities locality num- same same number ber spot horizon Mode of occurrence of fossils Remarks 16835 1589 16983 conglomeratic layers with pebbles of var- collected thickness 1.5 m over a distance of ious sizes (maximum diameter 15 cm); 20m pebbles irregularly scattered in sandy to silty matrix; fossils mostly concentrated in lenses 16836 1590 16984 5 to 10 cm thick bed full of molluscs bulk sample (5 liters) 16837 1591 silts with molluscs and bryozoans partly bulk sample (5 liters) concentrated in layers 16838 1592 2 m thick silt with small pebbles and many overlies 1.5 m thick conglomerate (compo- scattered molluscs nents with diameter up to 10 cm); bulk sample (20 liters); collected over a distance of 50m 16839 1593 16986 1.5 m thick silts overlying 20 cm of con- Pachycrommium and other naticids predomi- glomerates extremely rich in molluscs nant; collected over a distance of 30 m; bulk sample (25 liters) 16840 1594 16987 1.2 m thick silts with scattered molluscs Melongena, Anadara, and large Corbula pre- especially in upper part dominant 16841 1595 75 cm thick bed crowded with Arca patri- underlies 16840 directly; other important cia; matrix silty; specimens irregularly faunal elements include Melongena, Corbu- embedded; no preferred position, no ori- la, Mytilus, Anadara; collected over a dis- entation tance of 40 m 16842 1596 conglomeratic lenses with fossils collected thickness 4 m over a distance of 50 m; bulk sample (2 liters) 16843 1597 16988 20 cm thick Arca patricia bed in silts additional faunal elements: Bulla, Melon- gena, Mytilus, Corbula; collected over a distance of 70 m 16844 1598 16989 silts rich in scattered molluscs, few solitary Pachycrommium predominant; collected corals and fragments of colonies thickness 1.9 m over a distance of 30 m; bulk sample (15 liters) 16845 1599 molluscs scattered in silts Corbula, Anadara, Melongena predominant; collected thickness 70 cm over a distance of 20 m 16846 1600 20 cm thick Arca patricia bed resting on collected over a distance of 20 m; underlies silts 16845 directly 16847 1601 35 cm of finely bedded silts with layers of Mytilus, some corals 16848 1602 40—70 cm thick bed with Arca patricia; underlies 16847 directly; bulk sample (5 li- Melongena, fragments of Mytilus, few ters) oysters 16849 1603 50 cm thick bed consisting almost exclu- few Melongena; bulk sample (1 liter); sepa- sively of fragments of Mytilus rated from overlying 16848 by 20-25 cm thick bed of lignite 16850 1604 25 cm thick silty bed rich in Arca patricia, underlies 16849 directly fewer Melongena, oysters, shell frag- ments 16851 1605 silty bed with large oysters and few Arca lateral equivalent of 16850; Arca patricia patricia largely replaced by oysters 16852 1606 16993 scattered in silts Pachycrommium predominant; collected over a distance of 60 m 16853 1607 17002 silts with scattered molluscs and corals on upper surface of subjacent conglomerate bed: in situ Solenastrea, Goniopora and fragments of branching corals 60 BULLETIN 323 APPENDIX 3 Continued PJ [Peter : : Equivalent micro- Jung] fone gn NMB feld ossil localities locality num- same same number ber spot horizon Mode of occurrence of fossils Remarks Río Cana (1979 field season) 16854 1608 17003 silts with a small lens full of molluscs bulk sample (5 liters) 16855 1609 silts with concretions and small lenses of bulk sample (5 liters); collected over a dis- molluscs; large in situ coral head tance of 80 m (Montastrea) 16856 1610 17004 silts with a layer full of branching corals Eurytellina predominant; corals: poritids and and molluscs Stylophora; bulk sample (10 liters); collect- ed over a distance of 60 m 16857 1611 silts with some indurated layers containing bulk sample (5 liters); collected over a dis- large soritids, and lenses with molluscs tance of 130 m and locally coral fragments 16858 1612 16962 alternation of silts and indurated layers large echinoid; crab claws; few coral frag- ments; red algae nodules; molluscs; collect- ed thickness 2 m over a distance of 10 m 16859 1613 silts with concretions; corals predominant collected over a distance of 40 m 16860 1614 16963 silts with indurated layers full of corals (Pavona sp.); probably in situ 16861 1615 silts with indurated layers rich in corals platy corals concordant to bedding plane, branching poritids fragmented 16862 1616 16964 silts with scattered solitary corals and mol- collected thickness 3 m over a distance of luscs 60m 16863 1617 hard silty beds full of corals poritids dominant 16864 1618 stratified silts with scattered molluscs 16865 1619 17008, silts with many indurated layers in lower collected thickness 2 m over a distance of 17009 part; scattered molluscs and corals; coral 140m beds appear to have slumped 16866 1620 17010 molluscs scattered in silts; very few Thy- collected thickness 2 m over a distance of sanus 40m 16867 1621 predominantly molluscs scattered in silts overlies 16866; collected thickness 4 m over a distance of 20 m 16868 1622 17011 predominantly molluscs scattered in silts overlies 16867; collected thickness 2 m over a distance of 20 m 16869 1623 17016 silts with scattered molluscs collected thickness 4 m over a distance of 30m 16870 1624 silts with few scattered molluscs overlies 16869; collected thickness 5 m over a distance of 20 m 16871 1625 17017 silts with few scattered molluscs overlies 16870; collected thickness 6 m over a distance of 20 m 16872 1626 sandy to pebbly silts with few scattered collected thickness 3.5 m over a distance of molluscs 50 m; large burrows in upper 2 m 16873 1627 17021 pebbly sands with concretions; few corals, collected thickness 4 m molluscs, and echinoids 16874 1628 limestone with coral colonies; not clear if collected thickness 10 m over a distance of in living position; skeletons badly altered 80m i 16875 1629 limestone with corals and coral-inhabiting collected thickness 5 m over a distance of balanids; corals in living position; coral 5m preservation poor 16876 1630 limestone with corals and Lithophaga, cor- collected thickness 12 m over a distance of al preservation poor 50 m 16877 1631 limestone with corals (Millepora) and few collected thickness 5 m over a distance of coral-inhabiting balanids 20 m 16878 1632 silts with concretions Cañada de Zamba; few Spondylus and Ku- phus DOMINICAN REPUBLIC NEOGENE: SAUNDERS ET AL. 61 APPENDIX 3 Continued PJ [Peter З ; Equivalent micro- peso. fossil localities NMB field locality num- same same number ber spot horizon Mode of occurrence of fossils Remarks 16879 1633 silts with layers rich in molluscs Cañada de Zamba; collected over a distance of 40 m 16880 1634 silts with layers rich in molluscs Cañada de Zamba; collected over a distance of 50 m 16881 1635 coral rubble; mainly platy corals; deposit Cañada de Zamba; collected thickness 2 m apparently in situ; fragments of branch- over a distance of 10 m ing corals Río Gurabo (1979 field season) 16882 1636 silts with coral rubble alternating with in- (715850) durated layers 16883 1637 scattered in 60—80 cm thick bed of silts (215854, 16811) within coral rubble Río Cana (1979 field season) 16884 1638 limestone full of corals few large oysters; brachiopods; collected thickness 3 m over a distance of 15 m 16885 1639 17024 stratified sands and silts with badly round- Limopsis and Natica predominant; collected ed pebbles (maximum diameter 8 cm); thickness 7 m coral fragments and molluscs Río Yaque del Norte (1979 field season) 16908 1662 17161 conglomerates; corals and algae as compo- collected thickness 3 m nents of conglomerate 16909 1663 silts with coral head a single, derived specimen of a large land snail Río Mao (1979 field season) 16910 1664 17175 silts with some indurated layers; fossils collected thickness 10 m over a distance of scattered 150 m; bulk sample (5 liters) 16911 1665 limestone blocks with corals blocks fallen from overlying Mao Limestone 16912 1666 scattered in silts collected over a distance of 200 m; bulk sam- ple (10 liters) 16913 1667 17307 silts with thin layers full of molluscs bulk sample (30 liters) (=17269) 16914 1668 17176 scattered in silts; some layers full of mol- collected over a distance of 140 m; bulk sam- luscs and Amphistegina ple (5 liters) (=16931) 16915 1669 30 cm thick bed full of molluscs; silty ma- bulk sample (10 liters); same horizon as trix 16927 16916 1670 scattered in silts overlies 16915 directly 16917 1671 silts with 20 cm thick bed full of molluscs bulk sample (5 liters) (716923) 16918 1672 silts with 30-40 cm thick bed full of mol- bulk sample (5 liters); stratigraphically about luscs; partly cross-bedded 2 m above 16917 (=16924) 16919 1673 scattered in silts collected thickness 2.5 m over a distance of 70m Río Gurabo (1979 field season) 16920 1674 scattered in silts (715909) 16921 1675 scattered in indurated 2-4 m thick silty massive corals apparently in place, branching bed full of coral rubble; base channeled corals fragmented; coral deposit forms a flat lens up to 4 m thick and 100 m long; collected over the whole coral deposit (715808) 62 BULLETIN 323 APPENDIX 3 Continued PJ [Peter : i Jung] Equivalent micro- NMB беа fossil localities locality num- same same number ber spot X horizon Mode of occurrence of fossils Remarks Río Mao (1979 field season) 16922 1676 silts with 20 cm thick bed full of molluscs bulk sample (10 liters) and Amphistegina 16923 1677 silts with 20 cm thick bed full of molluscs bulk sample (20 liters) (716917) 16924 1678 17177 silts with 30-40 cm thick bed full of mol- bulk sample (20 liters) (=16918) luscs; partly cross-bedded 16925 1679 indurated silts full of molluscs top part of bed of 16924 16926 1680 17178 silts with 30 cm thick bed full of molluscs bulk sample (20 liters); same horizon as 16924 16927 1681 silts with 30 cm thick band full of molluscs bulk sample (25 liters); same horizon as 16915 16298 1682 silts with 40 cm thick bed full of molluscs bulk sample (20 liters); same horizon as 16924 and 16926 16929 1683 silts with 25 cm thick bed full of Amphiste- tellinids predominant among molluscs; bulk gina; few molluscs sample (5 liters) 16930 1684 20 cm thick bed full of Amphistegina bulk sample (5 liters) 16931 1685 scattered in silts (=16914) 16932 1686 from two 5-10 cm thick and 1-2 m long bulk sample (5 liters) lenses with molluscs Río Gurabo (1979 field season) 16933 1687 lens of large coral heads in silty matrix; the maximum thickness of lens 3 m; lateral ex- whole coral material appears to have tension of lens 6 m; lens is embedded in slumped; large corals not in place material of 16934 16934 1688 scattered small molluscs and mostly collected over a distance of 20 m and ca. 3 m branching corals in silts; corals fragment- of thickness (=15855) ed; slumping Río Yaque del Norte (1979 field season) 16935 1689 17184 pebbly silty sands with scattered molluscs; collected thickness 4 m; some fossils rolled also concentrated in horizons 16936 1690 1 m thick silts with scattered molluscs and bulk sample (5 liters) corals 16937 1691 30 cm thick conglomeratic lens with abrad- overlies 16936 directly ed corals and molluscs 16938 1692 17188, 3 m thick silts with scattered molluscs and overlies 16937 directly 17189 few corals 16939 1693 20 cm thick conglomerate with abraded corals, mostly Siderastrea corals and few molluscs 16940 1694 silts with scattered molluscs collected thickness 1 m; overlies 16939 di- rectly 16941 1695 scattered in silts stratigraphically from above 16940; collected thickness 1.5 m Е 16942 1696 17190 20 ст thick silt full of Turritella bulk sample (2 liters) 16943 1697 0.5 m thick conglomerate with rolled but corals probably not in living position; Sider- well-preserved corals and few molluscs astrea, Coscinaraea, Stylophora 16944 1698 0.5 m thick bed of Montastrea, Siderastrea; many of the coral heads appear to be in liv- matrix sandy silts ing position 16945 1699 shelly conglomerate with some scattered molluscs and a few corals DOMINICAN REPUBLIC NEOGENE: SAUNDERS ET AL. 63 APPENDIX 3 Continued PJ [Peter j З Equivalent micro- Jung] dl NMB field ossil localities locality num- same same number ber spot horizon Mode of occurrence of fossils Remarks Rio Yaque del Norte (1980 field season) 17265 1710 scattered in silts same horizon as 16936 17266 1711 17298, silts with scattered molluscs and one soli- collected thickness 4 m over a distance of 60 17299 tary coral m 17267 Л? 17302 scattered in silts, one fragment of Stylo- collected thickness 15 m over a distance of phora 100 m 17268 1713 from 3 lenses full of fragile molluscs and solitary corals; maximum thickness of a lens 60 cm Río Mao (1980 field season) 17269 1714 17307 silts with thin layers full of molluscs (716913) Arroyo Zalaya (1980 field season) 17270 1715 17308, silts with scattered molluscs collected thickness 10-15 m over a distance 17309, of 1 km 17310 17271 1716 17311, silts with few scattered molluscs collected thickness 10-15 m over a distance 17312, of 800 m 17318; 17314 Rio Yaque del Norte (1980 field season) 17272 1717 concretionary sandstones with pebbles, collected thickness 2 m over a distance of 80 broken corals, large Spondylus, large Pec- m ten, Anodontia, Plicatula 17273 1718 silts with scattered fossils; corals transport- collected thickness 2 m over a distance of ed 200 m; underlies 17272 directly 17274 1719 gritty rubble bed with coral heads, solitary collected thickness 1.2 m over a distance of corals, large oysters, pectinids, Kuphus, 130 m; underlies 17273 directly internal moulds of gastropods, and large echinoids 17278 1720 silts with scattered molluscs and corals collected thickness 3 m over a distance of 100 m; overlies 17272 directly 17276 1721 concretionary, well-bedded limestone with collected thickness 3 m; overlies 17275 di- coral fragments and red algae nodules, rectly burrows 17277 1722 2 m thick coral carpet; colonies in situ; few collected over a distance of 50 m molluscs 17278 1723 silty sandstone (upper part concretionary) Vasum predominant; collected thickness 1.5 with scattered molluscs; shelly detritus m over a distance of 70 m 17279 1724 rubble bed with clasts of marlstone and re- collected thickness 1.4 m crystallized broken corals 17280 1725 pebbly bed with scattered molluscs 17281 1726 40 cm thick, conglomeratic lens with mol- luscs 17282 1727 bed full of pebbles and molluscs 17283 1728 conglomerate with small pebbles rich in Cymia, Phos, Conus predominant molluscs; few corals 17284 1729 conglomerate with coarse pebbles, rolled mainly Melongena, Vasum; corals: Coscinar- and broken corals; some corals have grown on pebbles aea, Siderastrea 64 BULLETIN 323 APPENDIX 3 Continued By [Peter : : Jung] Equivalent micro- NMB feld fossil localities locality num- same same number ber spot horizon Mode of occurrence of fossils Remarks Río Yaque del Norte (1980 field season) 17285 1730 concretionary siltstones with few scattered fossils 17286 1731 sands and silts with scattered fossils and 2- collected thickness 3 m; bulk sample (5 liters) 3 layers with molluscs 17287 1732 17323 silts rich in molluscs collected thickness 2.5 m; bulk sample (5 li- ters) 17288 1733 17324 scattered in silts collected thickness 2.5 m 17289 1734 15-20 cm thick layer full of Turritella bulk sample (5 liters) 17290 1735 17323, scattered in silts; includes 40 cm thick con- collected thickness 5 m 17326, glomeratic layer with molluscs 17327 APPENDIX 4 REGISTER OF TU MACROFOSSIL COLLECTING LOCALITIES (Information supplied by Dr. Emily Vokes. Asterisks indicate localities plotted on one or more of the Text-figures.) TU 1205.—Roadcut at K 15-16, highway from Santiago to San Jose de las Matas, west of the bridge over Río Yaque del Norte at Santiago de los Caballeros. TU 1206.— Roadcut at K 17, highway from Santiago to San Jose de las Matas, west of bridge over Río Yaque del Norte at Santiago de los Caballeros (=K 14 of Pflug, 1961). TU 1207.—Roadcut at K 19, highway from Santiago to San Jose de las Matas, west of bridge over Río Yaque del Norte at Santiago de los Caballeros. TU 1208.—Roadcut, both sides of highway from Mao to Los Quemados, at ridge 4 km east of Los Quemados. TU 1209* —Roadcut, both sides of the road, 2 km west of Los Quemados (and 0.6 km east of Río Gurabo) on road to Sabaneta. TU 1210*.— Río Gurabo, east bank, first bluff downstream from ford on Los Quemados-Sabaneta road (=USGS 8544). TU 1211*.— Río Gurabo, west bank, second bluff below the ford on Los Quemados-Sabaneta road (=USGS 8546). TU 1212*.— Río Gurabo, east bank, third bluff below the ford on Los Quemados-Sabaneta road (=USGS 8548). TU 1213*.— Río Gurabo, east bank, fourth bluff below the ford on Los Quemados-Sabaneta road (=USGS 8549). TU 1214*.—Río Gurabo, fifth (-USGS 8550), sixth (=USGS 8551), seventh (=USGS 8552), and eighth (=USGS 8553) bluffs on both sides of river below ford on Los Quemados-Sabaneta road. TU 1215*.— Río Gurabo, bluffs on both sides, from the ford on Los Quemados-Sabaneta road, upstream to approximately 1 km above the ford (-USGS 8539-8543; Maury's Zone D). TU 1216*.— Roadcut at junction of road (south side of Río Yaque) from Santiago to Mao, with side road to “La Represa,” 27 km west of bridge over Río Yaque del Norte at Santiago de los Caballeros. TU 1217*.—Roadcut 1 km south of Potrero, or 5.5 km south of junction with road from Santiago de los Caballeros to Mao (south side of Río Yaque). TU 1218*.— Río Amina, bluffs on east side below the dam “La Represa," 2 km south of Potrero. TU 1219*.—Rio Amina, bluffs on east side of river immediately upstream from ford that is 2 km west of Potrero and about 3 km downstream from “La Represa” (=USGS 8516). TU 1220*. — Río Amina, bluffs on west side of river, about one- half km above the ford, which is 2 km west of Potrero, and about 3 km downstream from “La Represa” (=USGS 8517). TU 1221.—Roadcut 4.5 km south of bridge at Guayubin, on road to Sabaneta. TU 1222.— Roadcut 4.5 km north of plaza in Moncion, on road to Los Quemados. TU 1223.— Roadcut 5.5 km north of plaza at Moncion, on road to Los Quemados. TU 1224.—Roadcut 6.1 km west of Los Quemados, or 3.5 km west of Río Gurabo, on road to Sabaneta. TU 1225*. — Banks of Arroyo La Sabirma on west side of the Río Mao, upstream from Mao Adentro and downstream from Cercado de Mao, about 11 km by (winding) road or 8 km airline, south of Mao. TU 1226*.—East bank of the Río Yaque del Norte, below the village of Baitoa, and above the confluence of the Río Yaque and the Rio Bao (=USGS 8558, 8668). DOMINICAN REPUBLIC NEOGENE: SAUNDERS ET AL. 65 TU 1227*.— Arroyo Zalaya, which crosses road to Jánico from Santiago de los Caballeros, 11 km south of bridge over Río Yaque del Norte at Santiago. TU 1227A*.— Turbidity flow lens (ca. 30" long, 6" thick) about two feet above base of outcrop at point approximately 75 feet down- stream from highway bridge. TU 1228*.—Río Cana, west side, first bluff below the ford at Caimito on Los Quemados-Sabaneta road. TU 1229*. — Río Cana, east side, bluffs about 1 km below the ford at Caimito on Los Quemados-Sabaneta road. TU 1230*. — Río Cana, east bank, just above the ford at Caimito on Los Quemados-Sabaneta road (=USGS 8534; Maury's Zone H). TU 1231.— Río Gurabo, float found in river gravel above and below ford on Los Quemados-Sabaneta road. TU 1245.— Roadcut 5 km south of bridge at Guayubin, on road to Sabaneta. TU 1246*.— Río Gurabo, both sides from 1 km to 2 km (airline) upstream from ford on Los Quemados-Sabaneta road (=USGS 8538; Maury's Zone E). TU 1247.— Top ofthe bluff, east side Río Gurabo, at the horsetrail, which is about 2 km above the ford on Los Quemados-Sabaneta road. TU 1248* — Río Amina, first bluff downstream from ford at Pot- rero, on west side of river. TU 1249.— Roadcut 8.6 km west of the plaza at San Cristobal, on road to Bani (=loc. H-20001 of Bermudez, 1949). TU 1250*.— Río Verde, south bank, just above the ford at the crossing of a side road that connects Duarte Highway and La Vega- Moca Highway, about 10 km north of La Vega. TU 1251*.—Rio Verde, north bank, high bluffabout 0.5 km down from the ford at the crossing of a side road that connects Duarte Highway and La Vega-Moca Highway, about 10 km north of La Vega. TU 1252.— Arroyo Las Lavas, at crossing of Duarte Highway K 18.5 west of Santiago de los Caballeros on road to Navarette (=USGS 8663). TU 1253.— Road cut on west side of road from Santiago de los Caballeros to Baitoa, 1 km north of the village of Baitoa (=USGS 8559). TU 1254.—Roadcut at top of hill, 4 km west of Duarte Highway, on road to Presa Tabera; approximately 15 km south of Santiago de los Caballeros. TU 1255.—Roadcut 13.9 km east of Río Yaque del Sur, at Quita Coraza, on road from Azua to Barahona (54.5 km east of Barahona). TU 1256.—Roadcut 5 km south of Río Yásica, on old Puerto Plata-Santiago de los Caballeros highway (=loc. 15003 of Bold, 1968). TU 1277*. — Río Gurabo, both sides, upstream from the horsetrail to 0.5 km above the trail, or approximately 2 km (airline) to 2.5 km above the ford on Los Quemados-Sabaneta road (=Maury’s Zone TU 1278*.— Large arroyo on east side of Río Gurabo just at the ford on Los Quemados-Sabaneta road. TU 1279*. — Roadcut, south side of Los Quemados-Sabaneta road, 2.5 km west of Los Quemados and 0.3 km east of ford over the Río urabo. TU 1280* — Río Mao, bluff on west side about 1 km north of Cercado de Mao (=USGS 8733). TU 1281.—Road metal quarry on highway, south side of Río Yaque, 1 km east of Guayubin on road to Mao. TU 1282*. — Arroyo Beyaco, tributary of the Río Cana to the east, about 1 km above the ford at Caimito on Los Quemados-Sabaneta Toad (=Maury’s Zone I). TU 1283.— Río Yaque del Norte, south bank, just across from Water purification plant at Santiago de los Caballeros. TU 1284.— Río Yaque del Norte, south bank, at junction of road to San Jose de las Matas and road to Canela, 6 km west of Santiago de los Caballeros (? = USGS 8702, 8 km below Santiago). TU 1292*.— Río Mao, west bank, bluffs about 1.5 or 2 km up- stream from Mao Adentro, or about 9 km (by road) south of Mao (=USGS 8528). TU 1293*. — Río Mao, west bank, bluff just below Paso Chorrera, or about 12 km (by road) south of Mao (=USGS 8519, 8520; Bluff 1 of Maury). TU 1294*.—Río Mao, west bank, bluffs just above Paso de los Perros, about 5 km (by road) north of Moncion-San Jose de las Matas road (=USGS 8525; Bluff 3 of Maury). TU 1295.— Road cuts in vicinity of junction of road to Naranjo with Moncion-San Jose de las Matas road, about 3 km east of the crossing of the Río Mao at Bulla. TU 1296*. —Río Gurabo, both sides, from about 0.5 km above the horsetrail to approximately 1 km above the trail, or about 2.5 to 3 km (airline) above the ford on Los Quemados-Sabaneta road (=Maury’s Zone F). TU 1297*. — Río Gurabo, both sides, from about 1 km to 1.3 km above the horsetrail, or about 3 to 3.3 km (airline) above the ford on Los Quemados-Sabaneta road (=Maury's Zone G). TU 1298*.— Río Gurabo, east bank at large eastward bend, about 1.5 km above the horsetrail, or 3.5 km (airline) above the ford on the Los Quemados-Sabaneta road (=USGS 8737). TU 1299.—Roadcut, west side Los Quemados-Moncion road, 2 km south of Los Quemados. TU 1300*.— Río Gurabo, west side, approximately 4 km by road (3.5 km airline) below the ford on Los Quemados-Sabaneta road (=USGS Bluff Q). TU 1301*. – Río Cana, east bank about 2 km above the ford at Caimito on Los Quemados-Sabaneta road. TU 1302.—Samba Hills Ridge; hill slope 2.5 km west of Guayubin (on south side of road, south side of Río Yaque). TU 1303.— Roadcut, 3.5 km south of Guayubin, on road to Sa- baneta. TU 1304.—Roadcut, 4 km south of Guayubin, on road to Sa- baneta. TU 1305.— Oyster reef, unconformably on top of Cercado type sand, gully crossing Sabaneta-Guayubin road 15 km south of Gua- yubin. TU 1306.— Fields beside road, 19 km south of Guayubin, on road to Sabaneta (Arca patricia Zone). TU 1334.— Roadcuts, 2 and 2.3 km (same level) east of Martinez, which is about 9 km (airline) south of Mao. TU 1335.— Roadcut, 5.6 km northeast of Martinez, or 1 km north of Entrada de Mao (approximately 9 km airline) southeast of Mao. TU 1336*.— Río Mao, east bank just downstream from Paso Ji- ménez, or approximately 6 km (airline) south of Mao (=USGS 8532). TU 1337*.—Barranca de Remolina, west bank Río Mao, approx- imately 3 km south of the plaza at Mao (=USGS 8530). TU 1338*.—Roadcut, 0.3 km west of the ford over Río Gurabo, on the Los Quemados-Sabaneta road, or 2.9 km west of Los Que- mados. TU 1339.—Roadcut, 13.1 km south of bridge over Río Yaque del Norte at Santiago de los Caballeros, on the road to Jánico (9.4 km north of Jánico). TU 1340.—Roadcut, 18.9 km south of bridge over Río Yaque del Norte, at Santiago de los Caballeros, on the road to Jánico (5.8 km north of Jánico). TU 1341.— Roadcut, north side of highway, 6 km west of Sanchez, on Samana Highway (Ostrea haitensis reef). TU 1342*. — Río Gurabo, east bank, approximately 4 km by road (3 km airline) below the ford on Los Quemados-Sabaneta road (=USGS 8554). 66 BULLETIN 323 TU 1343*.— Río Gurabo, west bank, approximately 4.3 km by road (3.3 km airline) below the ford on Los Quemados-Sabaneta road (Bluff R of USGS). TU 1344*. — Río Gurabo, west bank, approximately 5 km by road (3.5 km airline) below the ford on Los Quemados-Sabaneta road (=USGS 8735). TU 1345*.—Río Gurabo, east bank, approximately 5.5 km by road (3.7 km airline) below the ford on Los Quemados-Sabaneta road (=loc. H15248 of Dohm and Bermudez; see Bold, 1968, p. 15). TU 1346.—Road metal quarry on north side ofroad from Santiago de los Caballeros to San Jose de las Matas, about 1 km south of the bridge over Río Yaque del Norte, at Santiago. TU 1352* —Río Gurabo, east bank at first bluff above the ford that is approximately 1 km south of Gurabo Afuero. TU 1353*.— Arroyo Puñal, outcrops on south side, above the crossing of the trail from Guayubal to Yabanal, which intersects the paved highway 1.5 km south of Guayubal (ca. 12 km airline south- east of Santiago de los Caballeros). TU 1354*. —Cañada de Zamba, a tributary on the west side of the Río Cana, approximately 2.5 km east of the village of Zamba, which is 7 km north of Cruz de Santiago (Santiago Rodriguez), on road to Guayubin; or 4.5 km (airline) below the ford at Caimito. TU 1355*.—Rio Cana, west side, just below the mouth of Cañada de Zamba (see loc. TU 1354), which is 4.5 km (airline) below the ford at Caimito. TU 1356*. — Río Cana, west side, just above the mouth of Cañada de Zamba (see loc. TU 1354), which is 4.5 km (airline) below the ford at Caimito. TU 1357.—Río Yaque del Norte, bluff on west side, just above new (1980) water plant at south edge of Bella Vista, 3 km (by road) south of bridge at Santiago de los Caballeros. TU 1358*.—Río Gurabo, west side, at and downstream from mouth of Arroyo La Cabra, approximately 6 km (airline) above the ford on Los Quemados-Sabaneta road. TU 1359*.—Río Gurabo, east side, at long bluff that extends upstream from mouth of Arroyo Palero, approximately 5.5 km (air- line) above the ford on Los Quemados-Sabaneta road. TU 1360.— Roadcut, 0.5 km south of Las Caobas, on road to Los Ingenitos, which is on the west side of Río Gurabo. TU 1361.— Roadcut, 3 km south of Las Caobas, on road to Los Ingenitos, which is on the west side of Río Gurabo. TU 1362*. — Trail that leads to top of bluff, east side of Río Yaque del Norte, just downstream from Baitoa. TU 1363*. — Boca de los Rios, above the waterfall in Arroyo Hon- do, which enters Río Yaque del Norte from the east, just below the confluence with Río Bao, downstream from Baitoa. TU 1364*. — Boca de los Ríos, below the waterfall in Arroyo Hon- do, which enters Río Yaque del Norte from the east, just below the confluence with Río Bao, downstream from Baitoa. TU 1365*. — Río Gurabo, west bank, approximately 4 km (airline) below the ford on Los Quemados-Sabaneta road. TU 1366*. — Río Gurabo, west bank, approximately 4.5 km (air- line) below the ford on Los Quemados-Sabaneta road (=loc. H15249 of Dohm and Bermudez; see Bold, 1968, p. 16). TU 1367.— Roadcut 5.6 km west of fort at Mao, on road to Los Quemados. А TU 1368.—Roadcut, 0.5 km east of junction of road to Мопсіоп at Los Quemados, on Los Quemados-Sabaneta road. TU 1369* —Roadcut at junction of road to new bridge and old road to the ford over Río Gurabo, 2.4 km west of Los Quemados, on Los Quemados-Sabaneta road. TU 1370.— Río Guanajuma, a tributary of Río Amina from the west, bluffs on south side above the ford, which is approximately 1.5 km above the confluence with Río Amina. TU 1371.— Río Guanajuma, a tributary of Río Amina from the west, bluffs on south side below the ford, which is approximately 1.5 km above the confluence with Río Amina. TU 1372.— Roadcut, 2 km south of Las Caobas, on road to Los Ingenitos, which is on the west side of Río Gurabo. TU 1373*.— Along trail at mouth of Arroyo Palero, west side Río Gurabo, approximately 5.5 km (airline) above the ford on Los Que- mados-Sabaneta road. TU 1374*.— Río Gurabo, east side, at long bluff approximately 0.5 km below the mouth of Arroyo Palero, or approximately 5 km (airline) above the ford on Los Quemados-Sabaneta road (? - USGS 8739). TU 1375*.—Río Gurabo, west side, at long bluff approximately 0.5 km below the mouth of Arroyo Palero, or approximately 5 km (airline) above the ford on Los Quemados-Sabaneta road. TU 1376*.— Río Gurabo, east side, about 0.25 km above mouth of Arroyo La Cabra, or approximately 6 km (airline) above the ford on Los Quemados-Sabaneta road. TU 1377* —Río Gurabo, west side, about 0.5 km above mouth of Arroyo La Cabra, or approximately 6.4 km (airline) above the ford on Los Quemados-Sabaneta road. TU 1378*. — Río Gurabo, west side, at high bluffabout 1 km above mouth of Arroyo La Cabra, or approximately 6.6 km (airline) above the ford on Los Quemados-Sabaneta road. TU 1379*. — Río Mao, east bank, at mouth of Arroyo Bajon, just below Paso de los Perros, about 5 km (by road) north of Moncion- San Jose de las Matas road (across from Bluff 2 of Maury, and loc. USGS 8526). TU 1380.—Roadcut at top of hill, 12.5 km south of traffic circle at Santiago de los Caballeros, on road to Baitoa. TU 1381*.— Arroyo Babosico, bluffs just up from confluence with Río Yaque del Norte at La Barranca, approximately 8 km upstream from Santiago de los Caballeros. TU 1382.— Roadcut, approximately 6 km west of Las Caobas, on Los Quemados-Sabaneta road. TU 1403.— Arroyo Babosico, which enters Río Yaque del Norte from the west at La Barranca, approximately 8 km upstream from Santiago de los Caballeros, south side at first bluff below bridge on Las Charcas-La Barranca road. TU 1404.— Arroyo Babosico, which enters Río Yaque del Norte from the west at La Barranca, approximately 8 km upstream from Santiago de los Caballeros, north side at second bluff below bridge on Las Charcas-La Barranca road. TU 1405.— Arroyo Babosico, which enters Río Yaque del Norte from the west at La Barranca, approximately 8 km upstream from Santiago de los Caballeros, south side at fourth bluff below bridge on Las Charcas-La Barranca road. TU 1406.—Roadcuts, Santiago-Jánico road, from 3 to 5 km west of junction with road to Baitoa, or 15 to 17 km northwest of bridge over Río Yaque del Norte at Santiago de los Caballeros. TU 1407.— Roadcut, Santiago-Jánico road, 6.6 km west of junc- tion with road to Baitoa, or 18.5 km northwest of bridge over Río Yaque del Norte at Santiago de los Caballeros. TU 1408.— Roadcut, 1 km east of junction of road to Martinez and road to Mao, at Entrada de Mao, approximately 9 km (airline) south of Mao. TU 1409.— Roadcut, 0.5 km west of junction of road to Martinez and road to Mao, at Entrada de Mao, approximately 9 km (airline) south of Mao. TU 1410.— Río Mao, bluff on east side, 1 km upstream from Paso de Chorrera, or about half-way between Maury's Bluff 1 and Bluff 2 (=USGS 8521-8523). TU 1411.—Río Guanajuma, which is a tributary of Río Amina from the west, bluff on north side just downstream from trail at Higuerito Penuelas, which goes to the river approximately 2.5 km upstream from the confluence with Río Amina; or about 1 km above DOMINICAN REPUBLIC NEOGENE: SAUNDERS ET AL. 67 the ford on the road to Potrero. TU 1412.—Río Guanajuma, which is a tributary of Río Amina from the west, bluff on south side just upstream from trail at Hi- guerito Penuelas, which goes to the river approximately 2.5 km upstream from the confluence with Río Amina; or about 1 km above the ford on the road to potrero. TU 1413.—Río Gurabo, bluff on east side between the upper and lower fords at Gurabo Afuero, or about 0.5 km (airline) downstream from loc. TU 1352. TU 1414.—Roadcut (new in 1981) on Mao-Los Quemados road, 2.2 km northeast of junction at Los Quemados. TU 1415.—Roadcut (new in 1981) on Los Quemados-Sabaneta road, 1.8 km west of junction at Los Quemados, coral reef strati- graphically below level at locality TU 1209. TU 1416.— Roadcut on new (rerouted in 1982) Los Quemados- Sabaneta road, 1 km east of Las Caobas. TU 1417.— Río Gurabo, coral reef on east side of river, approx- imately 4.5 km (airline) above the ford on Los Quemados-Sabaneta road. TU 1418.— Río Gurabo, shells from upper parts of conglomerate bed, west side of river, approximately 4 km above the ford on Los Quemados-Sabaneta road. TU 1419.— Arroyo La Cabra, bluffs approximately 0.5 km up- Stream from its confluence with Río Gurabo, which is about 6 km (airline) above the ford on Los Quemados-Sabaneta road. TU 1420.— Arroyo Bellaco (or Beyaco on topographic maps), which is a tributary of Río Cana from the east, first canyon above the ford at Las Caobas Adentro, 3 km southwest of Las Caobas. TU 1421.— Arroyo Bellaco (or Beyaco on topographic maps), which is a tributary of Río Cana from the east, second canyon above the ford at Las Caobas Adentro, 3 km southwest of Las Caobas. TU 1422. — Arroyo Bellaco (or Beyaco on topographic maps), which is a tributary of Rio Cana from the east, coral reef that is exposed for approximately 1 km below the ford at Las Caobas Adentro, 3 km southwest of Las Caobas. TU 1423.— La Isabela Fm., Type locality, 2 km southeast of site Of La Isabela (original city), north coast, approximately 12 km due west of Luperon (see Marcano and Tavares, 1982). TU 1434.— Roadcut 1 km east of the ford on Río Amina (see loc. TU 1219), at Potrero. TU 1435.—Roadcut 1.5 km north of junction at El Limpio, on road from Piedra Gorda (which is 25 km west of Santiago and 24 km east of Mao, on south side of Río Yaque) to Cuesta Arriba. TU 1436.—Roadcut 5 km north of junction at El Limpio on road from Piedra Gorda to Cuesta Arriba (see loc. TU 1435). TU 1437. —Roadcut 0.5 km east of Los Caobas, on new (rerouted 1982) Los Quemados-Sabaneta road (approximately same place as loc. TU 1360, but about 20 m higher stratigraphically). TU 1438.—Roadcut 0.5 km south of bridge at Guayubin, on road to Sabaneta. ; TU 1439.—Roadcut 16 km south of traffic circle at Santiago de los Caballeros, on road to Baitoa. TU 1440.—Río Gurabo, east bank, approximately 3.5 km (airline) below the ford on Los Quemados-Sabaneta road (=USGS 8556; Bluff U). TU 1441.—Roadcut at top of hill at Noriega, which is 6.6 km (by road) south of Santiago de los Caballeros, on east side of Río Yaque (Arca patricia Zone). TU 1442.—Roadcut just north of Arroyo Lopez, about 2.5 km west of Baitoa road and about 11 km (airline) south of Santiago de los Caballeros. TU 1443.—Río Yaque del Norte, east bank, at López, just up- stream from mouth of Arroyo López, between upper and middle hard limestone ledges. TU 1444. —Río Yaque del Norte, east bank, at López, approxi- mately 0.5 km upstream from mouth of Arroyo López, between middle and lower hard limestone ledges. TU 1445.—Río Yaque del Norte, west bank, at “La Ventana” tunnel (López-Angostura hydroelectric project), between hard ledges just upstream from entrance to tunnel. TU 1446.—Río Yaque del Norte, west bank, at “La Ventana" tunnel (López-Angostura hydroelectric project), hard ledges ap- proximately 0.5 km downstream from entrance to tunnel. TU 1447.— Access road to “La Ventana" tunnel (López-Angos- tura hydroelectric project), approximtely 0.5 km north of entrance to tunnel, on west side of Río Yaque, about 20 m above river level and locality TU 1446. TU 1448.—Río Yaque del Norte, west side, bluffs extending for approximately 1 km upstream from the village of La Barranca. TU 1449.— Río Yaque del Norte, west bank, large gravity flows exposed along road that leads down to river at village of La Barranca. TU 1450.— Arroyo Dicayagua, a tributary of the Río Yaque del Norte, southwest of Santiago de los Caballeros, bluffs on both sides from bridge on highway to San Jose de las Matas, upstream for approximately 2 km. TU 1451.— Arroyo Babosico, bluffs on both sides exposed up- stream from the bridge at La Barranca to the junction with Arroyo Zalaya, about 1 km above the bridge. TU 1452.— Arroyo Zalaya, bluffs on both sides exposed from crossing of the trail at village of Zalaya upstream for approximately ] km. TU 1453.— Arroyo Zalaya, from above the waterfall (which is approximately 1 km above the bridge on Santiago-Jänico road; see loc. TU 1227) to the headwaters. TU 14534. —Shallow-water gravity flows into the deep-water beds of Arroyo Zalaya, one just above waterfall, one about 0.5 km up- stream (see loc. TU 1227A). TU 1454.—Roadcut at top of hill (Loma La Furria), 7 km south of junction with Santiago-Jánico road at Las Charcas (or approxi- mately 13 km south of Santiago), on Löpez-Angostura hydroelectric project access road. TU 1455.—Río Guanajuma, west side at large bend, approxi- mately 1.5 km upstream (south) from trail at Higuerito Penuelas (see locs. TU 1411, 1412). TU 1456.—Río Guanajuma, east side, long platform approxi- mately 1 km upstream from trail at Higuerito Penuelas (see locs. TU 1411, 1412). 68 BULLETIN 323 APPENDIX 5 REGISTER OF USGS MACROFOSSIL COLLECTING LOCALITIES (from Vaughan et al., 1921; includes only those localities cited in Appendices 2, 3, or 4, and (or) plotted on maps included with this publication; asterisks indicate localities plotted on maps) USGS 8516*.— Province of Santiago, bluffon right bank Río Ami- na at ford near Potrero. T. W. Vaughan and C. W. Cooke, collectors. May 2, 1919. USGS 8517*.— Province of Santiago, left bank of Río Amina about 0.5 km upstream from crossing at Potrero. T. W. Vaughan and C. W. Cooke, collectors. May 2, 1919. USGS 8519*.— Province of Santiago, left bank of Río Mao about 0.8 km above the ford at Cercado de Mao; specimens mostly from lower part of bluff. T. W. Vaughan and C. W. Cooke, collectors. May 3, 1919. USGS 8520*.— Province of Santiago, bluff on left bank Río Mao about 0.8 km above ford at Cercado de Mao; specimens from upper part of bluff. C. W. Cooke, collector. May 4, 1919. USGS 8521*.— Province of Santiago, bluff on right bank of Río Mao about 1.7 km above Paso Bajito at Cercado de Mao; fossils from basal 4.5 m of section. T. W. Vaughan and C. W. Cooke, collectors. May 4, 1919. USGS 8522* — Province of Santiago, bluff on right bank of Rio Mao, about 3 to 3.5 km above Cercado de Mao; fossils from 4.5 to 9 m above water. T. W. Vaughan and C. W. Cooke, collectors. May 4, 1919. USGS 8523*. — Province of Santiago, bluff on right bank of Río Mao about 1.7 km above [Paso Bajito at] Cercado de Mao, 33 m above water level. C. W. Cooke, collector. May 4, 1919. USGS 8524*.— Province of Santiago, bluff on right bank of Río Mao, about 3 to 3.5 km above Cercado de Mao. Loose, probably from between 8522 and 8523. T. W. Vaughan, collector. May 4, 1919. USGS 8525*.— Province of Santiago, long bluff on left bank of Río Mao opposite Hato Viejo, about 5 km above the ford (Paso Bajito) at Cercado de Mao. T. W. Vaughan, C. W. Cooke, and D. D. Condit, collectors. May 5, 1919. USGS 8526*. — Province of Santiago, second bluff on left side of Río Mao about 3.5 km by trail above the ford (Paso Bajito) at Cercado de Mao. T. W. Vaughan and C. W. Cooke, collectors. May 6, 1919. USGS 8527*.— Province of Santiago, along the bluff on right bank Río Mao, opposite Cercado de Mao, first bluff below Paso Bajito. T. W. Vaughan and C. W. Cooke, collectors. May 6, 1919. USGS 8528*.— Province of Santiago, long bluff on left side Río Mao at head of a long eastward reach about 3.5 km below Cercado de Mao, the second bluff on the left side below Paso Bajito. T. W.Vaughan and D. D. Condit, collectors. May 6, 1919. USGS 8530*. — Province of Santiago, bluff on left side of Río Mao, about 3.4 km above intake of irrigation ditch at Valverde (Mao), first bluff above the town. C. W. Cooke, D. D. Condit, collectors. May 7, 1919. USGS 8531*.— Province of Santiago, right bank of Rio Mao, about 4.3 km above mouth of irrigation ditch at Valverde (Mao), first bluff on right bank above Valverde. C. W. Cooke and D. D. Condit, collectors. May 7, 1919. USGS 8532*.— Province of Santiago, bluff on right bank of Río Mao, opposite Mao Adentro, from the coralliferous beds 4 to 24 m above the bottom of the exposure. T. W. Vaughan, collector. May 7, 1919. USGS 8533*.— Province of Santiago, bluff on right side of Río Mao, opposite Mao Adentro, from lower part of the exposure. T. W. Vaughan, collector. May 7, 1919. USGS 8534.— Province of Monte Cristi, bank of Río Cana at Caimito, road from Las Caobas to Sabaneta. T. W. Vaughan and C. W. Cooke, collectors. May 10, 1919. USGS 8538*.— Province of Monte Cristi, left bank Río Gurabo about 1.6 km southeast of the upper ford at Gurabo Adentro, road from Las Caobas to Los Quemados, bluff 10 of traverse. T. W. Vaughan and C. W. Cooke, collectors. May 9, 1919. USGS 8539* — Province of Monte Cristi, left bank Río Gurabo about 1.3 km above upper ford at Gurabo Adentro, bluff 8 of tra- verse. T. W. Vaughan and C. W. Cooke, collectors. May 8, 1919. USGS 8540*. — Province of Monte Cristi, right bank Río Gurabo about 0.4 km above upper ford at Gurabo Adentro, about 180 m downstream from station 8539, bluff 7 of traverse. T. W. Vaughan and C. W. Cooke, collectors. May 9, 1919. USGS 8541*.— Province of Monte Cristi, right bank Río Gurabo, about 0.8 km above upper ford at Gurabo Adentro, bluff 6 of tra- verse. T. W. Vaughan and C. W. Cooke, collectors. May 9, 1919. USGS 8542*.— Province of Monte Cristi, left bank Río Gurabo about 660 m above upper ford at Gurabo Adentro, bluff 5 of traverse. T. W. Vaughan and C. W. Cooke, collectors. May 9, 1919. USGS 8543*. — Province of Monte Cristi, right bank Río Gurabo about 240 m above upper ford at Gurabo Adentro, bluff4 oftraverse. T. W. Vaughan and C. W. Cooke, collectors. May 9, 1919. USGS 8544*. — Province of Monte Cristi, right bank of Río Gu- rabo, about 150 m above middle ford at Gurabo Adentro, bluff 3 of traverse. T. W. Vaughan and C. W. Cooke, collectors. May 9, 1919. USGS 8545*.— Province of Monte Cristi, left bank of Río Gurabo, about 60 m downstream from middle ford at Gurabo Adentro, bluff 2 of traverse. T. W. Vaughan and C. W. Cooke, collectors. May 8, 1919. USGS 8546*. — Province of Monte Cristi, left bank of Río Gurabo just above lower ford at Gurabo Adentro, bluff 1 of traverse. T. W. Vaughan and C. W. Cooke, collectors. May 9, 1919. USGS 8548*.— Province of Monte Cristi, right bank of Río Gu- rabo, about 150 m below lower ford at Gurabo Adentro, bluff A of traverse. T. W. Vaughan and C. W. Cooke, collectors. May 8, 1919. USGS 8549*. — Province of Monte Cristi, right bank of Río Gu- rabo about 0.4 km below the lower ford at Gurabo Adentro, bluff C of traverse. T. W. Vaughan and C. W. Cooke, collectors. May 8, 1919. USGS 8550*. — Province of Monte Cristi, left bank of Río Gurabo, second bluff on left side below lower ford at Gurabo Adentro, bluff D of traverse. T. W. Vaughan and C. W. Cooke, collectors. May 8, 1919. USGS 8551*.— Province of Monte Cristi, right bank of Río Gu- rabo, third bluff on right bank below lower ford at Gurabo Adentro, bluff E of traverse. T. W. Vaughan and C. W. Cooke, collectors. May 8, 1919. USGS 8552*. — Province of Monte Cristi, left bank of Río Gurabo, about 0.8 km below lower ford at Gurabo Adentro, bluff F of tra- verse. T. W. Vaughan and C. W. Cooke, collectors. May 8, 1919. USGS 8553*.— Province of Monte Cristi, right bank of Río Gu- rabo, about 180 m downstream from collection 8552, bluff G of traverse. T. W. Vaughan and C. W. Cooke, collectors. May 8, 1919. USGS 8554*.— Province of Monte Cristi, right bank of Río Gu- rabo, about 2 km due north of lower ford at Gurabo Adentro, bluff P of traverse. T. W. Vaughan and C. W. Cooke, collectors. May 8, 1919. USGS 8555*.— Province of Monte Cristi, right bank of Río Gu- DOMINICAN REPUBLIC NEOGENE: SAUNDERS ET AL. 69 rabo, about 0.4 km northwest of bluff G, station 8553, bluff S of traverse. T. W. Vaughan and C. W. Cooke, Collectors. May 8, 1919. USGS 8556*.— Province of Monte Cristi, right bank of Río Gu- rabo, about 3 km north of the lower ford at Gurabo Adentro, bluff U of traverse. T. W. Vaughan and C. W. Cooke, collectors. May 8, 1919. USGS 8558*. — Province of Santiago, fossils fallen from upper part of bluff on right bank of Río Yaque del Norte below Baitoa. C. W. Cooke, collector. May 14, 1919. USGS 8559.— Province of Santiago, roadside at top of hill leading down to Baitoa on road from Santiago. C. W. Cooke, collector. May 15, 1919. USGS 8663.— Province of Santiago, Arroyo las Lavas, crossing of road from Santiago to Monte Cristi. T. W. Vaughan and C. W. Cooke, collectors. April 23, 29, 1919. USGS 8668*.— Province of Santiago, Baitoa, bluff of yellow sand- stone along Río Yaque del Norte. D. D. Condit, collector. April 19, 1919. USGS 8702.— Province of Santiago, bluff on south bank of Río Yaque del Norte, 8.6 km west of Santiago. D. D. Condit, collector. April 20, 1919. USGS 8733*.— Province of Santiago, bluff along west side of Río Mao, 1.7 km northwest of Paso Bajito, near Cercado de Mao. D. D. Condit, collector. May 6, 1919. USGS 8735*.— Province of Monte Cristi, left bank of Río Gurabo, about 3.4 km below Gurabo Adentro, bluff W of traverse near base of cliff. D. D. Condit, collector. May 8, 1919. USGS 8737*.— Province of Monte Cristi, Rio Gurabo, about 5 miles above Gurabo Adentro; base of coralliferous limestone and above conglomerate. D. D. Condit, collector. May 9, 1919. USGS 8738*.— Province of Monte Cristi, Río Gurabo, about 8.5 km above Gurabo Adentro; beds near base of coralliferous limestone and above conglomerate. D. D. Condit, collector. May 9, 1919. USGS 8739*.— Province of Monte Cristi, about 9.5 km up Río Gurabo from Gurabo Adentro; fossils from below conglomerate. D. D. Condit, collector. May 9, 1919. REFERENCES CITED Berggren, W. A., Kent, D. V., Flynn, J. J., and Van Couvering, J. A. [in press]. Cenozoic geochronology. Geology. Bermudez, P. J. 1949. Tertiary smaller Foraminifera of the Dominican Republic. Cushman Lab. Foram. Res., Spec. Publ. No. 25, 322 pp., 6 text-figs. Biju-Duval, B., Bizon, G., Mascle, A., and Müller, C. 1982. Active margin processes: Field observations in Southern Hispaniola. Pp. 325—344 in Watkins J. S., and Drake, C. L. (eds.), Am. Assoc. Petrol. Geol., Mem. 34. Biju-Duval, B., Jung, P., and Saunders, J. 1980. Field trip guide E. Río Gurabo, pp. 140-166. Ninth Ca- ribbean Geological Conference, Santo Domingo, Domin- ican Republic. Field Guide, 279 pp. Blow, W. H., and Banner, F. T. 1962. Part 2: The Tertiary (Upper Eocene to Aquitanian) Glo- bigerinaceae, in Fundamentals of Mid Tertiary strati- graphical correlation, pp. 1-163, 17 pls., 20 text-figs. Cam- bridge University Press. Bold, W. A. van den 1968. Ostracoda of the Yague Group (Neogene) of the northern Dominican Republic. Bull. Am. Paleontol., vol. 54, No. 239, pp. 1-106, 10 pls., 8 text-figs., 20 tables. 1969. Neogene Ostracoda from southern Puerto Rico. Carib. J. Sci., vol. 9, Nos. 3-4, pp. 117-133, 2 pls., 3 text-figs., 1 table. 1972. Contribution of Ostracoda to the correlation of Neogene formations of the Caribbean region. Sixth Carib. Geol. Conf. Margarita (1971), Trans., pp. 485-490, 1 text-fig., 6 tables. Caracas. Bolli, H. M., and Bermudez, P. J. 1965. Zonation based on planktonic foraminifera of Middle Miocene to Pliocene warm-water sediments. Bol. Infor- mativo, Asociacién Venozolana de Geologia, Mineria y Petróleo, vol. 8, No. 5, pp. 119-149, 1 pl., 2 tables. Bolli, H. M., and Saunders, J. B. 1985. Oligocene to Holocene low latitude planktic foraminifera. In Bolli, H. M., Saunders, J. B., and Perch-Nielsen, K. (eds.), Plankton stratigraphy, pp. 155—262, 45 text-figs. Cambridge University Press. M., Saunders, J. B., and Perch-Nielsen, K. (Eds.) RUM stratigraphy, pp. 1-1032. Cambridge University ress. Bolli, H. 1985, Bowin, C. 1975. The geology of Hispaniola. In Nairn, A. E. M., and Stehli, F. G., The ocean basins and margins, vol. 3, pp. 501—552, 9 text-figs., 2 tables. Plenum Publishing Corp., New York. Broderip, W. J., and Sowerby, G. B. 1829. Observations on new or interesting Mollusca contained, for the most part, in the Museum of the Zoological Society. Zool. J. (London), vol. 4, pp. 359-379, pl. 9. Butterlin, J. 1954. La géologie de la République d’Haiti. Inst. Francais d’Haiti, Mem., No. 1, 446 pp., 26 pls., 20 text-figs. Butterlin, J., Ramírez, R., and Hoffstetter, R. 1956. Ile d'Haiti — Hispaniola et iles adjacentes: République d’Haiti— République Dominicana. pp. 351-414 in Lex- ique Stratigraphique International. Amérique Latine. Fas- cicule 2b: Antilles. Centre National de la Recherche Scien- tifique Paris. Case, J. E., and Holcombe, T. L. 1980. Geologic-tectonic map of the Caribbean region. U.S. Geol. Survey. Miscellaneous Investigations Series. Map I-1100. Clench, W. J., and Turner, R. D. 1956. The family Melongenidae in the Western Atlantic. John- sonia, vol. 3, No. 35, pp. 161-188, 16 pls. Cooke, C. W. 1920. Geologic reconnaissance in Santo Domingo (Abst.). Geol. Soc. America, Bull., vol. 31, pp. 217-219, 1 table. 1921. Orthaulax, a Tertiary guide fossil. U.S. Geol. Survey, Prof. Paper 129-B, pp. 23-37, 4 pls. Cushman, J. A. 1919. Fossil Foraminifera from the West Indies. pp. 21—71 in Vaughan, T. W. (ed.), Contributions to the geology and paleontology of the West Indies. Carnegie Institution of Washington. Dorreen, J. M. 1979. A recorrelation of Miocene formations in the Dominican Republic. J. Petrol. Geol., vol. 2, No. 1, pp. 47-53, 4 figs. Eva, A. N. 1980. Pre-Miocene seagrass communities in the Caribbean. Pa- laeontology, vol. 23, pt. 1, pp. 231-236. Frost, S. H. 1977. Miocene to Holocene evolution of Caribbean Province reef- building corals. Third International Coral Reef Sympo- sium, Miami, 1977. Proc. vol. 2 (Geology), pp. 353-359. 70 BULLETIN 323 Frost, S. H., and Langenheim, R. L., Jr. 1974. Cenozoic reef biofacies: Tertiary larger foraminifera and scleractinian corals from Chiapas, Mexico. Northern Illi- nois University Press, De Kalb. Illinois. 388 pp. Gabb, W. M. 1873. On the topography and geology of Santo Domingo. Amer. Philos. Soc., Trans., new ser., vol. 15, pp. 49-259, 2 maps. Hedberg, H. D. (ed.) 1976. International stratigraphic guide. John Wiley and Sons Inc., N.Y. 200 pp. Heneken, J. S. 1853. On some Tertiary deposits in San Domingo. With notes on the fossil shells, by J. C. Moore, Esq., F.G.S.; and on the fossil corals, by W. Lonsdale, Esq., F.G.S. Geol. Soc. London, Q. J., vol. 9, pp. 115-134, 7 text-figs. Lonsdale, W. 1853. Notes on the fossil corals of San Domingo. In Heneken, J. S., On some Tertiary deposits in San Domingo. Geol. Soc. London, Q. J., vol. 9, pp. 132-134. Marcano, E. de J., and Tavares, I. 1982. Formacion La Isabela— Pleistoceno Temprano. Mus. Nac. Hist. Nat. Santo Domingo, Publ. Exp. No. 3, pp. 1-30, 9 photographs, 2 tables, map. Maury, C. J. 1917a. Santo Domingo type sections and fossils. Pt. 1. Bull. Am. Paleontol., vol. 5, No. 29, pp. 1—251, 39 pls. 1917b. Santo Domingo type sections and fossils. Pt. 2. Bull. Am. Paleontol., vol. 5, No. 30, pp. 1—43, 3 pls., 1 text-fig., 1 table. 1919. A proposal of two new Miocene formational names. Sci- ence (N.S.), vol. 50, No. 1304, p. 591. 1922. The Recent Arcas of the Panamic Province. Palaeontogr. Am., vol. 1, No. 4, pp. 163-208, 3 pls. 1929. Porto Rican and Dominican stratigraphy. Science (N.S.), vol. 70, No. 1825, p. 609. 1931. Two new Dominican formational names. Science (N.S.), vol. 73, No. 1880, pp. 42-43. Moore, J. C. 1850. On some Tertiary beds in the Island of San Domingo: From notes by J. S. Heneken, Esq., with remarks on the fossils. Geol. Soc. London, Q. J., vol. 6, pp. 39-44. 1853. Notes on the fossil mollusca and fish from San Domingo. In Heneken, J. S., On some Tertiary deposits in San Do- mingo. Geol. Soc. London, Q. J., vol. 9, pp. 129-132. Olsson, A. A. 1932. Contributions to the Tertiary paleontology of northern Peru. Part 5. The Peruvian Miocene. Bull. Am. Paleontol., vol. 9, No. 68, pp. 1-272, 24 pls. 1961. Mollusks of the Tropical Eastern Pacific, particularly from the southern half of the Panamic-Pacific faunal province (Panama to Peru). Panamic-Pacific Pelecypoda. Paleon- tol. Res. Inst., Ithaca, NY, pp. 1-574, 86 pls. Palmer, H. C. : 1979. Geology of the Moncion-Jarabacoa area, Dominican Re- public. pp. 29—68, 7 text-figs., 1 pl., 3 tables, in Nagle, F., Palmer, H. C., and Antonioni, G. A. (Lidz, B., and Nagle, F., eds.). Hispaniola: Tectonic focal point of the Northern Caribbean— Three geological studies in the Dominican Republic. Miami Geol. Soc., 96 pp. Pflug, H. D. 1961. Mollusken aus dem Tertiär von Santo Domingo. Acta Humboldtiana, Ser. Geol. et Palaeont., No. 1, pp. 1-107, 26 pls., 1 text-fig. Pilsbry, H. A. 1922. Revision of W. M. Gabb's Tertiary Mollusca of Santo Do- mingo. Acad. Nat. Sci. Philadelphia, Proc., vol. 73, pp. 305-435, pls. 16-47, 48 text-figs. Pilsbry, H. A., and Johnson, C. W. 1917. New Mollusca of the Santo Domingan Oligocene. Acad. Nat. Sci. Philadelphia, Proc., vol. 69, pp. 150-202. Ramirez, R. 1950. Descripción de algunos moluscos del Mioceno del Valle del Cibao de la Republica Dominicana. Univ. Santo Do- mingo, Publ., ser. 4, vol. 70, No. 1, pp. 7-39, 7 pls. 1956. Paleontología Dominicana. Univ. Santo Domingo, Publ., ser. 4, vol. 103, No. 2, pp. 1-26, 8 pls. Rutsch, R. 1942. Beitráge zur Kenntnis tropisch-amerikanischer Tertiár- mollusken. VII. Larkinien (Arcidae) aus dem Jungtertiár von Trinidad (B.W.I.). Eclogae geol. Helv. vol. 35, No. 2, pp. 213-223, pl. 7. Saunders, J. B., Jung, P., Geister, J., and Biju-Duval, B. 1982. The Neogene of the south flank of the Cibao Valley, Do- minican Republic: A stratigraphic study. Ninth Carib. Geol. Conf. (Santo Domingo, 1980), Trans., vol. 1, pp. 151- 160, 4 text-figs. Seiglie, G. A. 1978. Comments on the Miocene-Pliocene boundary in the Ca- ribbean region. Ann. Centre Universitaire Savoie, vol. 3, sci. nat., pp. 71—86, 1 pl., 8 text-figs., 2 tables. Sowerby, G. B., II 1850. Descriptions of new species of fossil shells found by J. S. Heneken, Esq. In Moore, J. C., On some Tertiary beds in the Island of San Domingo: From notes by J. S. He- neken, Esq., with remarks on the fossils. Geol. Soc. Lon- don, Q. J., vol. 6, pp. 44-53, pls. 9-10. Stoddart, D. R. 1972. Catastrophic damage to coral reef communities by earth- quake. Nature, No. 239, pp. 51-52. Vail, P. R., Mitchum, R. M., Jr., and Thompson, S., III 1977. Seismic stratigraphy and global changes of sea level, Part 4: Global cycles of relative changes of sea level. pp. 83-97, in Seismic stratigraphy— Applications to hydrocarbon ex- ploration. Payton, C. E. (ed.). American Assoc. Petrol. Geol. Mem. 26. Vaughan, T. W. 1919. Fossil corals from Central America, Cuba, and Porto Rico with an account of the American Tertiary, Pleistocene and Recent coral reefs. United States National Museum, Bul- letin 103, pp. I-VI, 189-524, I-XIV, pls. 68-152, text- figs. 4-25. Vaughan, T. W., Cooke, W., Condit, D. D., Ross, C. P., Woodring, W. P., and Calkins, F. C. 1921. A geological reconnaissance of the Dominican Republic. Geol. Surv. Dom. Rep., Mem., vol. 1, pp. 1-268, 23 pls. Vokes, E. H. 1979. The age of the Baitoa Formation, Dominican Republic, using Mollusca for correlation. Tulane Stud. Geol. Pa- leontol., vol. 15, No. 4, pp. 105-116, 2 pls., 3 text-figs. Weyl, R. 1940. Bau und Geschichte der Cordillera Central von Santo Do- mingo (Westindien). Veróff. Deutsch-Dominik. Tropen- forschungsinst. Hamburg, Bd. 2, 60 pp., 12 text-figs., 9 pls., 2 maps. 1966. Geologie der Antillen. Bornträger, Berlin. УШ + 410 рр., 24 pls., 124 text-figs., 16 foldouts. Woodring, W. P. 1973. Geology and paleontology of Canal Zone and adjoining parts of Panama. Description of Tertiary mollusks (addi- tions to gastropods, scaphopods, pelecypods: Nuculidae to Malleidae). U.S. Geol. Survey, Prof. Paper 306-E, pp. 453- 539, pls. 67-82. Zoppis, R. 1969. Atlas geológico y mineralógico de la Republica Domini- cana. 8 maps at 1:250.000 with explanations. BULLETINS OF AMERICAN PALEONTOLOGY, VOLUME 89 PLATE 1 DOMINICAN REPUBLIC NEOGENE: SAUNDERS ET AL. 71 EXPLANATION OF PLATE 1 Río GURABO The Cercado Formation, and the contact between Cercado Formation and the Gurabo Formation. Figure Page 1. The basal conglomerate of the Gurabo Formation overlies sands and silty sands of the Cercado Formation. On this right bank cliff close to locality 15910, conglomerate lies directly on sands, having cut across the intervening coral debris bed. This situation is illustrated in the night hand его ше wsfipurc oem "ucc cuc 12:013; 15 2. The basal conglomerate of the Gurabo Formation at NMB locality 16182. The well-rounded, poorly sorted nature of the pebbles and cobbles is apparent. At this locality, the conglomerate is only 2 m thick (see left hand sketch of Text-fig. 9)................ К 13, 15 3. Coral bed at the top of the Cercado Formation at NMB locality 16184. It shows a thicket of branching colonies (?a poritid) still in place, but distorted due to compaction and possible slight lateral movement. The individual coral fragments are still in contact at therspolntsofsbreakage: энше кышына ио CUI Е E UR D T2555 4. Sand of the upper part of the Cercado Formation at NMB locality 16188. Bedding is picked out by small molluscs and by countless pink shells of Amphistegina that appear as white threads in the photograph ............................................. ЕЛ2 315 5. Cross-bedded, coarse-grained, pebbly sand near the base of the Cercado Formation at ММВ locality 16206. Thin conglomerates and lignites are also common at this level; examples of these can be seen in Text-figure 8........................................ 11, 15 72 Figure 1. BULLETIN 323 EXPLANATION OF PLATE 2 Río GURABO Gurabo Formation (comments on the corals by Dr. J. Geister) Massive to bedded silt and sandy silt at NMB locality 15929. Based on microfossils, the Miocene-Pliocene boundary is placed about 1 m above river level in the smooth, pale-colored silt of the right foreground of the photograph. Silts rich in microfossils and with macrofossils in lenses or scattered throughout cross the boundary with no lithologic change .......................... . Parallel-bedded, calcareous silts alternately richer and poorer in corals at NMB locality 15837. The corals include typical reef dwelling forms like Montastrea, Solenastrea, Porites and Agaricia as well as typical soft-bottom dwellers such as Thysanus, T: eleio- phyllia, Antillophyllia and Placocyathus. In spite of the abundance of true reef corals there is no bioherm development at this outcrop. Reef corals apparently lived in more or less coherent patches spread over a subhorizontal or slightly inclined sea floor. The main limitation to the formation of bioherms seems to have been the scarcity of hard substrate and the existence of stress conditions, perhaps due to high silt influx. Soft-bottom dwellers can, on the other hand, flourish under such conditions. The coral development here is best described as biostromal e uuum 13, . A large lens of massive coral heads at NMB locality 15855. Note 1 m scale. Many of the coral blocks are overturned and broken, suggesting downslope movement, perhaps in a sediment slide. This is almost certainly a slumped mass. Above and below it the bedding is relatively distinct. Many of the broken, branching colonies still show considerable coherence with the broken pieces in close proximity to each other. This either means only a small amount of total movement, or protection during movement within a considerable mass of sediment. The larger heads could have collapsed in place and then could have been moved in the whole sediment slide. 3, upper center— Montastrea sp. (inverted); left (inverted) and right (smooth surface by measuring rule)— massive Goniopora jacobiana; Lower center— branching Goniopora sp. 4, the top of the picture has flat-lying fragments of Stylophora; upper left—ends of branches of a single colony of thinly branched poritids; center left—thicker branches of Goniopora sp. ...... 10213: . Sand in the lower part of the Gurabo Formation at NMB locality 16170. Burrows with diameters up to several cm are very common at this level. Many are wholly or partly infilled with broken shell fragments and tests of Amphistegina ...................... 12 Page 16 16 16 16 BULLETINS OF AMERICAN PALEONTOLOGY, VOLUME 89 PLATE 2 BULLETINS OF AMERICAN PALEONTOLOGY, VOLUME 89 PLATE 3 DOMINICAN REPUBLIC NEOGENE: SAUNDERS ET AL. 73 EXPLANATION OF PLATE 3 Río GURABO Mao Formation Figure Page IL. N The youngest outcrops of the Mao Formation on the Río Gurabo are at NMB locality 16119, 900 m above the base of the stratigraphic column. They consist of channeled sands and conglomerates with common contorted slump masses of silt. Text-figure 13 shows some ofsthérdepositionalipatterosiob soy cura е E qs ccr x. uM 14-17 . A high cliff section at NMB locality 16093, showing interbedded calcareous silty clays and indurated calcarenites. Some of the harder beds contain coral debris and may be conglomeratic. The fine-grained interbeds have an open-marine, reltively deep-water foraminiferal fauna x1 er ынна с pu MU EUN Lc о ът 15 - Conglomerate with a coarse sand matrix at NMB locality 16042. Pebbles up to 10 cm in diameter occur with fragments of branching corals in a bed that varies in thickness from 10 cm to 40 cm. This bed is in a series of deep-water silts with influxes of terrigenous апахотосіазос аер (SOC ехо о) Ce... d T Us UT MM E M 14-16 . Pebble-filled channel cut into underlying foraminiferal silt and taken as the base of the Mao Formation, at NMB locality 16011. Conglomeratessandseross-beddeds coarse sands tollowsabovet ИЗЕУ 14, 16 . Badly sorted, channeled conglomerate marking the base of the Mao Formation at NMB locality 15997. Pebbles are of melanocratic igneous rocks and quartz. The bed passes up into a pebbly grit with scattered silt с1азїз...................................... 14, 16 74 BULLETIN 323 EXPLANATION OF PLATE 4 Río CANA Arca patricia beds Figure Page 1. Left bank cliff with Arca beds close to NMB locality 17000 and section shown in Text-figure 18. Interbedded sands and silts with several lignitic clays and with the individual shells of the lowest Arca bed shown in Text-figure 18 clearly visible as white spots one- tO OR He wA UP te OUSCEOD acc. occ Or dere les OR IE en i ae boron TU RAE UO Reale OTE 20 2. NMB locality 16841. Shell bed packed with Arca patricia, many specimens having articulated valves. Each arm of scale is 20 cm.. 22 3. Conglomerate with Arca shown in Text-figure 17a. Collections from NMB localities 16839 and 16986 were taken in the shell-packed [51:8:10.9,7 ro aro еее ке еи ОО 22 . Rhythmic sequence of Arca beds shown in Text-figure 17d, where the succession of lignitic clays, dark silts and shell beds is shown graphically. This view shows NMB localities 16848 to 16850 and 16992. Scale is 1.2 m long ................................ 20). 274 BULLETINS OF AMERICAN PALEONTOLOGY, VOLUME 89 BULLETINS OF AMERICAN PALEONTOLOGY, VOLUME 89 PLATE 5 DOMINICAN REPUBLIC NEOGENE: SAUNDERS ET AL. ТӘ EXPLANATION OF PLATE 5 Río CANA Cercado, Gurabo and Mao formations Figure Page It: Foreset beds in the Mao Formation in a left bank cliff at 630 m above the base of the stratigraphic column shown in Text-figure 15. These steeply-dipping beds of conglomerate and coarse sands are shown on the right side of Text-figure 19. Each arm of the scale is UEC A N SO TL LONE ML RU PR ы суза ЫНЫ a) tyes valet) Bo RU SUE 21, 22 . NMB locality 17015 in the Gurabo Formation. Cross-bedded sands discordantly cutting a pebbly grit that shows load cast structures penetrating the clayey silts below. The 1 m straight part of the rule stands in front of the right load structure .................... 22 . Right bank cliff at NMB locality 16963 in the Gurabo Formation. Silt packed with flat fragments of either Helioseris or Leptoseris ... 20 . Right bank cliff at NMB locality 17007 in the Gurabo Formation. Silt with prominent calcareous concretions typical of the middle part of the Río Cana section. Coral debris (including the forms seen in Plate 5, figure 3) is common together with benthic foraminiferal faunasjaudiscatteredamolluses СКАЯ ОО ОПОЛЕ О. 20,22 . Approximately at NMB locality 16960 near the base ofthe Gurabo Formation. Calcareous sandy silt with frequent harder concretionary layers. The white spots are tests of Sphaerogypsina. This is a very characteristic foraminiferal species in these shallow marine beds, wui are also ricn insbe, 0oz0aRmolluscssandieoralsene er ee 22 . Right bank cliff shown schematically in Text-figure 17c. Festoon cross-bedded sands, the upper portion of which are thick with interlocking burrows of Callianassa-type that are up to 5 cm in diameter. Immediately above is a molluscan-rich silt with a layer of Arca-shellstatsits.baseen ee ee осы ГАК ILL EET 20,22 76 BULLETIN 323 EXPLANATION OF PLATE 6 Río CANA Mao Adentro Limestone Figure Page de Northern end of Río Cana gorge. Exposure on left bank at NMB locality 16884, close to NMB locality 17023. This is near the top of the limestone sequence. Broken and transported corals, both massive and branching forms, indicate movement downslope. The beds are irregular and seem to show channeling consistent with deposition on a slope. The foraminiferal fauna has a high ratio of planktic to benthic foraminifera, and suggests a water depth greater than 100 m—and perhaps twice that amount ...................... 21522 . The base of the limestone at the south end of the gorge. This is shown schematically in Text-figure 20, where the NMB localities are also given. Sands, heavily burrowed at the top, are followed by pebbly calcarenite which is not rich in corals but is followed by a carpet of branching poritids that forms the base of the coral-rich section... n 21507 . View into the gorge slightly downstream from the section shown in Plate 6, figure 2. Dr. Geister (written commun., 1984) writes: “Limestone massive to bedded (beds 0.5 to 1.5 meters), very rich in branching corals (Stylophora, Porites). Some massive corals (Montastrea) and platy corals (Goniopora, Leptoseris). Many if not most of the corals do not seem to be in place and were probably transported downslope. Corals badly preserved due to diagenetic alteration” ....... sss 212927 PLATE 6 BULLETINS OF AMERICAN PALEONTOLOGY, VOLUME 89 BULLETINS OF AMERICAN PALEONTOLOGY, VOLUME 89 EXPLANATION OF PLATE 7 Río МАО Maury's Bluffs 2 and 3 Figure Page 1. 2 Maun s BII 2 on the lett Bank ofthe Rio Мао a ee „Т 32 1. General view of silts with harder parts standing out due to secondary concretions. A schematic view of the whole cliff is given in Text-figure 31. 2. Detail of shell bed (NMB loc. 16930) where this comes down close to river level towards the eastern end of the left bank cliff. Oriented shells of Dentalium are very conspicuous. The matrix is packed with Amphistegina. 3, 4 Maury's'BlufiS'abthe easterm(downstreani)end ^ л A ao Ее See ee 31.32 3. The high cliffs are composed of sands, partly flat-bedded and partly cross-bedded, with the bedding often picked out by calcareous concretions. The cliffs descend towards the east where they are schematically shown in Text-figure 33. 4. Detail of NMB locality 16913, showing cross-bedding picked out by small molluscs and by countless shells of Amphistegina. All shell horizons lens rapidly. The matrix is calcareous, silty sand. The complete absence of planktic and deeper-water benthic foraminifera and of calcareous nannofossils attests to the shallow water, inshore nature of the beds. "IV ІЯ SAIANNVS :HN39O3N| Or THOdH[ NVOININOG Y N EXPLANATION OF PLATE 8 Río MAO AND Rio YAQUE DEL NORTE Figure Page 1. General view of Maury's Bluff 1 on the left bank of the Río Mao. A microfossil sample (from NMB loc. 17175) shows a slightly more open marine assemblage than is found mBun md? ОИ a e ТҮГҮ. 25.31 2. NMB field party packing macrofossils from NMB locality 16910 at Bluff 1 on the Río Mao, April 9, 1979 ............................. eene 23 3. Löpez section on the Rio Yaque del Norte. At NMB locality 17323 (plotted on Text-fig. 25), calcareous silt has molluscs, Amphistegina and soritids packed into burrows. The dark eireles are concentrations GF WOM o Lue ooo Ls Ri S Dc зу m сз к c p i culis ee 25 4. López section on the Río Yaque del Norte, showing a Turritella shell bed on strike with the shelly conglomerate of NMB locality 16939 ............................... 25 5 . Arroyo López on the Río Yaque del Norte. View downstream showing section drawn schematically in Text-figure 26. In the foreground is the edge of the island formed by the conglomerate bed sampled at NMB locality 17274... ee 25, 26 8L єтє NILATING W = E E ti - 2 u o 7 > & tj Ё о > § 2 Y > E) ti o Z d О = Q Q K = z = = ti оо © BULLETINS OF AMERICAN PALEONTOLOGY, VOLUME 89 PLATE 9 | Se Jae LAS cdi 2 CAD 3 polygen. congl. Entrance to Arroyo Hondo — _ = 4 ^N 2 ко E و‎ E E QE c nme E = Je m x a INS 17284 17282- | 17283 | 17280 Approx. position of unconformity Position from which fig. 2 was taken EXPLANATION OF PLATE 9 Río YAQUE DEL NORTE Baitoa Formation Panoramic views of the hypo- stratotypic section of the Baitoa Formation upstream from López below the confluence of Río Bao and Río Yaque del Norte.. p. 39 These photographs were taken in 1980 just after Hurricane Allen had made it necessary to let un- usually large amounts of water down the river from a dam situ- ated upstream. This removed a great deal of vegetation from the lower part of the cliffs making the section better exposed than it had been for years, and allowing us to measure the section and to collect extensively from it (see Text-fig. 23) 1. View upstream. The gorge in the center of the photograph is the entrance of the Arroyo Hondo indicated on the sketch (above). 2. View downstream. The mouth of the Arroyo Hondo is again indicated on the sketch. Position from which fig. 1 was taken Entrance to Arroyo Hondo "IV LI SAIANNVS :HN35DO8N DITANdTY NVOININOG 6L Date Due АРВ-8-@—1995 EXPLANATIONS OF FIGURES IN POCKET INSIDE BACK COVER Note: These captions are updates of those printed directly on the figures. They have been printed on paper that has a PERMANENT adhesive backing and may be peeled off and stuck down on the figures, or in any other desired location. Text-figure 4. — Map and columnar section of Río Gurabo (area 2 of Text-fig. 3), showing geographic and stratigraphic positions of NMB collecting localities. Open squares or rectangles represent sam- ples collected for microfossils and lithologic analyses; black circles represent samples collected for macrofossils. Text-figure 5. — Map of Río Gurabo (area 2 of Text-fig. 3), showing geographic positions of selected TU and USGS collecting localities. Text-figure 6.—Columnar section for Río Gurabo, showing li- thologies and ages. Text-figure 15.—Map and columnar section of Río Cana (area 1 of Text-fig. 3), showing geographic and stratigraphic positions of NMB localities, and geographic positions of TU localities. Open squares represent NMB localities collected for microfossils and lith- ologic analyses; black circles represent NMB localities collected for macrofossils. A = Arca beds. Lithologies are portrayed as in Text- figure 16. Text-figure 16.—Columnar section for Río Cana, showing li- thologies and ages. A = Arca beds. Text-figure 21.— Map of Río Yaque del Norte (area 6 of Text-fig. 3), showing geographic positions of NMB, TU, and USGS collecting localities. Open squares represent NMB localities collected for mi- crofossils and lithologic analyses; black circles represent NMB and TU localities collected for macrofossils. See Text-figures 25 through 28 for details of localities on the southern portion of this map area. Text-figure 25. — Columnar section of cliffexposures on Río Yaque del Norte north of Baitoa, showing lithologies and stratigraphic po- sitions of NMB collecting localities (see Text-fig. 21 for geographic positions of these localities). See also Plate 9. Text-figure 29. —Map of Río Mao (area 3 of Text-fig. 3), showing geographic positions of NMB, TU, and USGS collecting localities. Open squares represent NMB localities collected for microfossils and lithologic analyses; black circles represent NMB localities col- lected for macrofossils. Geographic positions of Maury's Bluffs 1, 2 (see Text-fig. 31), and 3 (see Text-fig. 33) are also shown. Text-figure 34. —Map of the central portion of Río Amina (area 4 of Text-fig. 3), showing geographic positions of NMB, TU, and USGS collecting localities. Open squares represent NMB localities collected for microfossils and lithological analyses; black circles rep- resent NMB samples collected for macrofossils. Text-figure 4 Map and columnar section of Rio Gurabo showing topographic and stratigraphic position of NMB localities. RIO GURABO о 300' 600 900 1200 1500 — Z LEGEND 16114 - 16116 Sample collected. for microfossils or lithology Distance over which macrofossils collected Point sample collected for macrofossils < 2 сш ЛЕН 16106 -16108 3 Rio Mao LL] Upper Cenozoic RÍO Amino [2 Oligocene - Early Miocene ? 5 Cañada Zaloya 6 Rio Yaque del Norte [Б] Mesozoic 7 City of Sontiago 8 Arroyo Puñal 9 Rio Verde 16092 ,160' 16089-16091 16071-16088 16062-16070 16039-16061 16021-16023 3 16008- 16015 45994-15996 15997 - 46006 45990. 15991 16124 d 121 = 16115 - 15833 _ 15831 = ese |- 16109 | 15850, 77 í 15834 7 1, | 7 800 7 | if Y | $ // ? | $ II 4 à Ч \ 15978 2 S HI \ NEN // // // N N | 45829 NEN \\ \\ \\ \\ \\ 15977 d M \ 15974 - 15976 Д1 m 15973 SS D | 145972 a M 3 M 15969 , 15970 EG 15818 \\ \\ \\ Е? SN \ us n M 15817 1 ZÁ d T 15967 e" J} 1 15816 m T 1 BAR 15813 // 15966%—4 "NN 4 СМ 2m ` S y МЈ ©, 15968 : 15965 4 de Mt | 15823 | hese >= oe v | 915964 771 / dE - 15825 : 15963. j; | y 9812 rd DO 15961 15962 pa UN i QA UAM M NS VS | 15827| 15826 y” 15810 1581 y м = 15959,15960 \ \ A ZA отша, > E 41 —1 F TT 16074-75 \ N E eid adn 2 2 i TER 15954 - 15957 a 11 "m 15953 5 | Wut Y 1018933 = 15952 E / 45808, 16921 18934 | 15821 : 15947 & x \ 07745935 ц: 15948 —H Su MÁ etseo? МС 15936 , {7180 15949 — й \\ RES 15937 о у “М S em S 240, 3 15835, > ER 4594534. RF NH Ф 15944 1612322 Ф 23 d 15941 | eese — el y 15940 кета 159 15943 15938 16125 „16126 1 16127 8 rH 15838 T 15837 16128 асе: 16129 - 16132 Y) 15839, 15840, 15841 16135 16133 , 16134 ea. | | 16136 Г 15979 16137 16138, 17181 dd 16139, 16140 16141 - 16147 45277 45976 E 45975 15974 С | юе КЕЁ un ı 15819 PP um = - 15933 LES Jem 46149 16150,17182 EN ees H 15968 15932 H-15967 sea} 15981 г 19965766 I 18017 ваа 15815 | Ч 5 а 15816 2 NM ер | emi. беш F^ 189 15959 F-15961 58 | 15803 46151 TED 15937 |- 15949 ~ م‎ 15960 la: - 15812 45811 15805 16152 А h E AY, | 15863 1 15941. 45948 a - w^] -15835168 — 15810| 7 A 1 MAJA s = бз A] [— 15944 Ь 15806 J. NA | 16124 Aet \ | 15836 | 15807 Fx 45945 |- 15947 H 16125 a cum ^ D^ he rn 15946 L 46126 ) | 15809| 15808; A کے‎ 15838 46921 | 46127 es کے‎ | L 1612 === | 15837 16128 \ k 16129 TA 16154 А 15864 + 46130 = T— -— 74 L 16131 15839 L 16132 16155 EE: 71 15865 , 16810 16156 NE 15866 16157 ) X X у [15867 , 16808 Tol ees OS Hj Ak Vt 6869 16135 | ТРЕ E вето a ا‎ 15871,16809 | 15844 300 4 16161 4 D a 5. 15872 46162 z 15873 16141 = 3 4 /16142 + 16137 i oms 16163, 16164 : inane 48143 - 16138 -— 15875 16145 - 15852 1. я 19850,6892 вав a Г 15854, 16811,16883 - 7 L صا‎ —= | 15855,16934, 15856 - 15849 ў 16147 кеі b "5857,16933 - 19858 I 16165 107 7 45877 15876 16166 ‚16167. 15878 i 15879 + 16148 16168 Y 15880 L 16149 \ L 16150 16169 ko Een Le 16153 | з 16170 97 15883 18186 16m E — 15866 i 16155 15864 E EE [20 ww REL inae n F—16158 | 15871, y 16173 Z N [I*896 16809 - 45870 16172 7 7 di quu 15884 Б 46174 а 0 n = 15877 — 15872 I Iıser 15885 21616 : - — 15876 a i = 108 | 45878 Ss 45890 Jt 2004 Pe DL. WR E - 45879 - 15878 x X 15989 y 1066 1680—70, 16176-16179 Ll) - 15880 | — 16168 оф L 16169 - 15882 - 5 16170 | 15883 16181 ,16182 f 15891 H 16171 x - 15884 AERA — XI E 16172 - 15890 15885 - 15886 ad — 15892 46174 | 15887 Feen 16180 5 - 45889 a 16177 O A S icd Base Gurabo F.m 16185 88 FL Sr 15894 3 xr 16187 G - 16184 ER, | S > L 16185 = 16168 - 15895 16188 9, L 15895 || 16188 ESTA HE 16189 = wu; 2 - 15906 589 - 15905 X BEA 15897 16190 — 15907 15904- 45902 | 15899 16189 3а 15896 192 um 99e 906 - 15910 | 15908 33 - 1594 5 16190 e a — 15915 — 15914 16191 К 16192 16197 Î = 45917 — 15916 8194 ү L 16199 - 16199 77 15906 = 15905 só 15904 RR 247 45907 E 46202 PI ATI 08 H 16203 7 клу | уа i E M Ur 15910 F 16205 | MESES cAMP “ie ES 15909, 16920 L 16206 F 16207 - 16208 E E 10590 EA - 45922 12519 + 1 16193 , 16194 L 46228 F 16212 1591 L 16229 16195 9 (^ 45912 S / 1593 I- 16259 Y KN | 16215 y 16216 - 45923 16217 | 15924 H 16241] 16231 16196 15914 | 16263 H 16242 | 16232 => - 16260 [ 16218 p 15915 be 16197, 16198 15917 16199 a 16200 9 -ARY Base Cercado F.m 16241, 16242 Text-figure 5 Map of Rio Gurabo showing position of USGS and TU localities. RIO GURABO 100 200 300 400 500m 0 300 600 900 1200 4500" N LEGEND Sample collected for microfossils or lithology USGS 8735 Distance over which macrofossils collected Point sample collected for macrofossils N 0 10 20km 4 Rio Cana 2 Rio Gurabo AYUBIN Cip { L Upper Cenozoic E 8 A о [57] Oligocene - Early Miocene ? 5 Cañada Zalaya 3 va [5] мешок ra da sí l & 8 Arroyo Puñal S N & Y 9 Rio Verde а x 1 ESPERANZA NAVARRETE [ ZAMBA J ES, 4 ART у tora RANTS а ay ns 5 TAS SANTIAGO BULLA MOCA 8 C BAITOA 11 I II // U // / (l \ NS 0 S \\ y, \ $ \ 0 0 \ Ф \ \\ \\ \\ Leo M 58 \ USGS 8552 TU 1211 TU 1210 - New road TU1338 USGS 8543 (Approx. position) TU 1209 B TU1369 TU 1215 USGS8541 USGS 8540 | Pi USGS 8539 USGS 8538 TU1246 USGS 8737 / т\изт5 SEE TU 1374 TU1376 TU1377 TU1378 Text-figure 6 Columnar section of Rio Gurabo giving lithologies and age. Р > E б |2 ш O > ML a = ao |= D uloizio шо | 5| о 2 |о|Ојш = |Ы |2 ZO uiaizizio HEHE ш JIa aia A о | —|o a >|с a О J © z О E 4 > a ©) и. О > > [| s z z ul > О N aix шШк [2 zz < 4 ш Olea ola —|> = ещ 4 J E pa О a 5ا‎ 1012 о |2 a, «1 | «5 ul N 2 z = O E < > a = o О и. N E o O a ш > 5 T О boo! a E ч a al l> E (5 a ale Who 8 Ola |Z z ш Wir 4 pel > ы ро J| Ww 8 z О © = H = 4 > a О u. o o 4 o a ul «li > > RIO GURABO Large & small scale cross-bedded sands, pebbly sands & conglo- merates showing channeling & load casting. Plant material common. Molluscs infrequent Interbedded channeled conglomerates, silts & pebbly sands Shelly pebbly sand' Shelly & pebbly limestone with corals Interbedded hard silts with packed coral debris & softer highly fossiliferous calcareous silts with abundant microfossils. Rare pebble beds Calcareous silt with thin beds of corals & one lens of brachiopods F? Interbedded hard & softer highly calcareous silts. Often highly fossiliferous with corals, molluscs & foraminifera. Minor pebbly intervals Massive calcareous silts with coral debris beds & minor pebbly sand lenses Fossiliferous calcareous silts interbedded with coral debris beds & thin conglomerates & sands Calcareous fossiliferous silts with few coral debris beds Silts channeled by fossiliferous pebbly sandy silts Calcareous clayey silt with scattered molluscs Poorly sorted sands, irregularly bedded with cross-beds & channels; base erosional. Lenses of conglomerate & scattered silt clasts Massive calcareous clayey silts very rich in microfossils. Infrequent macrofossils Calcareous fossiliferous silts Massive calcareous silts rich in microfossils with scattered molluscs & infrequent corals. Thin continuous beds or lenses of shell debris or coral debris sometimes with a sandy matrix. Infrequent burrowing Biostromal coral beds separated by softer highly fossiliferous calcareous silts Bedded calcareous silts & sandy silts rich in microfossils & with scattered corals & molluscs Calcareous silts rich in coral heads & debris. Molluscs & fora- minifera common. Decimetric hard & soft layering produced by secondary cementation Calcareous silts with frequent coral beds & scattered corals & molluscs. Rich in foraminifera Laminated silty sands with cross-bedding. Foraminifera & molluscs concentrated in burrows & also following bedding or scattered throughout. Isolated corals Calcareous silts with common algae & foraminifera & scattered corals & molluscs Polygenetic conglomerate of well rounded, poorly sorted components. Coral debris in upper part Calcareous silt with packed corals, calcaerous algae & scattered pebbles. Irregularly bedded Sands with abundant planar cross-bedding picked out by concentrations of Amphistegina shells. Frequent burrows filled with shell debris Shelly pebbly sands with shelly conglomeratic lenses Poorly sorted pebbly sands with shelly conglomeratic lenses Lignites & lignitic clays in pebbly silts & cross bedded sands Cross-bedded sands, lignitic silts, conglomeratic lenses & pebble beds with shells. Hard concretionary layers Irregular pockets of pebbles & shells in the basal sands Highly irregular karst surface cutting across dipping limestones of the Tabera Formation Text-figure 15 Map and columnar section of Rio Cana showing topographic position of NMB, USGS and TU localities and stratigraphic position of NMB localities. RIO CANA 0 100 200 300 400 500m о 300' 600' 900' 1200 1500 N LEGEND Sample collected for microfossils or lithology Distance over which macrofossils collected Point sample collected for macrofossils IAYUBIN MOCA N $ 10 20km 4 Rio Cana 2 Rio Gurabo Cig |o 5 IE A о [E] Oligocene - Eorly. Miocene ? 5 Cañada Zalaya 6 Rio Yaque del Norte A — 7 City of Santiago 4 4 8 Arroyo Puñal € Y 9 Rio Verde 2 Ss VALVERDE! ESPERANZA NAVARRETE Я m vx Y y 8 ez 3 > Morga L 'EMADOS N SANTIAGO 8 17023 17022 (approx. position) 17020,17021 16865 16864 17007. fo "s 16863 16862 ed | 16861 16965 16963 Б 16860 16962 16813 16814 Doe ي‎ $e 16859 I 16858 aCe T a „Т / TU 1356 [| 16822 16881 wes ЗРЯ 16816 169617 16817 p-16960 16959 à TU 1354 o о о c o o 16878 N [ee 16820 16977 g 16829 a i [I Ш u Il 1 \ 16830 IN 16831 \ AN 16832 Y \\ Il A I E ү = 16833 и 169785 d 1 1 16979 16834 / M \\ N M Ш Ш 1 7 ^ 1 ^" Y N 2 Y Y Y Y Y ГА Y ww 1 n Il Il и 16984 i [| 4504 -17 08 — 16868 -17009 -17008 — 16865 -17010 — 46 867 zx — 16866 FL o Eorum 16990,16991 -16864 к 6851 16847 -17007 15097 - 16863 s 43 — 27 - 16862 LS 16852 ere -16861 16963 7ے‎ iio A^ A ^. ^v mo OO me ~ ~ = TU 1229 > -16859 г ng Reise 5 TIEREN = h16815 -17006 J = — 16814 ee - 1581-16-18 T 9/80 : =o —4687 16 965 mn, 16879, \ 1016970 Ac —46878 € 46 985 = 16823 S e м. ii u en 8 аг "sb M SS e = 1 SO ae —16960-61 y 08 16959 PEE = / - Lp o c Д р > \ 16973 : S —16974 re - 16827 p RN & E -16975 ndr "E — 16828 Sann ar - 0/21 -16976 TT bee Z 7 E DELE - 46829 -1 El A de Es bia alatus оссе j er II VS Tm Los A M 1 3 ( 5651655 gt 000, 17001 ji 2 TIO —16978 a 1 —16979 — —16834 N air y in 16998 е —16980 ZEN T \ TU 1228 -16981 ES -16982 p YU — 16835, 16938 Г $ > Wr * A 16984 -16836 De А d El Caimito —16837 Bee - -16838 IE S —46840 =h16987- 16839 —46990 16991 —16841-52 ,16988/89/93 —16992 246996 TU 1230 -17001 A 1000,01 898' a -16999 ‘ @ -17003 —16854 -17002 -16853 -16855 KS „ 9 Y er Y -17004 —16856 | -16857 -17005 rozê TU 1282 -17026 -17025 -17027 -17028 -17033 17034 217888 - 17032 -17031 1004: 16874 12004 -17024 16885 1100- | EN | e ae = 16884 -17023 —16874 T^ [ \ 800- -~17022 —16875 —16876 —16877 — 17021 —16873 —16872 — 17020 \ A KO) 1 \ -17019 17018 -17017 —16871 -16870 —17016 —16869 -17048 -17014 — 17043 -17012 ! 4504 AS №. | Tu 4301 \\ \\ | \\ 16855 \\ \ OM T= 1 \\ 11 H 7i M 2 M 2 M M \ > 11 Mic И ES 1/ ES // lI EUN, 16857 [ - \\ 17005 1 M M \\ \\ \\ \\ \\ \\ \\ \\ \\ ` \\ 1025—50 11 1] 11 jj 7026-4 // // 47027 % // // // 77 FeeL tay dt A Е) О 17029-17031 о "s 9 > 4703217033 NS x DX 17034 é f Text-figure 16 Columnar section of Rio Cana giving lithologies and age. w | ш N НИЕ ре «1. cic > ulgizi. LiololY 2ш Еј ш =1О|<|2 ш|<|2|= |5 Oe а|®|т ditizici- 12001 uJ 2. LJ CO; |, О? " а. Lu 2) e © > | l | | | = / O Woo] | к ч | > a e | О и. | | | | | | | ш 2. uJ Qo O > ш Oleic, 11010 EM = бы ТЕ > > | ш 2T ope Cic aia о ш < uiz H- ] © 4 > ш = © N ш Z| w Ші < E x EF -— als > > zu ac «wi А wj = = E E E O 4 (|< o|lz — | > | @ ру [© сю [и > z Ф Фф d mn m 2 | s z| H- ES 2 en o Oo PES ul aq Z NIS O =. + o > a Ш C im Lie ч zx > e) eo < eo O X а. O © 4 o a ul o RIO CANA Bedded pebbly sands & minor conglomerates Massive sand with scattered molluscs & plant debris Sands with coral debris & molluscs No Outcrops This is possibly Mao Clay Thin bedded sandy limestones with molluscs, corals & a few pebbles Alternating calcareous siltstones & coral limestones Mainly coral limestones with corals in position of growth, interbedded with calcareous siltstones with coral debris, molluscs & foraminifera. Sedimentary slopes sometimes visible Massive coral limestones with scattered large heads in position of growth Coral rubble interbedded with thin limestones & pebbly highly calcareous sands with frequent burrows Cross-bedded & channeled pebbly sands Pebbly coarse sands Strong foreset bedding in coarse sands & conglomerates Channeled & cross-bedded coarse sands & conglomerates. Large oysters scattered throughout: Laminated & convoluted fine sands & silts Fine sands with conglomerates towards top. Channeled & locally slumped & convoluted Massive to bedded silts with scattered molluscs Sands & conglomerates cross-bedded and channeled at the base Clayey silt Conglomerates & cross-bedded sands & silts Bedded calcareous sands & silts Calcareous siltstone with conglomeratic lenses Massive calcareous silts. One bed of large oysters Calcareous silts with scattered molluscs Massive coral rubble beds interbedded with calcareous silts & sands. A few richer shell beds Massive to irregularly bedded rubbly calcareous silt with corals, bryozoa, molluscs & prominent Sphaerogypsina. Some layers thick with burrows Conglomerates & pebbly & silty sands with molluscs, corals & foraminifera. Lenses & pockets of pebbles. Channels. Burrowed surfaces Clayey silt with lignite levels & shell beds. Minor conglomerates Conglomerates, coarse sands & silty sands. Cross-bedded & channeled with common burrows & occasional thin lenses of shell debris Silts & silty sands with several distinct shell beds pre- dominantly composed of Arca but also rich in oysters & sometimes passing laterally into conglomerates. Lignitic clays between the shell beds Coarse pebbly sands & conglomerates with interbedded clayey silts. Cross-bedded & with thin lenses of molluscs & coral debris Channeled & cross-bedded sands with frequent carbonaceous clays & lignites. Lenses of conglomerate & shell debris Polygenetic poorly sorted conglomerates interbedded with pebbly coarse sands Text-figure 21 Map of Rio Yaque del Norte showing position of NMB, USGS and TU localities. RIO YAQUE DEL NORTE 400 300 600 900 1200 1500' LEGEND Sample collected for microfossils or lithology Distance over which macrofossils collected Point sample collected for macrofossils N аа d ict AYUBIN 1 шшр Cenozoic H Rio Afina & [E] Oligocene - Eorly Miocene ? 5 Cañado Zalaya E: Mesozoic 5 e 8 Arroyo Puñal 9 Rio Verde SS SANTIAGO BULLA EN cm MOCA P AE Я JANICO N E kK AWE Estimated - T 10°/? 20°/010° 17294 \ \\ \\ \\ \\ \\ \\ \\ 17319 \\ \\ ue \\ P. 17318 چ چ چ‎ AO Ег // 17278 тетт RE Y 7 // [| // Il I TITS Z Z Z — — — — — — — / 1 een; 3 $ и Y YY n << Arroyo // // 4 N / > // \\ Se) N 7 N | сы es 17276 I a ا‎ 47316,17 317 \\ 0 20002 M \\ \\ ivi 17274 \\ \ Text - Figure 26 \ - // // „=== || |4273 P4 7 ; / 7 : E 1 López m 17272 I] /] T // себ? j Arroyo LOS eedem ue Е DS S hes ee N r SE E SE | N | N iI > N 1 \\ M E Text - Figure 25 ii N N N N \\ 17484 - 17190 2 16935- 16944 17191, 17192 : 17265 17320-17327. E TU 1364 TU 1363 4, <) o, Do 16945 17279-17290 TU1226 USGS 8558 USGS 8668 Tu 1362— * Text - Figure 28 359/0509 17328 ( Approx. position) Baitoa 17166 Text-figure 25 Columnar section of cliff exposures on the Rio Yaque del Norte north of Baitoa giving lithologies and stratigraphic position of NMB localities. LOPEZ Section continues upwards for at least 20 m but thicknesses can only be estimated Silty sand Conglomerate, poorly sorted with components up to 25 cm. Coral fragments & shells. Corals growing on some cobbles Shelly pebbly sand Sandy shelly conglomerate. Pebbles av. 2-3 cm up to 8 cm Silty sand with scattered shells. Occasional pebbles up to 4 cm Sandy conglomerate with components up to 8 cm. Large broken coral heads 16942 17190 Silty sand with scattered shells & pebbles. Minor lenses of 16943 polygenetic conglomerate & of shell debris 16940 Poorly sorted conglomerate with components up to 10 cm. 16939 Large broken coral heads near top 16938 Silty sand with lenses & burrows packed with shells. Cross- 17189 bedded towards top. One 15 cm diameter bored tree stem 17188 16937 Shelly silty sand forming a prominent ledge due to con- cretions. Passes laterally into conglomerate lenses Turritella bed well exposed in Arroyo Hondo 16936 17265 | | Silts with scattered shells. One tree stem 2 m long Shelly siltstone Shelly sand with large cobbles at base Cross-bedded sand with conglomeratic shelly lenses Sandy silt with lenses & burrows packed with shells Near normal water level at mouth of Arroyo Hondo 17327 Shells packed in silty sand matrix ay E Heavily burrowed silt. Amphistegina & small shell fragments e. с pack burrows. Piece of wood at top of bed greater than 1.5 т pde D long. 20 cm shell bed in centre 17320 VESSAN 21223 ae a Very poorly sorted conglomerate with sand matrix. Compo- : nents mostly 2-6 cm but up to 20 cm. Broken shells. Oysters growing on corals 17290 Heavily burrowed silt with lenses of shells Turritella & Arca bed Silt with abundant shells. Scattered pebbles & cobbles up to 10 cm. Concretions common at top 17288 ( 17324 Silt with rich shell levels. Lignitic lenses. Oysters up to 10 cm Concretionary siltstone rich in shells 17323 Shelly silt with richer shell lenses. Concretions common at 17287 base Polygenetic conglomerate. Irregular thickness, erosional base 17286 Heavily burrowed sands & silts with shell lenses 17322 SEES 25—584 O c 2 2 Silt, irregularly bedded due to layers of concretions. Very rich in shells 17285 STA 17283 ES MWS b Pebbly fine sand rich in shells & with scattered large coral heads towards top Conglomerate, badly sorted with components up to 20 cm. Scattered large shells 16945 17284 | SA RSN D an Pebbly silty sand rich in shells. Pebbles scattered throughout & in layers & lenses of poorly sorted polygenetic components a“, x ko Discordant erosive contact with poorly sorted conglomerate ee Sea Via above 17191 “E 17321 Interbedded grits, sands & silts. Average bed thickness 15 cm. Grading & load casts common Bedded silt clasts in grit matrix. Up to 1 m long Conglomerate. Shows overall grading but badly sorted with components up to 15 cm right to top Conglomerate. Shows overall grading but is composite with a number of graded finer beds towards top Laminated silt clasts up to 1 m long. One coral head 50 cm Erosional base Coarse & fine pebble beds showing grading Rubble bed with shale clasts and one limestone block (1 m). Corals 5m + Very poorly sorted conglomerate with components up to 20 cm Finer conglomerate & coarse sand с? e Very poorly sorted conglomerate with components up to «e DIOS 14 cm Section continues downwards with a big thickness of conglomerates Text-figure 29 Map of Rio Mao showing position of NMB, USGS and TU localities. RIO MAO 0 300 600 900 4200 4500 TU1337 USGS 8530 — À Z LEGEND Sample collected for microfossils or lithology Distance over which macrofossils collected Point sample collected for macrofossils N Q 10 _20km 1 Rio Cana 2 Rio Gurabo Rio Mi ж Эй Ж э, О n AYUBIN 1 С Upper Cenozoic FEET Fr Dee E [e] [E] Oligocene - Eorly Miocene ? 5 Cañada Zalaya p re V 3 менюе 6 Rio Yaque del Norte = 7 City of Santiago 8 Arroyo Pufal 9 Rio Verde 74 SANTIAGO A MOCA AN Mo as USGS 8531 ce i AGO." y T: p IN E | a 4 : TU 1336 , USGS 8532 , USGS 8533 с = | 4 E x a // D RER TU 1292 , USGS 8528 к / N Г К \ // N 4 \\ / á Y d M Y N 7 LÀ Y N i 2 / \ S a / S fi 7 m / NS // 8 N TU 1225 P4 x / // N A \ 1 M 1 \\ ^ M 7 TU 1280, USGS 8733 Y) \, \ \\ \\ \\ 11 || 11 || || \\ B N USGS 8527 Cercado T Ri CUM. N ый ке шы == ae SS = N N > NS — € N M 16940 —€— N TU 1293 \ USGS 8519 , USGS 8520 bi S BLUFF 1 OF MAURY l IN NI // \ TTT Y 16803 |Р 16802 | uses 8521-8524 ү == Text - Figure 31 [| Y Y Y LA 16930 ! 16914, 16931 li ihe a 16932 y 5 pl us \\ 17176 LUFF 2 OF MAURY \ Text - Figure 33 ae N S9 17307 16929 16928 21695 (5927 Jese 16926 146917, 16923 NN 16919 — 16918 , 16924 1 iu Text А Наза 32 Tu 1294 USGS 8525 BLUFF 3 OF MAURY TU 4295 E of Bulla not plotted Text-figure 34 Map of central portion of Rio Amina showing position of NMB, USGS and dia RIO AMINA 0 100 200 300 500 m 0 300 600 900 1200 1500' = " HEROUM S x N SS қ \ ME 16957 (approx. position) \ LEGEND | / | \ \\ Sample collected \ Dd for microfossils or lithology Distance over which \ macrofossils collected \ \ \ Point sample collected x for macrofossils \ \ N m 10 20km 4 Rio Cana 2 Rio Gurabo AYUBIN Cip 1 LI Upper Cenozoic RARE A [2] Oligocene - Early Miocene ? 5 Cañada Zalaya N v 6 Rio Yaque del Norte 3 4 l [ЕБ] Mesozoic 7 City of Santiago 8 Arroyo Puñal S d H I3 n 9 Rio Verde 9 $ x т 1 2 S VALVERDE ESPERANZA NAVARRETE i: ZAMBA MAO Bo ] 3 > Nort á \ LOSQUEMADOS / SANTIAGO : | ` : 9 RODRIGUE. 7 неи SANTIAGO MOCA 6 8 C BAITOA ser tes JANI Ste TU 1219 =USGS 8516 = ei ug Lec SS “==. Re Er > "ue = 2 A TU 1220 = USGS 8517 P a. d m D * rd Tiesos , 1217 \\ N 16806 do 16954 м, => Nd 16955 N N \\ 6 Y \ \ TU 1218 16 804 себ LZZ 2/0 vvOo 6