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The temperature decrease of surface sea-water in high latitudes and of abyssal-hadal water in open oceanic basins during the past 75 million years
SHORTER
COMMUNICATION
The temperature decrease of surface sea-water in high latitudes and of abyssal-hadal water in open oceanic basins during the past 75 million years* CESARE EMILIANI The Marine Laboratory, University of Miami
(Received 5 December, 1960) Abstract--Oxygen isotopic analysis of Upper Cretaceous belemnites from Alaska and Siberia gave temperatures of about 14°C. Similar measurements on shells of calcareous benthonic Foraminifera from sections of Globigerina-ooze sediments of Tertiary age from the eastern equatorial Pacific gave a temperature of 10.4°C for the Middle Oligocene, decreasing to 2"2°C in the Late Pliocene. Thus, a temperature decrease of both surface water at high latitudes and abyssal-hadal water in open oceanic basins, amounting to about 12°C, appears to have occurred during the past 75 million years. This temperature decrease was probably not linear with time and, although very slow, may have had an important effect on the abyssal and hadal fauna. By comparison, temperatures similar to the present ones may have obtained throughout geologic time in at least some portions of the equatorial thermosphere. If constant temperature is more important for the survival of archaic forms than other factors, the equatorial pelagic fauna should show more archaic affinities than other marine faunas. Oxygen isotopic analysis of Upper Cretaceous belemnites from Alaska and Siberia indicated that surface water temperature at high latitudes and, therefore, also the bottom temperature in all open oceanic basins, was about 14°C (EPsTEiN, 1959). A correction for a probably slightly greater concentration of 0 TM in sea water (cf. EMILIANI, 1955, p. 541), partly compensated by the absence of ice caps, might raise this value by one or two degrees centigrade. Some of the deep-sea cores collected in the eastern equatorial Pacific by the Swedish Deep-Sea Expedition 1947-1948 and described by A R ~ N r U S 0952) Were found to contain sections of GIobigerina ooze sediments of Tertiary age. These sediments were found outcropping (core 53), covered by younger red clay (core 57), or covered in continuity by Pleistocene Globigerina ooze (cores 58 and 62). Micro-paleontological analysis (EMILIANI, 1956) indicated that the sediments of core 53 are of Middle Oligocene age and those of core 57 of Lower-Middle Miocene age. The sediments of the lower portions of cores 58 and 62, underlying comformably the PJeistocene sediments, may be considered of Late Pliocene age. Shells of benthonic calcareous Foraminifera, belonging to a number of different species, were separated from the Tertiary sediments, and the 018/016 ratio in the shell carbonate was d:termined following the method of paleotemperature analysis devised by UREY (1947) and developed by UREV, EPSTEIN and co-workers (EPSTEIN, et aL, 1951, 1953). The Oligocene, Miocene and Late Pliocene foraminiferal assemblages gave temperatures of, respectively, 10.4 °, 7.0 °, and 2.2°C (EMILIANI, 1954). It was concluded that the temperature of the bottom water of the Pacific ocean had d~creased about 8°C during the Tertiary. A similar decrease was inferred for the temperature of the surface water of the polar and subpolar seas, which determines the temperature of the bottom water in all open oceanic basins. The value of th~ temperature decrease was found in agreement with estimates based on paleontological, paleobotanical, and geological evidence (EMILIAN~, 1954). If the evidence from the Tertiary deep-sea cores is combined with that from the Upper Cretaceous belemnites, the temperature of both surface water in the high latitudes and abyssal-hadal water in *Contribution No. 305 from The Marine Laboratory, University of Miami. 144
Shorter Communication
145
all open oceanic basins appears to have decre,ased about 12°C during tl~ past 75 million years (Fie. 1). Although the available data arc few and the chronological control very poor, the temperature decrease does not seem to have been linear with time. Tbe effect on the abyssal and hadal fauna might have been marked, although probably very gradual. The temperature values from the deep-sca core,s, m0ntioned above, were used by BRUUN (1956, 1957) and WOLFF (1960) to suggest that the Tertiary abyssal fauna might have been largely killed by the temperature change, and that most of the modern abyssal and hadal fauna might be very young. M~Nz[~ and I~mPJ~ (1958) reviewed six groups of marine invertebrates and concluded that, in effect, the abyssal fauna contains fewer archaic types than the fauna living within 2,000 m. from the surface (see also M~.Nzms, et al., 1961). A closely reasoned study of the problem, however, led ZENKEVITCH and BIRSTEIN (1960) tO conclusions quite contrary to those of M~NzI~ and IMBal~. In the course 15-
A (.3 O
+
IO-
hi n" :3 I" IV" IM rl =E w )- S -
0100
75
50 TIME
25 (xlO 6 YEARS
0 B.P.)
FIG. 1.
of their analysis, ZENKEVITCHand BmSTEIN (1960, p. 13) dismiss the paleotemperature results from the deep-sea cores with the following discussion : ' Determinations of bottom water temperatures were made by EMILIANI(1954) for the Oligocene from Cassidulina spinifera Cushman and Jarvis, and for Miocene from Gyroidina zelandica Finlay and Laticarinina bullbrooki Cushman and Todd. All three species of Foraminifera used for the determination of paleotemperatures arc diagnostic fossils for shallow water deposits of their respective ages. It is very doubtful that they lived in abyssal depths contemporaneously. According to CUSHMANand STAINFORTn (1945), C. spinifera and L. bullbrooki inhabited depths ranging from 50 to 200 m. Most probably there was a secondary shifting of empty shells of these Foraminifera to a greater depth, such as was proved by EMIUA~ and EPSTEIN (1953) to have occurred for Elphidium. If so, the temperature determined for these species refers not to the abyssal but to the bathyal and sublittoral zones. This explains the higher values of water-temperature compared with those of the abyssal waters of today and makes agreement with the far-reaching inferences by BRUUNfrom the data of EMILIANIimpossible (BmSTEIN, 1959).' This discussion includes several incorrect statements, partly because papers by STAINFORT8 (1948), BECIO,~ANN0953) and EMILIANI (1956) were not considered, and the conclusion reached is unsupported. The Globigerina ooze sections of cores 53, 57 and 58 consist of typical, homogeneous and unstratified Globigerina ooze sediment, without any evidence of faunal displacements, or deposition by turbidity currents, submarine slumping, etc. The isotopic analyses were made not only on the
146
Shorter Communication
three species mentioned by ZENKEVrrC8 and BIRSTEIN, but o n all benthonic calcareous species encountered in the cores in question. A list of the species which are stratigraphically significant was published by EMILZA~ (1956): CUS.MAN and STAINFORTrt (1945) did not say that Cassidulina spinifera and Laticarinina bullbrooki inhabited depths ranging from 50 to 200 m but stated that the Cipero Marl formation, where these two species occur, was probably deposited at a depth greater than 90-180 m, although probably not greater than 400-500 m (STAINFORTH, 1948). BECKMANN (1953) made a thorough micropaleontological and stratigraphic analysis of the Oceanic formation of Barbados and concluded that both this formation and the analogous Cipero Marl formation were probably deposited at a depth between 1000 and 1500 m. Two of the extinct species listed in EMtLIAN[ (1956), i.e. Laticarinina bullbrooki and Gyroidina planulata, occur in the Oceanic formation. SENN (1948) suggested that the Oceanic formation might have been deposited at a depth of a few thousand metres, but this view is not shared by other geologists (cf. BECKMANN, 1953). Whatever the actual depth of deposition of the Cipero Marl and the Oceanic formation might have been, benthonic Foraminifera are generally far less exact depth indicators than ZENKEVlTCH and BIRSTEINapparently believe. In fact, three of the four extant benthonic species listed by EMILIANi (1956), i.e. Cassidulina subglobosa, Pullenia quinqueloba and Eggerella bradyi, have depth habitats of, respectively, 22 to 5400 m, 50 to 3400 m, and 235 to 5700 m (data from PHLEGER,et al., 1953), a clear example of wide depth dispersion. The fourth extant benthonic species, Nodogerina challengeriana, originally described from southwest of New Guinea, at a depth of 220 m, has not been reported from deep-sea cores. Finally, the extinct species Sphaeroidinella rutschi occurs also in the Miocene sections of the deep-sea cores 233 and 234, which were raised from depths of, respectively, 4125 and 3577 m in the equatorial Atlantic (PriLEGER, et al., 1953). From the above discussion it app:ars that there are no reasons to doubt the validity of the isotopic temperatures as representing bottom temp:ratures of the ocean water at the given times, localities, and depths. The displaced Elphidium shells mentioned by ZENKEVlTC8 and BmSTEIN refer to a littoral sediment (the Lomita Marl of southern California) and to storm effects having no relationship with the present problem. The evidence presented above indicates that abyssal and hadal temperatures have not remained constant during geologic time. This is not surprising because abyssal and hadal temperatures in open oceanic basins are conditioned by surface temperatures in the high latitudes, and these have been known to have changed markedly even on paleontological and paleobotanical evidence alone. In addition to the slow temperature decrease from the Late Cretaceous to the Late Cenozoic, there is some evidence that abyssal temperature in some regions may have undergone more rapid changes during the Pleistocene in response to the glacial-interglacial cycles. Thus, oxygen isotopic analysis of calcareous benthonic Foraminifera from a deep-sea core from the equatorial Atlantic indicated a variation of about 2-3°C (EMILIAN[, 1958, FIG. 5), if a correction is made for the greater concentration of 0 TM in sea water during glacial ages. Aside from temperature oscillations during the Pleistocene (3-4°C in the equatorial Pacific, and 6-7°C in the equatorial Atlantic; see EMIL1ANI, 1955), the equatorial thermosphere, at least in portions, may have maintained temperatures similar to the present ones throughout geologic time. If constant temperature is more important for the survival of archaic forms than other factors, the equatorial pelagic fauna should show more archaic affinities than other marine faunas. REFERENCES
ARRHENrOS, G. (1952) Sediment cores from the east Pacific. Swedish Deep-Sea Exped. 1947-1948, Repts., 5, (1), 227 pp. BECKMANN, J. P. (1953) Die Foraminiferen der Oceanic Formation (Eocaen-Oligocaen) von Barbados, KI. Antillen. Eclogae Geol. Helvetiae, 46, 301-412. BIRSTEIN, J. A. (1959) Paleotemperatures and the origin of the abyssal fauna. Priroda, 5, 21-28. BRUUN, A. F. (1956) The abyssal fauna : its ecology, distribution and origin. Nature, Lond. 177, 1105-1108. BRUUN,A. F. (1957) Deep Sea and abyssal depths. Ch. 22 in : Treatise on Marine Ecology and Paleoecology, 1, Ecology, Mem. GeoL Soc. Amer., 67, 641-672. CtlSI-IMAN, J. A. and STAINFORTH, R. M. (1945) The Foraminifera of the Cipero Marl formation of Trinidad, British West Indies. Cushman Lab. Foram. Res., Spec. Publ., No. 14, 74 pp. EraILIANI, C. (1954) Temperatures of Pacific bottom waters and polar superficial waters during the Tertiary. Science, 119, 853-855.
Shorter Communication
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EMILIANI, C. (1955) Pleistocene temperatures. J. Geol., 63, 538-578. EMILIANI,C. (1956) On paleotemperatures of Pacific bottom waters. Science, 123, 460--461. EMILIANI, C. (1958) Paleotemperature analysis of core 280 and Pleistocene correlations. J. Geol, 66, 264-275. EMILIANI, C. and EPSTEIN, S. 0953) Temperature variations in the Lower Pleistocene of southern California. J. Geol. 61, 171-181. EPSTEIN, S. 0959) The variations of the 01s/01~ ratio in nature and some geologic implications. In : Researches in Geochemistry, (Ph.H. AaELSON, Ed.), 217-240, John Wiley, New York, 511 pp. EPSTEIN, S., BUCHSaAUM,R., LOWENSTAM,H. and UREV, H. C. (1951) Carbonate-water isotopic temperature scale. GeoL Soc. Amer. Bull., 62, 417-425. EPSTEIN, S., BUCHSBAUM,R., LOWENSTAM,H. and UREV, H. C. (1953) Revised carbonate-water isotopic temperature scale. Geol. Soc. Amer., Bull., 64, 1315-1325. MENZIES,R. J. and IMaRIE,J. (1958) On the antiquity of the deep-sea bottom fauna. Oikos, 9, 192-210. MENZIES, R. J., IMaRIE, J. and HEEZEN,B. C. (1961) Further considerations regarding antiquity of the abyssal fauna with evidence for a changing abyssal environment. Deep-Sea Res., 8, 79-94. PHLEGER, F. B, PARKER, F. L. and PEIRSON, J. F. (1953) North Atlantic Foraminifera. Swedish Deep-Des Exped. 1947-1948, Rep. 7, l, 122 pp. SENN, A. (1948) Die Geologie der Insel Barbados B. W. I. (Kl. Antillen) und die Morphogenese der umliegenden marinen Grossformen. Eclogae GeoL Helvetiae, 40, 199-222. STAINFORTH,R. M. (1948) Description, correlation and paleoecology of Tertiary Cipero Marl Formation, Trinidad, B.W.[. Amer. Assoc. Petrol. GeoL, Bull., 32, 1292-1330. UREV, H. C. (1947) The thermodynamic properties of isotopic substances. J. Chem. Soc., 1947, 562-581, WOLFF, T. (1960) The hadal community, an introduction. Deep-Sea Res., 6, 95-124. ZENKEVITCr~,L. A. and BIRSTEIN,J. A. (1960) On the problem of the antiquity of the deep-sea fauna. Deep-Sea Res., 7, 10-23.
COMMUNICATION
The temperature decrease of surface sea-water in high latitudes and of abyssal-hadal water in open oceanic basins during the past 75 million years* CESARE EMILIANI The Marine Laboratory, University of Miami
(Received 5 December, 1960) Abstract--Oxygen isotopic analysis of Upper Cretaceous belemnites from Alaska and Siberia gave temperatures of about 14°C. Similar measurements on shells of calcareous benthonic Foraminifera from sections of Globigerina-ooze sediments of Tertiary age from the eastern equatorial Pacific gave a temperature of 10.4°C for the Middle Oligocene, decreasing to 2"2°C in the Late Pliocene. Thus, a temperature decrease of both surface water at high latitudes and abyssal-hadal water in open oceanic basins, amounting to about 12°C, appears to have occurred during the past 75 million years. This temperature decrease was probably not linear with time and, although very slow, may have had an important effect on the abyssal and hadal fauna. By comparison, temperatures similar to the present ones may have obtained throughout geologic time in at least some portions of the equatorial thermosphere. If constant temperature is more important for the survival of archaic forms than other factors, the equatorial pelagic fauna should show more archaic affinities than other marine faunas. Oxygen isotopic analysis of Upper Cretaceous belemnites from Alaska and Siberia indicated that surface water temperature at high latitudes and, therefore, also the bottom temperature in all open oceanic basins, was about 14°C (EPsTEiN, 1959). A correction for a probably slightly greater concentration of 0 TM in sea water (cf. EMILIANI, 1955, p. 541), partly compensated by the absence of ice caps, might raise this value by one or two degrees centigrade. Some of the deep-sea cores collected in the eastern equatorial Pacific by the Swedish Deep-Sea Expedition 1947-1948 and described by A R ~ N r U S 0952) Were found to contain sections of GIobigerina ooze sediments of Tertiary age. These sediments were found outcropping (core 53), covered by younger red clay (core 57), or covered in continuity by Pleistocene Globigerina ooze (cores 58 and 62). Micro-paleontological analysis (EMILIANI, 1956) indicated that the sediments of core 53 are of Middle Oligocene age and those of core 57 of Lower-Middle Miocene age. The sediments of the lower portions of cores 58 and 62, underlying comformably the PJeistocene sediments, may be considered of Late Pliocene age. Shells of benthonic calcareous Foraminifera, belonging to a number of different species, were separated from the Tertiary sediments, and the 018/016 ratio in the shell carbonate was d:termined following the method of paleotemperature analysis devised by UREY (1947) and developed by UREV, EPSTEIN and co-workers (EPSTEIN, et aL, 1951, 1953). The Oligocene, Miocene and Late Pliocene foraminiferal assemblages gave temperatures of, respectively, 10.4 °, 7.0 °, and 2.2°C (EMILIANI, 1954). It was concluded that the temperature of the bottom water of the Pacific ocean had d~creased about 8°C during the Tertiary. A similar decrease was inferred for the temperature of the surface water of the polar and subpolar seas, which determines the temperature of the bottom water in all open oceanic basins. The value of th~ temperature decrease was found in agreement with estimates based on paleontological, paleobotanical, and geological evidence (EMILIAN~, 1954). If the evidence from the Tertiary deep-sea cores is combined with that from the Upper Cretaceous belemnites, the temperature of both surface water in the high latitudes and abyssal-hadal water in *Contribution No. 305 from The Marine Laboratory, University of Miami. 144
Shorter Communication
145
all open oceanic basins appears to have decre,ased about 12°C during tl~ past 75 million years (Fie. 1). Although the available data arc few and the chronological control very poor, the temperature decrease does not seem to have been linear with time. Tbe effect on the abyssal and hadal fauna might have been marked, although probably very gradual. The temperature values from the deep-sca core,s, m0ntioned above, were used by BRUUN (1956, 1957) and WOLFF (1960) to suggest that the Tertiary abyssal fauna might have been largely killed by the temperature change, and that most of the modern abyssal and hadal fauna might be very young. M~Nz[~ and I~mPJ~ (1958) reviewed six groups of marine invertebrates and concluded that, in effect, the abyssal fauna contains fewer archaic types than the fauna living within 2,000 m. from the surface (see also M~.Nzms, et al., 1961). A closely reasoned study of the problem, however, led ZENKEVITCH and BIRSTEIN (1960) tO conclusions quite contrary to those of M~NzI~ and IMBal~. In the course 15-
A (.3 O
+
IO-
hi n" :3 I" IV" IM rl =E w )- S -
0100
75
50 TIME
25 (xlO 6 YEARS
0 B.P.)
FIG. 1.
of their analysis, ZENKEVITCHand BmSTEIN (1960, p. 13) dismiss the paleotemperature results from the deep-sea cores with the following discussion : ' Determinations of bottom water temperatures were made by EMILIANI(1954) for the Oligocene from Cassidulina spinifera Cushman and Jarvis, and for Miocene from Gyroidina zelandica Finlay and Laticarinina bullbrooki Cushman and Todd. All three species of Foraminifera used for the determination of paleotemperatures arc diagnostic fossils for shallow water deposits of their respective ages. It is very doubtful that they lived in abyssal depths contemporaneously. According to CUSHMANand STAINFORTn (1945), C. spinifera and L. bullbrooki inhabited depths ranging from 50 to 200 m. Most probably there was a secondary shifting of empty shells of these Foraminifera to a greater depth, such as was proved by EMIUA~ and EPSTEIN (1953) to have occurred for Elphidium. If so, the temperature determined for these species refers not to the abyssal but to the bathyal and sublittoral zones. This explains the higher values of water-temperature compared with those of the abyssal waters of today and makes agreement with the far-reaching inferences by BRUUNfrom the data of EMILIANIimpossible (BmSTEIN, 1959).' This discussion includes several incorrect statements, partly because papers by STAINFORT8 (1948), BECIO,~ANN0953) and EMILIANI (1956) were not considered, and the conclusion reached is unsupported. The Globigerina ooze sections of cores 53, 57 and 58 consist of typical, homogeneous and unstratified Globigerina ooze sediment, without any evidence of faunal displacements, or deposition by turbidity currents, submarine slumping, etc. The isotopic analyses were made not only on the
146
Shorter Communication
three species mentioned by ZENKEVrrC8 and BIRSTEIN, but o n all benthonic calcareous species encountered in the cores in question. A list of the species which are stratigraphically significant was published by EMILZA~ (1956): CUS.MAN and STAINFORTrt (1945) did not say that Cassidulina spinifera and Laticarinina bullbrooki inhabited depths ranging from 50 to 200 m but stated that the Cipero Marl formation, where these two species occur, was probably deposited at a depth greater than 90-180 m, although probably not greater than 400-500 m (STAINFORTH, 1948). BECKMANN (1953) made a thorough micropaleontological and stratigraphic analysis of the Oceanic formation of Barbados and concluded that both this formation and the analogous Cipero Marl formation were probably deposited at a depth between 1000 and 1500 m. Two of the extinct species listed in EMtLIAN[ (1956), i.e. Laticarinina bullbrooki and Gyroidina planulata, occur in the Oceanic formation. SENN (1948) suggested that the Oceanic formation might have been deposited at a depth of a few thousand metres, but this view is not shared by other geologists (cf. BECKMANN, 1953). Whatever the actual depth of deposition of the Cipero Marl and the Oceanic formation might have been, benthonic Foraminifera are generally far less exact depth indicators than ZENKEVlTCH and BIRSTEINapparently believe. In fact, three of the four extant benthonic species listed by EMILIANi (1956), i.e. Cassidulina subglobosa, Pullenia quinqueloba and Eggerella bradyi, have depth habitats of, respectively, 22 to 5400 m, 50 to 3400 m, and 235 to 5700 m (data from PHLEGER,et al., 1953), a clear example of wide depth dispersion. The fourth extant benthonic species, Nodogerina challengeriana, originally described from southwest of New Guinea, at a depth of 220 m, has not been reported from deep-sea cores. Finally, the extinct species Sphaeroidinella rutschi occurs also in the Miocene sections of the deep-sea cores 233 and 234, which were raised from depths of, respectively, 4125 and 3577 m in the equatorial Atlantic (PriLEGER, et al., 1953). From the above discussion it app:ars that there are no reasons to doubt the validity of the isotopic temperatures as representing bottom temp:ratures of the ocean water at the given times, localities, and depths. The displaced Elphidium shells mentioned by ZENKEVlTC8 and BmSTEIN refer to a littoral sediment (the Lomita Marl of southern California) and to storm effects having no relationship with the present problem. The evidence presented above indicates that abyssal and hadal temperatures have not remained constant during geologic time. This is not surprising because abyssal and hadal temperatures in open oceanic basins are conditioned by surface temperatures in the high latitudes, and these have been known to have changed markedly even on paleontological and paleobotanical evidence alone. In addition to the slow temperature decrease from the Late Cretaceous to the Late Cenozoic, there is some evidence that abyssal temperature in some regions may have undergone more rapid changes during the Pleistocene in response to the glacial-interglacial cycles. Thus, oxygen isotopic analysis of calcareous benthonic Foraminifera from a deep-sea core from the equatorial Atlantic indicated a variation of about 2-3°C (EMILIAN[, 1958, FIG. 5), if a correction is made for the greater concentration of 0 TM in sea water during glacial ages. Aside from temperature oscillations during the Pleistocene (3-4°C in the equatorial Pacific, and 6-7°C in the equatorial Atlantic; see EMIL1ANI, 1955), the equatorial thermosphere, at least in portions, may have maintained temperatures similar to the present ones throughout geologic time. If constant temperature is more important for the survival of archaic forms than other factors, the equatorial pelagic fauna should show more archaic affinities than other marine faunas. REFERENCES
ARRHENrOS, G. (1952) Sediment cores from the east Pacific. Swedish Deep-Sea Exped. 1947-1948, Repts., 5, (1), 227 pp. BECKMANN, J. P. (1953) Die Foraminiferen der Oceanic Formation (Eocaen-Oligocaen) von Barbados, KI. Antillen. Eclogae Geol. Helvetiae, 46, 301-412. BIRSTEIN, J. A. (1959) Paleotemperatures and the origin of the abyssal fauna. Priroda, 5, 21-28. BRUUN, A. F. (1956) The abyssal fauna : its ecology, distribution and origin. Nature, Lond. 177, 1105-1108. BRUUN,A. F. (1957) Deep Sea and abyssal depths. Ch. 22 in : Treatise on Marine Ecology and Paleoecology, 1, Ecology, Mem. GeoL Soc. Amer., 67, 641-672. CtlSI-IMAN, J. A. and STAINFORTH, R. M. (1945) The Foraminifera of the Cipero Marl formation of Trinidad, British West Indies. Cushman Lab. Foram. Res., Spec. Publ., No. 14, 74 pp. EraILIANI, C. (1954) Temperatures of Pacific bottom waters and polar superficial waters during the Tertiary. Science, 119, 853-855.
Shorter Communication
147
EMILIANI, C. (1955) Pleistocene temperatures. J. Geol., 63, 538-578. EMILIANI,C. (1956) On paleotemperatures of Pacific bottom waters. Science, 123, 460--461. EMILIANI, C. (1958) Paleotemperature analysis of core 280 and Pleistocene correlations. J. Geol, 66, 264-275. EMILIANI, C. and EPSTEIN, S. 0953) Temperature variations in the Lower Pleistocene of southern California. J. Geol. 61, 171-181. EPSTEIN, S. 0959) The variations of the 01s/01~ ratio in nature and some geologic implications. In : Researches in Geochemistry, (Ph.H. AaELSON, Ed.), 217-240, John Wiley, New York, 511 pp. EPSTEIN, S., BUCHSaAUM,R., LOWENSTAM,H. and UREV, H. C. (1951) Carbonate-water isotopic temperature scale. GeoL Soc. Amer. Bull., 62, 417-425. EPSTEIN, S., BUCHSBAUM,R., LOWENSTAM,H. and UREV, H. C. (1953) Revised carbonate-water isotopic temperature scale. Geol. Soc. Amer., Bull., 64, 1315-1325. MENZIES,R. J. and IMaRIE,J. (1958) On the antiquity of the deep-sea bottom fauna. Oikos, 9, 192-210. MENZIES, R. J., IMaRIE, J. and HEEZEN,B. C. (1961) Further considerations regarding antiquity of the abyssal fauna with evidence for a changing abyssal environment. Deep-Sea Res., 8, 79-94. PHLEGER, F. B, PARKER, F. L. and PEIRSON, J. F. (1953) North Atlantic Foraminifera. Swedish Deep-Des Exped. 1947-1948, Rep. 7, l, 122 pp. SENN, A. (1948) Die Geologie der Insel Barbados B. W. I. (Kl. Antillen) und die Morphogenese der umliegenden marinen Grossformen. Eclogae GeoL Helvetiae, 40, 199-222. STAINFORTH,R. M. (1948) Description, correlation and paleoecology of Tertiary Cipero Marl Formation, Trinidad, B.W.[. Amer. Assoc. Petrol. GeoL, Bull., 32, 1292-1330. UREV, H. C. (1947) The thermodynamic properties of isotopic substances. J. Chem. Soc., 1947, 562-581, WOLFF, T. (1960) The hadal community, an introduction. Deep-Sea Res., 6, 95-124. ZENKEVITCr~,L. A. and BIRSTEIN,J. A. (1960) On the problem of the antiquity of the deep-sea fauna. Deep-Sea Res., 7, 10-23.