NATIONAL OCEANOGRAPHIC PROGRAM—1965 OT 
The study of the Pleistocene cores has provided a remarkable (but still incom-- 
plete) picture of the Pleistocene epoch. Thus, a continuous temperature record 
for the past 375,000 years was reconstructed using Urey’s method of istotopic- 
paleotemperature analysis. C™ and Pa™/Th™ measurements have provided a 
partial time scale for these reconstructions, showing that the temperature varia-- 
tions were quasi-periodical, with a quasi-periodicity of about 40,000 years. An 
important observation is that the apparent agreement between C™“ and Pa*’/’ 
Th*” data over the entire range of C“ dating shows that cosmic ray flux has not 
changed markedly during the past 60,000 years. 
While the study of Pleistocene deepsea cores has greatly clarified the history 
ot the Pleistocene, the study of longer columns of deep sea sediments should 
clarify the history of earlier geological periods. Geophysical measurements and 
geological-paleontoicgical observations suggest that the deep sea sediments may 
represent only the past 100 million years of the earth’s history. It appears 
possible, in fact, that the older Sediments may have been swept away by the: 
upper branches of convection cells in the mantle. Even so, 100 million years 
is a time interval which compares favorably with the duration of many geo- 
physical, geochemical, and biological phenomena to be studied. Furthermore,. 
areas of the central and western Pacific and the eastern Indian Ocean, and 
especially areas on the concave side of island ares (such as the Caribbean) and 
portions of the ancient Tethys (Gulf of Mexico, Caribbean, Mediterranean) may 
have remained undisturbed by the activity of convection currents in the mantle 
for more than 100 million years. Older Mesozoic and even Paleozoic or Pre-- 
Cambrian sediments may be preserved in some of these areas. 
In general, section of unconsolidated deep sea sediments up to 1,090 meters: 
thick have been noticed in the Atlantic Ocean, and sections about 300 meters 
thick occur over much of the Pacific. Sampling of such sediment thicknesses 
requires the usage of a drilling vessel. Preliminary tests conducted off Guada- 
lupe Island in the eastern Pacific and in the Caribbean have demonstrated the: 
feasibility of the operation. 
In addition to the rate problems mentioned above, coring through the deep sea 
sediment cover will clearify many important problems related to the origin, 
structure, and evolution of the ocean basins. Thus, for instance, cores through 
the deep sea sediment cover of the Atlantic Ocean should provide a conclusive 
test for the contention that this ocean opened up about 100 million years ago by 
drift of the Americas with respect to Europe and Africa. If this contention is 
eorrect, shallow water sediments of Mesozoic age should be found underneath 
younger pelagic sediments. 
For a proper approach to the problems mentioned, stratigraphic sections of 
deep sea sediments as complete as possible are necessary. Two basic difficulties, 
however, are opposed to such completeness. First, as shown by the study of 
the cores obtained with the piston corer, unconformities are common in deep 
sea Sediments even in areas considered “stable”. Second, coring techniques will 
not yield a 100 percent recovery of the sediment encountered. The latter diffi- 
culty may be minimized by collecting pairs of cores from any given location, 
rather than single cores. The former may be minimized by suitable geographical 
dispersion of the coring locations. Continuous stratigraphic records may then 
be reconstructed by intercorrelating the cores thus obtained. The problem of 
intercorrelation is a difficult one, however, requiring the simultaneous usage 
of unrelated parameters. An example of the method, involving Pleistocene cores, 
is shown in figure 1. 
The dating of the stratigraphic record obtained from the deep sea floor is a 
problem of fundamental importance for the interpretation of all measured para- 
meters. Dating may be achieved essentially in two ways: 
(1) K/A dating of voleanic ash layers which may be encountered at different 
levels within the sediments; and (2) correlating the sedimentary record with 
marine epicontinental deposits outcropping on the continents and related to the 
established geological time scale. 
The first method implies the occurrence, within the sampled deen sea sedi- 
ments of volcanic ash layers, and the usefulness of this material for K/A dating 
(neither one of these two things is assured). The second method involves classi- 
cal paleontological method, which while not as exact as successful K/A dating 
of ash layers, will still provide a fairly adequate time scale. For the all im- 
portant purpose of assuring a time scale (at least by the paleontological method), 
Globigerina-ooze sediments of the tropical and subtropical North Atlantic, the 
