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During the last few years, several studies have shown that under certain conditions the amino acid racemization reaction can be used to estimate the age of fossil materials and also to deduce paleotemperatures (see Bada and Schroeder, 1975; and Schroeder and Bada, 1976, for reviews). Since racemization is a chemical reaction, there are two variables which can affect the extent of racemization in a fossil, time and temperature. If the temperature history of a fossil can be evaluated, then the extent of racemization in that fossil can be used to estimate its age, or, alternatively, if the age can be estimated using some other dating technique, then the extent of racemization can be used to estimate the average temperature to which the fossil has been exposed during its depositional history. All of the samples which have been used so far in studies of amino acid racemization in marine sediments have come from ocean areas where bottom water temperatures have probably been fairly constant over the last several million years (Savin et al, 1975). In certain oceanic areas, however, bottom water temperatures may not have been constant throughout the past, and the fluctuations in temperature may, in turn, be detectable by amino acid racemization, provided the age of the sample can be estimated, using some other independent dating method. In this instance, the amino acid racemization reaction is used as a paleothermometer. An example of this application is provided by the results presented here for Leg 42A, Sites 372 and 376. Site 372 was located southeast of Menorca in the Western Mediterranean, whereas Site 376 was west of Cyprus in the east (see Hsü et al., this volume).

Racemization of Isoleucine in Foraminifer Tests from Leg 42A, Sites 372 and 376