Racemization radiocarbon-dated

Bada, J. L., Master, P. M., Hoopes, E., Darling, The Dating of Fossil Bones Using Amino Acid Racemization, In Radiocarbon Dating, pp. 740-756, Berkeley, University of California Press, 1979. 

Taylor, R.E., Ennis, P.J., Slota, P.J. Jr and Payen, L.A. (1989). Non-age-related variations in aspartic acid racemization in bone from a radiocarbon-dated late Holocene archaeological site. Radiocarbon 31 1048-1056. 

Amino acid racemization dates on bone have been reported for 36 sites throughout the world (14-18,80-32). At 25 of these localities, ages derived from independent evidence such as radiocarbon dating, geological interpretation, and historical records were available for comparison and agreed well with the racemization ages. Some of these comparisons are listed in Table I. 

Means of Calibrating Racemization Rates. Theoretically, the racemization technique has an eflFective dating range of 500,000 years in cool temperate environments. One problem in working with these older samples is finding an appropriate calibration sample. Radiocarbon-dated bones 17-20,000 years old provide suitable calibrations for the last... 

Table III. Racemization of Aspartic Acid in Holocene Radiocarbon-Dated Aboriginal Skeletons from California...

These various comparisons demonstrate that the Laguna skull radiocarbon date of 17,150 years is correct, that the dated Laguna material is indeed the original skull, and that the kasp value derived from the racemization and radiocarbon analyses of the Laguna skull can be used to calibrate the amino acid racemization reaction for the southern California coast. 

This work demonstrated that AAR could give reasonable dates from smaller samples of bone than were necessary for radiocarbon, and had a time depth of at least 70 000 years, and possibly more if one of the more slowly racemizing amino acids such as alanine was used. The key paper came in 1974 (Bada et al., 1974), which published dates of between 6000 and 48 000 BP for various samples of human bone from the Californian coast (Table 8.1). The SDM (San Diego Museum) samples from site W-2 were from a shell midden near La Jolla excavated in 1926. Subsequently, it appears that 19 individual burials were recovered in a rescue operation from this site, known as La Jolla Shores SDM-16755 is thought to refer to more than one individual (La Jolla Shores I and II), with a third (La Jolla Shores III) identified as SDM-16740 (Taylor et al., 1985 Table 8.1). Site W-34 was located between Del Mar and Solano Beach, from a shell midden which had been largely destroyed by coastal... 

Goodfriend, GA., and Rollins, H.B. (1998) Recent barrier beach retreat in Georgia Dating exhumed salt marshes by aspartic acid racemization and post-bomb radiocarbon. J. Coast. Res. 14, 960-969. 

Accuracy of Racemization Dates beyond the Range of Radiocarbon. 

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