Correlation and chronology of Pacific Coast marine terrace deposits of continental United States by fossil amino acid stereochemistry technique, evaluation, relative ages, kinetic model ages, and geologic implications

Abstract

Enantiomeric (D/L) ratios of six or more amino acids have been determined in Pleistocene mollusks from fifty-one terrace localities on the Pacific coast of the United States from Puget Sound, Washington, to San Diego, California. Samples have been selected for the purpose of evaluation of various aspects of the amino acid dating technique as well as for the application of the technique to unresolved chronologic problems. Samples with known stratigraphic relationships (upper and lower Pleistocene, Pliocene) have been examined to document the relationships between geologic age and extent of racemization. Most genera investigated exhibit the expected trend of increasing extent of racemization with increasing age, but some genera do not document this trend, probably because of contamination during diagenesis. Of all genera examined in this manner, the bivalve mollusk Saxidomus appears to be the most reliable.