Variations in racemization/epimerization ratios and amino acid content of Glycymeris shells in raised marine deposits in the Mediterranean

► Glycymeris shells are adequate for AAR dating of raised coastal deposits. ► The distribution of the organic matrix within the shells calls for standardized sampling. ► Variability and time-averaging doesn't allow discrimination among MIS substages in Mediterranean deposits. ► Mineral diagenesis does not strongly affect the amino acid content or mineralogy of Glycymeris. ► Large sample sets are not only desirable but necessary.