Journal of California and Great Basin Anthropology

In the Winter 1974 issue of The Journal of California Anthropology, Christopher Drover described his preliminary work on a method which uses growth rings from two species of archaeologically recovered Chione for deriving seasonality data, or the season(s) when food resources were exploited. Drover's method draws heavily on Barker's (1970) and Berry's (1972) studies of growth periodicity in Chione clams. The method is based on the idea that in both C. undatella and C. fluctifraga, the pelecypods' mantles generally contract and cease the secretion of calcium carbonate during the colder winter periods. When a shell's growth is relatively inactive, a semiopaque concentric annual groove will be externally visible. A winter death should be marked by such an incipient groove ("major groove," "disturbance groove," or "annual groove") at the ventral margin of a shell. Death at other seasons, it is argued, can be estimated from the shell's growth since the last winter groove was formed.