APPARENT AGES OF MARINE SHELLS - IMPLICATIONS FOR ARCHAEOLOGICAL DATING IN HAWAII

The conventional C-14 ages of 8 marine shells of known age and 11 mari ne shells stratigraphically associated with dated wood charcoal show c onsiderable variation from expected ages. One source of this variation is seashore geology; comparison of 6 AMS dates on 3 species of shallo w-water, herbivorous gastropod shells from Pleistocene limestone and H olocene volcanic coasts shows that shells from Pleistocene limestone c oasts can have apparent, or reservoir, C-14 ages up to 620 yr greater than shells of the same species from volcanic coasts. The relatively g reat variation in apparent ages of Hawaiian marine shells poses proble ms for their use in dating archaeological sites. For best results, an archaeological marine shell should be sourced to a particular local en vironment, and the apparent age of shells in that environment determin ed by dating well-provenienced shells of known age.