Formative Age and Rate of Beachrock, Developed on Ohuratabaru Coast, North of Miyako Island, SW Japan

Abstract

Ohuratabaru coast lies in the northern part of Miyako Island, where beachrock develops continu- ously about 400 m in length and 70 m in width. Eight calibrated ¹⁴C ages reported previously were used to estimate formative age and rate of beach rock. They suggest that beachrock was formed from inland toward the present strand line between ca. 1,500 cal BP and present time. The average formative rate of beachrock evacuated from age and distance indicated 3～7 cm/y.