US Geological Survey


Date of this Version



Published in GEOLOGY. v 10, p 23-26, JANUARY 1982.


Uranium-series analysis of the coral Allopora californica Verrill from the 2nd, 32-m Eel Point terrace on San Clemente Island, California, has yielded an age of 127,000 ± 7,000 yr. The Eel Point terrace is thus correlative with numerous terrace localities on the southern California mainland, with coral reefs on Barbados and New Guinea dated about 120,000 yr, and with substage 5e of the marine oxygen-isotope record. A tectonic uplift rate of about 0.20 m/1,000 yr has been calculated assuming a sea level slightly higher than the present one at the time of terrace formation. Extrapolation of this uplift rate allows age estimates to be made for other terraces on the island.