The age and origin of the Little Diomede Island upland surface

Geomorphology and projected uplift rates indicate that the upland surface o f Little Diomede Island may represent a high sea level stand that occurred 2.6 million years ago in the Bering Strait. The 350-363 m upland surface of the island could be correlative with the York terrace, an uplifted marine terrace previously recognized on the southern flanks of the York Mountains, Seward Peninsula. The modem surface of Little Diomede Island is composed o f a cryoplanation terrace enclosing a central blockfield and rimmed with to rs. Beryllium-10 cosmogenic isotope analysis of two tors and three outcrops from the upper surface indicate the island has been under the influence of a subaerial periglacial environment at least for the last 36 000 years (MI S 3) and probably for 254 000 (MIS 7/8). Unequivocal evidence does not exis t to support glaciation of Little Diomede Island.