De Long Islands - Quaternary Geology

Quaternary Geology

The De Long Islands were once major hills within the Great Arctic Plain that once formed the northern part of Late Pleistocene “Beringia” between Siberia and Alaska during the Last Glacial Maximum (Late Weichselian Epoch). These islands are what remains of about 1.6 million square kilometers of the formally subaerial Great Arctic Plain that now lies submerged below the Arctic Ocean and East Siberian Sea. At this plain's greatest extent during the Last Glacial Maximum, sea level was 100-120 m below modern sea level and the coastline was located 700-1000 kilometers north of its current position. This plain was neither extensively glaciated during the Late Pleistocene nor during the Last Glacial Maximum because it lay in the rain shadow of the Northern European ice sheet. The Great Arctic Plain was submerged, except for the New Siberian and other isolated islands, within a relatively short time span of 7,000 years during the Early-Middle Holocene.

During the extremely frigid polar climate of the Last Glacial Maximum (Late Weichselian Epoch), 17,000 to 24,000 BP, small passive ice caps did form on the De Long Islands. Fragments of these ice caps are preserved on Jeannette, Henrietta, and Bennett Islands. Traces of former Late Weichselian slope and cirque glaciers in the form of buried ground ice deposits are preserved on Zhokhov Island.