The Middle Paleozoic rocks consist of predominately folded and faulted basaltic, andesitic, and dioritic volcanoclastics, tuffs, lavas, dikes, and sills.

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.

[4][5][6] 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.

Traces of former Late Weichselian slope and cirque glaciers in the form of buried ground ice deposits are preserved on Zhokhov Island.

During 1902 the attempts to reach Sannikov Land, deemed to be beyond the De Long Islands, continued while Zarya was trapped in fast ice.

Leaving the ship, Russian Arctic explorer Baron Eduard Toll and three companions vanished forever in November 1902 while travelling away from Bennett Island towards the south on loose ice floes.