[1] Along the southern coast of this island he found well-preserved bones, ivory, peat, wood, and even a tree within 40-meter (130-foot) high sea cliffs that expose Late Pleistocene sediments.

Their highest point is located on Bennett island, with an elevation of 426 m. They are part of the East Siberian Lowland, forming a geographical continuum with the continental plains further south.

At this plain's greatest extent, sea level was 100–120 m below modern sea-level and the coastline lay 700 to 1000 kilometers north of its current position.

This plain did not undergo extensive glaciation during the Late Pleistocene or the Last Glacial Maximum because it lay in the rain shadow of the Northern European ice sheet.

During the frigid polar climate of the Last Glacial Maximum, 17,000 to 24,000 BC, small passive ice caps formed on the adjacent De Long Islands.

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

The sea submerged the Great Arctic Plain (except for the New Siberian and other isolated islands) within a relatively short time span of 7,000 years during the Early–Middle Holocene.

[8][9][10] As noted by Digby[11] and numerous later publications, this archipelago consists of a mixture of folded and faulted sedimentary and igneous rocks ranging in age from Precambrian to Pliocene.

[2][13][15][16] As noted by Baron Eduard V. Toll in his account of the New Siberian Islands,[17] sizeable and economically significant accumulations of fossil ivory occur within them.