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Shelf zone of the East-Siberian Sea is one of the least studied marine areas of the Russian Arctic. One of the important unsolved problems is the existence of a ice sheet in the area of the New Siberian Islands, and the debate about the age and genesis of underwater ridges (bars). Based on geological and geophysical field work condicted by VSEGEI in 2018 and 2020, laboratory research, and data analyses, two types of submarine ridges, principally different in morphology, sediment composition, age, and genesis were identified. Ridges located within the submarine plain on the outer periphery of the submerged valley of the Pra-Kolyma river and around the New Sibir’ Island are asymmetric, have a relative height of 1–2 m to 4–6 m, an average width of 2–4 km (up to a few tens of km) and an average length of 25– 30 km (up to 100 km). According to the sampling data, the ridges of this type are composed of very dense clayey-silt without inclusion of coarse clastic material. The age of the deposits forming the ridges is Late Pleistocene (18–13 ka BP). Formations of the Upper Pleistocene age are exposed in the inter-ridge hollows. The composition, morphology, and age of the ridge deposits suggest that their genesis is associated with denudation processes, but the mechanism of their formation is not obvious. The second type of ridges includes a system of coastal bars located at a distance of up to 30 km from the coast of New Sibir’ Island and composed of fine-grained, well-sorted sands. The width of the ridges varies from 1 to 2 km, the height is from 4 to 8 m, and the length is 10–15 km. The ramparts have a slightly asymmetric shape, with a gentler slope from the side of the island. This system of ridges was formed as a result of accumulative processes in the Holocene. The obtained data do not support the hypothesis of the extension of the Late Pleistocene ice sheet to the shelf.
Sergeev et al. (Sat,) studied this question.