The Lomonosov Ridge is situated between oceanic abyssal regions of the Eurasian Basin, on the one side, and the region of the Central Arctic Uplifts including the abyssal Makarov Basin - on the other. As its morphology and internal structure indicate, it consists of three distinct segments. The shallowest (= 400 m) Canada-Greenland segment is composed mostly by felsic and metamorphic rocks (basic igneous - at the part facing Alpha-Ridge). In the Near-Polar segment the ridge has double-crested top with the basin in-between. The structural trend here is at acute angle to the ridge axis and upper crust consists of basic crystalline rocks. The 12 km-thick upper crust of the 150 km-wide Siberian segment of the Lomonosov Ridge consists mainly of felsic and metamorphic rocks. The ridge's continental crystalline crust is 20-22 km thick, with upper and lower crusts thickness of about half of the above. Neogene-Pleistocene hemipelagic, Paleogene bathyal and possible Cretaceous deposits comprise the sedimentary cover.