The ridges of the deep ocean separate the basin into at least 4 different parts
Towering mountain ranges known as submarine ridges run through and around the Arctic Ocean basin. These ridges were formed when the earth’s continental plates slowly separated, leaving gaps in the earth’s crust. Molten rock moved up into the gap, forming a new part of the ocean floor - the ridges that now divide the Arctic Basin into many sub-basins. Some of these submarine ridges run in straight lines for over 1,500 kilometres, and are steep and narrow, having widths of only about 200 metres. A number of peaks and valleys occur along the ridges, with crests rising to within a kilometre of the ocean surface.
The central submarine ridge, the Lomonosov Ridge, runs 1,770 kilometres from Ellesmere Island to the New Siberian Islands, a distance equivalent to that separating Toronto from Halifax! This ridge divides the Arctic Basin into two main basins: the Eurasian Basin - also called the Nansen Basin, and the Amerasian Basin - also known as the North American or Hyperborean Basin. Within the Eurasian Basin, the Nansen-Gakkel Ridge runs from east to west, dividing the basin into the northern Fram Basin, and the southern Nansen Basin. The geographic North Pole is located over the floor of the Fram Basin. The Nansen Basin is the smallest of the sub-basins within the Arctic Ocean. The Barents Abyssal Plain, an incredibly flat expanse, is located in the heart of the Fram Basin, at depths of over 4,400 metres.
The Alpha-Mendeleev Ridge divides the Amerasian Basin into the Canadian Basin and the Makarov Basin. The Makarov Basin is comprised of two abyssal plains, the Wrangel Abyssal Plain and the very deep Siberian Abyssal Plain, that lies 4,000 metres below the ocean surface. The Canadian Basin is the largest sub-basin of the Arctic Ocean, and is comprised of the Chukchi and Mendeleev Abyssal Plains at depths of 2,100 and 2,900 metres. The Canadian Abyssal Plain also lies in the Canadian basin, and is the deepest region in this part of the Arctic Ocean, reaching depths of about 3,850 metres.