Water

Ice shelves

When a glacier reaches the sea, it stretches into a floating snout. The confluence of various floating snouts gives origin to the formation of an ice shelf: a kind of flat shelf that floats on the sea and is anchored to the ground by the tongues that feed it. The most extensive ice shelf is the Ross Ice Shelf in Antarctica, with an average thickness of 300 m and a surface area of 530,000 km2 , equal to the area of France -  it is bounded on the sea-front by ice walls up to 200 m high. The various tongues of ice that feed the ice shelves move at different speeds, and this, together with sea currents and wave motion, causes a great instability of the margins. In fact enormous fractures called chasms form, as for example the one seen on the Filchner Ice Barrier in Antarctica, that is 100 km long and 400 m to 5 km wide. These impressive fractures are the prelude to the detachment of enormous portions of the ice shelf that form gigantic tabular icebergs, which drift away . Scientific research base camps built on ice shelves were involved in the formation of these enormous icebergs that drifted away, as in the case of two American base camps and a Soviet one.