Land-Fast Ice

Land-fast ice is the shore-attached form of fast ice, frozen to the coast or to grounded features and immobile through the season, the term used interchangeably with fast ice in the WMO Sea-Ice Nomenclature (WMO No. 259). Its seaward boundary is the flaw lead or shear zone where it meets mobile drift ice. Land-fast ice supports indigenous travel, ice camps, and resupply over-ice roads, and its thickness and extent are charted because the break-out date governs the coastal navigation window. Thickness typically reaches 1.5 to 2.5 m of first-year ice by late winter in the Arctic, anchored by bottom-fast ice in shallows.