A fjord or fiord (pronounced /fjɔːd/ or pronounced /fiːɔːd/) is a long, narrow inlet with steep sides, created in a valley carved by glacial activity.
The seeds of a fjord are laid when a glacier cuts a U-shaped valley through abrasion of the surrounding bedrock by the sediment it carries. Many such valleys were formed during the recent ice age. Glacial melting is also accompanied by a rebound in the earth's crust as the ice load is removed. In some cases this rebound may be faster than the sea level rise. Most fjords are, however, deeper than the adjacent sea; Sognefjord, Norway, reaches as much as 1,300 m (4,265 ft) below sea level. Fjords generally have a sill or rise at their mouth caused by the previous glacier's terminal moraine, in many cases causing extreme currents and large saltwater rapids (along the Pacific Northwest coast of North America (see skookumchuck). Saltstraumen in Norway is often described as the worlds strongest tidal current. These characteristics distinguish fjords from rias (e.g. the Bay of Kotor), which are drowned valleys flooded by the rising sea.
