A long, narrow arm of the sea which is the result of the ‘drowning’ of a glaciated valley; the classic text is J. P. Syvitski et al. (1987).

Fiords are distinctive because of their great depth, and the overdeepening of their middle sections which are deeper than the water at the mouth. Søgnefjord, for example, is 1 200 m deep, but its mouth is only 150 m below sea level. The shallow bar at the seaward end of the fiord is thought to represent the spreading and thinning of ice as it was released from its narrow valley and spread out over the lowland; see Nesje et al. (1992) Geomorph. 5, 6 on Søgnefjord. Norway’s 2004 nomination for its fjords to be added to the UNESCO World Heritage List makes interesting reading: the geomorphology is outlined, together with issues of management, developmental pressures, and environmental pressures. Glaciation may not be the only fiord-forming factor; see Nesje (op. cit.) on fracture systems and Søgnefjord.