Fjord , also spelled fiord , long narrow arm of the sea, commonly extending far inland, that results from marine inundation of a glaciated valley. Many fjords are astonishingly deep; Sogn Fjord in Norway is 1, m 4, feet deep, and Canal Messier in Chile is 1, m 4, feet. The great depth of these submerged valleys, extending thousands of feet below sea level , is compatible only with a glacial origin. It is assumed that the enormous, thick glaciers that formed in these valleys were so heavy that they could erode the bottom of the valley far below sea level before they floated in the ocean water. After the glaciers melted, the waters of the sea invaded the valleys. Fjords commonly are deeper in their middle and upper reaches than at the seaward end. This results from the greater erosive power of the glaciers closer to their source, where they are moving most actively and vigorously. Because of the comparatively shallow thresholds of fjords, the bottoms of many have stagnant water and are rich in black mud containing hydrogen sulfide.
We put design at the heart
This lists the logos of programs or partners of NG Education which have provided or contributed the content on this page. Powered by. A fjord is a long, deep, narrow body of water that reaches far inland. Fjords are often set in a U-shaped valley with steep walls of rock on either side. Sognefjorden, a fjord in Norway, is more than kilometers nearly miles long. Fjords were created by glacier s. In the Earth's last ice age , glaciers covered just about everything. Glaciers move very slowly over time, and can greatly alter the landscape once they have moved through an area.
A true fjord is formed when a glacier cuts a U-shaped valley by ice segregation and abrasion of the surrounding bedrock. The work of the glacier then left an overdeepened U-shaped valley that ends abruptly at a valley or trough end. Such valleys are fjords when flooded by the ocean. Thresholds above sea level create freshwater lakes. In some cases this rebound is faster than sea level rise. Fjords generally have a sill or shoal bedrock at their mouth caused by the previous glacier's reduced erosion rate and terminal moraine.
Nesje , S. Dahl, V. Valen and J. Source: Wikipedia. A fjord, as the Sognefjord , is per definition a glacially overdeepened valley, usually narrow and steepsided, extended below sea level and naturally filled with seawater. Give or take the usual Geological uncertainty and disagreements. The Pleistocene climate was characterized by repeated glacial cycles, ending years before now, by the introduction of the mild Holocene sub-epoch. Four major glacial events have been identified through the Pleistocene, as well as many minor intervening events.