Strandflat ([ The shallow and protected waters of strandflats are valued fishing grounds that provide sustenance to traditional fishing settlements.][ Outside Norway proper, strandflats can be found in other high-latitude areas, such as Antarctica, Alaska, the Northern Canada, the Russian Far North, Greenland, Svalbard, Sweden, and Scotland.
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The strandflats are usually bounded on the landward side by a sharp break in slope, leading to mountainous terrain or paleic surface. On the seaward side, strandflats end at submarine slopes.[
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The concept of a strandflat was introduced in 1894 by Norwegian geologist Hans Reusch.[
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Norwegian strandflat
Characteristics
Strandflats are not fully flat and may display some local relief, meaning that it is usually not possible to assign them a precise elevation above sea level.
The width of the strandflat varies from and occasionally reaching up to in width.
On the landward side, the strandflat often terminates abruptly with the beginning of a steep slope that separates it from higher or more uneven terrain.
Overall, strandflats in Nordland county are larger and flatter than those of Western Norway.
Geological origin
Despite being together with the most studied coastal landform in Norway,
In his original description, Reusch regarded the strandflat as originating from Coastal erosion prior to glaciation,
Frost weathering, glaciers and sea ice
The Arctic explorer Fritjof Nansen agreed with Reusch that marine influences formed the strandflat, but added in 1922 that frost weathering was also of key importance.[ In his analysis, Nansen argued that the strandflat formed after the fjords of Norway had dissected the landscape. This, he argued, facilitated marine erosion by creating more coast and by creating nearby for eroded material.]
In 1929, Olaf Holtedahl favoured a glacial origin for the strandflat, an idea that was picked up by his son Hans Holtedahl. Hans Holtedahl and E. Larsen went on to argue in 1985 for an origin in connection to the Quaternary glaciations with material loosened by frost weathering, and sea-ice transporting loose material and making the relief flat.
Deep weathering and antiquity
Contrary to the glacial and periglacial hypotheses, Julius Büdel and Jean-Pierre Peulvast regard weathering of rock into saprolite as important in shaping the strandflat. Büdel held that weathering took place in a distant past with tropical and sub-tropical climates, while Peulvast considered that present-day conditions and a lack of glaciation were enough to produce the weathering. As such, Peulvast considered the saprolite found in the strandflat, and the weathering that produced it, to predate the Last glacial period and possibly the Quaternary glaciations.[ For Büdel, the strandflat was a etchplain dotted with .]
In 2013, Odleiv and co-workers put forward a mixed origin for the strandflat of Nordland. They argue that this strandflat in northern Norway could represent the remnants of a weathered peneplain of Triassic age that was buried in sediment for long time before made flat again by erosion in Pliocene and Pleistocene times.[ Haakon Fossen and co-workers disagree with this view citing thermochronology studies to claim that the strandflat in Western Norway was still covered by sedimentary rock in the Triassic and did only got free of its sedimentary cover in the Jurassic. Same authors note that movement of geological faults in the Late Mesozoic imply the strandflats of Western Norway took their final shape after the Late Jurassic or else they would occur at various heights above sea level.][ To this Holtedahl added that in Trøndelag between Nordland and Western Norway the strandflat could be a surface formed before the Jurassic, then buried in sediments and at some point freed from this cover.][ In the understanding of Tormod Klemsdal strandflats may be old surfaces shaped by deep weathering that escaped the uplift that affected the Scandinavian Mountains further east.]
The strandflat at Bømlo is considered by Ola Fredin and co-workers to be equivalent to the sediment-capped top of Utsira High offshore west of Stavanger.
Outside Norway
Strandflats have been identified in high-latitude areas such as the coast of Alaska, Arctic Canada, Greenland, Svalbard, Novaya Zemlya[
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In Antarctica, strandflats can be found in the Antarctic Peninsula
In Robert Island in the South Shetland Islands, raised strandflats show that the island has been subject to a relative change in sea level.
Gallery
File:Siggjo viewed towards east.JPG|Aerial view of the strandflat at Bømlo
File:Southern_Goddo.JPG|Aerial view of the strandflat at Goddo island near Bømlo
File:Leaving_Lochmaddy_-_geograph.org.uk_-_929584.jpg|Skerry zone of a strandflat in Lochmaddy, Hebrides
Explanatory footnotes
Citations
General literature
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Fridtjof Nansen (1904). "The Bathymetrical Features of the North Polar Seas". In Nansen F. (ed.): The Norwegian North Polar Expedition 1893–1896. Scientific results, Vol IV. J. Dybwad, Christiania, 1–232.
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Hans Reusch (1894). Strandflaten, et nyt træk i Norges geografi. Norges geologiske undersokelse, 14, 1–14.
