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Rauk
Landform in Sweden and Norway
From Wikipedia, the free encyclopedia
Sweden
Rauks are common on the island of Gotland, Sweden and on the smaller islands belonging to Gotland County.[1] Fårö island in Gotland, is particularly rich in rauks.[2] While Fårö is on the northern end of Gotland Holmhällars raukfält at Vamlingbo in the southern end of Gotland is also rich in rauks.[3] Rauks in Gotland often occur in groups or fields, so-called raukfält.[4] Rauks can be found both near Gotland's many cliffs or far away from these.[5]
Other localities with rauks include Byrum on northwestern Öland neighboring Blå Jungfrun island, Hovs Hallar and Kullaberg in northwestern Scania and Härnön in northern Sweden's High Coast.[2] Rauks on Öland are made up of limestone.[2] A few rauks are located in the Scandinavian Mountains in northern Sweden's Sarek[6] and Padjelanta[7] national parks.
Norway
In Norway, there are rauks in Trollholmsund where, according to local lore, the rauks are petrified trolls.[8] In Trollholmsund, rauks are made up of dolomite rock. Varanger Peninsula in northern Norway is rich in rauks and they also occur elsewhere along the Finnmark coastline.[8]
In Norway the term rauk is also applied to isolated residual mountains in the flat strandflat landscape along the coast.[9]
Geology
Rauks are usually formed by wave erosion.[1][5] On Öland and Gotland, rauks are chiefly formed along or near the escarpment known as the Baltic Klint.[4] Gotland rauks consist of limestone representing reefs that existed in the Silurian period.[4][5][10] As waves batter against limestone cliffs, pre-existing vertical fractures begin to erode and widen. Eventually this leads to the formation of caves that merge, and the remaining central rock has now become rauks.[4]
The rauks of Gotland formed after the last ice age. It is unclear to which extent different rauks in Gotland started to form from a cliffed coast, a dissected coast or from glacial landforms.[5] A comparison of photographs from 1900 and from 1966 has shown that some rauks had been destroyed during that period.[5]
Carl Linnaeus, who visited Gotland in 1741, was the first scientist to describe rauks.[4] He called them stenjättar (stone giants) while also noting the ruiniform shape of same rauks.[4]
In Sarek National Park rauks originate as aeolian landforms, thus, contrary to other rauks, they are shaped more by wind than by water.[6] These rauks are made of sandstone that belongs to the Sierggavággenappe (Swedish: Sierggavággeskollan) of the Scandinavian Caledonides.[6]
