Jutulhogget

Nytt bilde (19)

Picture from http://www.norgei3d.no. The name Jutulhogget is adapted from a local legend, according to which the troll in Rendalen intended to steal the water in Glåmdalen from his neighbour and attempted to cut through the hill between the valleys. The Glåmdalen troll woke up however, and killed the Rendalen troll before he had finished his job. The Rendalen troll was buried outside the mouth of Jutulhogget. Jutulhogget is one of Norways most dramatic and interesting landforms. It is also very easily accessible, by car you can park  at the western edge of the canyon – only few hundred meters from the main road from Oslo to Trondheim through Østerdalen.

Jutulhogget is up to 250 m deep and not much more than 100 m wide at its narrowest.  The canyon was cut down due to a glacial lake outburst flood from Glacial Lake Lower Glåmsjø towards the end of the last deglaciation. The discharge through the ice is calculated to 170 000 cubic meter pr second (Berthling & Sollid 1999, Norwegian Journal of Geography).  Glacial Lake Lower Glåmsjø stretched from Atna in the Glåmdalen valley and Åkrestrømmen in the Rendalen valley to the south, where the remaining ice was damming the lake, and northwards to the main water divide. Before the flood, the lake had a stable outlet north of Røros towards the Gaula river. Shorelines high up on the valley sides at about 665 m asl mark the former lake level. In the area of Jutulhogget, the hills between Glåmdalen and Tylldalen/Rendalen valleys were below the lake level – creating a narrow connection. Due to this connection, water flowed across the hills when the outburst flood was initiated in Rendalen and dug out Jutulhogget during the course of this event.

Outside the mouth of Jutulhogget, large flood deposits are found with a few stones almost the size of houses. These rocks are not rounded. Rather than beeing transported along the bed,  they have been lifted and transported maybe a couple of kilometers by kolks (http://en.wikipedia.org/wiki/Kolk). The largest boulders are found at the top of the deposit as the water discharge rises rapidly as the water melts a tunnel through the ice, and then shuts off rapidly.

Even though the main issues regarding the development of Jutulhogget is known, there are details that we disagree on. An important question is whether Jutulhogget was formed during one event, or if the glacial lake was emptied and filled several times. The landforms around Jutulhogget indicate several events. There are a few shorelines between the level of Nedre Glåmsjø and the present lowest level across the western part of Jutulhogget. These shorelines, which are only found in the Glåmdalen valley, suggest that there were several stable outlets across Jutulhogget for shorter periods until a new outburst floods cut Jutulhogget further down. A conceptual model is presented in Berthling and Sollid (1999). The flood deposits east of Jutulhogget have several distinct leves, also indicative of several outburst floods. However, south of the ice where the water emerged in a fjord, the level of this fjord was raised and fine grained material deposited. Here, only traces of one flood have been found. This paradox of course make Jutulhogget still more exiting and interesting in terms of scientific investigations.

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