Case Study: Lake District

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Geology of the Lake District

  • Three main rock types are Skiddaw, Borrowdale and Windmere

Skiddaw Group

  • The rocks in the Skiddaw group are the oldest in the Lake District. They were formed as black muds and sands settling on the sea bed about 500 million years ago. They have since been raised up and folded by tectonic forces. These rocks are found mainly in the north and the mountains they form are typically smooth, with many streams occupying deep gorges.

Borrowdale Volcanic Group

  • Rocks of the Borrowdale Volcanic Group are found in the central Lake District and consist of very hard lava and ash formed in major eruptions about 450 million years ago.that have withstood erosion and make up the highest mountains such as Scafell, Helvellyn and Great Cable.
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Geology of the Lake District

Windmere Group

The Windmere Group are sedimentary mudstones, sandstones, siltstones and some limestone formed in the sea about 420 million years ago. These were latyer folded and faulted, pushed up, and eroded down to their present levels forming the gentler scenery of the southern part ot the Lake District around Morecambe Bay

  • Huge masses of granite were intruded about 400 million years ago deep below the Lake District. Erosion has revealed outcrops in Eskdale, Ennerdale and at Shap.
  • Approximately 320 million years ago a tropical sea covered the Lake District. The shell and skeletal remains of huge numbers of small marine animals formed the carboniferous limestone which crops out at Whitbarrow, Yewbarrow and Scout Scar in the south.
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Glaciation in the Lake District

Glaciation of the Lake District is extremely complex. There have been many glaciations in the last 400,000 years and all have left their mark on the landscape. The present landscape of the Lake District is largely the result of glaciation during the Pleistocene period, during the last million years. Over twenty glaciations occured during the Pleistocene. However, some of the depositional landforms seen today are the result of the most recent phase of glaciation, the Loch Lomand Stadial, which took place between 12,880 and 11,500 years ago. This was a brief episode of glacial re-advance in Upland Britain.

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Erosional Landforms in Lake District

  • The Helvellyn Range is an 11km long ridge over 600m high with numerous glacial erosional landforms.The summit of Helvellyn itself, 950m above sea level, is a pyramidal peak. However, it is not as sharply pointed as many such landforms, having been eroded during the coldest part of the glacial period when ice completely covered this area. It also lacks more than two corries on its flanks, hence has been less sharply eroded by the retreat of their back walls.
  • Corrie glaciers formed and reoccupied corries from earlier glaciations moving downslope under gravity into the nearby valleys allowing valley glaciers to form. One such corrie, now containing Red Tarn, is seperated from its southerly neighbout, Nethermost Cove, by the very narrow arete, Striding Edge.
  • Ice from Red Tarn flowed into the valley of Glenridding, forming a valley glacierlarge enough to create a small glacial trough. This in turn fed into a much larger valley glacier and glacial trough, today occupied by Ullswater. From here, ice was channelled out of the central Lake District in a northeasterly direction. Although Ullswater forms a typical ribbon lake, being long and narrow, its floor is quite irregular due to the presence of resistant bands of volcanic rock.
  • Nofolk Island is a roche mountonnee formed on an outcrop of this rock in the middle of the lake.
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Erosional Landforms in Lake District

  • On the west side of the Helvellyn Range, there is a series of truncated spurs and hanging valleys, formed as a glacier moved through the trough now occupied by Thirlmere. One of the hanging valleys now contains a stream, Helvellyn Gill, which has a series of small waterfalls as it drops 500m in just over 2km from Low Moss into Thrilmere. 
  • Walla Crag, to tis north, is a very steep truncated spur with some near vertical, bare rock outcrops.
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Depositional Landforms in Lake District

  • There are many drumlin fields in the Lake District, formed as ice moved radically in all directions- south to Lancashire, east into North Yorkshire and northwest to the Solway Firth. There are extensive drumlin fields just south of Kendal. The drumlins lie on carboniferous rocks and are up to 125m high. They have broad rounded tops and are frequently steep-sided. Some of the drumlins are rock-cored whilst others consist entirely of till. The orientation of the Drumlins is NW/SW around Kendal and NNW/SSE near Furness, showing the southward movement of the ice. Fieldwork research in the area has shown that they have an average elongation ratio of 3:1. They are rarely found above 300m above sea level.
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