Ruskin Museum
Coniston, Cumbria.
Geology & Coniston
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Geology & Coniston
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Coniston is fortunate in that there are two totally different rock groups represented in the area. Each "rock group" is made up from a number of different rock "formations". This variation in rock types makes it an interesting location for the amateur geologist or interested fell-walker. The geology of the Coniston area is best viewed from somewhere like Grizedale Forest, which is to the east of Coniston. The terrain from the forest to west of Coniston consists of wooded, agricultural land, with gentle rolling hills of relatively low relief. The rocks underlying this area are marine sedimentary rocks from the "Windermere Supergroup". There is then a major change to a bracken-covered area with few trees, steep, craggy, rocky terrain and mountains. All of the rocks here are of volcanic origin. They are part of the rock group known as the Borrowdale Volcanic Group (BVG).
Volcanic rocks of the Coniston Fells were laid down around 460 million years ago. The total thickness of the BVG laid down in the Lake District is over 7km, yes 7km thick, a staggering amount. After the volcanic period the area subsided beneath the sea. In sub-tropical shallow waters teaming with marine life, the Coniston Limestone was laid down. This was not the limestone frequently seen from the Carboniferous period but a less pure limestone from the much earlier Ordovician. Slowly the sea deepened and over a long time period large amounts of muds and sands were deposited. These are the Windermere Supergroup sediments that are also of great thickness. Due to the collision of two continents some 420 million years ago the rocks have been intensely heated and squeezed. They have also been uplifted and now the once horizontal beds dip roughly south east at up to 90 degrees. This means that if you walk up the coppermines valley the rocks get older the further you walk. Or to put it another way, you are walking back in geological time. The other major event that affected the area in a big way happened about 2 million years ago. This was the start of the ice age. Successive glaciations carved out the valleys and scooped out hollows where now tarns such as Low Water and Blind Tarn are. This mountain and valley terrain is what makes the Lake District so special. Coniston Rocks |
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VOLCANIC ROCKS: Hammer is 23.5 cm long. |
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SEDIMENTARY ROCKS |