Coniston Limestone

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Coniston Limestone is the sedimentary rock formation around Coniston in the English Lake District. It is late [[Ordovician or possibly early Silurian in age and rests unconformably upon the Borrowdale Volcanic Group of rocks, which subsided beneath the sea, after the volcanic period.

Since the seas that gave rise to these deposits were teeming with life, there are fossils.

This is unlike the limestone that usually originated in the Carboniferous period but a less pure limestone from the earlier period.

Slowly the sea deepened and, over a long period, muds and sands were deposited. These are the Windermere Group sediments that are also of great thickness.

Due to the collision of two tectonic plates, 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, progressing up the coppermines valley, the rocks become older.

The other major event that affected the area 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 remain.