Gritstone
From Wikipedia, the free encyclopedia
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Gritstone — otherwise called Millstone grit — is a sedimentary rock composed of coarse sand grains with inclusions of small stones. It is a coarser version of sandstone. It was laid down in the late (upper) Paleozoic era, in the Carboniferous period, in delta conditions.
As gritstone is a sedimentary rock it frequently shows signs of cross-bedding or current bedding. It is quarried for building material. British gritstone was used for millstones to mill flour and grindstones to sharpen blades.
The rock is much loved by English climbers, among whom it has almost cult status and is often referred to as "God's own rock". The rough surface provides outstanding friction, enabling climbers to stand on or grip the subtlest of features in the rock.
