This is an SSSI so please treat to the area with respect and to not do any damage to the stones.
The stones
This is Gritstone and it is a hard, coarse-grained, siliceous sandstone. Sandstone is made up of small particles of sand usually deposited at a river delta and is created as more and more material is deposited and the pressure cause the material to compact. Gritstone is a name especially applied to such sandstones that are dug up for building material. British Gritstone was used to create millstones used mill flour, to grind wood into pulp for paper and for stones to sharpen blades. "Grit" is often applied to sandstones composed of angular sand grains and is also used in a powder form to make abrasives either projected by air or attached to paper. The size of the particles in Gritstone range from powder grains of less than 0.5mm but may commonly contain particles right up to small pebbles of 10mm diameter.
"Millstone Grit" was a colloquial term used for a succession of Gritstone which are to be found in the English Peak District and Pennines of northern England, which has become a formal term. These sediments were laid down in the late (upper) Paleozoic era, in the Carboniferous period, in deltaic conditions. The Millstone Grit Group is now a formal name for these rocks.
Millstone grit is a very durable rock and this is why it was used to make millstones and has been used as a building material; however when exposed to constant severe weather is will suffer from weathering. The rocks at this location have suffered from this type of wreathing.
The process
Weathering is the breaking down of material, such as rock, through contact with the Earth's atmosphere, such as waters and biological organisms. This occurs in situ and is not the same as erosion, which is the movement of rocks and minerals by things like water, ice, snow, wind, waves and gravity. Erosion causes the materials to be moved and deposited at other locations. Two different classifications of weathering exist – physical and chemical; both can involve a biological component. Mechanical or physical weathering involves the breakdown of rocks and soils through direct contact with atmospheric conditions, like heat, water, ice and pressure. The other type is chemical weathering. This involves the direct effects of chemicals produced by the atmosphere and is known as biological weathering in the breakdown of minerals. While physical weathering is increased in very cold or very dry environments, chemical reactions are most intense where the climate is wet and hot. Both types of weathering however occur together, and each tends to accelerate the other. For example, physical abrasion makes particles smaller particles and therefore increases their surface area, making them more susceptible to rapid chemical reactions.
Both physical and chemical weathering will result in rock changing their appearance and the longer they are exposed to the elements that are causing it the more apparent these changes will be. For example rock that have been subject to long term weathering may have smooth faces, grooves, rounded edges, sculpted shapes indicating a direction of the prevailing wind or harder material exposed as the softer is eroded away.
So hopefully you have learned something about the reason the rocks around you look the way they do, so time for some questions.
Questions
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Describe the stone, concentrate on the surface of the stone.
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What evidence can you find that these rocks have suffered weathering?
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What is the height of the tallest stones?
Please include a photo of your visit if you are willing and don’t worry about giving answers away in your photos.
Thanks for attempting this cache, hope you liked the location.
treboR