The council said two companies were applying to Mendip district council for permission to test drill for the gas, which is found in shale formed from deposits of mud, silt, clay and organic matter.

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Because of abundant solar ultraviolet radiation at the surface, organic molecules might not be preserved as well as clay minerals.

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Dubbed Mount Sharp, it appears to be an unusual layer-cake of clay and other sedimentary deposits that may be relics of ancient water flows and organic chemistry.

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