Cliff Rigg Quarry, a large gash in the hillside above Great Ayton. The gash is the result of extensive quarrying of whinstone, a hard volcanic rock that was primarily used for making into setts or cobbles for road making. It is said that the streets of Leeds are made from Great Ayton cobbles. The rock is a vertical intrusion, up to 30m wide, originating from a volcano centred on the Island of Mull off the west coast of Scotland, 58 million years ago. It surfaces at various places en route before disappearing under the North Sea near Whitby. On its passage through North Yorkshire it is known as the Cleveland Dyke.