The upper whinstone layers of High Force (Dolerite) contrast sharply with the lower, sandstone, shale and limestone. The water erodes these softer rocks more quickly, to the extent that periodically, they can no longer support the harder dolerite, which collapses into the river. The waterfall has so far retreated 700m (2,297ft) into its gorge. High Force is England’s largest waterfall by volume
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