Canyards Hills (grid reference SK250950) is a 64.1 hectare (158.4 acre) biological and geological site of Special Scientific Interest in South Yorkshire. The site was notified in 1990. This site possesses the most impressive examples in England and Wales of 'ridge-and-trough' or 'tumbled ground.' Beneath a 10 m high cliff, the north-facing valley side above Broomhead Reservoir is a chaotic mass of sub-parallel ridges, separated by intervening narrow areas of marshy ground.