Description: The rock seen here is Carboniferous Limestone. Limestone has fissures and is slightly soluble in water. This means that the rivers have been able to carve deep, narrow valleys and have then often found a route underground, creating caverns and leaving dry valleys behind. Sometimes, as at Winnats Pass, the caves have collapsed, leaving a deep, narrow gorge. The pass is now the main route west out of Castleton since the collapse of the Mam Tor road, and suffers from tourist traffic congestion. It is also rumoured to be haunted by the ghosts of two murdered lovers.