Spheroidal Weathering

Locality 6: Look for the "onion-skin" features in this photograph:

The Salisbury Crags dolerite sill has crude columnar joints and a number of joint planes parallel to the upper and lower surfaces. The joint planes provide pathways for water flow, leading to preferential weathering, especially at joint intersections where wethering can penetrate from three directions and lead to the formation of rounded corners. The formation of shells of decayed rock is known as spheroidal weathering.