Spheroidal weathering

A detour to North Queensferry today to examine this spheroidal weathering of dolerite in Carlingnose Point Nature Reserve. I'm considering placing an earthcache here so needed to check it out.

Spheroidal weathering is caused by water seeping through joints in the dolerite, which causes more erosion at points where the joints meet, leading to spherical structures. It's also known as "onion-skin" weathering as the layers peel off as if from an onion.

A beautiful nature reserve, with rare plants, insects and birds which also affords striking views of the Forth Rail Bridge.