Erosion through weathering has created the surface features of scars, scree and limestone pavement. Limestone is soluble in acidic rainwater. It is a permeable rock, meaning water can pass through it.

Erosion through weathering has created the surface features of scars, scree and limestone pavement. Limestone is soluble in acidic rainwater. It is a permeable rock, meaning water can pass through it.

The central roundel is made of onyx and the pavement also includes purple porphyry, green serpentine and yellow limestone. Also part of the original material are pieces of opaque coloured glass – red, ...