Sue Clifford, co-founder of the arts and environment organisation Common Ground, reflects on what England's limestone landscapes mean to her, the way water has carved out vast underground cave systems.

This is the first of four essays in which writers reflect on the way their bedrock geology has shaped their favourite landscapes. Limestone, as Sue Clifford says, is not only the stone of choice for many of Britain's architectural landmarks, but in the wild it also supports a wealth of flowers, creating its own micro-climates in the klints and grykes that characterise karst scenery. Limestone, she acknowledges, rejoices in its own specific vocabulary.

In the other essays, the walker and geologist Ronald Turnbull addresses sandstone, the sculptor Peter Randall-Page describes what it's like working with Dartmoor's obdurate granite boulders, and the Welsh poet Gillian Clarke writes about Snowdonia's slate.

Producer: Mark Smalley.