When a schoolboy found the Lyme Bay astrolabe in 1967, a story which should have made headlines instead vanished from local memory. More than fifty years had passed before writer and activist Horatio Morpurgo began to ask why. The more he learnt about this rare navigational instrument and its recovery from the sea near his home, the more intrigued he became.The trail leads over unstable cliffs to dissenting chapels to a neglected story about Atlantic slavery and empire. Marine conservation, Extinction Rebellion and the politics of immigration: each has its say. He encounters sea fans, Mary Anning’s ink, John Fowles’ writing studio – and beneath these, faultlines as deep in the geology as they are in the culture.A Guide to the Unconformity is what happens when you ask one question of one short stretch of the coastline, then wait long enough for it to answer.
