Where beaches and harbors have frequently been taken to signify openness and intermingling, a different coastal setting, the cliffs of Dover, overtly bespeaks opposition and closure. Demarcating the British coast at its closest point to continental Europe, the cliffs often stand for Britain’s supposedly elemental insularity. However, the chalk composing the cliffs makes them, in their own way, as malleable and permeable as a beach. I argue that poems by Matthew Arnold, W. H. Auden, and Daljit Nagra contest the cliffs’ association with an exclusive Britishness by focusing on their material composition. In these poems, the cliffs’ chalk—formed by fossilized marine microorganisms at a time when what would become Britain was at the bottom of a prehistoric sea—attests to Britain’s geohistorical contingency. Arnold, Auden, and Nagra use this chalk geology to develop a new model of British identity as contingent, permeable, and linked with the wider world. In these poems, that is, Dover’s cliffs collapse oppositions rather than enforcing them: they blur the lines between Britain and the world, past and present, organic and inorganic, human history and geological history. The literature of the Dover cliffs thus highlights the revisionary potential of this distinctive kind of littoral space.