Chalk doesn’t proclaim itself. It is usually out of view, buried in the ground below. Every so often, when a highway is being carved through a mountain, or when the sea and wind erode the side of a hill, that’s when the green cover comes off, then you can see it. The White Cliffs of Dover are all chalk, piled hundreds of feet high. (via Thinking Too Much About Chalk : Krulwich Wonders… : NPR)
