The real story behind the world’s ‘wandering rocks’

Creating surreal-looking scenes, these glacial erratics inspire legends but also offer scientists clues about climate change over millennia.

Deposited thousands of years ago by a glacier, the Obelisk boulder looms over Scales Moor in England’s Yorkshire Dales National Park.
Photograph by TOM RICHARDSON

Ever come across a rock that looked strangely out of place? The odds are good that it’s a glacial erratic, transported by an ice flow and left somewhere else when melting occurred, in some cases hundreds of miles away from the original location.

Erratics can range from palm-size pebbles to boulders as big as houses. They rest in fields, on mountainsides, and under the sea. But these wandering rocks—like the one pictured, near Ingleborough mountain, in England’s Yorkshire Dales—stand out from their surroundings.

(Discover the forgotten fossil hunter who transformed Britain’s Jurassic Coast.)

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