The sculpted silhouettes of Hopewell Rocks rise from the muddy waters of the Bay of Fundy in Canada’s New Brunswick province. These sandstone-and-conglomerate sea stacks were spared during the glacial sweep of the last ice age, but bear the effects of centuries of tidal erosion. The Bay of Fundy sees some of the world’s greatest tidal variability, and the constant flow continues to shape these rocks.

(Photograph shot on assignment for, but not published in, the National Geographic special publication Canada’s Incredible Coast, 1990)