Photo of the Day 43

Devil's Marbles, Australia, 2000

Photograph by Cary Wolinsky

Colossal orbs of rosy granite serve as props for visitors' snapshots in Australia's Northern Territory. Known as the Devils Marbles, these naturally rounded boulders formed over a billion years ago when cooling magma in the Earth's crust forced up mounds of sandstone-covered granite. Wind, water, chemical, and mechanical erosion shaped the granite into their distinctive shapes, revered by Aborigines as the eggs of the Rainbow Serpent.

(Photo shot on assignment for, but not published in, "Australia: A Harsh Awakening," July 2000, National Geographic magazine)