Earle McBride and Dane Picard were traveling across France conducting geologic field work in 1988 when they took time out to play tourists at Omaha Beach, site of one of the most ferocious battles during the D-Day invasion more than 40 years earlier. It was a miserably cold and blustery day. They tarried just long enough to scoop a sample of beach sand into a little baggie.

McBride, a professor emeritus in the Jackson School of Geosciences at The University of Texas at Austin, collects sand pretty much any chance he gets. By analyzing sand from modern dunes, beaches and rivers from a wide range of sites around the world, he can link the mineral compositions of ancient sandstones to the kinds of environments that forged them.

Read the complete story about McBride and Picard’s discovery at Omaha Beach.