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Thursday, October 28, 2010

Photo: Oldest Known Ocean Crust Found on Greenland


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A "sheeted dike complex," seen here with intervening layers of volcanic rock, is a telltale sign of ocean crust that has been stranded on land.

A newly discovered sheeted dike in Greenland has been dated to 3.8 billion years ago, pushing back by hundreds of millions of years evidence for plate tectonics in Earth's early history.

Photograph © Science