The rocks dug up from the lower part of Earth's crust in the coming weeks will be the closest anyone has come to the vast, churning part of the planet called the mantle, which lies between the crust and the core. On a 140-meter (460-foot) ship that resembles an oil platform, the 30-member scientific team will bring back rocks from 2 kilometers (1.2 miles) beneath the sea off Costa Rica's Pacific coast. "This will be a big step forward but we're still not getting to the mantle -- the mantle is still 3 kilometers (2 miles) away," said the expedition's co-chief, Damon Teagle, of Britain's University of Southampton. An examination of rocks from the crust and mantle could shed light on how tectonic plates -- vast pieces of the Earth's crust -- formed and how they move. When the plates move against one another they can cause earthquakes. Read More
