News Picks : Massive asteroid may have initiated Earth's tectonic activity
14 April 2014
Ars Technica: An asteroid 37 km (23 mi) in diameter may have struck Earth 3.26 billion years ago as the last major impact of the Late Heavy Bombardment period. Donald Lowe and Norman Sleep at Stanford University found tiny spherical rocks embedded in the Barberton greenstone belt in South Africa; they believe the rocks were deposited from the vaporized rock that the impact would have thrown into the atmosphere. The strike would have created a 500-km crater and caused 10.8-magnitude earthquakes. The timing of the impact coincides with the beginning of tectonic activity on Earth, and the impact could have been strong enough to fracture Earth's crust, kickstarting the movement of tectonic plates. However, the evidence that such an impact occurred is far from conclusive, and other theories may be more likely.