Evidence of plate tectonics early on

From Times Staff and Wire Reports

Scientists have identified an expanse of rock in Greenland as a remnant of Earth’s crust dating back 3.8 billion years, a finding that shows the dynamic geological process called plate tectonics was occurring early in the planet’s history.

A Norwegian team reported Friday in the journal Science that these ancient layered rocks from southwestern Greenland originally were formed on the sea floor of primordial Earth.

They are made up of thin sheets of formerly molten rock, and look a bit like a layer cake. They contain a mix of volcanic rocks associated with the formation of new crust.