Sea floor records ancient Earth

The ancient sea floor was discovered in southwest Greenla

A sliver of four-billion-year-old sea floor has offered a glimpse into the inner workings of an adolescent Earth.

The baked and twisted rocks, now part of Greenland, show the earliest evidence of plate tectonics, colossal movements of the planet's outer shell.

The unique find, described in the journal Science, shows the movements started soon after the planet formed.

If these observations are substantiated it will be a significant line of new evidence indicating that plate tectonics was active and familiar as early as 3.8 billion years ago," he said.

Plate tectonics is a geological theory used to explain the observed large-scale motions of the Earth's surface.

oceanic crust is created at plate boundaries known as mid-ocean ridges, where magma rises from the asthenospehere through cracks in the ocean floor, cools and spreads away.