Tiny rocks were not the only ones that fell from the sky and impacted the surface of Earth.

In new research presented at the Goldschmidt Conference, scientists have found that our precious planet was likely hit by ten times more massive impacts in the distant past than previously thought. These impacts would be similar in scale to the asteroid impact that wiped out the dinosaurs 65 million years ago, and they seem to have happened every 15 million years, particularly during a period stretching from 2.5 to 3.5 billion years ago.

The asteroids involved in these impacts would have been greater than ten kilometers in diameter, and their effect on the early Earth would have been different than what happened with those long-gone dinosaurs. The impacts threw molten particles up into the atmosphere and released vapors from under the surface of the Earth, all of which cooled, solidified, and fell back down to be embedded in the rock record. These tiny particles can now be found as glassy spheres in rough layers around the globe at various intervals.

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Early Earth was bombarded by series of city-sized asteroids (EurekAlert)