BOULDER, Colo. (CBS Las Vegas) – Back when the Earth was relatively young, about 3.8 billion years ago, the planet surface was scoured clean by a barrage of asteroids, according to a new model of the planet’s geological history.
The meteor storm would have blasted away most of the original rocks and resurfaced the outer layer of the Earth’s crust.
The model offers an explanation for the lack of rocks from the formation of the planet 4.5 billion years ago, reports Live Science.
“The surface of the Earth was heavily affected by all these collisions,” said lead study author Simone Marchi, a planetary scientist with the Southwest Research Institute in Boulder, Colorado. “There’s no doubt the crust was excavated, mixed and buried as a result of this bombardment.”
Marchi says the process would have given the young Earth a “face-lift” as the asteroids sterilized the planet and vaporized the planet’s oceans into steam.
“If you look at this model, Earth only became habitable after 4.2 billion years ago,” Marchi told Live Science.
Since there is little evidence on Earth, Marchi and his team looked to the moon, looking at the distribution and age of lunar craters to create a timetable of astronomical collisions in the early days of the planet’s formation.
“We now have a full model for the bombardment of the inner solar system,” Marchi said.
The report is published in the journal Nature.
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