Did a Killer Asteroid Drive the Planet Into An Ice Age?

by Fraser Cain on September 20, 2012

A simulation of the Eltanin strike

A simulation of the Eltanin meteor strike

When a mountain-sized asteroid struck the deep ocean off the coast of Antarctica 2.5 million years ago, it set off an apocalyptic chain of events: a devastating rain of molten rock and then a deadly tsunami that inundated the coastlines of the Pacific Ocean. But according to a team of Australian researchers, this was just the beginning. Then came a protracted ice age that killed off many of the Earth’s large mammals.

The Eltanin meteor, named after the USNS Eltanin which surveyed the area in 1964, is the only impact that has ever been discovered in a deep-ocean basin. These deep water impacts must be more common – so much of the planet is ocean – but they’re tricky to find because of the inaccessible depths of the impact craters. Researchers examining sediments in the area discovered tiny grains of impact melt and debris from meteorite fragments. Something big smashed this spot.

An asteroid strike on land is devastating, but an asteroid strike in the deep ocean is even worse. On both land and ocean, you get the plume of water vapor, sulfur, and dust blasted into the high atmosphere, raining molten rock down across a wide area. But for asteroid strikes in the ocean, this is followed by a devastating tsunami that inundates coastlines around the world. There are waves hundreds of meters high at the crash site, and they travel deep inland on every coastline. A local event becomes a global event.

But with the Eltanin meteor, this was followed by a prolonged ice age.

Professor James Goff and his colleagues from the University of New South Wales in Australia have been researching the Eltanin meteor and its after-effects. The timing of the impact seems to line up with geologic deposits in Chile, Australia and Antarctica. Geologists traditionally connected these deposits with slower geological processes, like glaciation. But Goff and his team think these deposits might have been dropped all at once by the devastating tsunami from Eltanin.

Here’s a video that shows how the impact and subsequent tsunami might have played out.

Although the Earth was already thought to be cooling in the mid to late Pliocene, the material kicked into the high atmosphere by Eltanin could have pushed the planet’s climate past the tipping point:

“There’s no doubt the world was already cooling through the mid and late Pliocene,” says co-author Professor Mike Archer. “What we’re suggesting is that the Eltanin impact may have rammed this slow-moving change forward in an instant – hurtling the world into the cycle of glaciations that characterized the next 2.5 million years and triggered our own evolution as a species.”

It was this time of a global ice age that transitioned the planet from the Pliocene to the Pleistocene. It was a bad time to be a Chalicothere or Anthracotheriidae, but a good time to be a hominid. So… thanks Eltanin.


View Larger Map

The location of the Elatin meteor crater

Original Source: Journal of Quaternary Science

About 

Fraser Cain is the publisher of Universe Today. He's also the co-host of Astronomy Cast with Dr. Pamela Gay.

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