After a violent youth, Earth said getting calmer in middle age

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SYDNEY, May 7 (UPI) -- Earth endured a tectonic upheaval 1.1 billion years ago that saw the world's continents collide and form a single supercontinent, Australian researchers say.

It was the most active period of tectonic motions in Earth's history but the globe has been getting calmer since, they said.

Martin Van Kranendonk of the University of New South Wales and Christopher Kirkland of the Geological Survey of Western Australia set out to reconstruct the history of plate tectonics to determine whether Earth has been getting more or less active over time.

Their analysis of 3,200 rock samples from around the world suggests tectonic activity increased from 3 billion years ago, when the Earth was very young, to a peak around 1.1 billion years ago and then fell, NewScientist.com reported Tuesday.

During the peak, all the continents collided and merged into a vast supercontinent called Rodinia, the researchers said, spanned by a mountain range that dwarfed today's Himalayas.

However, in its middle age the planet has calmed down considerably, they said.

Does that mean it will eventually go completely quiet?

"Eventually the Earth is going to run out of internal energy," Adrian Lenardic of Rice University, who wasn't involved in the study, said.

But it's unknown how long it might take for all of Earth's tectonic activity to stop, he said.