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Mercury’s surface still changing

MESSENGER’s snapshot of cliffs hints at tectonic activity within last 50 million years

11:00am, September 26, 2016
mercury image

RISE UP  A line of small scarps (arrows) on Mercury, seen in this image from the MESSENGER spacecraft, suggest that the planet has been tectonically active in the last 50 million years.

Mercury has gotten some new wrinkles in its old age. The innermost planet shows signs of relatively recent tectonic activity, a new study suggests.

Tiny cliffs on the surface — just tens of meters high and a few kilometers long — resemble breaks in the planet’s crust, researchers report online September 26 in Nature Geoscience. The diminutive sizes of the cliffs, their sharp edges and lack of large overlapping craters imply that the faults are geologically young — less than 50 million years old. That’s much younger than Mercury’s larger, eroded scarps seen elsewhere, which probably arose more than 3.5 billion years ago. The small scarps indicate that the surface still fractures as Mercury cools and contracts, the researchers suggest, though other explanations are possible.

Thomas Watters, a geologist at the Smithsonian Institution in Washington, D.C., and colleagues discovered the young escarpments in images taken by NASA

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