MESSENGER’s snapshot of cliffs hints at tectonic activity within last 50 million years
NASA, JHUAPL, Carnegie Institution of Washington
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.