Mars may have once had active plate tectonics, new study says

Valles Marineris, the largest canyon system in the solar system. Is it evidence for early plate tectonics on Mars?
Credit: NASA

Plate tectonics are a geological phenomenon that, in our solar system, have long been thought to be unique to Earth. The Earth’s crust is broken into seven different major sections or “plates,” kind of like a cracked eggshell. These plates move around, slide against each other and even move above and below each other. Earthquakes are a common result of all of this activity.

Other planets and moons in our solar system haven’t shown evidence of this so far, even though some are volcanically active, like Jupiter’s moon Io for example (volcanic activity is possible without plate tectonics). Mars has huge shield volcanoes, but they are thought to have been extinct for millions or billions of years. A lack of crustal movement would explain why Mars’ volcanoes have tended to become so large, much bigger than any on Earth, since they remained in one spot and just kept growing instead of moving around.

But now a new report challenges this view of Mars, suggesting that it did once have active plate tectonics, but that the crust was divided into no more than two plates and that they moved much more slowly than those on Earth, due to Mars’ smaller size and cooling of its interior early in its history.

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