There's more than one way to raise a mountain. On Earth, most mountain ranges form when giant continental plates collide, or when one plate slides beneath another, pushing up the overlying rock. But the mountains on Saturn's giant moon Titan seem to have resulted from a different process altogether. Scientists comparing radar images from the Cassini spacecraft with geophysical models say that the three ridges in this image, released yesterday, were created when Titan's gradual cooling after its formation caused partial freezing of the moon's subsurface ocean of water and ammonia. As a result, Titan contracted and the overlying icy crust sagged and wrinkled up like a giant prune. In an upcoming issue of the Journal of Geophysical Research, the scientists report that Titan may be the only body in the solar system to display this mechanism.
This article has been corrected. It originally stated that Titan's contraction was due to subsurface ice melting instead of freezing in the subsurface ocean.
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