Answered by Sophie Allan of the National Space Centre
While Mars no longer appears to be geologically active, we see from surface features that it once was very Earth-like in its geological processes. The surface of Mars plays host to the largest volcano in the Solar System, Olympus Mons, and a huge rift valley called Valles Marineris.
And it is this rift valley that indicates that Mars does in fact have tectonic plates. When analysing this ‘crack’ in the surface of Mars, scientists have found that the ‘matching sides’ are separated by a horizontal distance of 150 kilometres (93 miles). This suggests that the surface of Mars is effectively two large tectonic plates that were rubbing by each other.
However, since Mars cooled down much more rapidly than Earth, and therefore the molten rock beneath the plates has solidified, the process of tectonic plate formation appears to have ground to a halt