This lava plain in the volcanic region of Tharsis is riddled with pits that formed when voids in the lava collapsed. It makes for interesting features like this chain of craters. It also means there are probably many miles of subterranean caverns for future (very brave) explorers to map.
Radar reveals details inside the mile-thick mountain of ice at the north pole of Mars. The top view shows the topography of the ice cap, which grows and shrinks each season, adding a new layer of dust and ice each time.
The middle section contains a radar view from the Mars Reconnaissance Orbiter, with alternating bright and dark layers of dust and ice extending back into the far past of the Red Planet. Beneath the ice are additional, more opaque layers that may tell the tale of a time when Mars’ climate was different.
The bottom section is a true-color visual look at roughly the same region, taken earlier by a different spacecraft, the Mars Odyssey orbiter.
This mark in the Tharsis region of Mars is thought to be the result of a shock wave from a meteor that disintegrated before impacting the planet. The blast wave blew away the red dust on the surface to reveal the darker volcanic rock underneath. The affected area is roughly nine kilometers across.