... or Photogeology
Mars has just about a little bit of everything.
The Volcanos of Tharsis: Arsia Mons, Pavonis Mons, Ascaeus
Mons, and Olympus Mons:
Olympus Mons is the biggest volcano in the solar system:
Valles Marineris ("the Mariner Valley"):
and lots of Impact Craters
What have we learned?
An enormous photomosaic of Mars from the Viking Orbiter is here. (and I mean big -- 2.6Mb!)
But what's it like being on Mars?
Landers (Viking , Pathfinder ) have shown us:
Pathfinder gave us even better views, in 3D!