Geography of Mars Aurorae Sinus. The largest dark feature seen from Earth is Syrtis Major Planum. The shield volcano, Olympus Mons ("Mount Olympus"), rises 22 km above the surrounding volcanic plains, and is the highest known mountain on any planet in the solar system. It is in a vast upland region called Tharsis, which contains several large volcanos. See list of mountains on Mars. The Tharsis region of Mars also has the solar system's largest canyon system, Valles Marineris or the "Mariner Valley", which is 4,000 km long and 7 km deep. Mars is also scarred by countless impact craters. The largest of
Tohil Mons Tohil Mons Tohil Mons is a mountain on Io, one of Jupiter's moons. It stands at 5400 m (18,000 feet) and is located in the Culann–Tohil region of Io's antijovian hemisphere. It was named after the Mayan weather god Tohil. Tohil Mons is one of the most geologically complex mountains in the Solar System as the mountain shows evidence of forming from other mountains through tectonic and erosional processes, in combination with silicate volcanic rock or magma activity. The main massif of Tohil Mons has ridges and grooves, which indicate the presence of materials that have been tectonically displaced, including