Geologic map of the Tharsis Quadrangle of Mars

The Tharsis quadrangle lies within the sparsely cratered hemisphere (Carr and others, 1973) of Mars. Its geology is dominated by young volcanic features, including both circular constructs and lava plains; little evidence of primitive densely cratered terrain remains. Included are three of the four largest shield volcanoes in the Tharsis province, Olympus Mons, Ascraeus Mons, and Pavonis Mons, together with several smaller shields. The fourth shield, Arsia Mons, lies to the south of the map area, as does Labyrinthus Noctis at the west end of the equatorial canyon system. The terrain within the quadrangle has approximately 25 km of relief with the three shield volcanoes standing 9 to 25 km above the plains, which slope 0.2 degrees to 0.4 degrees to the north-northwest.