How Volcanoes Work

 Image Described in Caption
Image Mozaic of Mars -- The large fractured terrain in the center of the image is the Valles Marineris Canyon System, which is over 4000 kilometers long. The Tharsis Shield Volcanoes are shown on the upper left of the image. Olympus Mons lies out of view beyond the two Tharsis volcanoes shown here. The Tharsis volcanoes ries 10 to 18 km above the Tharsis Plateau. Courtesy of NASA/JPL.