Olympus Mons the height of Mauna Kea as measured from its base on the ocean floor). The total elevation change from the plains of Amazonis Planitia, over to the northwest, to the summit approaches . The summit of the mountain has six nested calderas (collapsed craters) forming an irregular depression × across and up to deep. The volcano's outer edge consists of an escarpment, or cliff, up to tall (although obscured by lava flows in places), a feature unique among the shield volcanoes of Mars. Olympus Mons covers an area of about , which is approximately the size of Italy, and it
Erebor Mons infrared images. It was discovered only when stereoscopic radar data allowed construction of an elevation map. It was imaged by Cassini radar 22 February and 10 April 2007. Erebor Mons is named after Erebor, the "Lonely Mountain" that appears in J. R. R. Tolkien's fictional world of Middle-earth, most prominently in "The Hobbit". The name follows a convention that Titanean mountains are named after mountains in Tolkien's work. The name was formally announced on November 13, 2012. Erebor Mons Erebor Mons is a mountain on Titan, the largest moon of the planet Saturn. It is located near Titan's equator, between