Olympus Mons orbit around Mars in 1971 during a global dust-storm. The first objects to become visible as the dust began to settle, the tops of the Tharsis volcanoes, demonstrated that the altitude of these features greatly exceeded that of any mountain found on Earth, as astronomers expected. Observations of the planet from Mariner 9 confirmed that Nix Olympica was a volcano. Ultimately, astronomers adopted the name "Olympus Mons" for the albedo feature known as Nix Olympica. Olympus Mons is located between the northwestern edge of the Tharsis region and the eastern edge of Amazonis Planitia. It stands about from the other
Olympus Mons large lava lake. Using geometric relationships of caldera dimensions from laboratory models, scientists have estimated that the magma chamber associated with the largest caldera on Olympus Mons lies at a depth of about below the caldera floor. Crater size-frequency distributions on the caldera floors indicate the calderas range in age from 350 Mya to about 150 Mya. All probably formed within 100 million years of each other. Olympus Mons is asymmetrical structurally as well as topographically. The longer, more shallow northwestern flank displays extensional features, such as large slumps and normal faults. In contrast, the volcano's steeper southeastern side has