Tharsis Montes

This image shows the three giant volcanoes known as the Tharsis Montes. Arsia Mons is in the lower left, Pavonis Mons is in the middle, and Ascreus Mons is in the upper right. Olympus Mons lies off the image to the upper left. These volcanoes lie in the center of the Tharsis region, and they form a line nearly 1500 km long. They are nearly 700 km apart, and each reaches nearly the same height as Olympus Mons (~25-27 km). These volcanoes are located on a large pile of lava flows , however, which is nearly 10 km high. Thus, the volcanoes are really only about 15 km tall. (Note: This is still more than half again the height of the Hawaiian volcanoes on Earth.) All three volcanoes seem to have formed together, and they were active for a very long time. Still, Arsia Mons appears to be slightly older than Pavonis Mons, and Ascreus Mons seems to be slightly younger. Therefore, volcanism in the Tharsis region may have slowly shifted north over time. A similar progression of volcanism is found in the Hawaiian Islands. Thus, the giant shield volcanoes on Mars may have formed over a mantle hotspot like that in Hawaii. (from digital mosiac of Viking 1 images, prepared for NASA by the U.S. Geologic Survey, published on the Mars CD-ROM VO_2014.)

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