Tyrrhenus Mons is one of the oldest Martian volcanoes. Tyrrhena Fossae is the largest of the channels dissecting the volcano. As well as being one of the oldest volcanoes, it is made of layers that include volcanic ash rather than just basaltic flows. This difference is evident in how the volcano is being eroded, creating broad intersecting sinuous channels. On Earth basaltic flows form broad shield volcanoes like Hawaii. Shield volcanoes can erupt from the central crater, as well as along the flanks. Volcanoes with ash layers, called composite volcanoes, form steeper sides like Mt Rainier and Mt Fuji. The major amount of material erupts only from the central caldera.

Orbit Number: 73059 Latitude: -20.5291 Longitude: 107.331 Instrument: VIS Captured: 2018-06-03 21:19

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NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Science Mission Directorate, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.