This image shows a small shield volcano covering Noctis Fossae in the eastern Tharsis region of Mars. The Tharsis region is located on the Martian equator and contains some of the solar system’s largest volcanoes.

Shield volcanoes have shallow-sloping sides and get their name from their resemblance to a warrior’s shield. They form from basaltic lava that flows easily, or has a low viscosity, and builds up over time to form a broad shield volcano profile.

The oval shaped depression in the center of the image is the summit pit of the volcano that contains a cooled lava pond. Emanating radially from the lava pond are several raised, leveed lava channels. Lava channels are narrow pathways through which lava flows onto the volcano surface. The volume of lava in the channel often fluctuates, and sometimes lava will overflow the channel. When this happens, lava congeals and cools along the edges of the channel forming natural levees and building up the lava channel above the surrounding surface.

Some of the largest volcanoes on Earth, such as Mauna Loa and Mauna Kea of Hawaii, are shield volcanoes.

Written by: Maria Banks

All of the images produced by HiRISE and accessible on this site are within the public domain: there are no restrictions on their usage by anyone in the public, including news or science organizations. We do ask for a credit line where possible: Image: NASA/JPL/University of Arizona

For information about NASA and agency programs on the Web, visit: http://www.nasa.gov. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif., manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems is the prime contractor for the project and built the spacecraft. The HiRISE camera was built by Ball Aerospace and Technology Corporation and is operated by the University of Arizona. The image data were processed using the U.S. Geological Survey’s ISIS3 software.