This image shows streamlined features in the northwest Tharsis region. The trough running diagonally to the left near the bottom of the image is part of the Jovis Fossae, a series of parallel troughs.

Streamlined features are carved by catastrophic floods. When a flood encounters an object, it diverts around it and erodes material in its path. One great example of a streamlined island is at the top left of the image between the branch of the channels. The flow was likely from the right to the left, as suggested by the fact that the island tapers off to the left. Part of the island stands higher than the rest. This section was probably higher than the floodwaters reached.

There is another streamlined island about one third of the way down the image. This island is very narrow, and its shape is also consistent with the flood coming from the right.

This island has a couple of dark slope streaks, as does an elongated mesa near the Jovis fossa (trough) at the bottom of the image. It is thought that small impacts and rockfalls can initiate the dust avalanches that are currently believed to form the slope streaks. The dark material for the slope streaks probably came from the dark layers visible at the top of the mesa; see subimage, approximately 300 meters (328 yards) across.
Written by: Kelly Kolb

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.