This image, taken by the High Resolution Stereo Camera aboard ESA's Mars Express spacecraft, shows regions of that might have been formed partly through the action of subsurface water, due to a process known as sapping.
The HRSC obtained the image during orbit 1,383 at a ground resolution of approximately 23.7 meters (77 feet) per pixel. The image has been rotated 90 degrees counter-clockwise, so North is to the left.
It shows the regions of Granicus and Tinjar Valles, lying at approximately 26.8 degrees north latitude and 135.7 degrees east longitude.
The northwest-aligned valles are part of the Utopia-Planitia region, an area thought to be covered by a layer of lava that flowed from the northwest flanks of Elysium Mons into the Utopia-Planitia Basin.
Today, this once-smooth volcanic plain is incised by channels of variable size and appearance, including Granicus Valles (toward the West, or bottom of the image) and Tinjar Valles (toward the North, or left side).
Both channel systems evolve from a single main channel entering the image scene from southeast (upper right), exhibiting an approximate width of 3 kilometers (2 miles) and extending 300 meters (1,000 feet) below the surrounding terrain at maximum.
The impressive sinuous lava channel emanates from the mouth of a radial, a circular drainage area and runs to the Elysium rise trending into a graben, which is terrain dissected by tectonic deformation.
Planetary scientists interpret the narrow, straight, 4-kilometer (2.5-mile) wide and 120-kilometer (75-mile) long graben as the source of both lava flows and debris flows that carved Granicus and Tinjar Valles.
Similar Elysium flank grabens at higher elevations lack outflow channels. This elevation dependence leads scientists to suggest that subsurface water, released by volcanic activity, later played a role in shaping the channels visible today.
Image resolution has been decreased for use on the Internet.
