Two generations of windblown sediments on Mars
This colorful scene is situated in the Noctis Labyrinthus region of Mars, perched high on the Tharsis rise in the upper reaches of the Valles Marineris canyon system.
Targeting the bright rimmed bedrock knobs, the image also captures the interaction of two distinct types of windblown sediments. Surrounding the bedrock knobs is a network of pale reddish ridges with a complex interlinked morphology. These pale ridges resemble the simpler “transverse aeolian ridges” (called TARs) that are common in the equatorial regions of Mars.
Dark sand dunes comprise the second type of windblown sediment visible in this image. The dark sand dune seen just below the center of the cutout displays features that are common to active sand dunes observed by HiRISE elsewhere on Mars, including sets of small ripples crisscrossing the top of the dune. In many cases, it is the motion of these smaller ripples that drives the advance of Martian sand dunes. The dark dunes are made up of grains composed of iron-rich minerals derived from volcanic rocks on Mars, unlike the pale quartz-rich dunes typical of Earth.
Image credit: NASA/JPL/University of Arizona