Ophir Chasma forms the northern portion of Valles Marineris, and this image features a small part of its wall and floor.
The wall rock shows many sedimentary layers and the floor is covered with wind-blown ridges, which are intermediate in size between sand ripples and sand dunes. Rocks protruding on the floor could be volcanic intrusions of once-molten magma that have pushed aside the surrounding sedimentary layers and “frozen” in place.
Images like this can help geologists study the formation mechanisms of large tectonic systems like Valles Marineris.
(The word “tectonics” does not mean the same thing as “plate tectonics.” Tectonics simply refers to large stresses and strains in a planet’s crust. Plate tectonics is the main type of tectonics that Earth has; Mars does not have plate tectonics.)
Written by: Kirby Runyon (4 November 2015)
More info and image formats at http://hirise.lpl.arizona.edu/ESP_042360_1755
Image: NASA/JPL/University of Arizona