These HiRISE images form a stereo pair to examine the topography of the margin of a flow.
The Phlegra Dorsa region consists of ancient hills that have been surrounded and partially buried by flows from the Cerberus Fossae to the south. These flows could have been mud-laden water floods or very large lava flows.
The margin visible here is similar to that on lava flows that have had a long history of liquid lava being injected underneath the solidified crust. Relatively fresh impact craters and recent dust devil tracks are also visible in this image.
The second half of this stereo pair has another well-known formation.
This is a stereo pair with ESP_026461_2080.
Photo credit: NASA/JPL/University of Arizona