Tell-Tale Bedrock in Tyrrhena Terra

Large craters, like this 50-kilometer diameter one, can uplift material from below and form a mountain-like central peak. Craters of this size on Mars become unstable as they form and collapse due to gravity. Craters with central peaks and terraced rims are referred to as "complex" craters. Geologists study these central peaks because the uplifted bedrock was once deep within the Martian crust. A 3D perspective shows heavily-fractured bedrock exposed within the peak, and also dark-toned and fragmental rocks that formed during the impact process. Sometimes, we observe similar rocks in the crater wall terraces. Some areas of the terrace show dark-toned materials coating and surrounding the white- and green-colored bedrock. This dark-toned rock was the once-molten material that was produced by the tremendous energy generated during the formation of the crater. Similarly, the impact melt material coats and surrounds the higher-standing bedrock of the peak. There are additional exposures of bedrock in the northern wall-terraces of the crater. Previous HiRISE images have focused largely on central structures, but clearly the wall-terraces of these craters may also be informative in our exploration of the Martian subsurface. More information is available at https://photojournal.jpl.nasa.gov/catalog/PIA22784