Complicated Lava Cooling

This HiRISE image shows a classic example of platy-ridged lava. Scientists think that this is the same as a lava type called "rubbly pahoehoe" on Earth.

In this lava, a crust of rubble forms as the lava partially cools but then tears up its own cover. Eventually, the rubble can form plates that can be rafted apart as the lava cools further, producing textures like those visible on terrestrial lava lakes that have cooled.

We see here a complex history of these processes. There are two different shapes of the rubble (at right, and top left/bottom center) indicating two stages of formation. The smooth area at center also is divided into two domains with different polygon styles, indicating that the rift opened, partially cooled, and then opened further.

The map is projected here at a scale of 50 centimeters (19.7 inches) per pixel. (The original image scale is 54.5 centimeters [21.5 inches] per pixel [with 2 x 2 binning]; objects on the order of 164 centimeters [64.6 inches] across are resolved.) North is up.

The University of Arizona, in Tucson, operates HiRISE, which was built by Ball Aerospace & Technologies Corp., in Boulder, Colorado. NASA's Jet Propulsion Laboratory, a division of Caltech in Pasadena, California, manages the Mars Reconnaissance Orbiter Project for NASA's Science Mission Directorate, Washington.