Daedalia Planum

Today's VIS image shows a small portion of the immense lava flows that originated from Arsia Mons. Arsia Mons is the southernmost of the three large aligned volcanoes in the Tharsis region. Arsia Mons' last eruption was 10s of million years ago. The different surface textures are created by differences in the lava viscosity and cooling rates. The lobate margins of each flow can be traced back to the start of each flow -- or to the point where they are covered by younger flows. Flows in Daedalia Planum can be as long as 180 km (111 miles). For comparison the longest Hawaiian lava flow is only 51 km (~31 miles) long. The total area of Daedalia Planum is 2.9 million square km – more than four times the size of Texas.

A rampart crater is located at the bottom of the image. Rampart craters are characterized by overlapping lobes with a raised edge at the margin of each part of the ejecta. Scientists believe this type of flow characterization forms when an impacting object readily melts ice in the subsurface. The presence of liquid water in the ejected material allows it to flow along the surface giving a fluidized appearance.