Tyrrhenus Mons

Today's VIS image crosses part of the flank of Tyrrhenus Mons. Tyrrhenus Mons is one of the oldest martian volcanoes. Unlike most of the other Martian volcanoes, it is made of layers that include softer volcanic ash rather than just basaltic flows. This difference is evident in how the volcano is being eroded, creating broad intersecting sinuous channels. Tyrrhena Fossae, the largest of the channels dissecting the volcano, is visible in this image.

On Earth basaltic flows form broad shield volcanoes like Hawaii. Shield volcanoes can erupt from the central crater, as well as along the flanks. Volcanoes with ash layers, called composite volcanoes, form steeper sides like Mt Rainier and Mt Fuji, with material erupting only from the central caldera. Tyrrhenus Mons more closely resembles composite volcanoes.