Tithonium Chasma - Layers

Layers

Images of rocks in the canyon walls almost always show layers. Some layers appear tougher than others. In the image below of Ganges Chasma Layers, as seen by HiRISE, one can see that the upper, light-toned deposits are eroding much faster than the lower darker layers. Some cliffs on Mars show a few darker layers standing out and often breaking into large pieces; these are thought to be hard volcanic rock instead of soft ash deposits. Because of its closeness to the Tharsis volcanic region, the rock layers may be made of layer after layer of lava flows, probably mixed with deposits of volcanic ash that fell out of the air following big eruptions. It is likely the rock strata in the walls preserve a long geological history of Mars. Dark layers may be due to dark lava flows. The dark volcanic rock basalt is common on Mars. However, light-toned deposits may have resulted from rivers, lakes, volcanic ash, or wind blown deposits of sand or dust. The Mars Rovers found light-toned rocks to contain sulfates. Probably having been formed in water, sulfate deposits are of great interest to scientists because they may contain traces of ancient life. MRO discovered sulfates, hydrated sulfates, and iron oxides in Tithonium Chasma with its CRISM instrument.

• Map of Coprates quadrangle showing details of Valles Marineris, the largest canyon system in the solar system. Some of the canyons may have once been filled with water.

• Tithonium Chasma Layers, as seen by HiRISE.