Coprates Quadrangle - 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. An example of hard layers is shown below in the picture of layers in the canyon wall in Coprates, as seen by Mars Global Surveyor. 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. The Mars Reconnaissance Orbiter Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) instrument found opaline silica in certain strata along and within the Valles Marineris canyon system. Because Iron sulfates were sometimes found near the opaline silica, it is thought that the two deposits were formed with an acid fluid.

• Ganges Chasma Layers, as seen by HiRISE.

• Layers in the canyon wall in Coprates, as seen by Mars Global Surveyor, under the MOC Public Targeting Program.

• Wide view of layers in wall of Valles Marineris, as seen by HiRISE under HiWish program.

• Close-up of layers in wall of Valles Marineris, as seen by HiRISE under HiWish program.

• Part of wall of Valles Marineris, as seen by HiRISE under HiWish program.

• Close-up of part of previous image of wall of Valles Marineris, as seen by HiRISE under HiWish program.

• Layers in Monument Valley. These are accepted as being formed, at least in part, by water deposition. Since Mars contains similar layers, water remains as a major cause of layering on Mars.

• Layers west of Juventae Chasma, as seen by HiRISE. Scale bar is 500 meters long.

• Orson Welles Crater, as seen by HiRISE. Layered, light-toned rocks seem to be under a dark mantling material. Layers may be sandstone, volcanic ash, or lakebed deposits.

• Corprates Chasma Fault, as seen by HiRISE. Layers in the rock face may be from volcanic, lacustrine, and/or aeolian sediments deposited in Valles Marineris.

• Ritchey Crater layers, as seen by HiRISE. The dark cap layer seems to be resistant to erosion, while the white middle layer is weak. Click on image to see more details. Scale bar is 500 meters long.

• Light colored layers in Eos Chaos, as seen by HiRISE.

• Two views of Melas Chasma Layered Deposits, as seen by HiRISE. Left picture lies north of other picture on the right. Pictures are not the same scale. Click on image to see details of layers.

• Tithonium Chasma Layers, as seen by HiRISE.

• Layers and dark dunes on the floor of a crater, as seen by HiRISE under the HiWish program. Groundwater may have risen up in the crater and cemented sediments with minerals.