This image shows an example of layers in the Martian north polar deposits. These deposits, part of the Planum Boreum dome, are composed mainly of water ice and small amounts of dust.
The layers within these deposits are exposed by shallowly-sloping troughs that cut into them. This image is particularly interesting because it crosses complicated trough geometry, making the layers appear curved and exposing multiple stratigraphic levels.
Note that layers of different thicknesses are visible. Layer thickness is directly related to the accumulation rate of the layer; a higher accumulation rate will lead to a thicker layer. However, a myriad of factors work together to influence accumulation rate, such as the amount of sunlight reaching the surface and the amount of water in the contemporaneous atmosphere.
This image, 1.2 kilometer in width (0.75 miles) shows enhanced color data. Redder areas have more dust, and the blueish-white areas have more ice; but much of the color may be due to dust and ice deposited on the wall of the trough, after the layers were exposed by trough formation (i.e., color may not directly relate to layer composition).
Written by: Kate Fishbaugh (19 November 2008)
This is a stereo pair with PSP_010014_2645 .
More info and image formats at http://hirise.lpl.arizona.edu/PSP_010198_2645
Image: NASA/JPL/University of Arizona