Portal:Mars/Selected picture/October 2008
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This image shows the north polar layered deposits at top and darker materials at bottom exposed in a scarp at the head of Chasma Boreale, a large canyon eroded into the layered deposits. The polar layered deposits appear red because of dust mixed within them, but are ice-rich as indicated by previous observations. The water ice in the layered deposits is probably responsible for the pattern of fractures seen near the top of the scarp. The darker material below the layered deposits may have been deposited as sand dunes, as indicated by the cross-bedding (truncation of curved lines) seen near the middle of the scarp. It appears that brighter, ice-rich layers were deposited between the dark dunes in places.
