Images: When Mars was a wetland

This is a CRISM image of a giant valley called the Chasma Boreale that is several miles deep and juts into the edge of the northern polar cap by about 250 miles. The top view is a near-true-color representation, and the bottom view, which conveys the strength of the spectral signature of ice, shows where ice is present. The bright white areas are rich in ice; the dark areas are not.

Photo by NASA/JPL/JHUAPL