These, too, must indicate periods when the wind was strong enough to move materials, consistently, in only one direction. The sand that makes up the north polar dunes is dark. Each spot and streak is composed of the dune sand. The bright surfaces are all covered with frost. This picture is located near 76.9 N, 271.2 W, in the north polar sand sea.
Illumination is from the lower left.
The 200 meter scale also indicates a distance of 656 feet. The ASU Planetary Geology Group is under the direction of Dr. Ronald Greeley.