NASA's Mars Reconnaissance Orbiter shows images of layered deposits at the north pole.
 
Dr. Ken Herkenhoff of the U.S. Geological Survey, Flagstaff, Ariz said, "Observations of the polar layered deposits are telling us about the material properties there. These deposits record relatively recent climate variations on Mars, like recent ice ages on Earth."
 
Similar layered deposits on Mars' south pole are also being probed by the Orbiter. The deputy team leader for that instrument, Dr. Roger Phillips of Washington University, St. Louis said, "The radar is penetrating through the entire thickness of these deposits and revealing the fine-scale internal layering."
 
Full story at NASA