SO WHERE'S THE ALIEN CIVILIZATION? The famous mesa known as The Face lies in the foreground at right, where it is slowly eroding along with the other mesas in Cydonia. About 300 meters (1,000 feet) high, its north and east sides (seen here) are covered with "pasted-on terrain." This is the term geologists give to a mantle of material that may be ice-rich and which they think was deposited during the last Martian ice age, more than half a million years ago. This view looks south; click on the image for a higher-resolution (340K) version.

Image credit: NASA/JPL/Arizona State University, R. Luk