Why do parts of the south pole of Mars look like swiss cheese? This little-understood landscape features flat-topped mesas nearly 4 meters high and circular indentations over 100 meters across. Since this swiss-cheese topography...

What created this unusual hole in Mars? Actually, there are numerous holes pictured in this Swiss cheese-like landscape, with all-but-one of them showing a dusty, dark, Martian terrain beneath evaporating, light, carbon-dioxide ice. The most unusual hole is on the upper right, spans about 100-meters, and seems to punch through to a lower level.