Perhaps the flash floods on Mars came during that terrible cosmic bombardment. Astronomer Tom Van Flandern 3 thinks the asteroid bombardment blew away the atmosphere and flipped Mars on its axis. There is presently no surface water on Mars - but probably much underground water in the form of permafrost. Gigantic water-carved canyons bear witness of enormous floods in the past. Three Tharsis shield volcanoes rise 6 to 11 miles above the surrounding plateau, attaining elevations of 11 to 16 miles high.
Flat basins suggest former oceans.
It is not hard to imagine that these are the remnants of a settlement on the shores of an ancient Martian ocean. While NASA continues to ignore the strong scientific interest in the Face on Mars, hopefully new imagery from Surveyor this fall will tell us more. A number of tests of artificiality have been proposed since the area was discovered. These tests include a three dimensional structure, a lack of fractal patterns in the image, an apparent bilateral symmetry, being built on the Martian equator, being built with a culturally significant orientation, and serving an apparent culturally significant purpose. Yet the balance of the evidence, considered objectively, now weighs in favor of artificiality over a natural origin of the Cydonian landforms.