Well first of all we have no evidence that it was aliens that created the face. Though it is possible. I am sure NASA would love to see life on mars. But it is believed that it is like a butte or mesa. A

butte or mesa is a landform common in the American west. Some facts even show it maybe be a mesa. Scientist say it takes form of a mesa. They are both the same hieght and same sturucture.

Also from the new pictures from Mars Global Surveyor in 2001 shows great detail. It was taking in a cloudless summer day. There for the image of the picture wasn't ubstructed by any clouds. So the scientist at NASA could study it and determine if there was life on Mars or not. But as I said before Scientist have narrowed it down to either be something similar to a mese or butte.

So as I said before. The scientist at NASA have study that image for a long time. And have narrowed it down to be either a mesa or butte. But there is still some hope that there really is life on Mars. But for now all we can conclud is that the Face on Mars was formed naturaly and not form aliens.