I believe that the face, that you believe is made by aliens, is in fact just a natural landform. I believe so because, when you look at the face in a claoser view, It is all just natural rock. This rock was created by the natural effects of the planet. I also believe this because the rock is in a shape, looking from the surface of the planet, of an ordinary butte or mesa, which is a small flat like mountain. Especially the way it looks there has been no sign of any life on mars yet. The way the rock is shaped, it is only shadows that make the face anyway so it couldn't have intentionally have been a face. The rock alone by it's self is just a bunch of rock lumped in a form made by the planet. In conclusion, I say that the face is just a natural landform, and it has also been proven by the pictures gathered by the probes.