The human brain seems to be wired to recognize faces. That's why it's so startling to sometimes see them in pictures like this. Although the rock formation is completely random in nature, gosh darn it that looks like a face! It must be a spirit! It's especially disconcerting to some people when the face, again like this one, resembles the traditional depiction of the Devil. It freaks them out.
In fact, look closely at all of the rock in this picture and you'll see several faces. So either we're just seeing things or this wall of rock is seriously haunted. Which do you think is more likely?