If you thimk it is a alien civilisation you are mistaken. If you think it is where is the evadence like houses. I think it is a natural land like we have here on earth. It can be an astriod hiting the earth or it could very well be a mountain like we have on earth. Another thing i think it could be is an un earupted valcanneo like an other thing we have on earth. Also it can be where the inside of the planit has bin pushed out to cause a natural land form. There can also be other things it can be. The people that think that it is an alien civilisation they have to back there rason up with a lot of information and very detaild information to get me on there side. Even then I probibly wont believe them it would have to be a very low chance i would take there side.