It's the classic Mars scenario, as it was thought of 100-120 years ago. Makes for great stories, but isn't really scientifical... As that type of setting is something I really like (check out my Arnaron maps if I am allowed this plug), I'll be interested to see where you go with it.

As a side note the shape reminds me of http://en.wikipedia.org/wiki/File:Il...erieuse_03.jpg :-)