The "White Rock" formations in various craters on Mars offer plenty of opportunities for research and speculation.

Bob Clark posted some links below. http://habitablezone.com/space/messages/33602.html

From some of the available THEMIS infrared images, I did a little paste up here that shows some of the interesting features of the formation. Robert Shepherd has done a much more detailed examination, but I can't find the links! (Robert!!! Help!!!)

When we finally go to Mars, of course, our explorers will be able to chip away at this and other formations, climb their stair steps, and find out for us all just what is going on.

Until then, we'll continue to wonder and speculate!

Cheers, BRFelix