It looks like you found the giant Martian Spiders :)
I think that mud cracks on Mars could be larger than those on Earth, due to the lower gravity, but I wonder how large they get. I am not even sure how large they can get here on Earth. I have never seen them get very large on the Earth, but I have never really studied them. My particular interest in Geology has been they study of rocks and how they came into being. My particular interest was the Llano uplift area of Texas.