Martian Soils

I just got back from an industry-sponsored field trip, so you’ll have to forgive the hiatus and somewhat tardy posting on the Phoenix Mars Lander. I was actually out on the interstate, driving home from a post-trip trip when I heard on NPR that the Phoenix had survived the landing and had successfully begun transmitting. Exciting stuff, especially since this mission is explicitly going to be looking into the possibility for ice in the shallow subsurface.

A particularly rad picture, released by NASA and posted below for your eyeballs’ enjoyment, shows the polar Martian landscape, with some VERY interesting polygonal structures. I reckon that those images got some folks back at mission control into quite the tizzy.

Compare that image from (holy smokes!) MARS to a picture I snagged from University of Idaho’s soil orders website (below). This image was taken somewhere up in Alaska, and shows one of the classic features of an ice-influenced soil (a gelisol, by soil science terminology): polygonal structures caused by cycles of ice growth and decay.

All this talk of Martian “soils” raises interesting terminological issues, however, that are relevant to the terrestrial geology community as well. What, exactly, is a soil? And, more to the point, how are soils preserved in the rock record?

Next time on the Dynamic Earth, we’ll dive into the nitty gritty of soil classification schemes, both ancient and modern!