Desert Varnish

[arfur_rockford]

In many arid regions, rocks slowly aquire a dark coating of unknown origin. This so-called "desert varnish" is rich in iron oxides and mangese oxide. No one knows exactly how the coatings develop, although the presence of the metal oxides suggests some biological process contributes to their formation.

Comments

[firetower_flame]

ahh, the utah trip was glorius