Desert Varnish...Grand Canyon
Dark staining seen on some vertical rock faces in desert areas. What the varnish consists of is fairly well established. A fine windblown clay substrate hosts or traps dark pigmentation that is rich in iron and manganese oxides. The process by which the varnish forms is less well known.
See, for example,
http://fgms.home.att.net/desertv.htm
and
http://en.wikipedia.org/wiki/Desert_varnish
Getting this close to a wall of Kaibab Limestone that has been heavily stained requires doing a little walking along the rim trail, away from the popular overlooks at the shuttle stops. This example lies between Hopi Point and Mohave Point.
archiek 20/06/2008 17:18
The staining adds an extra layer of complexity to the images of these cliffs. Shapes, shadows, water markings, sediment layers and then the staining all make for wonderful photos like yours. Nicely done. -archieHenk Auwema 20/06/2008 8:28
I like your point of view and appreciate your explanationHenk