Desert Varnish & Lichen Crust - Homework Help

Desert Varnish & Lichen Crust,
By W.P. Armstrong, Wayne's World,
Palomar College,

"Rugged mountain peaks and sun-baked boulders throughout the arid southwest are often colored in beautiful shades of orange, green, yellow and gray. At first glance the colorful coatings resemble a layer of paint, but close examination reveals that this unusual phenomenon is caused by a thin layer of microscopic organisms."

This is a lengthy article with numerous photos.