Formation
Desert varnish forms only on physically stable rock surfaces that are no longer subject to frequent precipitation, fracturing or wind abrasion. The varnish is primarily composed of particles of clay along with iron and manganese oxides. There is also a host of trace elements and almost always some organic matter. The colour of the varnish varies from shades of brown to black.
Read more about this topic: Desert Varnish
Famous quotes containing the word formation:
“Out of my discomforts, which were small enough, grew one thing for which I have all my life been grateful—the formation of fixed habits of work.”
—Elizabeth Stuart Phelps (1844–1911)
“The moral virtues, then, are produced in us neither by nature nor against nature. Nature, indeed, prepares in us the ground for their reception, but their complete formation is the product of habit.”
—Aristotle (384–322 B.C.)
“The formation of an oppositional world view is necessary for feminist struggle. This means that the world we have most intimately known, the world in which we feel “safe” ... must be radically changed. Perhaps it is the knowledge that everyone must change, not just those we label enemies or oppressors, that has so far served to check our revolutionary impulses.”
—Bell (c. 1955)