- desert varnish
the dark, lustrous coating or crust, usually of manganese and iron oxides, that forms on rocks, pebbles, etc., when exposed to weathering in the desert. Also called desert polish.[1900-05]
* * *or patinaThin, dark red to black mineral coating (generally iron and manganese oxides and silica) deposited on pebbles and rocks on the surface of desert regions.As dew and soil moisture brought to the surface by capillary action evaporate, their dissolved minerals are deposited on the surface. Wind abrasion removes the softer salts and polishes the surface to a glossy finish. Both high evaporation rates and sufficient precipitation are necessary for desert varnish to form.
* * *▪ geologyalso called Patina,thin, dark red to black mineral coating (generally iron and manganese oxides and silica) deposited on pebbles and rocks on the surface of desert regions. As dew and soil moisture brought to the surface by capillarity evaporate, their dissolved minerals are deposited on the surface; studies indicate that the varnish materials generally are extracted from the surrounding rock and earth material. Wind abrasion removes the softer salts and polishes the patina to a glossy finish. The rate of varnish formation varies: it generally is thought to take about 2,000 years for it to form in arid areas, because it coats artifacts and natural objects known to be of such antiquity; but it has formed in less than 50 years in the Mojave Desert. Both high evaporation rates and sufficient precipitation are necessary for desert varnish formation.
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Look at other dictionaries:
Desert varnish — in Horseshoe Canyon, Canyonlands National Park, Utah. Desert varnish, or rock varnish is a orange yellow to black coating found on exposed rock surfaces in arid environments. Desert varnish is usually around one micron thick and present nanometre … Wikipedia
desert varnish — noun or desert polish : a dark coating or polish found on rocks and pebbles after long exposure in desert regions … Useful english dictionary
desert varnish — (not preferred) refer to rock varnish … Glossary of landform and geologic terms
desert varnish — noun Date: circa 1898 a dark coating which is found on rocks after long exposure in desert regions and whose color is due to iron and manganese oxides … New Collegiate Dictionary
desert varnish — /ˈdɛzət vanɪʃ/ (say dezuht vahnish) noun a dark coating, composed principally of fine grained clay minerals, found on rocks or stone in arid regions … Australian English dictionary
Desert pavement — near Barstow, California, in the Mojave Desert. A desert pavement is a desert surface that is covered with closely packed, interlocking angular or rounded rock fragments of pebble and cobble size … Wikipedia
Varnish — is a transparent, hard, protective finish or film primarily used in wood finishing but also for other materials. Varnish is traditionally a combination of a drying oil, a resin, and a thinner or solvent. Varnish finishes are usually glossy but… … Wikipedia
Varnish (disambiguation) — Varnish is a mixture used to harden primarily wood.* Varnish * Desert Varnish * Varnish cache A reverse proxy program … Wikipedia
desert — desert1 desertic /di zerr tik/, adj. desertlike, adj. /dez euhrt/, n. 1. a region so arid because of little rainfall that it supports only sparse and widely spaced vegetation or no vegetation at all: The Sahara is a vast sandy desert. 2. any area … Universalium
desert polish — noun see desert varnish … Useful english dictionary