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Topic: Desert varnish

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	BCZ Encyclopedia - Desert varnish (Site not responding. Last check: 2007-09-09)
		Desert varnish is a dark coating found on exposed rock surfaces in arid environments.
		Desert varnish forms only on physically stable rock surfaces that are no longer subject to frequent precipitation, fracturing or sandblasting.
		The varnish is primarily composed of particles of clay along with iron and manganese oxides.
	encyclopedia.bcz.com /en/Desert_varnish (327 words)

	Geotimes - September 2006 - Desert varnish baked in Mojave (Site not responding. Last check: 2007-09-09)
		For decades, desert varnish — the fl, shiny coating found on rocks in deserts from the Gobi to the Mojave — has puzzled scientists trying to unravel the mystery of how it forms.
		Subsequent analyses using microscopy and spectroscopy techniques suggested that silicon is the primary element in desert varnish, as Perry and colleagues reported in the July issue of Geology.
		Furthermore, Perry says that desert varnish “is a special case of silica glazes that appear to be widespread on Earth,” meaning that other silica-based coatings — such as those in caves, hydrothermal deposits and even on Mars — could also harbor evidence of past environments.
	www.geotimes.org /sept06/NN_Mojave.html (599 words)

	Desert varnish
		'''Desert varnish''' is a dark coating found on exposed Rock (geology)rock surfaces in arid environments.
		Desert varnish forms only on physically stable rock surfaces that are no longer subject to frequent precipitation (meteorology)precipitation, fracturing or sandblasting.
		The varnish is primarily composed of particles of clay along with iron and manganese oxidationoxides.
	www.territoriopc.com /eng/desert_varnish.php (346 words)

	Summary: Varnish
		Desert varnish is a hard, dark-brown or fl, dull or lustrous (if wind polished) coating that accumulates on the exposed surfaces of rock fragments and outcrops.
		Tone, intensity, and color of the varnish depend mostly on climate variations (e.g., precipitation) and on the relative age of the exposure of the rock surface.
		Varnish commonly forms on rocks that contain little or no iron and manganese, indicating that these elements are carried to the rock surface by wind, water, or both.
	www.tec.army.mil /research/products/desert_guide/lsmsheet/lsvarn.htm (678 words)

	Canyonlands National Park - Desert Varnish (U.S. National Park Service)
		Desert varnish is the thin red to fl coating found on exposed rock surfaces in arid regions.
		Varnish is composed of clay minerals, oxides and hydroxides of manganese and/or iron, as well as other particles such as sand grains and trace elements.
		The color of rock varnish depends on the relative amounts of manganese and iron in it: manganese-rich varnishes are fl; manganese-poor, iron-rich varnishes are red to orange; those intermediate in composition are usually a shade of brown.
	www.nps.gov /cany/naturescience/desertvarnish.htm (354 words)

	Desert Varnish & Lichen Crust - DesertUSA
		Desert varnish is a thin coating (patina) of manganese, iron and clays on the surface of sun-baked boulders.
		Instead, the rocks are coated with "desert varnish," a reddish layer of clay and iron oxide precipitated by remarkable bacteria.
		In fact, dating of varnished surfaces is of enormous importance to the study of desert landforms and to the study of early humans in America, since many artifacts lying on the ground become coated with desert varnish.
	www.desertusa.com /magdec97/varnish/dec_varnish.html (2060 words)

	Was there life on Mars? Shiny rock coating may hold the answer
		Desert varnish is found across the world in areas including the Atacama desert in Chile, the Mojave desert in Southern California, USA and Canyonlands National Park, Utah, USA.
		Desert varnish was used by prehistoric and Neolithic people to create images known as petroglyphs, which they crafted by scraping away the dark varnish to reveal the light rock underneath.
		Desert varnish is sometimes mistaken for fusion crust, the melted glassy exterior of a meteorite that forms when the meteorite passes through the atmosphere.
	www.eurekalert.org /pub_releases/2006-06/icl-wtl063006.php (720 words)

	WebWire® \| Was there life on Mars? Shiny rock coating may hold the answer (Site not responding. Last check: 2007-09-09)
		The source of the varnish, which looks like it has been painted onto the rocks, has intrigued scientists since the mid nineteenth century, including Darwin, who was so fascinated that he asked the geochemist Berzelius to investigate it.
		On desert rock surfaces, silica is dissolved from other minerals and then gels together to form a glaze, trapping organic traces from its surroundings.
		Desert varnish forms over tens of thousands of years and the deepest, oldest layers in the varnish may have formed in very different conditions to the shallowest, youngest layer.
	www.webwire.com /ViewPressRel.asp?aId=16046 (725 words)

	Origin of Desert Varnish (Site not responding. Last check: 2007-09-09)
		On the underside, where it is not exposed to the air, a varnished rock often acquires a glossy red-orange finish through interaction with water and minerals in the soil.
		The red coating on the underside of the varnished rocks, previously believed to be iron oxide, turned out to be 90% clay incorporating an iron oxide stain, similar to the iron in the fl finish on the rocks' exposed portions.
		In addition it was found that all desert varnish, whether it formed on the side of a cliff or on a 10-inch boulder, shares a similar composition.
	fgms.home.att.net /desertv.htm (541 words)

	Los Alamos National Laboratory (LANL): Laboratory scientist probes desert varnish for better understanding of past ...
		Desert varnish is actually a composite of alternating layers of materials, each having different compositions.
		Wayne believes that if desert varnish is as good at capturing and preserving airborne heavy metals and other elements as it appears, scientists could use it to infer what sorts of activities have been going on nearby.
		For example, since the minerals in desert varnish are also known to adsorb and hold radionuclides such as uranium and plutonium, relatively quick and simple techniques also could be used to determine if any sort of nuclear materials had ever been released (intentionally or unintentionally) into the local environment.
	www.lanl.gov /news/index.php/fuseaction/home.story/story_id/4949 (797 words)

	Paper: ON THE MECHANISM OF FORMATION OF DESERT VARNISH :: (Site not responding. Last check: 2007-09-09)
		Desert varnish coatings are found on rock surfaces throughout arid regions of the world.
		Understanding the organic components of desert varnish may help to resolve the question of the mechanism of formation of rock coatings, biomineralization processes, and bacterial fossilization and how to detect past microbial activity on planets.
		Desert varnish, however, is a complex phenomenon, an entire miniature Gaia, by itself, in which rocks, dust, bacteria and microcolonial fungi (MCF), water, and desert sun all play roles, which have not been clearly understood.
	www.medical-papers.com /varnish+bacteria+coatings+desert+acid (702 words)

	Living Martian Organisms Found
		An analysis of desert varnish was performed by researchers years ago in an effort to find the source.
		Desert varnish takes thousands of years to grow and is extremely hardy.
		This phenomenon, better known as "desert varnish," is a thin, dark, fl or reddish-brown coating acquired by rocks on deserts everywhere on Earth.
	www.xenotechresearch.com /mvarnish1.htm (1700 words)

	Desert Varnish And Lichen Crust
		In the Anza-Borrego Desert of southern California, the sun-baked boulders are devoid of lichens.
		The toxins cause the photosynthetic algal cells to deteriorate and the subsequent death of the fungal spouse.
		Lichens and desert varnish are also some of the most fascinating and complex of all living organisms.
	waynesword.palomar.edu /pljan98.htm (6649 words)

	Rock Varnish - In Depth
		Rock varnish is made up of a coating of clay particles (approximately 70%) combined with mineral deposits of iron and manganese oxides - - all probably wind-blown material that settled on the surface of rock.
		The bacteria reside within and beneath the microscopic layers of varnish, and are usually absent from the exposed surfaces.
		Exactly how rock varnish is formed is not completely known, but one theory is that varnish formation is a means by which these microbes protect themselves in their exposed, extreme environments.
	www.eduscapes.com /nature/rocvarnsh/index1.htm (419 words)

	Joshua Tree National Park
		The higher, slightly cooler, and wetter Mojave Desert is the special habitat of the undisciplined Joshua tree, extensive stands of which occur throughout the western half of the park.
		Desert vegetation, often times appearing to have succumbed to a sometimes harsh and unforgiving environment, lies dormant, anxiously awaiting the rainfall and moderate weather that will trigger its growth, painting the park a profusion of colors.
		For all its harshness the desert is a land of surprising variety and complexity, a land of extreme fragility.
	www.desertgold.com /park/parkmain.html (671 words)

	Desert varnish (Site not responding. Last check: 2007-09-09)
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		Limestone s, for example, typically do not have varnish because they are too water soluble and therefore do not provide a stable surface for varnish to form.
		Shiny, dense and fl varnishes form on basalt, fine quartzite s and metamorphosed shale s due to these rocks' relatively high resistance to weathering.
	www.purpleuniverse.com /true_associate-Desert_varnish.html (373 words)

	Len Milich: Desert Life
		Desert crusts are composed of a community of drought-resistant and heat-tolerant microbiota (algae, cyanobacteria, fungi, lichens, and mosses) held together by sticky polysaccharide secretions.
		In the Sonoran Desert, the brown and dessicated crust easily escapes notice until rain falls, after which the photosynthetic members of the community green within hours.
		The dark, often shiny surfaces of sun-baked porous rock are actually large colonies of bacteria, and are colloquially referred to as "desert varnish." The colonies obtain energy from inorganic and organic substances.
	ag.arizona.edu /~lmilich/varnish.html (454 words)

	Desert Pavement (Site not responding. Last check: 2007-09-09)
		Desert and consists of large, flat areas that are free of vegetation and covered with tightly packed, small stones.
		Desert pavements are usually dark in color due to a thin coating of desert varnish on the surface of the stones.
		Desert varnish consists of clay minerals and manganese oxides which impart the dark color.
	www.toddshikingguide.com /FloraFauna/Other1.htm (148 words)

	ROCKVARNISH
		The bacteria presence in varnish is thought to produce a cellular secretion crucial to the absorption process which incorporates deterial grains and complex metals from the environment.
		While it may be easy to comprehend Varnish as a method of spreading life throughout space or shielding things from harmful radiation, the act of imagining the potential applications in regards to natural circuitry is conceptually more elusive.
		This is understandable, as the circuitboard and varnish coating have many basic physical similarities, the fact that varnish lacks a software component(instructions), is without a power supply and resides in a harsh environment would seem to prevent one from making any functional comparison.
	www.worldblend.net /worldblendbu/ROCKVARNISH.html (1931 words)

	Desert Varnish (Site not responding. Last check: 2007-09-09)
		Desert varnish is a dark coating on rocks found in arid regions.
		The portion of the rock that sits above the level of the desert pavement is partially coated by a fl layer a few 10's of micrometers thick of desert varnish.
		At the contact with the desert surface, a dark ground-line band develops containing a thick layer of varnish which essentially completely coats the region of the rock in contact with the top layer of the soil.
	minerals.gps.caltech.edu /FILES/VARNISH (684 words)

	Astrobiology Magazine
		New research reveals that the dark coating known as desert varnish creates a record of life around it, by binding traces of DNA, amino acids and other organic compounds to desert rocks.
		The source of desert varnish has intrigued scientists since the mid-nineteenth century.
		Desert varnish was used to create images know as petroglyphs like these in Grimes Point, Nevada.
	www.astrobio.net /news/print.php?sid=2012 (488 words)

	DESERT VARNISH
		A thin dark shiny film or coating, composed of iron oxide accompanied by traces of manganese oxide and silica, formed on the surfaces of pebbles, boulders, and other rock fragments in desert regions after long exposure, as well as on ledges and other rock outcrops.
		It is believed to be caused by exudation of mineralized solutions from within and deposition byevaporation on the surface.
		The 3,000-foot escarpment known as the Vermilion Cliffs dominates the remainder of the wilderness with its thick Navajo sandstone face, steep, boulder-strewn slopes and rugged arroyos.
	www.websters-online-dictionary.com /definition/english/de/desert+varnish.html (683 words)

	SPACE.com -- New Way Suggested to Search for Life on Mars
		The coating, known as desert varnish, binds traces of DNA, amino acids and other organic compounds to desert rocks over the eons.
		Desert varnish has been found in the Atacama desert in Chile, the Mojave desert in California and Canyonlands National Park in Utah.
		New investigations with electron microscopes and other techniques finds instead that the varnish is mostly silica, which has mixed with other minerals to form a glaze that traps organic traces from the surroundings.
	www.space.com /scienceastronomy/060630_desert_varnish.html (543 words)

	Desert varnish shines as environmental monitoring tool
		Desert (or rock) varnish forms in arid and semi-arid regions as a composite of alternating layers of materials, each with different compositions.
		The components of desert varnish are very adept at capturing heavy metals, like lead, arsenic, zinc, cobalt, uranium and tungsten, that have been dispersed into Earth's atmosphere through natural phenomena, and through industrial activities like mining, smelting, oil refining, chemical processing and nuclear plant operations.
		Wayne believes that if desert varnish is as good at capturing and preserving airborne heavy metals and other elements as it appears, scientists could analyze it to infer what sorts of activities have been going on nearby.
	www.lanl.gov /worldview/news/releases/archive/04-022.shtml (639 words)

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