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17-675: Stony Plain may refer to: Reg , a landform consisting in a vast desertic stony plain Stony Plain, Alberta , a town in Canada Stony Plain (electoral district) , a provincial electoral district in Alberta Stony Plain 135, Alberta , an Indian Reserve in Canada Stony Plain Records , a Canadian independent record label Stony Plains ,

34-467: A bioregion of Australia Topics referred to by the same term [REDACTED] This disambiguation page lists articles associated with the title Stony Plain . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=Stony_Plain&oldid=943620630 " Category : Disambiguation pages Hidden categories: Short description

51-494: A long history of dust deposition beneath them. The dust is a record of ancient climate, just as it is on the deep sea floor and in the world's ice caps. Desert pavement surfaces are often coated with desert varnish , a dark brown, sometimes shiny coating that contains clay minerals. In the US a famous example can be found on Newspaper Rock in southeastern Utah . Desert varnish is a thin coating (patina) of clays, iron, and manganese on

68-404: A major part of varnish is clay, which could only arrive by wind. Clay, then, acts as a substrate to catch additional substances that chemically react together when the rock reaches high temperatures in the desert sun. Wetting by dew is also important in the process. An important characteristic of black desert varnish is that it has an unusually high concentration of manganese . Manganese

85-403: Is also a host of trace elements and almost always some organic matter . The color of the varnish varies from shades of brown to black. It has been suggested that desert varnish should be investigated as a potential candidate for a " shadow biosphere ". However, a 2008 microscopy study posited that desert varnish has already been reproduced with chemistry not involving life in the lab, and that

102-446: Is approximately one micrometer thick and exhibits nanometer -scale layering. Rock rust and desert patina are other terms which are also used for the condition, but less often. 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 oxides of iron and manganese . There

119-437: Is different from Wikidata All article disambiguation pages All disambiguation pages Desert pavement#Reg Geologists debate the mechanics of pavement formation and their age. Several theories have been proposed for the formation of desert pavements. A common theory suggests that they form through the gradual removal of sand , dust and other fine-grained material by the wind and intermittent rain, leaving

136-963: Is relatively rare in the Earth's crust, making up only 0.12% of its weight. In black desert varnish, however, manganese is 50 to 60 times more abundant. One proposal for a mechanism of desert varnish formation is that it is caused by manganese-oxidizing microbes ( mixotrophs ) which are common in environments poor in organic nutrients . A micro-environment pH above 7.5 is inhospitable for manganese-concentrating microbes. In such conditions, orange varnishes develop, poor in manganese (Mn) but rich in iron (Fe). An alternative hypothesis for Mn/Fe fluctuation has been proposed that considers Mn-rich and Fe-rich varnishes to be related to humid and arid climates , respectively. Even though it contains high concentrations of iron and manganese, there are no significant modern uses of desert varnish. However, some Native American peoples created petroglyphs by scraping or chipping away

153-547: The dark varnish to expose the lighter rock beneath. Desert varnish often obscures the identity of the underlying rock, and different rocks have varying abilities to accept and retain varnish. Limestones , 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 black varnishes form on basalt , fine quartzites and metamorphosed shales due to these rocks' relatively high resistance to weathering. Its presence has been cited as

170-465: The larger fragments behind. The larger fragments are shaken into place through the forces of rain, running water, wind, gravity, creep, thermal expansion and contraction, wetting and drying, frost heaving, animal traffic, and the Earth's constant microseismic vibrations. The removal of small particles by wind does not continue indefinitely, because once the pavement forms, it acts as a barrier to resist further erosion. The small particles collect underneath

187-517: The lava stones in the desert pavement at Cima Dome have all been at the surface the same amount of time as the solid lava flows right next to them. He wrote in a July 1995 article in Geology, that he concluded, "stone pavements are born at the surface." While the stones remain on the surface due to heave, deposition of windblown dust must build up the soil beneath that pavement. For the geologist, this discovery means that some desert pavements preserve

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204-478: The main component is actually silica and not clay as previously thought. The study notes that desert varnish is an excellent fossilizer for microbes and indicator of water. Desert varnish appears to have been observed by rovers on Mars, and if examined may contain fossilized life from Mars's wet period. Originally scientists thought that the varnish was made from substances drawn out of the rocks it coats. Microscopic and microchemical observations, however, show that

221-499: The pavement by transport of the clasts or excessive vegetative growth. A newer theory of pavement formation comes from studies of places such as Cima Dome, in the Mojave Desert of California, by Stephen Wells and his coworkers. At Cima Dome, geologically recent lava flows are covered by younger soil layers, with desert pavement on top of them, made of rubble from the same lava. The soil has been built up, not blown away, yet

238-472: The pavement surface, forming a vesicular A soil horizon (designated "Av"). A second theory supposes that desert pavements form from the shrink/swell properties of the clay underneath the pavement; when precipitation is absorbed by clay it causes it to expand, and when it dries it cracks along planes of weakness. Over time, this geomorphic action transports small pebbles to the surface, where they stay through lack of precipitation that would otherwise destroy

255-465: The pebbles or gibbers. Gibber is also used to describe ecological communities, such as Gibber Chenopod Shrublands or Gibber Transition Shrublands . In North Africa , a vast stony desert plain is known as reg . This is in contrast with erg , which refers to a sandy desert area. Desert varnish Desert varnish or rock varnish is an orange-yellow to black coating found on exposed rock surfaces in arid environments. Desert varnish

272-416: The stones remain on top. There are no stones in the soil, not even gravel. Researchers can determine how many years a stone has been exposed on the ground. Wells used a method based on cosmogenic helium-3 , which forms by cosmic ray bombardment at the ground surface. Helium-3 is retained inside grains of olivine and pyroxene in the lava flows, building up with exposure time. The helium-3 dates show that

289-606: The surface of sun-baked boulders. Micro-organisms may also play a role in their formation. Desert varnish is also prevalent in the Mojave desert and Great Basin geomorphic province. Stony deserts may be known by different names according to the region. Examples include: Gibbers: Covering extensive areas in Australia such as parts of the Tirari-Sturt stony desert ecoregion are desert pavements called Gibber Plains after

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