Soil Formation Under Desert Pavements
Desert pavements are common landforms in arid regions. They consist of flat or sloping surfaces where stones are closely packed angular or rounded, and generally exhibit low relief (Mabbutt, 1977). Pavements tend to form on both alluvial fan toposequences and on weathering volcanic flow fields in arid regions. Soils are often found under desert pavements and they play an important role in the evolution of pavements (McFadden et. al., 1987). In the past there have been several theories as to the formation pavements and soil development beneath them. Deflation, or the erosion of finer grained particles from a surface, stone concentration by wash erosion and upward displacement of stone due to shrink and swell clay characteristics were at one time believed to be the main factors in the formation of desert pavements (Mabbutt, 1977). However, more recent research has shown that desert pavements are born and maintained at the surface, and that the soil below them is mainly eolian in origin. Slow accretion of eolian dust below the pavement is a process that eventually develops cumulate horizons. Eolian dust in environments where pavements often develop is rich in carbonate salts and clays due to the fact it often originates from nearby playa lake evaporate basins (McFadden et. al., 1987). Soils that form below the pavements over time develop calcic horizons and clay rich structure due to the influx of these eolian fines through the pavement surface. In turn the development of mature or plugged calcic horizons effects the form of the pavement surface because it alters the water drainage infiltration rate and causes pavements to decline.
Desert Pavements
Desert pavements form in several di...
... middle of paper ...
...cFadden, Leslie D., 1988, Climatic Influences on rates and processes of soil development in Quaternary deposits of Southern California: Geological Society of America Special Paper 216, p. 153-175
Mc Fadden, L. D., Wells, S. G., and Jercinovich, M. J., 1987, Influence of eolian and pedogenic processes on the origin and evolution of desert pavements: Geology, v.15, p. 504-508.
Ritter, Process Geomorphology
Wells, Stephen G., Dohrenwend, John C., McFadden, Leslie D., Turrin, Brent D., and Mahrer, Kenneth D., 1985, Late Cenezoic evolution on Lava Flow surfaces of the Cima volcanic field, Mojave Desert, California: Geological Society of America Bulletin, v. 96, p. 1518-1529.
Wells, Stephen. G., and Mc Fadden, Leslie D., 1995, Cosmogenic 3He surface-exposure dating of stone pavements: Implications for landscape evolution in deserts: Geology, v. 23, p. 613-16.
Marshak, S. (2009) Essentials of Geology, 3rd ed. New York: W.W. Norton & Company, ch. 11, p. 298-320.
Studying the effects of weathering and erosion on the uplifted and exposed basalt sill is important to understanding the geological events that lead to mass movements in the area. My researc sought to determine exactly what happens to a rock that has been exposed to natural weathering such as thermal, biological, chemical, and wet-dry also referred to as slaking, on a qualitative and quantitative scale. The weathering of the rocks, though apparent on the exterior of the sample, has an extreme and transformative effect on the internal structure (Gupta et al., 1999). Weathering disrupted the internal crystalline structure by producing microfactures, voids, and the deposition of clay minerals (Gupta et al., 1999). Basalt is heavily affected by weathering when concerning porosity and the formation of ...
Eckel, Edwin B., ed. Nevada Test Site. Memoir 110 Boulder, CO: The Geological Society of America, 1968
Native Americans have undergone a horrific past of genocide, discrimination, forced acculturation, miscommunication, and misunderstanding. They were frequently dehumanized and stripped of basic human rights. Treated as “savages” they were herded into areas of confinement and robbed of their language, culture, and way of life. In many instances of genocide, experts have noted a type of historical trauma that may be passed down through families, known as generational trauma. While the potential effects of this concept are not proven, the stories, images, and memories of thousands of Native Americans continue to be shared with their children, thus perpetuating, and never forgetting the pain and embarrassment that their people have experienced.
United States Geologic Survey. USGS: Your Source for Science You Can Use. Ed. Marcia McNutt. The United States Department of the Interior, 2000. Web. 20 June 2010. .
"Recovery after the Rwandan Genocide. Ideas and Events Which Are Shaping Rwanda's History and Its People." Recovery after the Rwandan Genocide. Ideas and Events Which Are Shaping Rwanda's History and Its People. N.p., Dec.-Jan. 2014. Web. 09 Apr. 2014
Africa has been an interesting location of conflicts. From the conflict between Ethiopia and Eritrea to the revolutionary conflict in Libya and Egypt, one of the greatest conflicts is the Rwandan Genocide. The Rwandan Genocide included two tribes in Rwanda: Tutsis and Hutus. Upon revenge, the Hutus massacred many Tutsis and other Hutus that supported the Tutsis. This gruesome war lasted for a 100 days. Up to this date, there have been many devastating effects on Rwanda and the global community. In addition, many people have not had many acknowledgements for the genocide but from this genocide many lessons have been learned around the world.
...se two tectonic plates generated intense friction and pressure that generated enough heat to melt rocks. The descent of denser oceanic Farallon Plate into the asthenosphere produced magma that was made from basalt or andesite. Which is dark colored rocks with little silica. The buoyant magma pushed through the silica-rich continental crust, partially melting the crust that it moved though, and becoming more granitic in composition. About 100 million years ago, the granitic magma pooled at depths of only 2 to 5 miles beneath the surface (United States of America). The granitic terrain that makes up the Sierra, was once thought to have only local variations but was produced from one large mass of rock. It has been discovered however that hundreds of intrusions caused the variations in the granite that is displayed in Yosemite and in the Sierra Nevada range (Huber).
"Rwanda Genocide." Global Issues in Context Online Collection. Detroit: Gale, 2010. Global Issues In Context. Web. 12 Apr. 2010.
Blakey, R. C. (1996). Geologic history of western us. Informally published manuscript, Northern Arizona Univ, Flagstaff, AZ, Retrieved from http://www.jan.ucc.nau.edu
Basalt is a common extrusive igneous rock, there are a large number of volcanic provinces across Southeast Australia that have been found to contain basaltic lava flows. It is likely that these flows have come from volcanic activity caused by mantle plumes from the mesosphere. A variety of dating methods have been used to date these basaltic rocks, which have been aged from the Jurassic era right up to the late Cenozoic.
Over the period of around 100 days, with the death toll ranging somewhere between 800,000 to 1,100,000 the Rwandan genocide has become infamous for the high numbers of dead in such a short amount of time, and for the inadequate response of the UN an...
"Genocide in the 20th Century: Rwanda 1994." The History Place. N.p. N.d. Web. 30 Oct. 2012
Between the months of April and July in 1994 approximately one million people were killed in Rwanda. There are three ethnic groups in Rwanda, Hutu, Tutsi, and Aboriginal Twa. The genocide occurred between two different groups, the Hutu and Tutsi people. The Hutu composed close to 85% of the population while the minority Tutsi people make up approximately 14% with the Twa people composing the remaining 1%. The Republic of Rwanda like most African nations has a history of colonization from different European countries with different and conflicting ideas of governance and how a colony should be developed and used. It can be argued that many of the problems occurring in all African nations stem from previous colonization and subsequent exploitation. “ A Brief history” UN.org n.p. n.d. Web. 16 April 2014.
This report examines Toyota's HRM practices in Japan and looks at how changes were made when setting up the European plant in the UK. Toyota were faced by the pressure to remain internationally consistent with their HRM practices, which include, employee commitment, employee integration with the organization, flexibility and adaptability and lastly quality. However there were local cultural forces which also needed to be taken into account.