Divergent and Convergent Plate Margins Comparison

Divergent and Convergent Plate Margins Comparison â€Å"Compare and Contrast the Topographical Features at Divergent and Convergent Plate Margins.† Jenice Culzac According to the United States Geological Survey (USGS) â€Å"a tectonic plate (also called lithospheric plate) is a massive, irregularly shaped slab of solid rock, generally composed of both continental and oceanic lithosphere.†[1] There are two types of plates; Oceanic plates are younger crustal plates with a thickness of 5-9km of mainly basaltic composition and Continental plates are older crustal plates with thickness of 25-90Km of mainly granite composition. The area where two of these plates meet is referred to as a plate boundary. Plate tectonics is a recent theory developed around the late 1960’s from two pre-existing theories; Continental Drift by Alfred Wegener and Seafloor Spreading by Harry Hess. It suggests that the Earth is made up of eight large rigid and thick plates along with smaller ones as shown in Diagram 1 that move slowly and change size. Diagram 1 of a World map showing the tectonic plates and their direction of movement Plate tectonics has three types of plate margins or boundaries named accordingly by the type of movement; towards, away and parallel that occurs at these boundaries. They are Convergent, Divergent and Transform plate margins respectively. Due to these movements, associated landforms altering the world’s topography are created except for at Transform plate margins because the parallel movement of plates only causes the release of energy in the form of earthquakes. The aim of this essay is to compare and contrast the topographical features that occur at the Divergent and Convergent plate margins. It is imperative to know what topographical features both these plate margins produce in common at the forefront. Therefore as the discussion goes in depth as to how they are created by different processes, keeping in mind the vision of the end product which is of the same topography will enhance clarity and comprehension. The topographical features that both plate margins produce in common are volcanoes and mountain ranges. A volcano is a mountain like feature that has a vent in which lava, tephra and hot gases are expelled. A mountain range is an area of a series of mountains that are geologically related. Therefore, having established this each plate margin can be dealt with individually. Comparison Convergent plate margin also called Destructive plate margin occurs at a fault where two tectonic plates move towards each other. Due to the nature of the plates involved there can either be subduction in which the area is called a Subduction Zone or a collision in which it is referred to as Collision Zone. Density is the key factor that determines the end result of the plates involved. In the case where the plates moving towards each other are continental and oceanic such as the Indo- Austrlian and Pacific plates respectively. Oceanic plates although having a thickness of 5-9km as compared to continental’s thickness of 25-90km is denser. Hence when an impact occurs as illustrated in Diagram 2 the Oceanic plate subducts under the Continental plate into the mantle and is reabsorbed due to intense heat and pressure. The area at which this occurs is the Subduction Zone. Diagram 2 showing the convergence of an oceanic and a continental plate Lines of weakness referred to as faults can occur within the Continental plate during subduction. As the Oceanic plate subsides water is being taken along with it which produces steam. This build-up of steam adds to the pressure which then forces its way through the faults and allows for magma to erupt violently (referred to as lava when it reaches the Earth’s surface). The lava solidifies due to the cooler surrounding temperatures and forms volcanoes. A chain of these volcanoes is known as the Volcanic Arc. In the example of the plates given, this was how the Cascade Range in North America which is a part of the famously known Pacific Ring of Fire was formed. The frequency of eruptions and viscosity of lava will affect the height and gradient of these volcanoes. Therefore if the lava is less viscous it will run further distances away from the point of origin and create gentler gradients but if the lava is more viscous it will not flow as easily and solidifies at shorter dista nces allowing a faster accumulation. In addition to this scenario we can have the case in which the plates involved at a Convergent plate margin are both Oceanic. The same principle will apply and the denser of the Oceanic plates will subduct. The features produced will have the same general high relief however they are referred to as Island Arc. An example of such is the Japanese Islands where the Pacific and Philippine plates interact. The difference of names is understood if Diagram 2 and Diagram 3 are compared. The volcanoes formed in Diagram 3 are protruding from the Oceanic crust hence the Island (body of small land surrounded by water) term while in Diagram 2 the volcanoes formed protrudes from the continental plate hence the arc is just referred to as volcanic. Diagram 3 showing the convergence of two oceanic plates Volcanoes or volcanic activity are produced at Divergent plate margins regardless of the type of plates involved. When the plates move apart a gap is created which allows the magma to expel and the lava solidifies due to the same conditions as previously mentioned under Oceanic to Oceanic and Oceanic to Continental convergence. Mid ocean ridges are the dominant features formed however within these ridges are the under -water volcanoes. The ridge is indicated in Diagram 4 at the centre where it is labelled. Although the diagram gives the simplicity of an ocean ridge as two parallel lines, in actuality this ocean ridge is an extensive submarine mountain range. Diagram 4 showing the divergence of two oceanic plates The previous point introduces our second common feature, mountain ranges. At the Divergent plate margin the mid oceanic ridge would represent this submarine mountain range. Similarly at Convergent plate margins where Fold Mountains are formed this will represent the mountain ranges as well. These Fold Mountains are formed when two Continental plates travel towards each other. For example Eurasian and Indian plates which will have relatively the same densities. They will collide and fold by compressional forces forming these ranges. This is illustrated in Diagram 5 in which the Continental plate on the right is buckling having collided with the Continental plate on the left thus producing the peaks along the centre of the diagram which represents the mountain range. Diagram 5 showing the convergence of two continental plates With the example of the Continental plates given the Himalayas Mountain Range was formed with peaks of over 8,000 meters in height above sea level. Contrast On the contrary, there are differences between the topographical features of a Convergent and Divergent plate margin. These are Rift Valleys and Ocean Trenches created by divergence and convergence respectively. Rift valleys occur when faults lie at a 120 degrees angle within a Continental plate. When the plates move apart either one of the two scenarios occurs. Scenario one is the pull leaves a segment of the of the Continental plate in the centre which falls below referred to as graben as illustrated in Diagram 6 of the two opposite sides referred to as Horst in the same diagram creating a steep sided narrow valley. Diagram 6 showing the formation of a Rift Valley However, in scenario two instead of the centre segment falling, the lands on either side of the segment can rise due to a release in pressure. Overtime the said segment will reach to a point where it is below sea level causing the land mass to break away from the parent continent and creating a new ocean basin. A perfect illustration of this occurrence is the Great African Rift Valley. Diagram 7 indicates the zone of rifting which runs from Afar Triple Junction to South Mozambique and also offshore of the coast of Mozambique along the Kerimba and Lacerda grabens. Eventually the Somalian plate to the east will be completely separated from the Nubian plate on the west. Diagram 7 showing the location of the Great African Rift Valley Lastly is the ocean trenches formed at subduction zones of Convergent plate margins. According to Merriam Webster online dictionary an ocean trench is â€Å"a long, narrow, deep depression in the ocean bed, typically running parallel to a plate boundary and marking a subduction zone.† The steepness of the trench is reliant on the angle at which it is subducted. The movement and location of an ocean trench is illustrated in Diagrams 2 and 3. Diagram 8 gives a three dimensional view of Puerto Rico’s oceanic trench formed at the Caribbean and North America plate boundary. Diagram 8 of a 3 dimensional representation of the Puerto Rico Trench In summary the Divergent and Convergent plate margins have similar and different topographical features that would have been formed or is still forming as a result of tectonic plate movement. The similarities are volcanoes and mountain ranges while the differences are rift valleys and ocean trenches. Bibliography â€Å"Island.† National Geographic. http://education.nationalgeographic.com/education/encyclopedia/island/?ar_a=1#page =1(accessed September 30, 2014) Jaegar, Peter. â€Å"Plate Boundaries: Convergent, Divergent and Transform Boundaries.† Education Portal. http://education-portal.com/academy/lesson/plate-boundaries- convergent- divergent-and-transform-boundaries.html#lesson (accessed October 1, 2014) â€Å"Japan in a subduction zone.†Introduction in the Landforms and Geology of Japan. http://www.glgarcs.net/intro/subduction_2.html (accessed October1, 2014). Nelson, A. Stephan. â€Å"Earth structures, Materials, Systems and Cycles.† Earth System Science. http://www.earthsci.org/processes/geopro/introgeo/introgeo.html (accessed September 21, 2014). May 22 2013. â€Å"Plate tectonics: The ends (and beginnings) of the Earth Part 1.† Why? Because Science, September 30, 2014. http://whybecausescience.com/2013/05/22/plate-tectonics- the-ends-and-beginnings- of-the-earth-part-1/ Watson, J. â€Å"What is tectonic plate?† USGS. Last modified May 5, 1999. http://pubs.usgs.gov/gip/dynamic/tectonic.html Wood, James and Alex Gruth. â€Å"East Africas Great Rift Valley: A Complex Rift System.†Geology.com. http://geology.com/articles/east-africa-rift.shtml (accessed October 1, 2014). 1 [1] Watson, J. â€Å"What is tectonic plate?† USGS. Last modified May 5, 1999. http://pubs.usgs.gov/gip/dynamic/tectonic.html

White Treatment of Blacks in Notes of a Native Son Essay -- James Bald

The White Beginning To Black Paranoia Some people regard James Baldwin as one of the best essayists of all time because of his ability to enmesh argument within narrative. Baldwin aims to tell a story, yet every so often throughout ?Notes of a Native Son,? he takes a moment to analyze what has happened. As the essay ebbs and flows from narrative into argument, the reader hardly knows the tide has changed. During this change, Baldwin turns to analyzing what has just happened, allowing the reader to actively interpret his analysis as a central theme throughout the work. Throughout the essay, Baldwin?s main narrative dealt with how blacks are treated by white people. When analyzing this narrative, it can be seen that white minds caused black madness, because of how the blacks were treated. Baldwin spends a majority of ?Notes? telling about his father?s life. Baldwin?s father eventually died from an illness of the mind, which plagued him for the last years of his life. His father was the first of a generation of free men. He kept to himself most of the time, had very dark skin, and was a preacher. He always had good intentions, but somehow those intentions never turned out well. As a result of his life, he had a great paranoia, which kept him from getting close to his children, and fueled his angry temper. James Baldwin noticed this paranoia as a young child. Part of the essay talks of when Baldwin was a young boy. One of his teachers, who happened to be white, was interested in a play he wrote, and wanted to take him to see one at the theater. They went to the play and later when Baldwin?s father was laid off his job, this woman became more and more important to helping the family. Even th... ...Baldwin reflects saying, ?now that my father was irrecoverable, I wished that he had been beside me so that I could have searched his face for the answers which only the future would give me now? (84). Baldwin wishes his father was there so he could look into his own future, and see how to cure his bitter madness. In ?Notes,? the narrative of his father?s life, Baldwin realizes, may eventually become the continuation of his own life, unless he learns from what has happened to his father. This essay tells the story of the latter half of his father?s life, and the first half of his own. These two half-lives can be spliced together to represent an African American?s life anywhere during this time period. Works Cited Baldwin, James. ?Notes of a Native Son.? 1955. James Baldwin: Collected Essays. Ed. Toni Morrison. New York: Library of America, 1998. 63-84.

Critical Thinking: The Yellow Wallpaper Essay

I. Ask questions A. Is John her husband? 1. Is John really a physician? 2. Did John really faint? B. Is Jennie really John’s sister? C. Is Mary really a nanny? D. Does she really have a baby? F. Is mansion really â€Å"vacation† home? 1. Did her room really used to be a nursery? 2. Is she in an insane asylum? G. The wallpaper 1. Does the wallpaper really grow? 2. Is there really a â€Å"creeping† figure behind the pattern? H. Is she crazy? II. Define terms and concepts A. Phosphates – â€Å"A salt of phosphoric acid† The Marriam-Webster Dictionary B. Delirim Tremens – â€Å"Violent delirium with tremors† The Marriam-Webster Dictionary Tollie 2 C. Florid Arabesque 1. Florid – â€Å"Very flowery in style, tinged with red† The Merriam-Webster Dictionary. 2. Arabesque – â€Å"A complex and elaborate decorative design of intertwined lines suggesting flowers, foliage, animals, geometric patterns, ect., used in drawing, painting, low relief, metalwork, etc.† American English Dictionary. D. â€Å"Yellow smell† Charlotte Perkins Gillman, â€Å"The Yellow Wallpaper 1. â€Å"It is not bad—at first, and very gentle, but quite the sublest, most enduring odor I ever met† Charlotte Perkins Gillman, â€Å"The Yellow Wallpaper. 2. â€Å"hanging over me† The Yellow Wallpaper. 3. â€Å"now I am used to it† The Yellow Wallpaper. III. Accept uncertainties A. Not knowing if what she say is real or not. B. Not knowing if the woman in the wall paper is her.

Cell Phones in Schools Research Paper - 1801 Words

Over the last few decades, the growing popularity of cell phones, especially among teenagers, has resulted in school administrators questioning whether they should allow students to use cell phones during class hours. Before the popularity of cell phones increased, the biggest concern of school administrators was the possibility of drug dealing; however, as the prevalence of cell phones grew, the concerns changed to fears of inappropriate use and distractions. In the early 90’s, states began banning cell phones and pagers in schools as an attempt to stop communication between drug dealers (Ballaro, Ginsburg). According to Patricia O’Neill, a Montgomery school board member, â€Å"[t]here was a view that only drug dealers and gang members had†¦show more content†¦The ban on cell phones during school hours not only creates safety concerns, but also hinders students from reaching their full academic potential as they gain popularity among teenagers; thus, schools should consider reevaluating their cell phone policies. Advocates for the repeal of cell phone bans in school argue that students should be allowed to carry their phones with them throughout the day for safety reasons as well as for the convenience of the student’s parents. Due to recent events, such as the shooting at Sandy Hook or even the terrorist attack on 9/11, many people, parents especially, have brought up that point that students should have their cell phones with them while at school in case an emergency occurs. Dr. Joyce D. 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