Category: Plate Tectonics

The theory of tectonics has been brought forward by many scientists in the world, but all of them have come to one conclusion. Plate tectonics is the study of how the planet plates (earth plates) are shaped and driven by geographical forces which are found in the earth, and it is a result of these forces that keep these plates at constant motion on the earths surface. The outermost layer of the earth is made up of a solid shell and these solid shells are crack into many large pieces and these pieces are called earth plates and they are usually 50 miles (80km) thick (Naomi, 2003).

In history, this theory was told by many geological scientists, but the first comprehensive plate tectonic theory was formulated by the scientist from Germany know as Alfred Wegener and this was in 1912 (Naomi, 2003). In his hypothesis, he declares that the earth seven continents are made up of lighter rocks which rest on heavier materials, and these materials are sometimes called crustal material and lighter materials usually float on the heavier crustal material (Naomi 2003), this can be compared to icebergs floating on the water at sea. The theory of Plate tectonics states that the earth was made up of one continent millions of years ago, but this one continent broke down into many continents and they drifted from one another forming several continents and these continents are today; Africa, Australia, Europe, Antarctic, Asian, South and North America. While several small earth plates exist apart from these 7 major ones and these are Arabian plates, Nazca plate, and Philippines plate. Also, this theory explains how major earths features like mountains, volcanic eruptions and how they were formed and similar animals found in the earth could have lived on the earth continent when it was one block and on what is now widely seen as the seven continents which are found in the earth.

The theory of plate tectonics can be explained in two methods and the first method is spreading. In this method, the two tectonic plates are spreading apart forming cracks that will be found on the earths crust. These cracks will be filled with lava (molten rocks) and this lava will erupt if pressure from the earth surface builds up and as a result of that it will form new land, an example of a feature formed due to the spreading method is the rift valley which spread from Asia continent down to East Africa. The second method is called subduction, in this method, two tectonic plates move toward each other and the denser plate will be forced under the lighter plate which is found in the earth crust. Deep trenches have been formed in the ocean and sea as a result of subduction and this sometimes will give rise to earthquakes which are mostly found in places like Japan (Naomi, 2003).

Many geology scientists dont agree with the hypothesis brought forward by Alfred Wegener in the year 1912 but there is a general theory that is acceptable to all geology scientists. According to this general theory on plate tectonics they believe- the scientist- the earth surface has been broken down into many plates or shifting slabs and they are 50 miles in thickness, these plates are in constant motion which is relative to the individual tectonic plate and they are found above a hot layer know as the earth core. Most of the active volcanoes are found along shifting plates on the earths surfaces but sometimes these active volcanic mountains are not connected with the plate boundaries of the earths surface.

References

Naomi, C. (2003).Plate tectonics: an insiders history of the modern theory of the Earth. London: Westview Press.

Introduction

Plate tectonics refers to movements on Earths surface, that is, the lithosphere. This is a theory in science explaining such movements. The lithosphere is made up of large broken rock masses also referred as tectonic plates (Oreskes 424). These tectonic plates are suspended on molten layer of Earths crust that comes immediately below the lithosphere; this layer is called asthenosphere.

Given that the asthenosphere is molten, these plates move on it with ease. The movement occurs at boundaries namely; transform boundaries, divergent and convergent boundaries (Oreskes 16). These three different boundaries give rise to the different forms of plate tectonics known today.

Types of Plate Tectonics

According to United States Geological Survey (USGS), there are three different types of plate movements; that is, divergent, convergent, and lateral plate slipping resulting from the three different plate boundaries that exist. Divergent plate movements occur when two oceanic plate move away from each other to form new oceanic crust at a zone of divergence. The zone of divergence results as the Earths crust separates (Earth Science). The separation results from hot magma arising from the magma in the continental mantle. This magma has large pressure that causes the crust to crack and separate.

Convergent plate movements are the opposite of divergent and it occurs when two oceanic plates collide leading to loss of crust at a convergent point. Convergent movements involve collision between two plates and these two plates may be either continental or oceanic (USGS).

Convergent plate movements come after divergent plate movements because after the plates break up in the latter, they meet at another point and collide hence the subduction. On the other hand, lateral slipping occurs when two plates move in opposite direction slipping over each other at a transform boundary. The two plates eventually jerk apart due to pressure that mounts up in the mantle and this causes earthquakes (USGS).

The movement of these plates is facilitated by the fact that they float on the Earths molten magma on the region called asthenosphere, which lies, below lithosphere. As aforementioned, lithosphere is the outermost Earths crust that human beings can reach. Actually, lithosphere makes the tectonic plates (Rychert and Shearer 496). The molten magma heats up as the core of the Earth heats up which causes convectional currents within the molten magma. As the earth core cools, the molten magma cools and sinks and in the process, it pulls the plates attached to it hence the plate movement.

Earthquakes results from these plate tectonic movements along fault lines. Fault lines are cracks on lithosphere. As tectonic plates move, there is building up of pressure along the fault lines, and when this pressure exceeds the strength of lithosphere, earthquakes result to relieve the pressure mounting in the lithosphere. According to Rychert and Shearer, the lateral plate slipping form of movement is the one that causes many earthquakes around the world (498).

Conclusion

Plate tectonics describes the movement of fragments formed from broken lithosphere.

These fragments are suspended on the asthenosphere, which is molten hence offering good medium of movement. There are three different types of plate tectonics, that is, convergent, divergent, and lateral slipping. These movements cause earthquakes as the lithosphere releases mount up pressure in the Earths mantle. Earthquakes result mainly from lateral slipping moving and this occurs along fault lines, which are weak points on the lithosphere.

Works Cited

Earth Science. Plate Tectonics. Moorland School. N.d. Web.

Oreskes, Naomi. Plate Tectonics: An Insiders History of the Modern Theory of the Earth. California: Westview Press, 2003.

Rychert, Catherine, & Shearer, Peter. A Global View of the Lithosphere-Asthenosphere Boundary. Science Journals. 324(5):5926. 2009.

United States Geological Survey. Understanding Plate Motions. 1999. Web.

Introduction

The earth’s surface is composed of several plates that are in a constant state of motion. The plates are subjected to tectonic forces that compel them to move in different directions (Garrison, 2009). Generally, there are three major forces that prompt movement of plates on the earth’s crust.

These include transformational, divergent and convergent forces. Convergent forces push the earth’s plates towards each other leading to crashing effect. Transformational forces push the earth’s plates alongside each other while divergent forces tend to pull the plates apart (Gubbins, 1990).

Different features are formed depending on the kind of movements involved. Empirical studies conducted by geologists reveal that these movements result in geological features the earth’s surface. Resultant features include earthquakes, volcanic eruptions and mountain formation (Garrison, 2009).

Location of converging plates

When plates are pushed towards each other, they are eventually deformed. Additionally, certain features such as mountains and island arcs are generated (Gubbins, 1990). However, resultant features depend on which plates converge.

For instance, when two continental plates drift toward each other, they form a mountain as opposed to the case when continental and an oceanic plate converges. In this case, the two different plates form an island where the heavier continental plate lands on the oceanic plate (Garrison, 2009).

For instance, where there are volcanic eruptions during the convergence of the plates, magma solidifies on top of the oceanic crust to form a hard surface on the ocean. An example of a place commonly known for this incidence is American continent whereby the South American plate converged with Nazca plate to form Andes Mountain which is located in Chain (Garrison, 2009).

Moreover, it is evident that Tibet plateau in Asia was formed as a result of convergent tectonic forces. The feature resulted when the Indian plate slowly converged with the Asian plate. The oceanic crust between the two continental plates was submerged under them (Gubbins, 1990). Further evidence reveals that more convergence between the oceanic plates resulted into formation of Himalayas Mountain.

Location of diverging plates

Divergent tectonic forces triggered plates to pull away from each other resulting into formation of a new continental crust (Garrison, 2009. Mostly, this occurs where two oceanic plates diverge giving rise to a continental crust being formed at the middle (Cox & Hart, 1986).

A good example of features resulting from divergence includes the Ethiopian highlands in Eastern Africa and ridges formed in the mid-Atlantic. It is evident that due to tectonic forces, the Atlantic Ocean is widening slowly at an approximated length of 2 cm in a year (Garrison, 2009).

The location where tectonic plates slide along each other

In most cases, earth’s plates slip sideways alongside each other. This causes friction; thus there is an accumulation of intense pressure. There is a sudden release of the pressure being built up resulting in earth tremors (Cox & Hart, 1986). Though this transformational activity does not lead to the formation of spectacular features, faulting is a common occurrence.

For example, the San Andreas Fault was formed as a result of lateral slipping of earth plates. As mentioned earlier, earthquakes have been experienced in San Francisco during the 19th century (Garrison, 2009). These were believed to have been triggered by faulting in San Andreas. To date, there have been subsequent occurrences of earthquakes in the zone since the incidence.

Conclusion

To recap it all, it is imperative to reiterate that plate tectonic theory attempts to expound why certain conspicuous features are observed on the earth’s surface. Such features include volcanoes, faults, islands, ridges, plateaus, an earthquake.

It is also evident that the earth’s plates are usually subjected to three tectonic forces namely divergence, convergence and transformational forces. Through these forces, the plates tend to move in different directions thus resulting in different features. Scientists have for a long time, associated geological activities on the earth’s surface with movements in tectonic plates.

References

Cox, A. & Hart, R. (1986). Plate tectonics: how it works. California: Blackwell Publishing, Inc.

Garrison, T. (2009). Essentials of Oceanography. California: Cengage Learning.

Gubbins, D. (1990).Seismology and plate tectonics. New York: Cambridge University Press.

Pangaea

Pangaea was the supercontinent that existed about millions of years ago. The continent covered about one-third of the Earth’s surface. It consisted of all the continents which are known today. The supercontinent was formed about 300 million years ago as a result of the Earth’s tectonic plates’ movement. These plates pushed together to form the supercontinent, but the further movement of tectonic plates 100 million years ago caused the breaking of Pangaea into parts along the volcanic rift zones.

Subduction of Tectonic Plates

Subduction is the process of one plate’s moving or sliding under the other one. This process is typical for the regions of convergent boundaries. The oceanic lithosphere subducts, but the continental lithosphere does not subduct in any cases. The reason is in the fact that the oceanic lithosphere is characterized by a higher density. As a result, the older oceanic lithosphere can slide beneath the continental lithosphere when the continental lithosphere is not as dense as the oceanic lithosphere is, and it rides up causing the possible destruction of the older oceanic lithosphere.

A Convergent Plate Volcanic Belt vs. A Hot Spot Series of Volcanic Islands

Volcanoes usually form the belt along the convergent plate boundaries because of the subduction processes. The result of subduction is the older oceanic plates’ sinking to the mantle to form volcanoes as weak spots there because the magma breaks the ocean floor. As a result, the volcanic belt is created. On the contrary, a hot spot series of volcanic islands are formed not because of the subduction process, but because the Earth’s mantle has hot spots through which magma rises to the surface to form volcanoes. Thus, the volcanic mountains appear to form volcanic islands.

Transform Faults

A transform fault can be discussed as a specific fault or a boundary within the subduction zones. According to this type of fault, the tectonic plates slide past one another without destroying the lithosphere. This horizontal type of sliding is often the result of the processes observed in the subduction zones. Many transform faults are also observed in the ocean to be associated with the parallel movements of tectonic plates.

Sea-Floor Spreading

When volcanic activity is observed in oceans, the floor of the ocean begins to spread because of the impact of the volcanic energy. As a result, the oceanic crust becomes formed due to volcanic processes that are observed at mid-ocean ridges. The effects of the volcanic activity are the motions of the oceanic crust to spread from the ridge. The fractures appearing during the volcanic activity are also associated with the changes in the lithosphere and sea-floor spreading which causes the formation of the new floor of the ocean.

The Ring of Fire

The Ring of Fire is the name used to determine a series of volcanoes observed in the Pacific Ocean. This string of volcanoes is a result of the significant seismic activity of these territories because this is the region where several tectonic plates form different types of boundaries such as a convergent boundary, a divergent boundary, and a transform boundary. Different tectonic plates found in the Ring of Fire can crash into each other or pull apart from each other to form subduction zones and volcanoes in the first situation and sea-floor spreading in the second situation.

The theory of plate tectonics was introduced by the Canadian geophysicist John Tuzo Wilson (Garrison and Ellis 74). According to Wilson’s theory, the Earth’s outer layer is composed of nearly “dozen separate major lithospheric plates” that float on the asthenosphere (Garrison and Ellis 74). When the deformable asthenosphere is heated from below, it expands, becomes less dense, and rises (Garrison and Ellis 74).

When the asthenosphere reaches the lithosphere, it turns aside, “lifting and cracking the crust” to create the plate edges (Garrison and Ellis 74). The newly shaped pair of plates slides down to the swelling ridges that deviate from the spreading center. In the location of divergence, the new seabed is formed (Garrison and Ellis 74). Larger plates contain continental crust as well as oceanic ones. The major plates jostle about “like huge slabs of ice on a warming lake” (Garrison and Ellis 74).

In human terms, the movement of plates is rather slow, reaching up to 5 centimeters per year. The interaction between plates occurs in diverging, converging, and sideways-moving boundaries (Garrison and Ellis 74). Frequently, one plate may force another wrinkle into mountains or move it below the surface. There are two forces that may cause plate movement:

1. plates are shaped and slide off the elevated ridges of the spreading centers;
2. plates are tugged downward into the mantle by their edges that are dense and cool.

The evidence of many centuries of research indicates that the slow movement of plate tectonics recreates the Earth’s surface, shapes or destroys ocean basins, and splits or expands continents (Garrison and Ellis 74). The ancient granitic continents, the density of which is low, ride high in the lithospheric plates, barging on the asthenosphere that moves below them at a slow pace. This process has advanced since the Earth’s crust’s initial cooling and solidifying (Garrison and Ellis 76). Tectonic plates are defined as the cool external layers of convection currents in the upper mantle (Garrison and Ellis 74).

The system of plates is powered by heat. Because some parts of the mantle are heated more than others, convection currents are created when warm mantle material ascends, and cool material descends (Garrison and Ellis 75). The movement of plates is generated by gravity.

The concept of plate tectonics was developed from the ideas of continental drift (Garrison and Ellis 74). The theory of continental drift was introduced by the German researcher Alfred Wegener at the beginning of the 20th century (Tate). Wegener noticed that the fossil remains of some extinct plants or animals could be discovered on several continents that were not adjacent to each other (Tate). The observations allowed Wagner to make a conclusion that in the distant past, the configuration of continents was not the same as at the time of his research. Wegener’s discovery received the title “continental drift” (Tate).

The theory of continental drift fits in the discussion of plate tectonics because both of these phenomena result in considerable changes in the Earth’s surface. Critics rejected the possibility of continental drift due to the geological view of Earth’s mantle (Garrison and Ellis 62). However, scientists continued to develop Wegener’s theory. In particular, Japanese scientists Kiyoo Wadati and Hugo Benioff argue that volcanoes and earthquakes near Japan may be related to continental drift (Garrison and Ellis 73).

Works Cited

Garrison, Tom, and Robert Ellis. Oceanography: An Invitation to Marine Science. 9th ed., CENGAGE Learning, 2016.

Tate, Karl. “Plate Tectonics and Continental Drift (Infographic).” LiveScience. 2016. Web.

Abstract

This paper aims to show the relationship between the Plate Tectonics and Continental Drift theories which made advances in the field of geology.

Overview

Plate tectonics is a hypothetical movement of earth’s crust plates: a theory that ascribes continental drift, volcanic and seismic activity, and the formation of mountain belts to moving plates of the Earth’s crust supported on less rigid mantle rocks.

Plate Tectonics theory, formulated during the early 1960s, explains that earth’s crust comprise thin, rigid plates that depend its movement with each other; plate tectonics transfigured the study of the earth. It helped scientists to explain several geological events, such as earthquakes and volcanic eruptions as well as mountain building and the formation of the oceans and continents.

In 1912, German scientist Alfred Wegener examined the shapes of the continents and found that they fit together like a jigsaw puzzle. Using this observation, along with geological evidence he found on different continents, he developed the theory of continental drift, which states that today’s continents were once joined together into one large landmass, called Pangaea that split, and drifted apart into seven continents that we have today and in places collided again. This theory describes and illustrates the formation, alteration, and the exact movement of the continents across the Earth’s crust.

The first comprehensive theory of continental drift was suggested by the German meteorologist Alfred Wegener in 1912. The hypothesis asserts that the continents consist of lighter rocks that rest on heavier crustal material—similar to the manner in which icebergs float on water. Wegener contended that the relative positions of the continents are not rigidly fixed but are slowly moving—at a rate of about one yard per century.

According to the generally accepted plate-tectonics theory, scientists believe that Earth’s surface is broken into a number of shifting slabs or plates, which average about 50 miles in thickness. These plates move relative to one another above a hotter, deeper, more mobile zone at average rates as great as a few inches per year. Most of the world’s active volcanoes are located along or near the boundaries between shifting plates and are called plate-boundary volcanoes.

The peripheral areas of the Pacific Ocean Basin, containing the boundaries of several plates, are dotted with many active volcanoes that form the so-called Ring of Fire. The Ring provides excellent examples of plate-boundary volcanoes, including Mount St. Helens. However, some active volcanoes are not associated with plate boundaries, and many of these so-called intra-plate volcanoes form roughly linear chains in the interior of some oceanic plates. The Hawaiian Islands provide perhaps the best example of an intra-plate volcanic chain, developed by the northwest-moving Pacific plate passing over an inferred “hot spot” that initiates the magma-generation and volcano-formation process.

Between 1950s and 1960s, geologists found evidence behind the idea of tectonic plates and their movement. They used Wegener’s claim in various aspects of earth’s changes and used this evidence to confirm continental drift. In 1968, scientists incorporated most geologic activities into a theory called the New Global Tectonics commonly known as Plate Tectonics.

Plate tectonics theory – the Lithosphere Plates of Earth

According to U.S. Department of Interior, Geological Survey, this figure shows the boundaries of lithosphere plates that are active at present. The double lines indicate zones of spreading from which plates are moving apart. The lines with barbs show zones of under thrusting (subduction), where one plate is sliding beneath another. The barbs on the lines indicate the overriding plate. The single line defines a strike-slip fault along which plates are sliding horizontally past one another. The stippled areas indicate a part of a continent, exclusive of that along a plate boundary, which is undergoing active extensional, compressional, or strike-slip faulting.

Conclusion

Plate tectonics and continental drift theories formulated by Wegener that were later confirmed by evidences and findings of later scientists opened avenues in the advancement of geology, explaining the details of earth’s movements, and the occurrence of drifts, faults, plates and ridges in the earth’s crust caused by different forces.

However, biblically speaking, it is said that, “…all the fountains of the great deep came bursting through, and the windows of heaven were open;” it caused great earthquake which is the possible result of the drifting apart of the continents (KJVA, Gen 7.11).

Wegener relied on geological evidence and fossil records to support his theory that the landmass slowly separated through continental drift. In the 1960s researchers confirmed Wegener’s theory when they observed seafloor spreading and other phenomena. This research eventually led to the theory and study of plate tectonics.

References

“Continental Drift and Plate-Tectonics Theory.” Web.

Coney, Peter. “Plate Tectonics.” Microsoft® Encarta® 2007 [DVD]. Redmond, WA: Microsoft Corporation, 2006.

“Geology: Plate Tectonics.” Web.

Crystal, Ellie. “Continental Drift and Plates Tectonics.” Web.

The Holy Bible, English Standard Version, copyright © 2001 by Crossway Bibles, a division of Good News Publishers.

1769 King James Version of the Holy Bible.

The theory of tectonics has been brought forward by many scientists in the world, but all of them have come to one conclusion. Plate tectonics is the study of how the planet plates (earth plates) are shaped and driven by geographical forces which are found in the earth, and it is a result of these forces that keep these plates at constant motion on the earth’s surface. “The outermost layer of the earth is made up of a solid shell and these solid shells are crack into many large pieces and these pieces are called earth plates and they are usually 50 miles (80km) thick” (Naomi, 2003).

“In history, this theory was told by many geological scientists, but the first comprehensive plate tectonic theory was formulated by the scientist from Germany know as Alfred Wegener and this was in 1912” (Naomi, 2003). “In his hypothesis, he declares that the earth seven continents are made up of lighter rocks which rest on heavier materials, and these materials are sometimes called crustal material and lighter materials usually float on the heavier crustal material” (Naomi 2003), this can be compared to icebergs floating on the water at sea. The theory of Plate tectonics states that the earth was made up of one continent millions of years ago, but this one continent broke down into many continents and they drifted from one another forming several continents and these continents are today; Africa, Australia, Europe, Antarctic, Asian, South and North America. While several small earth plates exist apart from these 7 major ones and these are Arabian plates, Nazca plate, and Philippines plate. Also, this theory explains how major earth’s features like mountains, volcanic eruptions and how they were formed and similar animals found in the earth could have lived on the earth continent when it was one block and on what is now widely seen as the seven continents which are found in the earth.

The theory of plate tectonics can be explained in two methods and the first method is spreading. In this method, the two tectonic plates are spreading apart forming cracks that will be found on the earth’s crust. These cracks will be filled with lava (molten rocks) and this lava will erupt if pressure from the earth surface builds up and as a result of that it will form new land, an example of a feature formed due to the spreading method is the rift valley which spread from Asia continent down to East Africa. The second method is called subduction, in this method, two tectonic plates move toward each other and the denser plate will be forced under the lighter plate which is found in the earth crust. “Deep trenches have been formed in the ocean and sea as a result of subduction and this sometimes will give rise to earthquakes which are mostly found in places like Japan” (Naomi, 2003).

Many geology scientists don’t agree with the hypothesis brought forward by Alfred Wegener in the year 1912 but there is a general theory that is acceptable to all geology scientists. According to this general theory on plate tectonics they believe- the scientist- the earth surface has been broken down into many plates or shifting slabs and they are 50 miles in thickness, these plates are in constant motion which is relative to the individual tectonic plate and they are found above a hot layer know as the earth core. Most of the active volcanoes are found along shifting plates on the earth’s surfaces but sometimes these active volcanic mountains are not connected with the plate boundaries of the earth’s surface.

References

Naomi, C. (2003).Plate tectonics: an insider’s history of the modern theory of the Earth. London: Westview Press.

Our planet is a cosmic body, which has heoyid form and the surface with approximately 510 million km². As a result of the differentiation of the Earths matter, the division into geospheres has happened. The object of geotectonic study is lithosphere, which includes the Earth’s crust, and is usually the top layer of the mantle up to ten kilometers. The total capacity of the lithosphere varies from 5-25 km in mid-ocean ridges, volcanic arcs and continental rift zones. 100-200 km is on the periphery of oceans, continents and, in particular, on the ancient shield platforms. The lithosphere development is influenced by the endogenous and exogenous processes, such as tectonic, magmatic, metamorphic, accumulation, and nutrient (Hess 388-390)

The major structural units of the lithosphere plates are limited areas of the maximum tectonic, seismic and volcanic activity. The largest of them are Eurasian, American, African, Pacific, and Antarctic Indo-Australian. According to the theory of the tectonic plates, the plates under the influence of convection move with speed from the 1 millimeter to 10-20 cm per year. This move causes the destruction and the rupture of the continental blocks in the tension areas, their horizontal displacement and the young crust formation in the bed of newly formed oceans; accumulation, accompanied by thrust, folding and mountains forming – in the areas of compression. There are two main types of crust: continental and oceanic, which differ in their composition, structure and capacity. The continental crust is formed of three types of layers: sedimentary, granitic and basaltic. In the oceanic crust, the power which usually does not exceed 10.2 km, granite layer is absent (Carey 176).

The continents are large amounts of the continental crust type, much of which appears above the surface of the oceans, and peripherals are offshore zone and the continental slope. There are 6 continents: Eurasia, Africa, North America, South America, Australia and Antarctica, but in previous geological epochs their number was markedly lower, up to a single continental block Pangea, which was divided initially on Laurasia and Gondwana, further fragmentation and subsequently given the current configuration of the world. The main ancient platforms are Eastern European, Siberian, Sino-Korean, Arabian and Eurasian, African, Australian, Antarctic, North American, South American – on the respective continents. Platform cover is usually labor bedding, power up to 5 km, which increases in flat cup-shaped depressions or Syncline and decreases in the same flat elevations – anticline (Hess 377-380).

Synclines can be formed over the central parts of the panels (Syncline Hudson Bay in the Canadian Shield, of Bothnia in the Baltic) over peripheral (Caspian syncline in southern Russian platform), or joints is a special type Syncline gangway type Tunguska on the Siberian platform or Parana on American platform, with powerful basalts’ cover. Anticlines examples are Voronezh and Belarus to the Russian platform Anabas on the Siberian, Central Kansas, Nashvil-Tsyntsinati in North American. Specific types of platform structures are avlakogens that constitute intra-platform mobile linear zone. Usually it is deep (5-10 km), narrow (10-100 km) and elongated to 1000 km deflection, limited faults. In the present structure they look like narrow linear fold zones (Danish-Polish avlakogene) or Wide-Syncline basins, or a combination of linear deflections-graven and uplift, a handful (zone Vihyta North American platform). Provision is also less structural forms such as granite domes of old boards and bodies, boards of various ages’ consolidation deflections or depressions, vaults or performances, shafts, etc (Carey 204).

Moving (folded) zones are the next global structural element of the crust. This large (hundreds of kilometers), very extended (up to thousand kilometers) long zones, where the manifest intensive processes of tectonics, folding, magmatism are of different ages (White& McKenzie). They lay confined to the boundaries of lithosphere plates. The largest are the Mongol-Okhotsk, Mediterranean-Himalayan and Pacific mobile zones. Within the mobile zones stand folded regions and systems that differ in composition, structure and age of consolidation. Age folded areas, usually correlate with age, the last phase of folding: Baikal, Caledonian, Hercian, Cimmerian, Alpine and their analogues on different continents. Development of a mobile zone is characterized by repeated changes of the tectonic regimes, and periods of cyclical stretching of the horizontal compression. These processes are accompanied by complex multiple folding, the thrust and tectonic cover, considerable horizontal movement of crustal blocks and progeny. Along the platforms borders is the edge of the foothills bending, and in the rear mountain systems – the intermountain basins, which are filled with the products of erosion of the newly established mining facilities. Rift zones are formed from the transverse faults of the displaced segments on the mechanism of displacement to a distance of several tens to hundreds of kilometers. Typically, they correspond to the deep (5 km) gorge, which divide the ocean bed and slopes of underwater ridges. Probably in the axial rift of the mid-ocean areas due to the movements of the tectonic plates forms the new oceanic crust. The speed of the plate’s movement reaches from 2 to 18 cm / year (Hess 366-370). Thus, our planet is the only geological object that lives on the system of natural laws. Its main structural elements are in constant interaction of the complex, changing, and moving.

Bibliography

Carey, S. Warren. The tectonic approach to continental drift. In Carey, S.W..Continental Drift—A symposium, held in 1956. Hobart: Univ. of Tasmania. pp. 177–363. 1958. Print

Hess, Darrel. Mac Kings Physical Georaphy. 10^th edition. P.377-390.2009. Print

White, Richard and D. McKenzie,. Magmatism at rift zones: The generation of volcanic continental margins and flood basalts. Journal of Geophysical Research. 1989.Print

Introduction

Plate tectonics refers to movements on Earth’s surface, that is, the lithosphere. This is a theory in science explaining such movements. The lithosphere is made up of large broken rock masses also referred as tectonic plates (Oreskes 424). These tectonic plates are suspended on molten layer of Earth’s crust that comes immediately below the lithosphere; this layer is called asthenosphere.

Given that the asthenosphere is molten, these plates move on it with ease. The movement occurs at boundaries namely; transform boundaries, divergent and convergent boundaries (Oreskes 16). These three different boundaries give rise to the different forms of plate tectonics known today.

Types of Plate Tectonics

According to United States Geological Survey (USGS), there are three different types of plate movements; that is, divergent, convergent, and lateral plate slipping resulting from the three different plate boundaries that exist. Divergent plate movements occur when two oceanic plate move away from each other to form new oceanic crust at a zone of divergence. The zone of divergence results as the Earth’s crust separates (Earth Science). The separation results from hot magma arising from the magma in the continental mantle. This magma has large pressure that causes the crust to crack and separate.

Convergent plate movements are the opposite of divergent and it occurs when two oceanic plates collide leading to loss of crust at a convergent point. Convergent movements involve collision between two plates and these two plates may be either continental or oceanic (USGS).

Convergent plate movements come after divergent plate movements because after the plates break up in the latter, they meet at another point and collide hence the subduction. On the other hand, lateral slipping occurs when two plates move in opposite direction slipping over each other at a transform boundary. The two plates eventually jerk apart due to pressure that mounts up in the mantle and this causes earthquakes (USGS).

The movement of these plates is facilitated by the fact that they float on the Earth’s molten magma on the region called asthenosphere, which lies, below lithosphere. As aforementioned, lithosphere is the outermost Earth’s crust that human beings can reach. Actually, lithosphere makes the tectonic plates (Rychert and Shearer 496). The molten magma heats up as the core of the Earth heats up which causes convectional currents within the molten magma. As the earth core cools, the molten magma cools and sinks and in the process, it pulls the plates attached to it hence the plate movement.

Earthquakes results from these plate tectonic movements along fault lines. Fault lines are cracks on lithosphere. As tectonic plates move, there is building up of pressure along the fault lines, and when this pressure exceeds the strength of lithosphere, earthquakes result to relieve the pressure mounting in the lithosphere. According to Rychert and Shearer, the lateral plate slipping form of movement is the one that causes many earthquakes around the world (498).

Conclusion

Plate tectonics describes the movement of fragments formed from broken lithosphere.

These fragments are suspended on the asthenosphere, which is molten hence offering good medium of movement. There are three different types of plate tectonics, that is, convergent, divergent, and lateral slipping. These movements cause earthquakes as the lithosphere releases mount up pressure in the Earth’s mantle. Earthquakes result mainly from lateral slipping moving and this occurs along fault lines, which are weak points on the lithosphere.

Works Cited

Earth Science. “Plate Tectonics.” Moorland School. N.d. Web.

Oreskes, Naomi. “Plate Tectonics: An Insider’s History of the Modern Theory of the Earth.” California: Westview Press, 2003.

Rychert, Catherine, & Shearer, Peter. “A Global View of the Lithosphere-Asthenosphere Boundary.” Science Journals. 324(5):5926. 2009.

United States Geological Survey. “Understanding Plate Motions.” 1999. Web.