Geography
Tectonic Plates
Tectonic plates are large, rigid pieces of the Earth's lithosphere that fit together like a jigsaw puzzle. These plates float on the semi-fluid asthenosphere and are in constant motion, causing phenomena such as earthquakes, volcanic activity, and the formation of mountain ranges. The interactions between tectonic plates shape the Earth's surface and are fundamental to the study of plate tectonics.
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12 Key excerpts on "Tectonic Plates"
No longer available |Learn more- (Author)
- 2014(Publication Date)
- College Publishing House(Publisher)
____________________ WORLD TECHNOLOGIES ____________________ Chapter- 2 Plate Tectonics The Tectonic Plates of the world were mapped in the second half of the 20th century Plate tectonics (from the Late Latin tectonicus , from the Greek: τεκτονικός pertaining to building) (Little, Fowler & Coulson 1990) is a scientific theory which describes the large scale motions of Earth's lithosphere. The theory builds on the older concepts of continental drift, ____________________ WORLD TECHNOLOGIES ____________________ developed during the first decades of the 20th century (one of the most famous advocates was Alfred Wegener), and was accepted by the majority of the Geoscientific community when the concepts of seafloor spreading were developed in the late 1950s and early 1960s. The lithosphere is broken up into what are called Tectonic Plates. In the case of the Earth, there are currently seven to eight major (depending on how they are defined) and many minor plates. The lithospheric plates ride on the asthenosphere. These plates move in relation to one another at one of three types of plate boundaries: convergent, or collisional boundaries; divergent boundaries, also called spreading centers; and conservative transform boundaries. Earthquakes, volcanic activity, mountain-building, and oceanic trench formation occur along these plate boundaries. The lateral relative movement of the plates varies, though it is typically 0–100 mm annually (Read & Watson 1975). The Tectonic Plates are composed of two types of lithosphere: thicker continental and thin oceanic. The upper part is called the crust, again of two types (continental and oceanic). This means that a plate can be of one type, or of both types.
No longer available |Learn more- (Author)
- 2014(Publication Date)
- Academic Studio(Publisher)
______________________________ WORLD TECHNOLOGIES _______________________ _______ Chapter- 7 Plate Tectonics The Tectonic Plates of the world were mapped in the second half of the 20th century Plate tectonics (from the Late Latin tectonicus , from the Greek: τεκτονικός pertaining to building) (Little, Fowler & Coulson 1990) is a scientific theory which describes the large scale motions of Earth's lithosphere. The theory builds on the older concepts of continental drift, ______________________________ WORLD TECHNOLOGIES _______________________ _______ developed during the first decades of the 20th century (one of the most famous advocates was Alfred Wegener), and was accepted by the majority of the Geoscientific community when the concepts of seafloor spreading were developed in the late 1950s and early 1960s. The lithosphere is broken up into what are called Tectonic Plates. In the case of the Earth, there are currently seven to eight major (depending on how they are defined) and many minor plates. The lithospheric plates ride on the asthenosphere. These plates move in relation to one another at one of three types of plate boundaries: convergent, or collisional boundaries; divergent boundaries, also called spreading centers; and conservative transform boundaries. Earthquakes, volcanic activity, mountain-building, and oceanic trench formation occur along these plate boundaries. The lateral relative movement of the plates varies, though it is typically 0–100 mm annually (Read & Watson 1975). The Tectonic Plates are composed of two types of lithosphere: thicker continental and thin oceanic. The upper part is called the crust, again of two types (continental and oceanic). This means that a plate can be of one type, or of both types.
No longer available |Learn more- (Author)
- 2014(Publication Date)
- Learning Press(Publisher)
________________________ WORLD TECHNOLOGIES ________________________ Chapter-3 Plate Tectonics The Tectonic Plates of the world were mapped in the second half of the 20th century. Plate tectonics (from the Late Latin tectonicus , from the Greek: τεκτονικός pertaining to building) (Little, Fowler & Coulson 1990) is a scientific theory which describes the large scale motions of Earth's lithosphere. The theory builds on the older concepts of continental drift, developed during the first decades of the 20th century (one of the most famous advocates was Alfred Wegener), and was accepted by the majority of the Geoscientific community when the concepts of seafloor spreading were developed in the late 1950s and early 1960s. The lithosphere is broken up into what are called Tectonic Plates. In the case of the Earth, there are currently seven to eight major (depending on how they are defined) and many minor plates. The lithospheric plates ride on the ________________________ WORLD TECHNOLOGIES ________________________ asthenosphere. These plates move in relation to one another at one of three types of plate boundaries: convergent, or collisional boundaries; divergent boundaries, also called spreading centers; and conservative transform boundaries. Earthquakes, volcanic activity, mountain-building, and oceanic trench formation occur along these plate boundaries. The lateral relative movement of the plates varies, though it is typically 0–100 mm annually (Read & Watson 1975). The Tectonic Plates are composed of two types of lithosphere: thicker continental and thin oceanic. The upper part is called the crust, again of two types (continental and oceanic). This means that a plate can be of one type, or of both types.
No longer available |Learn more- (Author)
- 2014(Publication Date)
- Learning Press(Publisher)
____________________ WORLD TECHNOLOGIES ____________________ Chapter- 5 Plate Tectonics The Tectonic Plates of the world were mapped in the second half of the 20th century Plate tectonics (from the Late Latin tectonicus , from the Greek: τεκτονικός pertaining to building) (Little, Fowler & Coulson 1990) is a scientific theory which describes the large scale motions of Earth's lithosphere. The theory builds on the older concepts of continental drift, developed during the first decades of the 20th century (one of the most famous advocates was Alfred Wegener), and was accepted by the majority of the Geoscientific community when the concepts of seafloor spreading were developed in the late 1950s and early 1960s. The lithosphere is broken up into what are called Tectonic Plates. In the case of the Earth, there are currently seven to eight major (depending on how they are defined) and many minor plates. The lithospheric plates ride on the ____________________ WORLD TECHNOLOGIES ____________________ asthenosphere. These plates move in relation to one another at one of three types of plate boundaries: convergent, or collisional boundaries; divergent boundaries, also called spreading centers; and conservative transform boundaries. Earthquakes, volcanic activity, mountain-building, and oceanic trench formation occur along these plate boundaries. The lateral relative movement of the plates varies, though it is typically 0–100 mm annually (Read & Watson 1975). The Tectonic Plates are composed of two types of lithosphere: thicker continental and thin oceanic. The upper part is called the crust, again of two types (continental and oceanic). This means that a plate can be of one type, or of both types.
eBook - PDFThe Impact of Geology on the United States
A Reference Guide to Benefits and Hazards
- Angus M. Gunn(Author)
- 2001(Publication Date)
- Greenwood(Publisher)
Fossils of plants and animals from the past provide additional data. Tectonic Plates The huge plates I described as barges glide at differential rates over the plastic mantle beneath. They are relatively solid slabs of rock, and they lie over the curved surface of the planet like a cap on one's head. By the second half of the 1960s this new powerful concept of global plate tectonics was fully documented and universally accepted throughout the scientific community. There are seven large plates, each covering an area many times the size of the United States, and several smaller ones. Each plate moves horizontally relative to others on the softer rock below the lithosphere. Boundaries where plates meet are the places where most seismic activity takes place, and these boundaries can be quite broad, not the narrow spaces suggested by lines on maps. On the Atlantic side of the United States the tectonic plate moves more slowly than, say, the Pacific plate at its contact with Central America in the area known as the East Pacific Rise. The Atlantic activity is opposite to that of the Pacific, so a tug of war ensues as the Atlantic part of the North American plate pushes westward against Canada and the United States, while the Juan de Fuca plate spreads and then subducts in an easterly direction (Figure 2.4). The Atlantic is winning this contest, and North America is moving toward Asia at a rate of four centimeters per year. Sometime in the geological future, it will become a part of that continent. One factor remains constant in all of this plate activity—the surface area of the earth. Hence the new oceanic lithosphere forming at the midocean ridges must be balanced by consumption of plate material elsewhere. We map these great plates on flat paper, but, as I indicated, they are moving on a spherical surface and that means parts of them move at different rates at different latitudes.
No longer available |Learn more- (Author)
- 2014(Publication Date)
- College Publishing House(Publisher)
__________________________ WORLD TECHNOLOGIES ________________________ Chapter- 1 Plate Tectonics The Tectonic Plates of the world were mapped in the second half of the 20th century Plate tectonics (from the Late Latin tectonicus , from the Greek: τεκτονικός pertaining to building) is a scientific theory which describes the large scale motions of Earth's lithosphere. The theory builds on the older concepts of continental drift, developed during the first decades of the 20th century (one of the most famous advocates was Alfred Wegener), and was accepted by the majority of the geoscientific community when the concepts of seafloor spreading were developed in the late 1950s and early 1960s. The lithosphere is broken up into what are called __________________________ WORLD TECHNOLOGIES ________________________ Tectonic Plates. In the case of the Earth, there are currently seven to eight major (depending on how they are defined) and many minor plates. The lithospheric plates ride on the asthenosphere. These plates move in relation to one another at one of three types of plate boundaries: convergent, or collisional boundaries; divergent boundaries, also called spreading centers; and conservative transform boundaries. Earthquakes, volcanic activity, mountain-building, and oceanic trench formation occur along these plate boundaries. The lateral relative movement of the plates varies, though it is typically 0–100 mm annually. The Tectonic Plates are composed of two types of lithosphere: thicker continental and thin oceanic. The upper part is called the crust, again of two types (continental and oceanic). This means that a plate can be of one type, or of both types. One of the main points the theory proposes is that the amount of surface of the (continental and oceanic) plates that disappear in the mantle along the convergent boundaries by subduction is more or less in equilibrium with the new (oceanic) crust that is formed along the divergent margins by seafloor spreading.
No longer available |Learn more- (Author)
- 2014(Publication Date)
- Academic Studio(Publisher)
________________________ WORLD TECHNOLOGIES ________________________ Chapter- 7 Plate Tectonics The Tectonic Plates of the world were mapped in the second half of the 20th century Plate tectonics (from the Late Latin tectonicus , from the Greek: τεκτονικός pertaining to building) is a scientific theory which describes the large scale motions of Earth's lithosphere. The theory builds on the older concepts of continental drift, developed during the first decades of the 20th century (one of the most famous advocates was Alfred Wegener), and was accepted by the majority of the geoscientific community when the concepts of seafloor spreading were developed in the late 1950s and early 1960s. The lithosphere is broken up into what are called Tectonic Plates. In the case of the Earth, there are currently seven to eight major (depending on how they are defined) and many minor plates. The lithospheric plates ride on the asthenosphere. These plates move in ________________________ WORLD TECHNOLOGIES ________________________ relation to one another at one of three types of plate boundaries: convergent, or colli-sional boundaries; divergent boundaries, also called spreading centers; and conservative transform boundaries. Earthquakes, volcanic activity, mountain-building, and oceanic trench formation occur along these plate boundaries. The lateral relative movement of the plates varies, though it is typically 0–100 mm annually. The Tectonic Plates are composed of two types of lithosphere: thicker continental and thin oceanic. The upper part is called the crust, again of two types (continental and oceanic). This means that a plate can be of one type, or of both types. One of the main points the theory proposes is that the amount of surface of the (continental and oceanic) plates that disappear in the mantle along the convergent boundaries by subduction is more or less in equilibrium with the new (oceanic) crust that is formed along the divergent margins by seafloor spreading.
No longer available |Learn more- (Author)
- 2014(Publication Date)
- Learning Press(Publisher)
____________________ WORLD TECHNOLOGIES ____________________ Chapter- 6 Plate Tectonics The Tectonic Plates of the world were mapped in the second half of the 20th century Plate tectonics (from the Late Latin tectonicus , from the Greek: τεκτονικός pertaining to building) is a scientific theory which describes the large scale motions of Earth's lithosphere. The theory builds on the older concepts of continental drift, developed during the first decades of the 20th century (one of the most famous advocates was Alfred Wegener), and was accepted by the majority of the geoscientific community when the concepts of seafloor spreading were developed in the late 1950s and early 1960s. The lithosphere is broken up into what are called ____________________ WORLD TECHNOLOGIES ____________________ Tectonic Plates. In the case of the Earth, there are currently seven to eight major (depending on how they are defined) and many minor plates. The lithospheric plates ride on the asthenosphere. These plates move in relation to one another at one of three types of plate boundaries: convergent, or collisional boundaries; divergent boundaries, also called spreading centers; and conservative transform boundaries. Earthquakes, volcanic activity, mountain-building, and oceanic trench formation occur along these plate boundaries. The lateral relative movement of the plates varies, though it is typically 0–100 mm annually. The Tectonic Plates are composed of two types of lithosphere: thicker continental and thin oceanic. The upper part is called the crust, again of two types (continental and oceanic). This means that a plate can be of one type, or of both types. One of the main points the theory proposes is that the amount of surface of the (continental and oceanic) plates that disappear in the mantle along the convergent boundaries by subduction is more or less in equilibrium with the new (oceanic) crust that is formed along the divergent margins by seafloor spreading.
eBook - PDFThe Sciences
An Integrated Approach
- James Trefil, Robert M. Hazen(Authors)
- 2022(Publication Date)
- Wiley(Publisher)
The central idea of the plate tectonics theory is that Earth’s surface is broken up into about a dozen large pieces (as well as a number of smaller ones) called Tectonic Plates (Figure 17.12). Each plate is a rigid, moving sheet of rock up to 100 kilometers (60 miles) thick, composed of the crust and part of the upper mantle. Oceanic plates have an average 8- to 10-kilometer thickness of dense rock known as basalt on top of the mantle rock. Continental plates have an average 35-kilometer thickness of lower density rock, such as granite, capping the basalt. The tectonic plate boundaries are not the same as those of the continents and oceans. Some plates have continents on all or part of their surface, whereas some are covered only 240 million years ago 120 million years ago Present FIGURE 17.11 Once the motion of continents was determined, scientists could deduce how Earth’s surface might have looked in the past. More than 200 million years ago, the present-day continents were joined together as the ancient “superconti- nent” Pangaea. 470 Chapter 17 Plate Tectonics by oceanic crust. Most of the North American continent, for example, rests on the 8,000-kilometer-wide North American Plate, which extends from the middle of the Atlantic Ocean to the Pacific Plate on the West Coast. About one quarter of Earth’s surface is covered by continent; the rest is ocean. On timescales of millions of years, the plates shift about on the planet’s surface, carrying the continents with them like passengers on a raft. Thus, it’s not the motion of the continents themselves that is fundamental to understanding Earth’s dynamics, but the constant motion of the underlying plates. Continental motion (what Wegener called continental drift) is just one manifestation of that plate motion. The Convecting Mantle Nothing happens without a force.
eBook - PDFThe Blue Planet
An Introduction to Earth System Science
- Brian J. Skinner, Barbara W. Murck(Authors)
- 2011(Publication Date)
- Wiley(Publisher)
PLATE INTERACTIONS AND EARTH’S LANDSCAPES One of the great strengths of the plate tectonic model is that it provides a coherent framework for hundreds of years’ worth of observations about Earth’s surface and the features of our landscape. These features and their connection to the plate tectonic model are most easily visualized by considering the processes that occur at dif- ferent kinds of plate margins—that is, the locations where lithospheric plates interact with one another by mov- ing together, splitting apart, or sliding past one another (FIG. 5.12). We now understand that the dynamic forces of plate tectonics, particularly the processes at work in these areas of active plate interaction, have fundamentally shaped the landscapes of Earth’s surface. Plate Margins Jostled by the underlying mobile asthenosphere, the lithosphere has broken into nine major plates and a large number of smaller plates. Because the lithosphere is rigid, the plates move as individual, coherent units. Interactions between plates occur along their edges, which are called plate boundaries or plate margins (Fig. 5.12). Plate boundaries are the most geologically active places on Earth. This is not too surprising—if you think about a plate the size of the Pacific Ocean rubbing past a plate the size of North America, it should be pretty clear that some epic geologic activity is likely to occur in such a location. Scientists have deciphered most of what we know about plate margins and the interactions that occur along them through the study of earthquakes and volcan- ism. In Chapter 6 we will look in greater detail at these processes and how they are related to the tectonic cycle. In the meantime, here is a summary of the basic types of plate boundaries: 1. Divergent plate margins are fractures in the lithosphere where two plates move apart. They are also called spreading centers, and they can occur in plates capped by either continental crust (FIG. 5.12A) or oceanic crust (FIG. 5.12B).
eBook - PDF- William Lowrie, Andreas Fichtner(Authors)
- 2020(Publication Date)
- Cambridge University Press(Publisher)
2 Plate Tectonics 2.1 HISTORICAL INTRODUCTION The Earth is a dynamic planet, perpetually changing both externally and internally. Its surface is constantly being altered by endogenic processes (i.e., of internal origin) resulting in volcanism and tectonism, as well as by exogenic processes (i.e., of external origin) such as erosion and deposition. These processes have been active throughout geological history. Volcanic explosions like the 1980 erup- tion of Mt. St. Helens in the northwestern United States can transform the surrounding landscape virtually instanta- neously. Earthquakes also cause sudden changes in the landscape, sometimes producing faults with displacements of several meters in seconds. Weather-related erosion of surface features occasionally occurs at dramatic rates, espe- cially if rivers overflow or landslides are triggered. The Earth’s surface is also being changed constantly by less spectacular geological processes at rates that are extremely slow in human terms. Regions that have been depressed by the loads of past ice-sheets are still rebounding vertically at rates of up to several millimeters per year. Tectonic forces cause mountains to rise at similar uplift rates, while the long-term average effects of erosion on a regional scale may occur at rates of centimeters per year or more. Where human activity affects the landscape, erosion rates can be an order of magnitude higher. On a larger scale the con- tinents move relative to each other at speeds of up to several centimeters per year for time intervals lasting millions of years. Extremely long times are represented in geological processes. This is evident in the lengths of the time intervals in a geological timescale (see Fig. 8.2). The Earth’s interior is also in motion. The mantle appears hard and solid to seismic waves, but is believed to exhibit a softer, viscous behavior over long geological time intervals, flowing (or “creeping”) at rates of several centimeters per year.
eBook - PDF- Tom Garrison, Robert Ellis(Authors)
- 2017(Publication Date)
- Cengage Learning EMEA(Publisher)
We now know through the great expanse of geologic time, this slow movement remakes the surface of Earth, expands and splits continents, and forms and destroys ocean basins. The less dense, ancient granitic continents ride high in the lithospheric plates, rafting on the slowly moving asthenosphere below. The more dense, younger basaltic oceanic crust rides lower on the as-thenosphere in the same way that a fully loaded containership floats lower than when it is empty (see Figure 2.4a). The dense and thin crust forms the low-lying ocean basins. This process has progressed since Earth’s crust first cooled and solidified. Figure 2.8 presents an overview of the tectonic system. This modern understanding of the ever-changing nature of Earth has given fresh meaning to historian Will Durant’s warning: “Civilization exists by geological consent, subject to change without notice.” Plates Interact at Plate Boundaries Figure 2.9 is a plot of about 10,000 earthquakes. Notice the odd pattern they form that generally traces out the plate boundaries. The lithospheric plates and their margins are shown in Figure 2.10 . Plates interact with neighboring plates along their mutual boundaries. The three types of plate boundaries that result from these interactions are: Divergent plate boundaries (two plates move apart from each other) recognize that isostasy was responsible for a continent’s ver-tical position and pave the way for a greater appreciation of Wegener’s ideas. In time, additional evidence began to support continental drift. Marine scientists probed the submerged edges of the con-tinents and found that the ocean bottom nearly always sloped gradually out to sea for some distance and then dropped steeply to the deep-ocean floor. They realized that these shelflike con-tinental edges were extensions of the continents themselves.
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