Continental Drift, Plate Tectonics, the North American Plate
- Pages: 4
- Word count: 760
- Category: Earth
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The experts and scientists have theories on how the the world’s plates move and how earthquakes occur. These theories on how the world’s plate move is called continental drift and the theory on how earthquakes occur is called plate tectonics. They also have a lot of information on the North American Plate and in which direction it is moving and information like that. Now let me tell you more about each of these topics.
Continental drift is when the Earth’s plates move in different directions. Scientists think that Continental Drift is caused by the heating and cooling of the Earth’s mantel which makes currents. These currents make the plates slide and move over the liquid and molten rock in the mantel. These currents made by the heating and cooling are called convection currents. The person who developed the theory of continental drift was named Abraham Ortelius in 1956.
He thought of this theory by noticing that the land of South America seemed to fit Africa like a jigsaw puzzle. He then thought up that the land must’ve been torn apart by earthquakes and floods. Later on Alfred Wegener made a fully developed hypothesis on how the continents came to be where they are today. This was that the Earth’s crust was once a supercontinent known as Pangeae. But the continents broke off not by earthquakes and flooding as Abraham Ortelius stated, but by volcanic activity due to thermal expansion. Then the new continents drifted by further expansion of the rip-zones. But then a theory without any expansion involved was developed by Frank Bursley Taylor. He proposed that the continents were dragged towards the equator by a lunar gravitational pull. But both of these theories were wrong, as I mentioned before, the continents move by convection currents in the mantel. This idea was founded by geologist Arthur Holmes. This is what continental drift is.
Plate tectonics are plates that make up all of the Earth’s crust, sort of like a giant jigsaw puzzle. When the plate tectonics shift earthquakes are usually the result. But when two big plates crash into each other larger earthquakes occur because the plates actually crash into each other, but when plates shift, like they’re supposed to, just mild earthquakes happen. Also, when plates crash into each other an event called subduction happens and what that means is one plate slides under the other and the end of the plate sticks up. When the plate comes down, where it is arched, it cracks and volcanoes are formed. These plates are located in the Lithosphere and the lithospheric plates ride on the Asthenosphere.The plates move in relation with one another and there are three types of boundaries. They are called collisional boundaries, divergent boundaries, and conservative transform boundaries. The tectonic plates are composed of two types of lithosphere. Continental and Oceanic. Then there is the upper part called the crust which also consists of two types, Continental and Oceanic. There are also major plates and minor plates. That is all about the tectonic plates.
The North American Plate. It is one of the major plates extending over most of North America, Greenland, Cuba, Bahamas, parts of Siberia, Japan, and Iceland. The plate includes both Continental and Oceanic crust. The inside or interior of the main landmass includes a granitic core called a craton. The eastern side of the plate is a divergent plate with the Eurasian plate to the north and the African plate to the south. The southerly boundary with the Cocos plate to the west and the Carribean plate to the east is a transform booundary. Hotspots are also thought to exist below the North American Plate. The most notable hotspots are the Yellowstone in Wyoming, Raton in New Mexico and Anahim hotspots in British Colombia. A hotspot is a volcanic region thought to be fed by underlying mantle that is anonymously hotter than the mantle elsewhere. The North American Plate moves in a roughly southwest direction away from the Mid-Atlantic Ridge. The motion of the plate cannot be driven by subduction as no part of the plate is subducted. Only one part is subducted which is comprising the part of the Puerto Rico Trench. But this section is very small.
The information about these topics is very interesting. Learning about tectonic plates, continental drift, and the North American Plate teaches you a lot abnout how the Earth was formed today. From Pangeae to where we are today, it was exciting learning about Earth and how it was formed.