Informative Essay Jaiden

The Earth and Whats Below

fault-lines-map.jpg
People don't realize that on earth's crust even when they are standing completely still they are still moving. plates constantly move and bump into each other, and we are on the plates so we are moving moving. Not only that but the plates move because the earth rotates at 1100 miles per hour, still moving (Alexander). On top of that the earth rockets around the sun at something like 67,000mph, moving fast on the surface of the earth (Read). Depending on how they are defined, there are usually seven or eight "major" plates: African, Antarctic, Eurasian, North American, South American, Pacific, and Indo-Australian. The latter is sometimes subdivided into the Indian and Australian plates. The plates have always been moving and changing the shape of the earth. The current motion of the tectonic plates is today determined by remote sensing satellite data sets, calibrated with ground station measurements and that tells us they move about 100mm annually (Barry). At the margins of the plates, where they collide or move apart or slide past one another, major landforms such as mountains, rift valleys, volcanoes, ocean trenches, and mid-ocean ridges are created.

Sea-floor spreading
New plate material is generated along the mid-ocean ridges, where basaltic lava is poured out by submarine volcanoes. This happens along the Pacific coast of South America. The trenches are sites where two plates of lithosphere meet; the one bearing ocean-floor basalts plunges beneath the adjacent continental mass at an angle of 45° (pg16), giving rise to shallow earthquakes near the coast and progressively deeper earthquakes inland.

Causes of plate movement
The causes of plate movement are all very hypothetical. It has been known for some time that heat flow from the interior of the Earth is high over the mid-ocean ridges, and so various models of thermal convection in the mantle have been proposed; the geometry of the flow in any convective system must be complex, as there is no symmetry to the arrangement of ridges and trench systems over the Earth's surface.
The concept of continental drift was set out in 1915 in a book entitled The Origin of Continents and Oceans by the German meteorologist Alfred Wegener, who recognized that continental plates rupture, drift apart, and eventually collide with one another.

Types of tectonic plates
There are two types of tectonic plates: continental crust and oceanic crust. Continental crust is deep, about 30 km(pg19), whereas oceanic crust is much shallower, only about 5 km thick. But is much denser.
Over 200 million years ago, there was only one continent, called Pangaea. That's why on a world map the continents have the mirrored coast effect line and look as if they could fit like a puzzle. (pg 13)

Plate margins
First we have destructive plate margins These occur when an oceanic plate and a continental plate converge (move together). They are destructive because some of the Earth's crust is lost, as one plate is forced under the other. constructive plate margins At a constructive plate margin, two plates move away from one another. As the plates move away, molten rock from the mantle rises up. The molten rock cools to form rift valleys or ocean ridges. conservative, or transform, plate margins These are also known as passive margins. Two plates slide past each other, either in different directions or in the same direction but at different rates. This type of margin is the main cause of earthquakes. As the plates move past each other, they may get stuck. This causes pressure to build up, until they slip past each other. This jolting is an earthquake. The San Andreas Fault in California, USA, is a conservative plate margin. In short The Earth is made up of a series of tectonic plates that move slowly. There are two types of plates: continental (deeper) and oceanic (denser) Where two plates meet is called a plate margin. Volcanoes and earthquakes can occur along plate margins. There are three types of plate margin: constructive, destructive, and conservative. and the theory of plate tectonics helps explain continental drift.

crust
The Rocky outer layer of the Earth, consisting of two distinct parts – the oceanic crust and the continental crust. The oceanic crust is on average about 10 km/6 mi thick and consists mostly of basaltic rock overlain by muddy sediments the continental crust is largely of granitic composition and has a more complex structure. (Pg 24) Because it is continually recycled back into the mantle by the process of subduction, the oceanic crust is in no place older than about 200 million years. (Pg27)

To wrap it all up The Earth is made up of a series of tectonic plates that move slowly.
There are two types of plates: continental (deeper) and oceanic (denser)
Where two plates meet is called a plate margin.
Volcanoes and earthquakes can occur along plate margins. There are three types of plate margin: constructive, destructive, and conservative.
and the theory of plate tectonics helps explain continental drift

Pangaea II is a possible future super-continent configuration. Consistent with the super-continent cycle, Pangaea Ultima could occur within the next 249 million years. This potential configuration, hypothesized by Christopher Scotese, earned its name from its similarity to the previous Pangaea super-continent. i don't exactly know if this is scientifically sound

work cited

David E. Alexander. "Earthquakes." Sage knowledge 10/7/2006. web
Read, HH. "plates and boundaries." Ed. Arie Poldervaart. New York: geological society of America, 1963. 409-429. Print.
Barry Rodger. "convergent and divergent faults." Nat.Geo. 5/23/2012. web

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