Earthquake
The land below us is always in motion. Plate tectonics studies these restless effects to give us a better understanding of the Earth and its past. New molten rocks are poured out in the form of magma from the mid-ocean ridges. The rock is recycled and re-entered back into the earth in deep ocean trenches through convection current. The convection current in the mantle drives plates around either against or away from each other. These collisions give rise to earthquakes, volcanoes, mountains, and continental drift. The crashing and spreading of the plates forms the landscape of the Earth as we see it today. The positions of the land masses today is a result of continental drift. During the Earth's existance, the magnetic fields have never been stable. Solidified magma containing magnetic imprints reveal periods of time when the Earth's magnetic fields have actually been reversed.Approximately 4.55 billion years ago, the Earth was just a ball of molten material. Since then, parts of the Earth have cooled forming the solid crust-mantle. This process has been occurring for roughly about 3.8 billion years. The mantle is about 2900 km. thick, which lies above a layer of molten magma that still exists today. The immense heat from the m
If the mantle is always being convected back down into the depths of the Earth, then why doesn't the continents disappear in the deep ocean trenches as well? The crust contains two different crusts: the granite continental crust and the basaltic oceanic crust. When a continent is pushing its way towards another, the oceanic crust sinks into the subduction zone. This accounts for about 81% of all magma that escapes to the surface. Like normal faults, these faults also cause vertical movements where one side is pushed upwards vertically on an inclined plane. Transform plates are caused by fracture zones. About 180 million years ago, Gondwana started to break up into South America-Africa, Australia-Antarctica, and India. This hypothesis corresponded to the periods of mass extinctions; ". Over the past 110 million years, the Earth's magnetic field has reversed about 80 times with North becoming South and vice versa. During the history of the Earth, this 'normal' magnetic field (North pole to true North) has not been constant. The average speed of sea floor spreading is about 2 cm. Because molten magma contains metallic substances such as iron, the cooled rock will possess a magnetic field parallel to the direction of the Earth's field. This kind of 'downward-fault' produces trench-like valleys called grabens similar to the Rhine Valley on the border of France and West Germany. These magnetic reversals are symmetrical to either side of the ridge.
Common topics in this essay:
Argon-40 Calcium-40,
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Silly Putty,
Using Broecker,
Nevada Range,
Germany Reverse,
South Asia,
Brunhes Epoch,
Alfred Wegener,
Alaska Asia,
magnetic field,
ocean floor,
continental drift,
floor spreading,
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ocean trenches,
land masses,
magma flows,
earth's magnetic,
hot magma,
sea floor spreading,
deep ocean trenches,
magnetic field rock,
ocean floor spreading,
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Acceptance Essays
