Plate Tectonics Theories Analysis Essay

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Plate Tectonics Theories Analysis

Since the beginning of human kind there has been a cloud of wonder regarding

the natural processes and patterns of our planet. Scientist interested in this field through

out the years, have developed many different theories to how our planet geological

features have come about. The most widely accepted theory in this field is that of plate

tectonics. For those who do not know much about the theory of plate tectonics; it states

that there are twenty plates that cover most of the Earth's surface area. These giant slabs

of rock are what is known as our lithosphere. These plates are said to slide on top of the

asthenosphere (an inner
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These plates move relative to one another above a

hotter, deeper, more stationary 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 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. Important evidence that supports the

theory of plate tectonics comes from the studies of the magnetic properties and the ages

of igneous rocks on the ocean floor. Some igneous rocks contain minerals that are

magnetic. These minerals provide a record of the direction of the Earth's magnetic field

at the time when the molten lava that formed the rock, cooled. A discovery that

geologists made was that some of the rocks also recorded reversals in the direction of the

magnetic field. Geologists also record the ages of igneous rocks on each side of what

what is known a mid-ocean ridge. Earth's mid-ocean ridges stretch around the planet.

Tectonically and volcanically active, they are the places where new crust forms.
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