The Earth's Crust Essay

453 WordsSep 22, 20092 Pages
The Core of the Matter The earth has three main levels: Crust, Mantle, Core Beneath the mantle is the Earth’s core. The Earth’s core consists of a fluid outer core and a solids inner core. Because the out core contains iron when it flows, it generates a magnetic field. This is the source of the Earth’s magnetic field. Plate tectonics is a relatively new theory that has revolutionized the way geologists think about the Earth. According to the theory, the surface of the Earth is broken into large plates. The size and position of these plates, where they move against each other are sites of intense geologic activity such as earthquakes, volcanoes, and mountain building. Plate tectonics is a combination of two earlier ideas continental drift and sea-floor spreading. Continental Drift – is the movement of continents over the Earth’s surface and in their change in position relative to each other. Sea-Floor Spreading – is the creation of new oceanic crust at mid-ocean ridges and movement of the crust away from the mid ocean ridge. Physical Properties of the Earth The outer most layers of the Earth can be divided by their physical properties into lithosphere and asthenosphere. Continental Drift In 1912 a German meteorologist used the fit of the continents, the distributions of fossils the similar sequence of rocks at numerous locations ancient climates and the apparent wondering of the Earth’s polar regions to support his ideas. Wegener used his observations to hypothesize that all of the present day continents were once part of a single supercontinent called Pangaea. Sea Floor Spreading In 1962 Harry Hess proposed that new ocean floor is formed at the rift of mid ocean ridges. The ocean floor and the rock beneath it are produced by magma that rises from deeper levels. Hess suggested that the

More about The Earth's Crust Essay

Open Document