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A new Paradigm… Plate Tectonics
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PANGEA In 1912 Alfred Wegener suggested that all continents were once connected about 300 million years ago into a supercontinent called PANGEA.
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Continental Drift Theory
Over time, he said they drifted apart, but he could not provide the mechanism that would explain this.
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The Structure of Earth The Earth is made up different types of layers.
The Lithosphere is divided into large plates. Convection currents in the asthenosphere move the plates.
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Crust: Rigid surface of the Earth. It can be between 0-100 km thick
Layers of the Earth Crust: Rigid surface of the Earth. It can be between km thick Continental Crust: Thicker parts of the crust (above the ocean) mainly granite Oceanic Crust: Thinner parts of the crust under the ocean, made of basalt. Mantle: Between the crust and the core. Largest volume of the earth. Mg, Fe, O, Si are key elements. The crust and mantle are called the lithosphere. (sphere of stone)
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Upper Mantle: Solid part of the mantle
Lower mantle: semi-solid and capable of movement (called the asthenosphere). Core: Outer part is liquid km thick. Inner is solid and mostly nickel and iron. *Believed to control the Earth’s magnetic field.
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Tectonic Plates The lithosphere is broken into 9 large, rigid pieces called plates. The plates are all moving in different directions and at different speeds (from 2 cm to10 cm per year)
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Pangaea
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