Geological Concepts

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Pangaea

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A supercontinent that existed during the late Paleozoic and early Mesozoic eras, forming approximately 335 million years ago and beginning to break apart about 175 million years ago.

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Continental Drift

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The gradual movement of the continents across the earth's surface through geological time.

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Mid-ocean ridges

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Underwater mountain ranges formed by plate tectonics. They occur at divergent boundaries where new oceanic crust is formed.

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Seafloor spreading

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The process by which new oceanic crust is formed at mid-ocean ridges and slowly moves away from the ridge.

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Normal polarity

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A state in which the magnetic north points towards the geographic north pole, similar to today's magnetic field.

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Magnetic Reversal

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A change in the Earth's magnetic field resulting in the magnetic north being aligned with the geographic south, and vice versa.

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Tectonic Plate

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A massive, irregularly shaped slab of solid rock, generally composed of both continental and oceanic lithosphere.

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Subduction Zone

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A region of the Earth's crust where tectonic plates meet and one plate is forced under another into the mantle.

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Convergent Boundary

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A tectonic boundary where two plates are moving toward each other, often causing one plate to slide beneath the other.

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Divergent Boundary

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A tectonic boundary where two plates are moving away from each other and new crust is forming from magma that rises to the Earth's surface.