Plate Tectonics and Earth's Crust

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Continental Crust

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The thick, older part of Earth's crust that forms the continents, composed mostly of granite and other light-colored rocks, and is typically much older than oceanic crust.

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Oceanic Crust

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The thinner, younger part of Earth's crust that forms the ocean floors, composed mainly of basalt and created at mid-ocean ridges through plate tectonics.

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Plate Tectonics

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The scientific theory explaining the movement of Earth's lithospheric plates on the semi-fluid asthenosphere, driving the formation and recycling of crustal rocks.

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Crustal Rocks

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Rocks that make up Earth's crust, both continental and oceanic, whose ages provide evidence for the movements of tectonic plates and the processes of plate tectonics.

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Mid-Ocean Ridges

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Underwater mountain ranges where new oceanic crust is formed as tectonic plates spread apart, resulting in younger rocks near the ridge and older rocks farther away.

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Plate Spreading

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The process by which tectonic plates move apart at mid-ocean ridges, leading to the creation of new oceanic crust and the gradual movement of existing crust away from the ridge.

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Ages of Oceanic Crust

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The increasing age of oceanic crust as it moves away from mid-ocean ridges, serving as evidence for the process of seafloor spreading and plate tectonics.

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North American Continental Crust

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The crust forming the North American continent, characterized by an ancient central core surrounded by younger crust, reflecting a history of complex plate interactions.

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Plate Interaction

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The various ways tectonic plates interact, including spreading, subduction, collision, and sliding past each other, which shape the Earth's crust and influence the ages of rocks.

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Evidence of Plate Movements

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Geological data, such as the age distribution of crustal rocks, patterns of earthquakes, and volcanic activity, that support the theory of plate tectonics and explain the movement of continental and oceanic crust.