The Earth's crust is primarily divided into two distinct types: oceanic crust and continental crust.
These two parts differ significantly in their composition, density, and thickness. Let's explore each in more detail:
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Oceanic Crust: This type of crust underlies the ocean basins.
- It is relatively thin, typically ranging from 5 to 10 kilometers (3 to 6 miles) in thickness.
- It is primarily composed of basalt, a dark-colored volcanic rock that is relatively dense.
- Oceanic crust is constantly being formed at mid-ocean ridges and destroyed at subduction zones, making it geologically younger than continental crust.
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Continental Crust: This type of crust forms the landmasses and continental shelves.
- It is considerably thicker than oceanic crust, ranging from 30 to 70 kilometers (19 to 43 miles) in thickness.
- It is composed of a variety of rocks, with granite being a major component. Granite is less dense than basalt.
- Continental crust is much older than oceanic crust, with some parts dating back billions of years. It is more complex in its structure and history.
In summary, the oceanic crust is thin, dense, and composed mainly of basalt, while the continental crust is thick, less dense, and composed of a wider variety of rocks, including granite. Their differences are fundamental to understanding plate tectonics and the evolution of our planet.
