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How is oceanic crust different from continental crust?
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oceanic crust
A cross section of Earth's outer layers, from the crust through the lower mantle.
Oceanic crust and continental crust are the two primary types of Earth's lithosphere, and they differ significantly in their physical and chemical properties.12
- Thickness: Oceanic crust is much thinner, averaging about 6 km (4 miles) in thickness, whereas continental crust is typically much thicker, averaging about 40 km (25 miles).12
- Density and Buoyancy: Oceanic crust is denser (about 2.9 to 3 grams per cubic cm) compared to the lighter continental crust (about 2.7 grams per cubic cm). Because of its lower density, continental crust has greater buoyancy, allowing it to float higher in the mantle and form landmasses, while the denser oceanic crust sits at much lower average depths.2
- Composition: Oceanic crust is primarily basaltic, making it richer in iron and magnesium. In contrast, continental crust is broadly granitic in composition.12
- Age and Formation: Oceanic crust is generally younger and is formed at spreading centers. Continental crust is formed primarily through processes at subduction zones, such as volcanic activity and accretion.12