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How does continental crust differ from oceanic crust beneath the sea?

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continental shelf The broad, gentle pitch of the continental shelf gives way to the relatively steep continental slope. The more gradual transition to the abyssal plain is a sediment-filled region called the continental rise. The continental shelf, slope, and rise are collectively called the continental margin.

Continental crust and oceanic crust differ significantly in their composition, density, and thickness, which dictates how they behave geologically beneath the sea.

Composition: Continental crust is broadly granitic in nature, whereas oceanic crust is basaltic, meaning it is richer in iron and magnesium.1
Density and Buoyancy: Continental crust has a lower density of approximately 2.7 grams per cubic cm, compared to the 2.9 to 3 grams per cubic cm of oceanic crust. Because it is less dense, continental crust is more buoyant and floats higher in the mantle.1
Thickness: Continental crust is typically much thicker, averaging about 40 km (25 miles), while oceanic crust is significantly thinner, averaging only about 6 km (4 miles).1

These fundamental differences create two distinct levels on Earth's surface. The higher-floating continental crust forms the continents and continental shelves, while the denser, thinner oceanic crust sits at a much greater average depth.1