Oceanic Crust

The oceanic crust is the outermost layer of Earth's lithosphere that is found under the oceans. It is primarily composed of basalt and gabbro rocks, and is thinner and denser than the continental crust.

Composition

The oceanic crust is made up of approximately 50% silica and magnesium, making it denser than the continental crust. It also contains minerals such as olivine, pyroxene, and plagioclase feldspar.

Formation

Oceanic crust is formed at mid-ocean ridges through the process of seafloor spreading. Magma rises from the mantle and solidifies to form new oceanic crust as tectonic plates move apart.

Age and Thickness

Oceanic crust is relatively young compared to continental crust, with the oldest oceanic crust being around 200 million years old. It is also thinner, typically ranging from 5 to 10 kilometers in thickness.

Study Guide

Here are some key points to remember about oceanic crust:

• Composition: Primarily composed of basalt and gabbro rocks, and contains silica and magnesium.
• Formation: Created at mid-ocean ridges through seafloor spreading.
• Age and Thickness: Younger and thinner than continental crust.

Be sure to understand the differences between oceanic and continental crust, and how oceanic crust is related to plate tectonics and the formation of ocean basins.

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