The Earth's crust

  • Exhibition Text

    • The Earth’s crust is its lightest, most buoyant rock layer. Continental crust covers 41percent of the Earth’s surface, though a quarter of that area is under the oceans. The continental crust is 20 to 80 kilometers thick. Its rocks hold four billion years of Earth history. The remainder of the Earth is covered by oceanic crust. This type of crust is young — none older than 170 million years — and is only about 8 kilometers thick.

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  • For Educators

    • Topic: Earth Science

      Subtopic: Earth Structure

      Keywords: Continental crust, Geology, Earth (Planet)--History, Earth (Planet)--Crust

      Audience: General

In This Section

The oldest rocks and minerals on Earth

The oldest rocks and minerals on Earth

Much of the evidence from the oldest period of the Earth’s history, the Hadean era (3.8 to 4.5 billion years ago), has been destroyed by erosion, burial, and modifications of the rocks as they were heated and compressed at depth.