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What do we know about the interior of the Earth?

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Hello and welcome to CoreFacts, where we're always short on time and big on science. I'm Dane Klima. Today's question is about the Earth's core.

What do we know about the interior of the Earth?

Five billion years ago the Earth was formed by a massive conglomeration of space materials. The heat energy released by this event melted the entire planet, and it is still cooling off today. Denser materials like iron sank into the core of the Earth, while lighter materials such as oxygen compounds and water rose near the surface.

The Earth is divided into four main layers: the inner core, outer core, mantle, and crust. The core is composed mostly of iron and is so hot that the outer core is molten, with about 10% sulfur. The inner core is under such extreme pressure that it remains solid. Most of the Earth's mass is in the mantle, which is composed of iron, magnesium, aluminum, silicon, and oxygen silicate compounds. At over 1000 degrees Celsius, the mantle is solid but can deform slowly in a plastic manner. The crust is much thinner than any of the other layers, and is composed of the least dense calcium and sodium aluminum-silicate minerals. Being relatively cold, the crust is rocky and brittle, so it can fracture in earthquakes.

And now you know. Join us every week for a new CoreFact. If you're looking for more in-depth science coverage, please check out the USGS CoreCast at usgs.gov/corecast. To have your own question potentially featured on the air, send it to corefacts@usgs.gov or leave a voicemail with us at 703-648-5600; however do remember that this may be a long distance charge, so long distance fees may apply.

CoreFacts is a produact of the U.S. Geological Survey, Department of the Interior.

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Title: What do we know about the interior of the Earth?

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Date Recorded: 8/27/2008


Usage: This audio file is public domain/of free use unless otherwise stated. Please refer to the USGS Copyright section for how to credit this audio.

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