Layers of the Earth

Inside the Earth

Earth’s Inner Core

At earth’s center is the inner core.

The inner core is composed of nickel and iron in solid form.

The depth from the surface is 6371 km

Earth’s Outer Core

Surrounding the inner core is an outer core.

The outer core is composed of nickel and iron in a liquid state.

The depth from the surface is 5150 km

Earth’s Mantle Around the core is the

thickest of Earth’s layers, called the mantle.

The mantle is composed mostly of compounds rich in iron, silicon, and magnesium.

Although the mantle is solid, high pressure and temperature cause it to behave as a liquid in some ways.

The depth from the surface is 2890 km

Earth’s Crust

Surrounding the mantle is the crust, a thin, rigid layer of lighter rocks that cover earth’s surface.

The depth from the surface is 0-65 km

Types of Crust

The crust covers earth’s entire surface; there is oceanic crust and continental crust.

Continental Crust

Continental crust: composed of granite at thicknesses of 35 km (60 km over mountain ranges)

Oceanic Crust

Oceanic crust: composed of basalt at thicknesses of about 5 km

Fact:

Suppose you could drive a car at 100 km/hr (62 mi/hr) from Earth’s surface to the center of the core. At that speed, the car would take about half an hour to drive through most continental crust, about another 29 hours to drive through the mantle, and about an additional 35 hours to drive to the center of the core.

Lithosphere

Earth’s near surface layers are further classified by their material properties.

Lithosphere: The crust and the upper most portion of the mantle together.

Asthenosphere

The thin, slush like layer of the mantle to which the lithosphere floats upon.

YouTube - The Solid Earth - Environmental Science

How do we know what Earth’s interior looks like?

Drilling

Wells drilled into Earth are mostly in the upper 7 km of the crust.

Deepest well is in Russia- took 20 years to drill a 12 km hole, cost more then $100 million.

Drilling stopped in 1989 after getting stuck at 12 km.

Volcanic Activity

Materials from earth’s interior are brought to the surface during volcanic activity.

Only useful to depths of about 200 km below the surface.

Study of Seismic Waves

Seismic earthquake waves travel time depends on properties of rock material that they pass through.

Certain waves cannot travel through liquid states.

Seismic waves allow travel faster in denser rock material.

Earthquakes for Kids