Earth Sciences: Earth's Internal Layers

Earth Sciences: Earth's Internal Layers

Earth is made up of several different layers, each with unique properties. In this video lesson, you will identify each layer of Earth and how it relates to Earth as a whole.

Earth's Core

Earth can be divided into three main layers: the core, the mantle and the crust. Each of these layers can be further divided into two parts: the inner and outer core, the upper and lower mantle and the continental and oceanic crust.

Earth's Core

Both the inner and outer core are made up of mostly iron and a little bit of nickel. The inner core is solid, while the outer core is liquid. This liquid flowing deep down below us is what produces Earth's electromagnetic current. And, it's pretty hot in the core - about as hot as the surface of the sun!

Earth's Mantle

The mantle is the thickest layer of Earth, making up about 85% of Earth's volume. The lower mantle is pretty solid stuff, while the upper mantle moves around like silly putty. This movement of rock without breaking is called plasticity, and the liquid part of the mantle is referred to as the asthenosphere.

Lithosphere

On top of the asthenosphere is the lithosphere, which also contains the entire crust. The slow-moving convection currents in the asthenosphere move the tectonic plates of the lithosphere around like ice on a pond, causing earthquakes and volcanoes on the surface. Though the continental crust is much thicker than the oceanic crust, it's made of material that is far less dense. This means that the continental crust 'floats' higher on the liquid mantle below than does the heavier oceanic crust that sinks down like a loaded cargo ship.

Multiple Choice

How does the mantle differ from the crust?

• The mantle is the thickest layer of Earth, while the crust is the thinnest.

• The mantle flows with convection currents, while the crust consists primarily of silicate rocks.

• The mantle is the least stable layer of Earth, while the crust is the most seismically active.

• The mantle consists mostly of lava, while the crust consists mostly of iron.

Multiple Choice

Which parts of the Earth are contained in the lithosphere?

• The upper mantle and the crust.

• The lower mantle and the crust.

• Both the inner and outer core.

• The outer core and lower mantle.

Multiple Choice

What is the cause of earthquakes, volcanoes, and mountains on Earth?

• Movements in the outer core.

• Convection currents in the mantle.

• Convection currents in the crust.

• Sinking of the oceanic crust.

Multiple Choice

Why is the inner core solid?

• Because it is under too much pressure to melt.

• Because it consists mostly of silicon.

• Because it is very hot.

• Because of plasticity.

Multiple Choice

How does the inner core differ from the outer core?

• The inner core is solid, while the outer core is liquid.

• The inner core is made of iron, while the outer core is made of lithium.

• The inner core is characterized by plasticity, while the outer core's key trait is thermal activity.

• The inner core is very cold, while the outer core is very hot.