Earth’s Internal CompositionIntegrated Science

There are two classification system

• The Earth’s interior has two different classification systems– System 1

• Crust• Mantle (Outer and Inner Mantle)• Core

– System 2• Lithosphere• Asthenosphere• Lower Mantle• Outer Core• Inner Core

System 1 – Based on elements that make it up.

• 3 Layers…like an egg– The crust is like an egg’s shell.– The mantle is like the egg white.– The core is like the egg’s yolk.

The Crust

• The crust is dirt and rock.– Made mostly of silicon and oxygen.

• It has two parts.– Continental Crust (Land)– Oceanic Crust (Ocean)

• The oceanic crust is much thinner than the continental crust.– Oceanic = 7 km – Continental = 40 km

The Crust

• Mountains in the continental crust have “roots”

• As the mountains wear away, they weigh less and the “roots” are pushed upwards.– This is a vertical movement. (upwards)• Vertical movement of the crust is called isostasy.

The Mantle

• It is made of a thick liquid, hot rock.– Mostly magnesium, oxygen, and silicon

• It is the majority of Earth’s interior.• It is more dense than the crust.• It has two parts– The upper mantle– The lower mantle

The Core

• The core is liquid metal.– Mostly iron

• The core is the most dense of the three layers.

System 2 – Based on Physical Properties (states of matter)

• Lithosphere– Crust and upper mantle

• Asthenosphere– Middle part of the mantle

• Lower Mantle– The lowest part of the mantle

• Outer Core– Core

• Inner Core– Core

The Lithosphere

• Cool, hard rock.• Broken into tectonic plates.• On average, 100 km thick (crust = 40 km).

The Asthenosphere

• It is soft rock but still flows like a liquid. – Like Silly Putty– Called “plastic”

• Its ability to move is important.– The Lithosphere’s tectonic plates float on the

Asthenosphere.– Responsible for movement of continents.

The Lower Mantle

• Made of solid rock.

The Outer Core

• Hot, Liquid Metal• As the Earth rotates the outer core moves and

flows– This movement produces Earth’s magnetic field

The Inner Core

• Made of hot, solid metal– Under intense pressure