Earth’s Interior Notes

The Four Layers

• Crust

• Mantle

• Outer Core

• Inner Core

• Based on

different

densities

Layer Composition Thickness State of matter

Crust Continental – Granite

Oceanic – Basalt

(lowest density)

Continental- 25 miles

Oceanic – 3-5 miles

(Thinnest Layer)

Solid rocks

Mantle Magma (liquid metals

with chunks of rocks)

Largest Layer

1,800 miles

solid rocks &

Liquid

Outer Core Nickel & Iron 1,400 miles Liquid

Inner Core Mostly Iron

(highest density)

760 miles Solid

The Crust

The Earth's Crust is

like the skin of an

apple.

Continental crusts are

thicker than oceanic

crusts

The Mantle

The Mantle is the largest

layer of the Earth.

The movement of the middle mantle (asthenosphere) is the reason that the crustal plates of the Earth move.

The Outer Core

The core of the Earth

is like a ball of very

hot metals. The

outer core is so

hot that the metals in

it are all in the liquid

state.

The Inner Core

The inner core of

the Earth has

temperatures and

pressures so great

that the metals are

squeezed together

and are not able to

move, so its solid.

Composed of iron

and nickel.

The Lithosphere

• Crust and upper mantle

• Rigid, brittle rock

• Moves together in plate tectonics

The Asthenosphere

• layer of middle mantle where

convection happens.

•Semi-rigid.

•Lithosphere Plates move due the

convection in the Asthenoshpere.

The Lithospheric Plates

The crust of the Earth is broken into many pieces called

plates. The plates "float" on the asthenosphere.

•Source of Earth’s interior heat started with the kinetic

energy of the collisions of metal, rock and ice fragments

converted into heat energy as the fragments impacted

with the growing Earth.

•As the Earth become compact, the gravitational energy

was converted into heat.

•The third source of heat is the decay of radioactive

elements that change to more stable forms, releasing heat

in the process. Radioactivity is one of the main sources of

heat inside the Earth.

Convection Currents

The middle mantle "flows"

because of convection

currents. Convection

currents are caused by the

very hot material at the

deepest part of the mantle

rising, then cooling and

sinking again --repeating

this cycle over and over.

Convection• Occurs because of difference of

temperatures of the materials.

• Occurs because heated material becomes

Less dense and rises

• While materials cooling down become more

dense and sink.

**** Will

See this again in

Oceans and

Atmosphere

Moho Boundary

• Separates the crust from the upper mantle.

Moho, or Mohorovičić

discontinuity, boundary

between the Earth’s crust

and its mantle. The Moho

lies at a depth of about 22

mi (35 km) below

continents and about 4.5 mi

(7 km) beneath the oceanic

crust. Modern instruments

have determined that the

velocity of seismic waves

increases rapidly at this

boundary. The Moho was

named for Andrija

Mohorovičić.

Seismic Waves• waves of energy that travel through

the Earth, and are a result of an

earthquake, explosion, or a volcano.

• We know about the layers of the

Earth because of theses waves.

2 types of waves:

1. P-wave - primary

wave, can travel

through liquids

and solids

2. S-wave - secondary

wave, Can only travel

through liquids

Main regions of Earth’s

interior:

1. Inner Core

2. Outer Core

3. Mantle

4. Crust

5. Magnetosphere

MAGNETOSPHERE

Region around Earth that

is influenced by Earth’s

magnetic field

- Rapid Rotation

- Metal (electrical conductor)

• magnetic field generation requires:

- Liquid Core

Will a compass lead you directly

to the geographic North Pole???

Magnetic Variation

A compass does not point directly to

the north pole but to the magnetic

north pole. This difference is called

magnetic variation.

Van Allen Belts

Two regions surrounding Earth

that capture high-energy

charged particles

**Particles originate in solar wind and

flares

a) outer belt - contains mostly

lighter electrons

b) inner belt contains

heavier protons

Charged particles then

collide with air molecules,

get excited, then…

Produce spectacular light show

called Auroras “Northern

Lights”

“Northern Lights”

more pics