Unit 4.3 Notes- Layers of the Earth

Unit 4c:

Earth’s
Interior

8TH GRADE

01

STRUCTURE

LOOK INSIDE OUR PLANET

1

2

4

3

​CRUST

​MANTLE

​OUTER CORE

​INNER CORE

The Crust

A layer of solid rock that includes both dry land and

the ocean floor

Characteristics of the Crust:

●8- 40 km thick, it is the thinnest layer

●We live on the surface of the crust

●It is the thickest underneath mountains and thinnest beneath the ocean floor

Oceanic Crust- crust beneath the ocean is made of basalt (a dark, fine grained rock).

Continental Crust- crust that forms continents, composition varies greatly. Overall
made of granite (a light color, coarse material)

Draw

Label the Correct Layers of the Earth

Multiple Choice

Which is thinner?

• Continental Crust

• Oceanic Crust

The Mantle

A layer made of rock that is very hot, but solid.

Characteristics of the Mantle:

●It is the densest layer and is about 3000 km.

●It is divided into different layers. (Lithosphere, Asthenosphere, Mesosphere

-the uppermost part of the mantle combined with the crust in one
single layer
- made of brittle rock

​ASTHENOSPHERE

​LITHOSPHERE

​layer of the Earth that lies below the lithosphere. It is a layer of solid rock where the extreme pressure and heat cause the rocks to flow like a liquid. The rocks in the asthenosphere are not as dense as the rocks in the lithosphere. This allows the tectonic plates in the lithosphere to move around on the Earth's surface.

• WHERE THE TECTONIC PLATES ARE LOCATED

Multiple Choice

Where are the tectonic plates located?

• The Outer Core

• The Lithosphere

• The Asthenosphere

• The Inner Core

The Outer Core and Inner Core

O: A layer of molten metal surrounding the inner core

I: A dense ball of solid metal

Characteristics of the Outer Core:

●2,258 km

●The only liquid layer

Characteristics of the Inner Core:

●1,222 km

●The hottest layer

​Movement of liquid inside the Outer core around the inner core is what is responsible for creating Earth's magnetic field.

Characteristics for all Layers

The deeper you go down the layers:

●

The Hotter the Temperatures

●

The Greater the Pressure

Reorder

Reorder the following from the hottest layer to the least hottest.

• Inner Core

• Outer Core

• Mantle

• Crust

1

2

3

4

• 1
• 2
• 3
• 4

Reorder

Reorder the following layers from least amount of pressure to most amount of pressure.

• Crust

• Mantle

• Inner Core

• Outer Core

1

2

3

4

• 1
• 2
• 3
• 4

Evidence of
Earth’s Interior

How do we know what’s inside the earth if no one
has ever seen it?

●Direct Evidence: Rock Samples

○Holes drilled 12.3 kilometers into the Earth have brought up
rock samples that gives clues about the structure and
conditions of Earth’s interior

○Volcanic activity brings up rock from over 100 km-
Volcanoes are a good window for activity inside the Earth

●Indirect Evidence: Seismic Waves from Earthquakes

○Seismic waves occur after an earthquake. The movement
of these waves act differently at different depths of the
Earth, providing evidence for the different layers of Earth.

Open Ended

Why are volcanoes a direct piece of evidence of what is inside Earth's interior?