Internal Forces - Layers of the Earth

Objectives

• Identify the layers of the earth

• Write 5 sentences to describe each layer

• Draw a diagram showing the structure of the Earth

Key terms:

Continental drift                    Deep sea Trench 

Pangea             Plate Tectonics

Plates                                  Tectonics

Divergent Plates                  Convergent Plates

Transform Plates                  Hot Spot

Sea Floor Spreading            Pillow Lava

Rift Valleys                            Subduction Zone

Collision Zones

Island Arc

Oceanic Crust

Continental Crust

Sima

Sial

Fold Mountains

Fault

The Earth is made up of three main layers. These are the core, mantle and crust.

The core

The core is the innermost layer of the earth.

It consists of the inner core and the outer core.

The core is very dense and extremely hot.

The inner core is solid and the outer core is liquid.

Temperatures at the core can rise to about 5500 degrees Celsius.

The center of the Earth is 6400km below the surface.

The mantle

The mantle is between the crust and the core

The mantle extends to a depth of 2900km

This can be divided into the upper mantle and the lower mantle.

The uppermost part of the mantle forms a part of the lithosphere

The mantle makes up 82% of the volume of the Earth.

The Crust

There are two types of crust

These are continental and oceanic crust

Geography students are frequently asked to differentiate between Oceanic and Continental crust. Table 1 below shows a comparison of the main characteristics.

 

Characteristic	Continental Crust	Oceanic Crust
Make up	Silica (Si) and Aluminum (Al)  SIAL	Silica (Si) and Magnesium (Ma) SIMA
Location	Only areas with continents or land	Continuous around the earth's crust
Thickness	Up to 70 km	6-10 km