The Earth is composed of three main layers - the crust, mantle, and core. The crust is the outermost layer and is made up of either dense oceanic crust or less dense continental crust. Below the crust lies the mantle, which is the thick middle layer of the planet. The core is at the center and is divided into a liquid outer core and solid inner core, both made primarily of iron.

1. Inside the Earth
Looking at the Earth’s layers

2. Composition (What it is made of)
• Crust
• Mantle
• Core

3. The Crust
• Outer layer
• 5-100 km thick
• 2 types of crust
– Oceanic (very dense,
made of basalt)
– Continental (less
dense, made of
granite)

4. Oceanic and Continental Crust

5. The Mantle
• Middle layer
• Very thick layer
( 2900 km)
• Rock on the top
• Part of the lithosphere

6. The Core
• Made mostly of iron
• Very hot ( 7000 °C)
• Outer core is liquid
Thickness is about
2221km
• Inner core is solid.
Thickness is about
1255 km radius

7. Earth’s Layers
• How are the earth’s
layers similar to an
egg?
• Egg white=mantle
• Shell=crust
• Yolk=core

8. Physical Structure of the Earth
(5 Layers)
• Lithosphere- rigid outer layer (crust)
• Asthenosphere- solid rock that flows
slowly (like hot asphalt)
• Mesosphere- middle layer
• Outer Core- liquid layer
• Inner Core- solid, very dense

9. Earth’s Spheres

10. The names of the four spheres are derived from the
Greek words for stone (litho), air (atmo), water (hydro),
and life (bio). Atmosphere
The atmosphere is the body
Lithosphere of air which surrounds our
The lithosphere is planet.
the solid, rocky crust The air of our planet is 79%
covering entire nitrogen and just under 21%
planet. oxygen; the small amount
remaining is composed of
carbon dioxide and other
gasses.

11. Tectonic Plates
• Earth’s crust is broken into about 19 pieces
These plates move on top of the
asthenosphere