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 makes up the bulk of the Earth's volume. At the center is the core, about 1/3 of the Earth's mass, which is mostly solid iron. The crust and upper mantle form separate tectonic plates that slowly move atop the asthenosphere.

1. Inside the Earth

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

6. The Core
• Made mostly of iron
• 1/3 of the earth’s mass
• Very hot

7. Earth’s Layers
• How are the earth’s
layers similar to an
egg?
• Shell=crust
• Egg white=mantle
• 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. Tectonic Plates
• Earth’s crust is broken into about 19
pieces
• These plates move on top of the
asthenosphere