The structure and age of the earth
Structure of the Earth.
The Earth is made of 3 main layers:
1. Crust.
The outer layer.
Thin and solid.
Where we live.
Made of rocks and soil.
2. Mantle.
The middle layer.
Very thick.
Made of hot, magma.
3. Core.
The inner layer.
Very hot and heavy.
Made mostly of iron and nickel.
Age of the Earth
The Earth is about 4.6 billion years old.
Scientists found this by studying rocks and meteorites.
How Do We Know What’s Inside the Earth?
1. Earthquake or Waves.
When earthquakes happen, waves travel through the Earth.
These waves move faster or slower in different materials.
Some waves cannot pass through liquids.
From this, scientists know the outer core is liquid the inner core is solid.
What Is Continental Drift?
Continental drift is the idea that continents were once joined together and slowly moved apart over millions of years.
What Are Tectonic Plates?
Tectonic plates are huge pieces of Earth’s crust that float on the hot mantle and move very slowly.
Key Points.
The Earth is about 4.6 billion years old.
Age is found by studying rocks and meteorites.
Oldest rocks give clues about Earth’s early history.
Fun Fact
If Earth were the size of an apple, the crust would be thinner than the apple’s skin.