Earth Science

Earth History

Formation of Earth

Study Tip
The extreme heat of the early Earth was a major factor in shaping its geography.

Planet Formation

  • The Earth formed nearly 4.6 billion years ago, along with the rest of the Solar System.
  • Gravity caused rocks, metal, dust, and gases from the solar nebula to come together.
  • Planetoids become larger until they are planets
Study Tip
The extreme heat of the early Earth was a major factor in shaping its geography.

Molten Earth

When Earth first came together it was really hot due to:

  • Gravitational Contraction
  • Gravity within an enormous body compresses the material in its interior, increasing its internal pressure and temperature.
  • Radioactive Decay
  • Radioactive decay releases heat.
  • Bombardment
  • Asteroid impacts were very common.
  • Earth was struck so much in its first 500 million years that the heat was intense

Differentiation

  • The separation of the Earth into layers based on density is known as differentiation.
  • The densest material moved to the center of the planet to create a dense, metallic core.
  • Materials with a moderate density became part of the mantle.
  • Lighter materials accumulated at the surface of the mantle to become the crust.

Early Solar System Materials

  • The only information we have from the Earth’s earliest years are from zircon crystals, meteorites, and lunar rocks.
Layers of  Earth
The different layers of Earth were split up into multiple layers.
Concept Check
  • What kinds of materials formed the Earth?
  • What is differentiation? What determines the order of the layers?