Home Link to Earth Structure Link to Biosphere Link to Atmosphere Link to Hydrosphere Link to Biogeochemical Cycles Link to Activities Geography4Kids Sections Search
Earth Structure and Composition


Once upon a time, billions of years ago, there was a whole bunch of atoms floating around the universe. Slowly those atoms and molecules came together and formed what we call the Earth. Now the Earth is a big ball of matter that circles the Sun once a year. What's inside the planet? Most of the Earth is composed of the mantle and the core.

outer layers of the earth The rules of density were in action when the Earth and its matter came together. Those rules explain how the heavier substances moved towards the middle and the lighter substances wound up on top. It's just like sand sinking to the bottom of a water glass.

The Mantles

Scientists break the mantle into two pieces. They have the upper mantle and the lower mantle. There are very small differences between the two layers. The upper mantle has Olivine (a very special rock), compounds with silicon dioxide, and a substance called Peridotite.

The lower mantle is more solid than the upper mantle. It has a lot of that Olivine rock, iron, magnesium, and many silicate compounds (those are ones with SiO2).

inner layers of the earth

The Cores

Don't get confused with the next part. There aren't two cores. Like the mantle, scientists break the core into two layers. First is the outer core. Imagine this huge sphere of molten iron (Fe), floating and flowing around the inner core. It's really a liquid. It's extremely hot and under a lot of pressure. Especially important is the idea that the outer core creates the Earth's magnetic field. It's a huge magnet in the center of the planet.

The inner core is under even more pressure. Even though it's just as hot as the outer core, there is such high pressure that it stays solid. Remember those rules about density? Well the most dense, most compact, heaviest matter is found in the inner core. It's not pure iron like the outer core. It has compounds that use the element iron.

Next page on the earth structure.
- Overview
> Composition
- Magnetic Field
- Structure
- Rock Types
- Tectonics
- Faulting
- Earthquakes
- Volcanoes


Link to Link to Link to Link to Link to Link to Rader Network Side Navigation

How to Build a Planet (NASA/Spitzer Video)
- or -

Earth Science Quiz

Structure of Earth Quiz

Useful Reference Materials (Planet Earth):
Wikipedia (Structure of the Earth):
Encyclopædia Britannica (Interior of the Earth):

- Geography4Kids: Earth's Mag. Field
- Chem4Kids: Solids
- Chem4Kids: Environmental Chemistry
- Chem4Kids: Elements
- Cosmos4Kids: Earth
- Cosmos4Kids: Mars
- Cosmos4Kids: Space Exploration
- Physics4Kids: Magnetic Fields
- Physics4Kids: Gravity

- NASA: Kennedy Space Center
- NASA: Goddard Spaceflight Center

Search for more information...

* The custom search only looks at Rader's sites.

Help Page Go for site help or a list of earth science and geography topics at the site map!
©copyright 1997-2015 Andrew Rader Studios, All rights reserved.
Current Page: | Physical Geography | Earth Structure | Composition of the Earth

** Andrew Rader Studios does not monitor or review the content available at these web sites. They are paid advertisements and neither partners nor recommended web sites.