Fifth Grade
Worksheets
The Layered Earth
Have you eaten a boiled egg? If you have, you know that it has are three layers. Much like an egg, the Earth also has three layers.
An egg has a thin outer shell. Earth does, also. It is called the crust. If you run your finger over an eggshell, you will feel small bumps. The shell can be thicker in some parts than in others. The Earth's crust is like that, too.
The crust of the Earth is very thin and rigid compared to the other layers. There are two types of crust, oceanic and continental. Beneath the ocean, the crust is only about five kilometers thick. The average thickness of crust below the continents is about 30 kilometers. But under mountain ranges it can be as thick as 100 kilometers.
Oceanic crust contains rocks made mostly of the elements oxygen and silicon. Continental crust is made up of two layers of rocks. The top layer is made of granite. The bottom layer is basalt. Elements in the Earth's crust include aluminum, iron, sodium, and calcium. Like an eggshell, Earth's crust can easily be broken.
The crust is the upper part of the lithosphere. This is the solid, top part of the Earth. It is broken up into at least seven sections called lithospheric plates.
