Layers of the Earth Mantle and Crust
Mantle • The mantle is made up of very hot solid rock. • The mantle is divided into two layers based upon the characteristics of those layers.
The Mantle • The mantle is the largest layer of the Earth. • Thickness: Approximately 1,800 miles (including the lithosphere and asthensphere) • Temperatures range: 1,600 to 4,000 degrees F Composition: oxygen, silicon, magnesium, iron and other minerals
Mantle’s Asthenosphere • Thickness is about 186 miles • Composition: • Plastic-like • Solid, but softer • “Asthenes” means “weak” • Unique? Makes the plates move! Because it’s slowly flowing.
Mantle’s Lithosphere • Thickness = About 62 miles • Composition: • Rigid layer • Rocky like Crust • “Lithos” means “Stone” • Unique? Made up by part of the Crust!
Convection Currents • Convection currents are a form of heat transfer • The convection currents transfer heat within the mantle and outer core. • This is also the cause for plate movement
Where the Mantle ends and the Outer Core begins is an area called the GUTENBERG DISCONTINUITY
Crust • This is the layer we live and walk on daily • This layer contains dry land and the ocean floor • The crust is thickest under high mountains and thinnest under the ocean • The crust under the ocean is called oceanic crust and is mostly made up of rocks such as Basalt
Crust • The crust that forms the continents is called the continental crust • This is usually made up of rocks such as granite