The Earth’s Layers

The Earth has 4 Layers The Crust is the layer that you live on, and it is the most widely studied and understood. The Mantle is much hotter and has the ability to flow. The Outer Core and Inner Core are hotter still and are under enormous pressure.

Continental Crust Crust Oceanic Crust The Earth's Crust is like the skin of an apple. It is very thin in comparison to the other layers. The crust is 5-100 km. thick There are two types of crust: Continental Crust and Oceanic Crust Both continental crust and oceanic crust are made of the elements oxygen, silicon, and aluminum.

Crust The temperature of the crust varies from air temperature at the top to 900 C. at the bottom (hot enough to melt rock!)

Mantle The mantle is the thickest layer of the Earth, 2900 kilometers thick. Very hot, dense rock like asphalt under a heavy weight. The temperature of the mantle varies from 900 Celsius at the top to about 3000 Celsius near the bottom!

The Mantle No one has ever visited the mantle. With present technology, we can’t drill far enough through the crust to get to the mantle. So how do scientists “know” about the mantle? They observe places where mantle rock pushes close to the Earth’s surface, such as where lava pours out of active volcanoes on the ocean floor.

Convection Currents in the Mantle Convection currents are caused by the very hot material at the deepest part of the mantle rising, then cooling, sinking again and then heating, rising and repeating the cycle over and over. When the convection currents flow in the mantle they also move the crust. The crust gets a free ride with these currents. The movement of the mantle is the reason that the plates of the Earth move! Convection Current Animation http://education.sdsc.edu/optiputer/flash/convection.htm http://www.absorblearning.com/media/item.action?quick=12p

The Core The core of the Earth is like a ball of very hot metals. 3000 C. to 4000 C. Iron & small amounts of nickel The Earth’s magnetism is caused by the core.

Outer Core The outer core is so hot that the metals in it are all in the liquid state. 2000 km thick Liquid metals (iron & nickel)

Inner Core Temperatures and pressures are so great here that the iron and nickel metals are squeezed together and vibrate in place as a solid.

Pressure In the core, the pressure is 45,000,000 pounds per square inch. You would be squeezed into a ball smaller than a marble if you were able to go to the center of the Earth!

On lined paper in your science binder, copy these questions and answer them in complete sentences: What causes the mantle to "flow"? What are the two main metals that make up the Earth’s core? How do temperatures and pressures change as you move from the crust toward the core?