Earth's Interior Notes

Get the sheet from the front and have out your colored pencils. How do we know what the interior of the earth looks like?

The Crust State of Matter: Solid Composition: cool rock (least dense) Thinnest layer: 0 -100 km State of Matter: Solid Composition: cool rock (least dense)

The Crust The crust is composed of two rocks. The continental crust is mostly granite. The oceanic crust is basalt. Basalt is much denser than the granite. Because of this the less dense continents ride on the denser oceanic plates.

The Lithosphere The crust and the upper layer of the mantle together make up a zone of rigid, brittle rock called the Lithosphere.

The Lithospheric/ Tectonic Plates The crust of the Earth is broken into many pieces (giant slabs of rock) called plates. The plates "float" on the soft, semi-rigid asthenosphere.

The Asthenosphere The asthenosphere is the hotter, softer flowing part of the middle mantle that flows like hot asphalt under a heavy weight. The movement of the middle mantle asthenosphere) is the reason that the crustal plates of the Earth move.

The Mantle Largest Layer State of matter: mostly liquid Thickness: 100 km – 2900 km State of matter: mostly liquid Composition: Molten Rock

Convection Currents The middle mantle "flows" because of convection currents. Convection currents are caused by the very hot material at the deepest part of the mantle rising, then cooling and sinking again --repeating this cycle over and over.

Convection Currents The next time you heat anything like soup or water in a pan you can watch the convection currents move in the liquid. When the convection currents flow in the asthenosphere they also move the crust. The crust gets a free ride with these currents, like the cork in this illustration. Safety Caution: Don’t get your face too close to the boiling water!

The Outer Core Composition: liquid iron and nickel Thickness: 2900 – 5100 km State of matter: so hot that it is in a liquid state

The Inner Core Composition: metal- mostly iron and nickel (most dense layer) Thickness: 5100 - 6378 State of Matter: Solid because the temperatures and pressures are so great that the metals are squeezed together and are not able to move about like a liquid, but are forced to vibrate in place.

Cross-Section of the Layers of the Earth

Review Questions The planet we call Earth has how many main layers? Write them in order from the center to the outside of the planet. Name the thickest layer Name the thinnest layer What are the Convection Currents? Challenge: What made them form into these layers?

Outer core Earth’s Crust Mantle Inner core

The End Have we ever seen part of the Mantle? Explain. Think-Pair-Share with your table: Have we ever seen part of the Mantle? Explain. © Copyright 2006.  M. J. Krech. All rights reserved.

Videos https://www.youtube.com/watch?v=NAHY6965o 08  https://www.youtube.com/watch?v=NAHY6965o 08   https://www.youtube.com/watch?v=Q9j1xGaxYz Y Discovery Education: What’s Inside the Earth?