DVD on Plate Tectonics: 3 minute clip on granite Background: How the Earth was made: 3.5 Billion years ago, oceans were dominant, the first continental crust was beginning to form…this would later become the continents.

CHAPTER 7: PLATE TECTONICS---Inside the Earth The Crust The Earth's Crust is like the skin of an onion. It is very thin in comparison to the other three layers. The crust is only about 3-5 miles thick under the oceans (oceanic crust) and about 25 miles thick under the continents (continental crust). The deepest spot is 43 miles. Notice how thick the continental crust is compared to the oceanic crust.

How thick is Oceanic crust? How thick is Continental crust? 3-5 Miles Thick 5-25 Miles Thick

The temperatures of the crust vary from air temperature on top to about 1600 degrees Fahrenheit in the deepest parts of the crust. You can bake a loaf of bread in your oven at 350 degrees F., at 1,600 degrees F. rocks begin to melt. What type of energy is produced using the heat from the inside of the Earth?

 The crust of the Earth is broken into many pieces called plates. There are about 15 plates.

 The plates "float" on the soft, plastic mantle which is located below the crust. These plates usually move along smoothly but sometimes they stick and build up pressure. The pressure builds and the rock bends until it snaps. This is what we feel as an Earthquake!

Notice in the picture above how thin the crust of the Earth is in comparison to the other layers. The seven continents and ocean plates basically float across the upper mantle which is composed of much hotter and denser material. Where inside the Earth is the densest material found?

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

The crust is composed of two basic rock types, granite and basalt. The continental crust is composed mostly of granite. The oceanic crust consists of a volcanic lava rock called basalt. Basaltic rocks of the ocean plates are much denser and heavier than the granitic rock of the continental plates. Because of this the continents ride on the denser oceanic plates. Clip on Granite

The Asthenosphere: The layer below the rigid lithosphere is a zone of asphalt-like consistency called the asthenosphere. The asthenosphere is the part of the mantle that acts like a solid and liquid. It flows and moves the plates of the Earth. What happens to the oceanic crust when it runs into the continental crust?

A B CD E What parts of the Earth’s interior do the letters represent? A. Oceanic Crust B. Continental Crust C. Lithosphere D. Lithosphere E.Part of the Lithosphere and the Asthenosphere (upper mantle)

AMAZING EARTH SCIENCE FACTS 1. The Earth consists of a solid inner core, a liquid outer core, a plastic-like __________and a thin rocky crust. 2. The _____________ is the crust and upper mantle 3. ________________ —high density, young age, thin, and made of basalt 4.__________________ —low density, old age, thick (think Mt. Everest) made of granite mantle lithosphere Oceanic crust Continental crust