1. Warm – Up 12/10/14  Please get out your layers of the Earth foldable that you made yesterday! On the yellow sheet of paper write your first and last name. Answer the following questions: ○ Explain why the inner core of the Earth is a solid. ○ Explain the flow of hot flowing rock in the mantle. ○ What layer of the Earth do we live on and explain what it is made of?

3. Theory of the Formation of Earth  4.6 BILLION years ago, Earth formed as bits of material collided and stuck together.  Denser materials Iron & Nickel = sank toward the center Less dense material = moved toward the surface.

4. Earth’s Layers  Inner core / Solid core Solid Composed of – ○ Nickel and Iron Enormous pressure The densest region  Outer core / Liquid core Liquid Composed of hot liquid metals The temp. & pressure is lower than the inner core

5. Earth’s Layers  Mantle The thickest layer. Composed of hot rock Less dense than the metallic core  Crust Thinnest Layer Composed of cooled rock 2 Types: Continental & Oceanic Crust

6. Earth’s Layers  Lithosphere Earth’s crust and the very top of the mantle together Most rigid of all the layers Where plate tectonics are found  Asthenosphere A layer of hotter, softer rock in the upper – middle mantle Sits directly under the Lithosphere Soft enough to flow slowly like hot tar

7. Tectonic Plates  The lithosphere is broken into many large and small slabs of rock called… tectonic plates  These plates fit together like a jigsaw puzzle that makes up the surface of Earth.

8. Continental Shift  1800’s German scientist Alfred Wegener hypothesized that the Earth’s continents were once joined in a single landmass and gradually moved or drifted, apart. http://app.discoveryeducation.com/search

9. Evidence for Continental Drift  Fossils Ancient reptiles (Mesosaurus) had been discovered in South America and Western Africa These fossils were not found any where else in the world.

10. Evidence for Continental Drift  Climate Greenland today lies near the Arctic Circle and is mostly coved in ice. Yet fossils of tropical plants can be found there. South Africa today has warm climate, yet its rocks were deeply scratched by ice sheets that once covered the area.

11. Evidence for Continental Drift  Geology Kinds of rocks that make up the continets Rock in Brazil matched the rock found in western Africa Limestone layers in the Appalachian Mountains of North America were exactly like the limeston in Scotland’s Highlands.

13. Pangaea  “Continents had once been joined in a huge superconinent”  Pangaea – Greek word meaning “all lands”  Was centered over the area where Africa lies today  Took 200 million years for the Pangaea to split apart  How did they move?

15. Pangaea  Sea Floor Found huge underwater mountain ranges, called mid-ocean ridges. These ridges appeared in every ocean, circling Earth like seams in a baseball

17. Pangaea  Sea-Flooring Spreading Ridges form along cracks in the crust. Molten rock rises through these cracks, cools, and forms new oceanic crust. Old crust is pulled away to make room for new material

19. Pangaea  Age of the Sea Floor Youngest rocks are closest to the ridge, while the oldest rock is farthest away

20. Pangaea  Ocean Trenches IF the sea floor has been spreading for millions of years, why is Earth not getting larger? ○ Huge trenches (deep canyons) in the sea floor ○ Dense oceanic crust is sinking in the asthenosphere ○ Old crust is being destroyed at the same rate that new crust is forming. ○ Same size earth!

22. Plate Movement  Tectonic Plates – rest on the asthenosphere  Rock in this layer and in the mantle move by convection  What is convection?? Is energy transfer by the movement of a material.  The hot, soft rock rises, cools, and sinks, then is heated and rises again. This is called a convection current- a motion that transfers hear energy in a material

24. Theory of Plate Tectonics  The theory states that Earth’s lithosphere is made up of huge plates that move over the surface of the Earth The Major Tectonic Plates: 1. North American 2. Nazca 3. South American 4. Eurasian 5. African 6. Indian 7. Australian 8. Antarctic 9. Pacific

25. Theory of Plate Tectonics  One plate could not shift without affecting the others nearby.  Plates can move apart, push together, or scrape past each other  Plate movement causes great changes in Earth’s crust Earthquakes Volcanoes Mountain Ranges