Layers of the Earth: Crust, Mantle, Outer Core, Inner Core

1. Layers of the Earth Pg. 16The Earth’s Interior Pg. 17 Add to Table of Contents:

2. The Earth’s Interior Pg. 17 • The Earth’s Interior can be broken up into 4 major zones: • Crust • Mantle • Outer core • Inner core • 1 Km= 0.62 Miles

3. 1. The Crust • The crust is very thin (average 20 km) & broken-up into plates. • This does not sound very thin but if you were to imagine the Earth as a football, the crust would be about ½millimeter thick. • The thinnest parts are under the oceans and go to a depth of roughly 10 km. It is more dense than under continents. • The thickest parts are the continents which extend down to 35 km on average. The continental crust in the Himalayas is some 75 km thick.

4. 2. The Mantle • A rocky layer located below the crust with a thickness of 2885 km.

5. The Mantle (cont…) • The mantle extends about half way to the center. It's made of solid rock and behaves like a thick liquid.

6. 3. The Outer Core • A layer about 2270 km thick, which is made of liquid iron & nickel. • The movement of this liquid core (and solid core) is responsible for the Earth's magnetic field

9. The Earth exhibits a magnetic field that reaches above our atmosphere. For a magnetic field to exist, either a permanent magnet must be in the Earth's interior, or ionized molecules are moving in a liquid medium in the Earth's interior. A permanent magnet cannot exist in the Earth's interior due to the high temperatures deep in the Earth. Therefore the magnetic field is thought to be produced by ionized iron moving about in the Earth's core.

10. 4. The Inner Core • It is made of solid iron and nickel with a radius of about 1216 km. • Temperatures in the core are thought to be 5000-6000°C and it's solid due to the massive pressure.

13. Why is the core so hot? • It's a combination of radioactivity (the radioactive materials in the Earth generate heat) and the residual heat from the formation of the Earth. When all of the matter that created the Earth fell together, it picked up kinetic energy falling in. When it stopped at the proto-Earth, the kinetic energy was turned into heat. The Earth hasn't cooled yet. But, the vast majority of the heat in Earth's interior—up to 90 percent—is fueled by the decaying of radioactive isotopes like Potassium 40, Uranium 238, 235, and Thorium 232 contained within the mantle. These isotopes radiate heat as they shed excess energy and move toward stability. "The amount of heat caused by this radiation is almost the same as the total heat measured emanating from the Earth." Read more at: http://phys.org/news62952904.html#jCp

14. Earth’s Interior Clip • http://www.youtube.com/watch?v=YHqlzCBpu_Q

15. Inner Core = 5000-6000 °C • °K = ? K = 5/9 (° F - 32) + 273 K = 5/9(5000°C -32) + 273 K = 2760 + 273 5000°C = 3033°K

16. What do you already know? How are scientists able to study the composition and size of the interior layers of the Earth? • By direct observation • By analyzing surface rock samples • By using seismic waves • By deep drilling into the interior layers

17. Copy this concept map and then complete it by filling in one appropriate descriptor at the end of each arrow. Use pages 239-241 in the textbook. When discovered Scientist Definition Theory of Continental Drift Supporting Evid What is missing? Rock Formations Continents Fossils

18. The Theory of Plate Tectonics • States that Earth's rigid outer shell, called the lithosphere, consists of seven large and numerous smaller segments called plates that are in motion relative to each other.

19. Origins • Alfred Wegner proposed Continental Drift when he noticed that the continents fit together like jigsaw pieces. • Later, with more evidence, this became the theory of Plate Tectonics

20. Evidence for Plate Tectonics • The evidence Wegner used for his original theory • Continents fit together • Matching Rocks & Fossils • Paleomagnetism: Study of the changes in Earth’s Magnetic Field

21. Evidence for the theory (cont…) • The edges of these plates (called Plate Boundaries), where they move against each other, are sites of intense geologic activity, such as earthquakes, volcanoes, and mountain building.

22. Types of Plate Boundaries • Divergent plate boundaries • Convergent plate boundaries • Transform fault boundaries

23. Divergent Plate Boundaries(constructive margins) • Two plates move apart • Mantle material upwells to create new seafloor • Continental rifts form at spreading centers within a continent

24. Divergent Plate Boundaries (cont…)

25. Convergent plate boundaries (destructive margins) • Plates collide, an ocean trench forms and lithosphere is subducted into the mantle • There are three types of Convergent Plate Boundary

26. Oceanic-continental convergence • Denser oceanic slab sinks into the asthenosphere • Pockets of magma develop and rise • Continental volcanic arcs form • e.g., Andes Mountain Range • e.g., Cascades Mountain Range

27. Oceanic-oceanic convergence • Two oceanic slabs converge and one descends beneath the other • Often forms volcanoes on the ocean floor • Volcanic island arcs forms as volcanoes emerge from the sea • e.g., Aleutian islands • e.g., Mariana islands

28. Continental-continental convergence • When subducting plates contain continental material, two continents collide • Can produce new mountain ranges such as the Himalayas

29. Example of a continental-continental Subduction

30. Transform Fault boundaries • Plates slide past one another • No new crust is created • No crust is destroyed