LAYERS OF THE EARTH!

1. An Introduction to Ch 12 LAYERS OF THE EARTH!

2. Journey to the Center of the Earth! http://www.educationalrap.com/59/layers-of-the-earth.html

3. Regions of the Earth • The Earth is made up of two major regions: • A mostly molten, central core • A mostly solid outer mantle and crust

4. Hydrosphere and Crust (0-35km) • The crust is the top, solid surface layer of the Earth • Oceanic crust is the crust under oceans, and continental crust is the crust under the continents

5. Hydrosphere and Crust (0-35km) • The Hydrosphere contains the bodies of water at or near the surface, including: • Frozen surface water • Liquid surface water • Ground water • Water vapour • All told the Earth’s water totals an estimated ~540 million kilometers, 97% of which is contained in the oceans

6. Quick Fact: • The crust and the upper mantle are part of what we call the Lithosphere! (the solid portion of the Earth) • The Aesthenosphere is the ductile – semi-liquid/solid part of the Earth located just below the Lithosphere. • The Aesthenosphere includes the upper mantle.

7. Let’s Journey to The Center of the Earth!

8. The Mantle: (35-2900km) • The mantle is the semi-solid layer directly below the crust. It can itself be broken into three distinct parts: • The Upper Mantle (35- 670 km) • The Transition Zone (300- 700km) • The Lower Mantle (670- 2900km)

10. The Upper Mantle:(35 - 670 km) • The contents of the upper mantle are not as well defined as the crust and other layers. • It includes xenoliths, rocks that were shot upward by explosive eruptions (some of which contain diamonds)! Processes that take place in the upper mantle have significant impact at the crust, in the form of: • Volcanic eruptions • Earthquakes • The introduction of some ores (metal compounds)

11. The Transition Zone:(300 - 700km) • About 1/5th of the way through the mantle, increases in pressure and temperature turn many minerals into tightly packed crystals. • This area is known as the transition zone because it separates the lower mantle from the upper mantle… Surface topography and bathymetry around South America (top) overlays variable topography on Earth's upper mantle. There is a visible transition (i.e. discontinuities at 410 km (middle) and 660 km) depth—this is the transition zone!.

12. Convection is a process where hot fluids rise and cool fluids fall. • What is a fluid?? • A fluid is a liquid or a gas! • Convection has several important influences on planet Earth. • Wind is caused by convection. • Convection in the mantle leads to many seismic events • Volcanic activity • Earthquakes • Continental Drift (more later) Convection Convection results in movement in a Lava Lamp!

13. The Lower Mantle:(670 - 2900km) • The lower mantle comprises nearly 50 percent of the Earth’s Interior. Rather than staying stagnant (still / unchanging), the lower mantle convects slowly creating superplumes (large rising jets of partially molten rock).

14. Under the Surface…

15. The Outer Core: (2900 - 5200km) • The outer core consists of liquid metal that flows turbulently . This movement creates the Earth’s main magnetic field. • The outer and inner cores generate so much heat, about 4000 to 5000 Kelvin, which contributes about one-fifth of the Earth’s internal heat which ultimately flows to the surface.

16. The Inner Core: (5200-6371km) • While most of the core is liquid, the inner core is solid. It is believed to be metallic iron although no studies have ever been performed on the core.

17. Summary: