Earth’s Interior Chapter 8, pages 233-237 Image from the website: http://serc.carleton.edu/quantskills/activities/interior_seismic.html Link for intro animation: http://www.precisiongraphics.com/portfolio/animation/

Earth’s Formation - Earth began to form in a process called accretion (gathering), where dust and debris collide and stick together to form a large mass.

- Eventually the mass got large enough to be called a Planetesimal (planet building block)

• The planetesimal began to cool as it spun through space.

- Oblate spheroid forms: The spinning motion caused Earth to form into a sphere bulging in the center. 7900 miles 7926 miles

Why does Earth have different layers? Differentiation (layering) of Earth’s interior is due to gravity and differing densities in molten state. - Earth’s main heat engine to create molten state : 1. radioactive decay (Uranium, Potassium, Thorium). 2. Pressure from asteroid collisions.

Earth’s 4 Layers Crust Mantle Outer core Inner core

1. Crust - Solid, rigid layer mostly Oxygen & Silicon (SiO2). - Depth of 7-70 km. - Two types: Oceanic and Continental

Earth’s Crust

2.Mantle Thickest of Earth’s Layers! - Plastic-like with liquid properties - Composed mostly of iron, silicon, and magnesium - Depth of 2890 km (from the surface) - 1000 °C Thickest of Earth’s Layers!

Earth’s Mantle

3. Outer Core - Liquid - Composed of iron and nickel - Depth of 5150 km (from the surface) - 3700 °C

4. Inner Core - Solid - Composed of iron and nickel - Extends to a depth of 6371 km (from the surface) - 4300 °C

Earth’s Inner Core

How the Earth Moves - Lithosphere is made up of the crust and the uppermost portion of the mantle and is solid. - Asthenosphere is made up of the upper mantle and is “plastic-like”.

Ooblek Observations -Write observations and conclusion in booklets titled Ooblek. Before the addition of water, is cornstarch a solid, liquid, or gas? When you try to pour the mixture into your hand, does the mixture behave like a solid, liquid, or gas? Explain When you try to roll the mixture into a ball and apply pressure, does the mixture act like a solid, liquid , or gas? Explain Conclusion: How does ooblek model the Earth’s outer core and inner core? From your observations and notes on Earth’s interior, compare Ooblek to Earth’s core. How does Ooblek help explain the difference between Earth’s outer core and inner core?

How do we know about Earth’s Interior? Drilling Earth’s Magnetic Field Seismic Waves

Drilling into the Earth Humans have been able to drill down about 12 km (approximately 7.6 miles) into the Earth’s crust. We have never drilled into the mantle, outer core, or inner core.

1. How do they occur? Features Categories 2. Where do they start?   Categories 1. How do they occur? 2. Where do they start? 3. Can they travel through solids? 4. Can they travel through liquids? 5. Can they travel through gasses? 6. How do they react when density changes? 7. Are they detected on the other side of the world? 8. Do they show up in Shadow Zones? 9. Can they travel through the inner core? 10. Can they travel through the outer core? Primary Wave (P-Wave) Secondary Wave (S-Wave)

Seismic (Earthquake) Wave Basics - Seismic wave: the energy released during an earthquake which travels through the Earth. -The point of origin of an earthquake is called the Focus. -The spot on the surface of the Earth directly above it is called the Epicenter.

3 Types of Seismic Waves: * Primary (P) waves * Secondary (S) waves * Surface waves Image is from the website: http://www.physicalgeography.net/fundamentals/10m.html

Primary Waves 1. Primary waves, also known as P-waves, - Travel through the Earth by compressing and expanding. - Can travel through solids, liquids, and gases. - Fastest seismic wave. Image is from the website: http://www.uwgb.edu/DutchS/EarthSC202Notes/quakes.htm

Secondary Waves 2. Secondary waves, also known as S-waves. - Travel in an up-and-down pattern much like the waves that move through water. - Can only travel through solid material, not liquids and gases. Secondary Waves Image is from the website: http://www.uwgb.edu/DutchS/EarthSC202Notes/quakes.htm

Surface Waves 3. Surface waves - produced as a rolling motion of ground along the surface of the Earth. - Surface waves are the most destructive. Image is from the website: http://www.uwgb.edu/DutchS/EarthSC202Notes/quakes.htm

Waves Tell Us Earth’s Composition. Scientists noticed that P-waves pass through the entire Earth, while S-waves can disappear. Image from the website: http://www.astro.virginia.edu/class/oconnell/astr121/guide12-s02.html

Shadow Zones - S-waves disappear when they encounter the liquid outer core. - As P waves pass from one type of material into another, they are refracted (or bent slightly). Image from the website: http://ww2.lafayette.edu/~malincol/Geol120/earthquaketopics.html

The poles of the magnet are located near the poles of the Earth. Magnetosphere Movement of the liquid outer core of the Earth generates a strong magnetic field that surrounds the planet. The poles of the magnet are located near the poles of the Earth. Image from the website: http://stargazers.gsfc.nasa.gov/resources/magnet_in_space.htm

Why is the Magnetosphere important? Image is from the website: http://stargazers.gsfc.nasa.gov/resources/magnet_in_space.htm It stretches out through the atmosphere and acts as a protective barrier to deadly, high-energy solar radiation. Creates brilliant light shows called auroras.

Earth’s Magnetic Field The Earth’s magnetic field allows us to use compasses to locate direction on the planet. A small magnetic needle that is allowed to spin freely aligns itself with the Earth’s magnetic field and points to the magnetic North Pole. Image from the website: http://www.navis.gr/navaids/compass.htm (top) and http://www.brasscompass.com/mapcompass.htm