Chapter 22.1: The Geosphere

Geology = The study of the planet E.’s composition & structure

In Notebook …

1. Draw and label a diagram of Earth that shows its 3 major layers.

2. What is each layer made up of? (Rock? Metals? Gas? Something else?)

3. What happens to temperatures as you move from the surface to the center?

4. What happens to pressure as you move from the surface to the center?

How do we know about Earth’s interior if we can’t see it?

1. Seismic (earthquake) waves Waves travel at different speeds in different mediums and materials

2. Samples of the shallow mantle fr. Volcanoes.

People used to think…

- Earth was a few thousand years old.

- Earth never changed.

Geologists discover that:

- Earth is billions of years old

-Earth is always changing (Mt. building, continents move, etc.)

Geosphere: Earth’s LayersMajor Layers1. Core2. Mantle3.Crust

Why Layers?• Separation due to DENSITY DIFFERENCES.

• While E. was molten, heavy things sank to center (metals); light things (silica rocks) floated

Early Earth: Origins: http://www.youtube.com/watch?v=asEiF05f1SwPart 2; 4 min http://www.youtube.com/watch?v=8OfNefK9o84&feature=related

Core Mantle Crust

Iron (85%)

Nickel (11%)

Sulfur (4%)

Density: ~11 g/cm3

Density: ~5 g/cm3

Density: ~3 g/cm3

Temperatures & Pressures

• Increase with depth

(Gets hotter with more pressure fr. Crust core)

The Composition of the Earth

CrustTypes of Crust

A. Continental• Less dense• Thicker • Older• Granite

B. Oceanic• Dense rocks like

basalt• Thinner• Younger• Basalt

Made of:•Light Rock layer (silicates)• Thinnest layer

Abundances of Elements in Earth’s

Crust

Silicon & Oxygen compounds = silicates

( ~ 74%)

These make crust light!

“Moho” =

boundary b/w crust & upper mantle

The Mantle• Composition:

Heavy Rock

• Less silica; more iron

3 Divisions of the Mantle

Lithosphere = Upper mantle + Crust“Plates”, Rigid Slabs

Asthenosphere = Softer, moving hot rock (Convection Currents)

Mesosphere = Stiffer rock near core

Convection in the Mantle (astheno)•Driven by temperature & density differences

Hot rock near core = less dense = rises

Cooler rock near crust = dense = sinks

Core• Composition: Heavy

Metals! (densest)

• Iron & Nickel

• Hottest Layer

• Most pressure

2 Layers of Core

• Inner Core– Solid iron and nickel– High pressure keeps it

solid

Outer Core• Liquid• High temp. keeps it liquid• Responsible for Earth’s magnetic field

Iron (85%)

Nickel (11%)

Sulfur (4%)

Density: ~11 g/cm3

The Core

Label Each Layer.

Be able to describe each layer: What is it made up of?; Is it solid? Liquid? “taffy-like”; What happens to temps., pressures, and density as you move through layers?

Self Quiz

1. Compare how constructive and destructive forces affect Earth’s surface.

2. List the 3 layers of Earth.3. Which layer has currents of moving rock?4. Which is the most dense layer?5. Which layer is made of light rocks like silicates?6. Which is more dense: Continental or Oceanic

Crust?7. Which layer of the mantle is part of Earth’s

plates?8. Which layer is made of heavy metals?

Answers to Self Quiz1. Constructive forces build new land/crust and

destructive forces destroy crust.2. Crust, Mantle, Core3. The asthenosphere – which is in the mantle4. The core5. The crust5. Oceanic crust is denser (but thinner)6. The upper mantle (and the crust make up the

lithosphere, or plates)7. CoreHow the Earth was Made:Part 1: http://www.youtube.com/watch?v=V1kTIZeq1Ck;Part 2: http://www.youtube.com/watch?v=SoRqVDQXj-AEarly Earth & plate tectonics http://www.youtube.com/watch?v=QDqskltCixA