Transcript Chapter 22.1: Earth’s Structure

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 Layers
Major Layers
1. Core
2. Mantle
3. 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=asEiF05f1Sw
Part 2; 4 min http://www.youtube.com/watch?v=8OfNefK9o84&feature=related
Core
Mantle
Crust
Sulfur (4%)
Nickel
(11%)
Iron (85%)
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
Crust
Made of:
•Light Rock layer
(silicates)
• Thinnest layer
Types of Crust
A. Continental
• Less dense
• Thicker
• Older
• Granite
B. Oceanic
• Dense rocks like
basalt
• Thinner
• Younger
• Basalt
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
Cooler rock near crust = dense = sinks
Hot rock near core = less dense = rises
Core
• Composition: Heavy
Metals! (densest)
• Iron & Nickel
• Hottest Layer
• Most pressure
2 Layers of Core
Outer Core
• Liquid
• High temp. keeps it liquid
• Responsible for Earth’s
magnetic field
• Inner Core
– Solid iron and nickel
– High pressure keeps it
solid
The Core
Sulfur (4%)
Nickel
(11%)
Iron (85%)
Density:
~11 g/cm3
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 Quiz
1. Constructive forces build new land/crust and
destructive forces destroy crust.
2. Crust, Mantle, Core
3. The asthenosphere – which is in the mantle
4. The core
5. The crust
5. Oceanic crust is denser (but thinner)
6. The upper mantle (and the crust make up the
lithosphere, or plates)
7. Core
How the Earth was Made:
Part 1: http://www.youtube.com/watch?v=V1kTIZeq1Ck;
Part 2: http://www.youtube.com/watch?v=SoRqVDQXj-A
Early Earth & plate tectonics http://www.youtube.com/watch?v=QDqskltCixA