I. Three main layers make up the Earth’s interior
A. Forms the outer layer
1. contains rocks, mountains, soil, water
2. thinnest layer of the three
3. crust beneath ocean = basalt
4. crust beneath continent = granite
A. Layer of solid, hot rock
B. Upper layer of mantle = lithosphere
C. Lower layer of mantle = asthenosphere
D. Lithosphere floats on top of the asthenosphere
A. Outer core
1. liquid molten iron and nickel
B. Inner core
1. solid ball of iron and nickel
I. Heat transfer
A. Movement of energy from warmer to cooler object
B. Three types
A. Energy transfer through empty space
B. Example – sun warming the Earth
A. Heat transfer by direct contact
B. Spoon heating up in a pot of soup
C. fig. 8, page 16
A. Heat transfer by the movement of a heated fluid
B. Soup heating up
C. fig. 9, page 16
D. Heat rises in the pot, then cools when it reaches the surface, then it sinks again
E. Called a convection current
F. fig. 10, page 17
G. Read convection in Earth’s Mantle paragraph
1. Mapping the ocean floor
A. Mid-ocean ridge is the longest chain of mountains in the world.
B. How did they find that out?
1. sonar – bounce sound waves off the ocean floor to determine depth
2. fig. 17 & 18 pg. 24
2. What is Sea-floor spreading?
A. The ocean floor moving apart
B. What’s the evidence?
3. Molten material –
A. Magma erupts through the mid-ocean ridge
B. Occurs over and over again
4. Magnetic Stripes –
A. Earth has magnetism in the core
B. Magma erupts bringing the magnetism with it
C. Sometimes the magnetism would be reversed
D. “North” would point “south”
E. Determined this fact from cooled molten material on the ocean floor
F. Fig. 21, pg. 26
5. Drilling samples –
A. Fig. 22, pg. 27
B. Samples of the ocean floor have been brought up from 6 km deep!
C. Evidence showed that the further away from the mid-ocean ridge the samples were taken, the older the rocks.
D. The younger rocks were always in the center of the mid-ocean ridge.
1. How can the ocean floor keep getting wider and wider? Is the planet growing?
2. New ocean floor is mead at the mid-ocean ridge.
3. Old ocean floor dives into deep underwater canyons.
A. Called deep-ocean trenches.
B. Subduction = old ocean floor sinking back into the mantle
C. Convection currents push the new crust at the mid-ocean ridge away from the ridge and toward a deep-ocean trench.
D. This occurs over tens of millions of years.
4. Subduction and Earth’s oceans –
A. Size and shape of the oceans changes.
B. Ocean floor is no older than 200 million years old.
5. Subduction in the Pacific Ocean –
A. Pacific Ocean is shrinking!
C. Deep-ocean trenches swallow more oceanic crust than the mid-ocean ridge can add new crust.
6. Subduction in the Atlantic Ocean –
A. Atlantic Ocean is expanding!
C. Mid-ocean ridge adds new crust and pushes the continents so the whole ocean is getting wider.
1. Do the continents look like they could fit together easily?
2. Alfred Wegener
A. Hypothesis = all continents had once been joined together in a single landmass
B. Called it Pangea
C. Pangea existed 300 million years ago
D. Over time it broke apart
E. Called the break up of Pangea – Continental Drift
3. Evidence to prove his theory
1. African and South American mtn. ranges lined up
B. Fossils –
1. found all over the different continents along edges
2. example – Glossopteris
1. climate had not changed, but positions of the continents have changed.
4. Rejection of Wegener’s Theory –
A. He explained how the continents moved
B. His theory was rejected because he could not physically prove it.
C. It was not accepted until 1960 that he was correct!
1. Plates –
A. The lithosphere is broken into separate sections.
B. Fig. 26, pg. 33
2. Theory of Plate Motion –
A. Combination of sea floor spreading, Earth’s plates, and continental drift.
B. Renamed Plate Tectonics
C. It explains the formation, movement, subduction of Earth’s plates.
D. How can the Earth’s plates move?
1. lithosphere floats on top of the asthenosphere
2. convection currents move the plates
3. movement causes volcanoes, mtn. Ranges, earthquakes and deep-sea trenches.
3. Plate Boundaries –
A. Lines where pieces of the Earth meet.
4. Transform boundaries –
A. Crust is neither created not destroyed
B. 2 plates slip past each other.
C. Fig. 27, pg. 34
5. Divergent boundaries –
A. 2 plates move apart
B. Occurs at the mid-ocean ridge and some continents
C. A rift valley forms.
6. Convergent boundaries –
A. 2 plates come together.
B. Creates a collision.
C. Either forms a deep-sea trench or a mtn. Range.
D. Fig. 28, pg. 36