Ch 9 NotesMr. Russo
Beaumont High School
Divergent boundary Convergent boundary Transform fault
boundary Oceanic Ridge Rift Valley Seafloor Spreading
Subduction Zone Trench Continental Volcanic
Arc Volcanic Island Arc Paleomagnetism Hot Spot
Ch 9 Vocab Matrix (Pg 45)
We will be able to describe the 4 pieces of evidence for the theory of continental drift.
Objective: Ch 9.1 Pg 47
Continental Drift – The continents had once been joined to form a single supercontinent◦Proposed by Alfred Wegner
Continental Drift
Pangaea – The supercontinent (All Land)◦Continents broke apart and drifted to their current position
Pangaea
Continental Puzzle – Continents appear to form a puzzle that can be put together
What evidence supports continental Drift?
Matching Fossils – Several of the same types of fossils on different landmasses
What evidence supports continental Drift?
Rock Types and Structures – Mountain belts that end on one coastline seem to reappear on a landmass across the ocean
What evidence supports continental Drift?
Ancient Climates – Found evidence of glacial ice in countries that shouldn’t have any glaciers
What evidence supports continental Drift?
Objective
The upper mantle and the crust act like a strong rigid layer. ◦This layer is called the lithosphere
Ch 9.2What is the theory of plate tectonics?
The lithosphere lies on top of the weaker mantle called the ASTHENOSPHERE
Plate – Plates are sections of the lithosphere◦7 Major plates◦Largest – Pacific Plate
◦Plates move 5cm/yr
Plates
Convergent
Divergent
Transform
What are the 3 types of plate boundaries?
Divergent Boundary – Occur when two plates move apart
Example – East African Rift Valley
Divergent Boundary
Example – East African Rift Valley
Convergent boundary – Occur when two plates move together
Convergent Boundary
Transform Boundary – When two plates grind past each other◦Example – San Andreas
Transform Boundary
Every Plate contains all 3 types of boundaries
Oceanic Ridge – Elevated area in the ocean, found along divergent boundaries
Ch 9.3Oceanic Ridge
Rift Valley – Deep faults found along divergent boundaries
Rift Valley
Seafloor Spreading – The process by which plate tectonics produce new lithosphere
Oldest part of the ocean floor is 180 million years old.
Seafloor Spreading
Subduction Zone – When one plate is forced down beneath another plate. (Convergent Boundary)
Subduction Zone
Trench – Surface Feature produced during a subduction zone.
Trench
Continental Volcanic Arc – When a continental and ocean plate collide, they produce volcanoes on the land.
Continental Volcanic Arc
Volcanic Island Arc – When 2 ocean plates collide, they produce volcanoes in the middle of an ocean, forming islands
Volcanic Island Arc
Mountains are formed when two continent plates collide.
Example – Himalayas in South Asia
Mountains
Transform Fault – Earthquakes – At Transform faults, plates grind past without destroying the lithosphere and produce earthquakes.
Example – San Andreas Fault , CA
Transform Fault - Earthquakes
Convergent Boundaries – Lithosphere is destroyed
Divergent Boundaries – Lithosphere is created
Transform Boundaries– Lithosphere is neither created nor destroyed.
Notice
Paleomagnetism – Study of changes in Earth’s magnetic field
Ch 9.4Paleomagnetism
Normal Polarity – Same magnetism as present day magnetic field
Normal Polarity
Reverse Polarity – Rocks that show opposite magnetism then present day
Reverse Polarity
The discovery of strips of rocks of alternating polarity across the ocean ridges.
What evidence supports theory of plate tectonics?
The youngest crust (Seafloor) is at the ridge crest, the oldest crust is further away
How old is the seafloor?
OldestYoungest
Hot Spot – A rising plume of mantle that creates a volcanic area (Hawaii)
Hot spot supports idea that the plates move over Earth’s surface
Hot spot
Shaded Region – Reverse Polarity
White Region – Normal Polarity
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