Chapter 9 Plate Tectonics. Sections 1-5 p. 248-270. 9.1 Continental Drift Wegener: Early Observations. German Scientist Alfred Wegener (1912) C ontinents had once been joined to form a single super continent Pangaea (‘all land’ ) S cientific hypothesis based on: Fossil evidence
Sections 1-5 p. 248-270
Shows depth of 900 m; brown represents areas of overlap
a) rock and mineral formations
b) climate evidence
c) land shape
d) vegetation species
e) fossil evidence
Be prepared to support your choice as to why these pieces of evidence are used to support the theory of continental drift.
a. millimeters per day
b. centimeters per year
c. meters per year
d. centimeters per day
Convergent boundaries : Compression forces push plates together
Divergent boundaries: Tension forces move plates apart
Transform boundaries: Shearing forces cause plates to slide against each other (opposite directions or same direction @ different rates)
Hot magma rises to fill the 'gap' creating:
new crust and mountain ranges
forms themid-ocean ridge.
Both earthquakes and volcanoes occur at this type of boundary.
Rising magma can build up above ocean surface to create a volcanic island (for example Surtsey, Iceland).
(ex. North American and Eurasian Plate form the Mid-Atlantic Ridge)
Ex. Kuril Islands and Marianas Trench: plunges deeper into the Earth's interior (~11,000 m) than Mt Everest, the world's tallest mountain, rises above sea level (~8,854 m).
1. Aleutian Islands, Alaska
________ and more ________ plate sinks below the other.
HIMILAYAN MOUNTAINS (like MT EVEREST and K2)
The 10 highest mountains in the world are found here
* Convergent Boundaries create ____________ and ________________, especially around the _________ Ocean in the _______________.
“RING OF FIRE”
3. ___________________ boundary:
Fault = a break in a body of rock. One block slides relative to the other (lots of friction)
What do you see? How did this happen?
San Andreas Fault- California/Mexico
a. an oceanic ridge
b. a continental-continental boundary
c. a transform boundary
d. an oceanic-continental boundary
compass points S
-contains large amts of Fe-bearing minerals
→ imaginary “strips” along seafloor
EQ occur within
or adj. to trench
a. 5 million years
b. 3 million years
c. 1 million years
d. 100,000 years
Be prepared to support why an isochron map provides evidence for seafloor spreading?
What is special about Hawaii?
1. Slab-Pull and
2. Mantle Convection
Be prepared to support your choice as to why convection currents drive plate movement.
b. continental drift
c. magnetic reversal
d. mantle convection
a. ridge push
b. slab pull