Study Guide – Plate Tectonics:
1. Convergent: Plates that collide with one another.
a. Oceanic-Oceanic: Two oceanic plates collide
Example: Japan, Philippines, Aleutian Islands
b. Oceanic-Continental: One ocean plate and one continental plate
collide (ocean plate is more dense, will subduct or go under the
lighter continental plate)
Example: Andes Mountains, Cascade Mountains
c. Continental-Continental: Two continental plates collide
Example: Himalayas (folded mountains)
2. Divergent: Plates moving apart.
a. Continental-Continental: Two continental plates moving apart
from one another, tearing apart earth.
Example: Great Rift Valley in Africa
b. Oceanic-Oceanic: Oceanic plates moving apart from one
another, when they move apart, new crust is continuously
created.
Example: Mid-Atlantic Ocean Ridge
- Older Rocks farther away from Ridge, younger rocks
located closer to Ridge
3. Transform: Plates that slide or slip past one another.
- Earthquakes
- Example: San Andreas Fault, California
Harry Hess: Sea Floor SpreadingHis theory of sea floor spreading is based on the ideas of the reversal of
the magnetic North and that younger rocks are located near mid ocean
ridges and older rocks located farther away from the ridges. Plates move
because new rock is continuously being created.
Convection cells drive plate tectonics-occurs in lower mantle.
Hawaii- Hot mantle plume stays put, island chain is created as new island is
created over the “hot spot.” Magma rises up, cools, creates new land, then
the plate moves off the “hot spot” and a new island is created that moves
over the “hot spot.”
Wegener’s clues to continental drift- page 247
1. Fossils
2. Rocks (mountain ranges, coal beds)
3. Puzzle like fit
4. Glaciers (climate clues, glaciers present in regions with warm dry
climates)
Pangaea-supercontinent
2 types of plates:
1. Ocean plate- Thick, made of basalt and more dense
2. Continental plate- Thin, made of granite and less dense