GEOGRAPHY

GEOGRAPHY

Plate movements
1. Divergent
  1. Oceanic - Oceanic
    1. Definition
      1. As two oceanic plates diverge, the edges of the plates are pushed upward to form ridges.
      2. Material from the mantle wells up through the ridges, cools and hardens to form a new ocean floor. This is called sea floor-spreading.
      3. New oceanic crust forming continuously and becomes older as it moves away from the ridge crest with seafloor spreading.
    2. Effects
      1. Mid-oceanic ridges
      2. Earthquakes
      3. Volcanoes
  2. Continental - Continental
    1. Definition
      1. As two continental plates pull apart, faults (cracks between rocks) occur.
      2. Land sinks between the faults, forming rift valleys
    2. Effects
      1. Rift valley
2. Transform
  1. Continental - Continental
    1. Effects
      1. Earthquakes
    2. Definition
      1. Plates move past each other in different directions.
      2. Tear faults form, acoompanied by earthquakes because of the great amount of stress built up in these areas.
      3. There is little volcanic avitivity and little crustal material is destroyed.
3. Convergent
  1. Oceanic - Oceanic
    1. Effects
      1. Oceanic trench
      2. Volcanoes
    2. Definition
      1. When two oceanic plates collide, one may sink beneath the other, producing an oceanic trench.
      2. Subducted plate melts and the magma rises and forms volcanoes.
  2. Continental - Continental
    1. Effects
      1. Fold mountains
      2. Earthquakes
    2. Definition
      1. When two continental plates collide, neither tends to subduct as their densities are similar.
      2. The two continental plates buckle and upfold, forming fold mountains.
  3. Oceanic - Continental
    1. Definition
      1. When a continental plate collides with an oceanic plate, the denser oceanic plate subducts under the lighter continental plate.
      2. At the subduction zone, an oceanic trench may form.
    2. Effects
      1. Oceanic trench
      2. Fold mountains
      3. Earthquakes (due to subduction)
      4. Volcanoes
Volcanoes
1. Shield volcanoes
  1. Properties
    1. Effusive eruptions
    2. Shield shape with broad base and gentle slopes
    3. Basaltic lava
    4. GTV: Low amount of dissolved gas; Higher temperature (1200 degrees); Low viscosity
  2. Examples
    1. Kilauea, Hawaii
    2. Mt. Washington, USA
2. Stratovolcanoes
  1. Examples
    1. Mt. Fuji, Japan
    2. Krakatoa, Indonesia
    3. Mt. St Helens, USA
  2. Properties
    1. Violent and explosive eruptions
    2. Cone shape with steep slopes
    3. Acidic lava
    4. GTV: High amount of dissolved gas; Lower temperature (800 degrees); High viscosity
3. Definition
  1. How do volcanoes form?
    1. Volcanoes can from either when on top of a hotspot or when tectonic plates converge or diverge. Magma escapes through cracks of the plate and rises to form a volcano.
  2. What is a volcano?
    1. A volcano is a vent in the earth from which molten rock, lava and steam issue.
  3. Where are volcanoes located?
    1. Most volcanoes are found along the Pacific Ring of Fire.

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	Created by Soong Rui Jie over 9 years ago