Download Plate Tectonics Notes I. Continental Drift A. Hypothesis stating that

Plate Tectonics Notes
I. Continental Drift
A. Hypothesis stating that Earth’s continents have moved from their
original positions.
B. Alfred Wegener, climatologist, proposed this hypothesis
C. Evidence for continental drift
1. Matching continental shapes
2. Matching mountain chains on separated continents
3. Matching rocks on separated continents
4. Matching fossils on separated continents
a. plants
b. animals
5. Matching paleo-climates
a. evidence of glaciers in now warm places
b. evidence of tropical settings in now cold places
II. Plate boundaries
A. Edges of major sections of Earth’s crust
1. Pacific, Asian, European, African, North American, South American
2. Minor plates in between, example Juan de Fuca and Nazca
B. Types
1. Transform—shearing
2. Convergent—compression
3. Divergent—stress
III. Subduction
A. Area along a plate boundary where one edge dives beneath another
1. Occur along oceanic and continental boundaries
a. Trenches form on the ocean floor
b. Example—Marianas Trench
2. Occur along oceanic and oceanic boundaries
a. Island arcs form--volcanic
b. Examples—Aleutian Islands and Japan
3. Volcanic chains trace the subduction zone on land
a. Cascade Mountains
b. Andes Mountains
IV. Sea-floor Spreading
A. Mid-ocean Ridges
1. Volcanic mountain chains where new sea floor erupts
B. Age of the sea floor
1. Younger at the ridges, older at the edges
C. Patterns of magnetism
1. Basalt on the sea floor “records” patterns of magnetic North pole
reversal.
2. Pattern is reflective from ocean ridges outward
D. Ocean floor topography
1. Ridges, basins, faults
V. Other evidence for the theory of Plate Tectonics
A. Hot spots
1. Areas of volcanic activity unrelated to plate boundaries
2. Examples—Hawaii and Yellowstone
B. Earthquake locations
1. Most locations of earthquakes are along or close to plate
boundaries
2. Example—San Andreas Fault
C. Volcano locations
1. Most volcanoes are located on or near plate boundaries
2. Examples—Cascades and Andes
D. Mountain ranges
1. All mountain ranges not volcanic are a result of plate movement
tension, and stress.
2. Examples—Rockies and Himalayas
E. Geothermal activity
1. Activity is usually located in areas of current or past volcanic
activity.
2. Examples—Japan and New Zealand
VI. Convection currents in the mantle are the driving force!