CONTINENTAL DRIFT THEORY

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CONTINENTAL DRIFT THEORY

• ABRAHAM ORTELIUS- 1596 1st Proposed the movement
  of continent
• ANTONIO PELLEGRINI Drew a map showing Europe,
  America and Africa together
• ALFRED WEGENER -1912 Proposed Continental Drift
  theory.

PANGAEA
PANTHALASSA
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DRIFTING OF CONTINENTS
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EVIDENCE IN SUPPORT OF THE CONTINENTAL DRIFT

• The Matching of Continents (Jig-Saw-Fit) Bullard
  in 1964.
• Rock of Same Age Across the Oceans- Radiometric
  dating.
• Tillite Sedimentary rock formed out of deposits
  of glaciers.
• Placer Deposite Deposits of gold in Ghana coast
  and veins in Brazil.
• Distribution of Fossils Lemur occur in India,
  Madagascar and Africa. Mesosaurus a small
  reptiles skeletons are found in southern cape
  province of south Africa and Iraver formation of
  Brazil.

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FORCES
Tidal (Due to attraction of Sun Moon)
Pole-felling (Due to rotation of earth)
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Post-Drift Studies

• Convectional Current Theory- Arthur Holmes in
  1930.
• Mapping of the Ocean Floor

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CONFIGURATION OF SEA FLOOR
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CONFIGURATION OF SEA FLOOR
CONTINENTAL MARGINS
MID-OCEANIC RIDGES

1. SHELF
2. SLOPE
3. TRENCHES

ABYSSAL PLAIN
1
4
2
3
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DISTRIBUTION OF EARTHQUAKES AND VOLCANOES

• Mid-Atlantic ridges
• It bifurcates a little south of Indian
  subcontinent with one branch moving into East
  Africa and other meeting Myanmar to New Guiana.
• Alpine Himalaya system.
• Rim of Pacific called Ring of Fire.

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SEA FLOOR SPREADING
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SEA FLOOR SPREADING

• The theory proposed by Hess in 1961.
• Volcanic eruptions are common along Mid-oceanic
  ridges.
• Rocks equidistant on either sides of crest of
  mid-oceanic ridges shows remarkable similarities.
• The Ocean crust rocks are much younger then
  continental crust.
• Sediments on the ocean floor are unexpectedly
  very thin.
• The deep trenches have deep-sheeted earthquakes.

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PLATE TECTONICS

• Theory proposed by McKenzie and Parker and Morgan
  in 1967.
• Tectonic Plate ore Lithosphere Plate is massive,
  irregularly-shaped slab of solid rock, generally
  composed of both continental and oceanic
  lithosphere.
• Thickness 5-100km in ocean and upto 200km in
  continental areas.

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MAJOR PLATES

1. Antarctica plate
2. North American Plate
3. South American Plate
4. Pacific Plate
5. India-Australia-New Zealand Plate
6. Africa Plate
7. Eurasia Plate

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Minor Plates

1. Cocos Plate Between Central America and Pacific
   Plate
2. Nazca Plate South America and Pacific Plate.
3. Arabian Plate South Arabian landmass.
4. Philippine Plate Asiatic and Pacific Plate
5. Caroline Plate Philippine and Indian Plate.
6. Fuji Plate North-east of Australia.

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PLATE BOUNDARIES

• DIVERGENT BOUNDARIES When two plates move away
  from each other.
• CONVERGENT BOUNDARIES When two plate move
  towards each other.
• TRANSFORM BOUNDARIES When two plates slide
  horizontally each other.

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RATE OF MOVEMENT

• Artic ridge has the slowest rate 2.5cm/year
• East Pacific Rise near Easter Island in the South
  Pacific fastest rate of movement 15cm/ year.

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FORCE OF MOVEMENT

• Arthur Homes and Herry Hess convectional current