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Transcript
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
DRIFTING OF CONTINENTS
LAURASIA
TETHYS SEA
GONDWANA
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 reptile’s skeletons are
found in southern cape province of south Africa and
Iraver formation of Brazil.
FORCES
Pole-felling
(Due to rotation of earth)
Tidal
(Due to attraction of Sun & Moon)
Post-Drift Studies
• Convectional Current Theory- Arthur
Holmes in 1930.
• Mapping of the Ocean Floor:
CONFIGURATION OF SEA FLOOR
CONFIGURATION OF SEA FLOOR
CONTINENTAL MARGINS
1. SHELF
MID-OCEANIC RIDGES
ABYSSAL PLAIN
2. SLOPE
3. TRENCHES
1
4
2
3
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.
SEA FLOOR SPREADING
SEA FLOOR SPREADING
• The theory proposed by Hess in 1961.
• Volcanic eruptions are common along Midoceanic ridges.
• Rocks equidistant on either sides of crest of midoceanic 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.
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.
MAJOR PLATES
1.
2.
3.
4.
5.
6.
7.
Antarctica plate
North American Plate
South American Plate
Pacific Plate
India-Australia-New Zealand Plate
Africa Plate
Eurasia Plate
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.
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.
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.
FORCE OF MOVEMENT
• Arthur Homes and Herry Hess
convectional current