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CONTINENTAL DRIFT THEORY. ABRAHAM ORTELIUS- 1596 1 st 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. LAURASIA. TETHYS SEA. GONDWANA.
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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
LAURASIA TETHYS SEA GONDWANA DRIFTING OF CONTINENTS
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 Tidal (Due to attraction of Sun & Moon) Pole-felling (Due to rotation of earth)
Post-Drift Studies • Convectional Current Theory- Arthur Holmes in 1930. • Mapping of the Ocean Floor:
CONFIGURATION OF SEA FLOOR CONTINENTAL MARGINS MID-OCEANIC RIDGES • SHELF • SLOPE • TRENCHES ABYSSAL PLAIN 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 • 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.
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 • Antarctica plate • North American Plate • South American Plate • Pacific Plate • India-Australia-New Zealand Plate • Africa Plate • Eurasia Plate
Minor Plates • Cocos Plate: Between Central America and Pacific Plate • Nazca Plate: South America and Pacific Plate. • Arabian Plate: South Arabian landmass. • Philippine Plate: Asiatic and Pacific Plate • Caroline Plate: Philippine and Indian Plate. • 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