CRASH COURSE-WORLD GEOGRAPHY Presented by - Bhanwar Singh Sirohi
PHYSICAL GEOGRAPHY - CONTINENTAL DRIFT THEORY AND SEA FLOOR SPREADING
ABOUT ME BA. (Hons) in Law from Awadh University I Defence Academy (115 Course) Cleared Civil Services Examination, 2012 Hobbies - Writing Poetry Course Fee Contribute Follow me on Unacademy at: https://unacademy.in/user/sirohib
CONTINENTAL DRIFT THEORY oet Tihe origin orcloninen Given by German geologist and meteorologist Alfred Wegner in 1 915 in his book, The Origin of Continents and Ocean:s According to this theory parts of Earth's crust slowly drifts over the liquid it Alfred Wegner in 1915 in hia mantle This theory was supported by fossil records There was a gigantic supercontinent which existed about 280 million years ago, named Pangea and one super-ocean called Panthalsa Pangea started to break into small supercontinents, named Laurasia and Gondwanaland about 150 million years ago (during Jurassic period) By the end of Cretaceous period, the continents separated into land masses that look like our modern day continents
GLANCE AT SOME EVIDENCES FOSSIL EVIDENCES Fossil plant Glossopteris found throughout India, South America, Southern Ossil plan Glssoprerls rouhd tnroughour Indld, SoUn Americd, 3ournern Africa, Australia and Antarctica Fossil of Mesosaurus found in both South America and South Africa Glacier deposits left over from million of years ago all over the southern hemisphere Similarity in rock structure on opposite sides of the Atlantic Ocean JIGSAW FIT S. America especially Brazil fits into Gulf of Guinea of Africa Antarctica fits into S. Australian Coast and S. E. African coast NW Australian coast fits E Indian Coast
Fossil evidence of the Tiassic land reptile Lystrosaurus. AFRICA INDIA SOUTH AMERICA AUSTRALIA AN ICA Fossil remains of Cynognathus,a tiassic land reptile approximately 3m long. Fossil remains of the freshwater reptile Mesosaurus Fossils of the fern Glossopteris. found in all of the southem continents, show that they were once joined
HYPOTHESIS The Pangea broke into continents that drove away in two directions Equatorward and Westward The movement towards Equator was because of Gravitational Differential Force or Centrifugal Force Force of Buoyancy The movement towards Westward direction was due to The tidal force of Sun and Moon The Pangea seperated in Angaraland or Laurasia and Gondwanaland in the Carboniferous period and the space between the two was filled with water - Tethys Sea
HYPOTHESIS Laurasia consisted of North America and Greenland & Eurasia (without India and Arabia) Gondwanaland consisted of Africa (with Arabia), South America, Australia, Antarctica and India South Pole was located near Durban, near Natal in South Africa During the Cretaceous period, eruption took place on Gondwanaland and also the Indian subcontinent, Madagascar, Australia and Antarctica broke away from it. Similarly the North America broke away and moved westwards due to Tidal forces
BEFORE SEPERATION AFTER SEPERATION
TRIAs 200 milhon years ago CRET ACEOUS so million years 900 PRESENT DAY