CONTINENTAL DRIFT THEORY PPT
- 1. Continental Drift Under The Guidance of By:- Ramshankar Kirar Pushpraj Singh Kaurav M.Sc. 1st year S.O.S Earth Science School Of Studies In Earth Science Jiwaji University, Gwalior
- 2. Content • Introduction • History • Significance • Force for drifting • Pangea/drift proof Shape clues Fossil clues Climate clues Rock clues • Proof was not enough • Conclusion • Bibliography
- 3. Introduction:- • The word tectonics came from the Greek word tektov (tekton –to build ; builder’’).This word is also the origin of other tect words , such as architect. • The very first detailed proposal of an idea along these lines as the plate tectonics theory was made by Alfred Lothar Wegener in 1911, under the name “Continental Drift”. • Wegener argued that there was once a supercontinent (which he named Pangea – meaning “all lands”)which split up over millions of years and gradually “drifted” over to their current places on earth ; at a rate of a few centimeters year.
- 4. History • Francis Bacon: In the mid 1600s Bacon noticed that there’s an odd puzzle piece fit between Africa and South America. • Antonio Snider-Pellegrini: In 1858 Antonio enhanced Bacon’s discovery by comparing the coastlines of Africa and South America but it was still rejected by most people. • F.B Taylor: postulated his concept of “horizontal zontal displacement of the continent’’ in the year of 1908 but Published only in the year 1910 The main purpose of his hypothesis was to explain the Problems of the origin of the folded mountains of tertiary period
- 5. Significance • It describes and explains the motion of portions(plates) of the earth’s crust. • It explain the mechanisms that created the continents, mountain ranges, the ocean floor, earthquakes, and other macro and some micro events on/in the earth’s crust. • We can track backward and look at what the earth looked like in past ages and extrapolate forward to see what could possibly be the future for our planet.
- 6. Alfred Wegener, a German meteorologist was the first to make an exhaustive investigation of the idea of continental Drift and to convince others to take it seriously. In his book The origin of the continents and oceans (1915) He drew a series of map showing three stages in the drift Process beginning with an original large landmass which He called Pangaea (meaning “all lands”)
- 8. Force For Drifting • Wegener proposed that the movement accountable for the drifting of continents was instigated by tidal force and pole-fleeing force • The polar-fleeing force relates to the rotation of the earth • The shape of earth • The second force that was proposed by Wegener ,the tidal force • Though ,most of the scholars considered these force to be insufficient
- 9. Pangea/Drift Proof • Wegener’s idea of continental drift was controversial at the time. • People wanted proof that this has and is occurring. • To prove his idea, Wegener found 4 major pieces of evidence: Shape Fossils Climates Rocks
- 10. Shape Clues The continents fit together like puzzle pieces. • Example of Shape: The east coast of South American and west coast of Africa match.
- 11. Fossil clues Identical index fossils were found on separate continents. Fossil e.g. 1: Mesosaurus An extinct reptile that lived on land and fresh water. Fossils of Mesosaurus have been found on South America and in Africa. These fossils were dated to the same geologic time frame. The continents of South American and Africa were one joined so the reptile could move freely from one landmass to the next. Other Index Fossils Include: -Cynognathus – Land Reptile -Lystrosaurus – Land Reptile
- 12. Continues…. Identical index fossils were found on separate continents. Fossil Example: Glossopteris Same Plant found on Africa, India, South America and Antarctica. The continents were once close together so the plants seeds were easily able to spread. It is not possible for the seeds of that plant to spread across the entire globe.
- 13. Climate Clues o Wegener noticed evidence of major climate changes o Climate Example: Tropical Plants in Arctic Area o Warm weather plant fossils were found in the Arctic. o Areas of land that were once in the topics, drifted apart and move toward the arctic. o Climate Example: Wegener noticed evidence of major Glaciation. o When a glacier moves, it scratches the land . o Glacier scratches can be seen in warm tropical areas. o Glacial evidence is found in area where there are no glaciers. o Area of land that were once in the arctic, drifted apart and moved toward the tropics.
- 14. Rock Clues Rock and rocks structures on different are the same where the land was once joined. Rock example: North America and Europe Rock Structures match where the Appalachian Mountains in the eastern united state once where jointed against the side of Europe. How is this possible ? The continents once were together when the mountains formed and then they separated – breaking in the existing mountain chain as North America and Europe move away from each other.
- 15. continuous…….. Rock example: Coal Fields Coal fields in North America and Europe match up when pieced together. How is this possible? When Laurasia formed after the breakup of Pangea, the continents of North America and Europe were once joined together. This supercontinent was located toward the equator and the type of humid swampy environments that are needed in order to form coal. After the coal formed the continent separated breaking the existing rock layers as North America and Europe moved away from each other.
- 17. Proof was not enough…. Despite these 4 major pieces of evidence, geologists of Wegener's time still did not believe his idea. The problem was that while Alfred was able to show evidence that it could have happened ,he was not able to explain how or why the continents moved. He needed to teII people what mechanism was causing the “so called’’ continental drift.
- 18. Conclusion • Paleomagnetic studies appear to provide support for Wegener’s ideas of continental drift. • The continents appear to have been joined over 200 million years ago. • Paleomagnetic evidence also suggests the continents have moved northwards.
- 19. Bibliography Earth Dynamic Systems(sixth edition) By: W. Kenneth Hamblin Physical geology(second edition) By: G.B. Mahapatra
- 20. Thank You