continental drift theory
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- 1. Continental drift theory
2. According to the hypothesis of continental drift, continents have moved slowly to their current locations.
Theory of continental was purposed by alferedwegner in (1912)
3. 4. Mechanism for Plate Tectonics
Seafloor Spreading provided insight to the mechanism for how the continents moved.
The magma which pushes up at the mid-ocean ridge provides the new land pushing the plates, and the subduction zones gobble up the land on the other side of the plates.
The mechanism was convection currents!
5. Thirteen plate on the world
6. About 225 million years ago , nearly all the land was united in one large land callled
7. Pangaea about 200 million years ago, before it began breaking up. The southern portion of Pangaea Gondwana, and the northern portion Laurasia.
8. The continents about 70 million years ago. Notice that the breakup of Pangaea formed the Atlantic Ocean. Indias eventual collision with Eurasia would form the Himalayan Mountains
9. 10. The position of the continents today. The continents are still slowly moving, at about the speed your fingernails grow. Satellite measurements have confirmed that every year the Atlantic Ocean gets a few inches wider!
11. 12. 13. Sea flour spreading
As the seafloor spreads apart at a mid-ocean ridge, new seafloor is created.
14. 15. Plate tectonic explain
16. Earthquakes and volcanoes occur mostly along or near trenches and mid-ocean ridges...
17. Mountain formation
19. 20. Thawaearthequakeekkakdanna
21. Evidence to support the theory
22. Continental drift fossil evidence
23. Puzzle Pieces
Continents look like
they could be part of
a giant jigsaw puzzle
24. Distribution of fossils of several organisms supported The theory that the continents were once joined together
25. Francis Bacon (1561-1626) first noted how coasts of Africa and South America fit.
26. Mesosaurus, a fresh water reptile that couldnt swim across the open sea
27. Sequence of Rocks
Same rock patterns found in South America, India,
Africa, Antarctica and Australia
28. Mountains in South America and Antarctica are believed to have formed as part of the same mountain chain.
29. Ancient Climates
Tropical plant remains (coal deposits) found in Antarctica
Glaciations in Africa, South America, India, and Australia during the same time
Deposits found inAntarctica.
Coal requires a warm, lush climate ===>
Whats Antarctica like today? ===>
31. Glossopteris, a seedfern whose seeds are too large to be carried far by wind
32. Fossils of Glossopteris are found in Permian rocks of South Africa, India, Australia, South America, and Antarcticaall regions that were once part of Gondwanaland.
33. Problems With The Theory
- No mechanism for movement of continents
34. Wind and currents could possibly move fossils 35. Theory was not accepted by scientists