Continental drift 2

  • 873 views
Uploaded on

 

More in: Travel , Technology
  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Be the first to comment
No Downloads

Views

Total Views
873
On Slideshare
0
From Embeds
0
Number of Embeds
0

Actions

Shares
Downloads
18
Comments
0
Likes
1

Embeds 0

No embeds

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
    No notes for slide

Transcript

  • 1. CONTINENTAL DRIFT
  • 2. Movement of the Earth’s continents relative to each other.
  • 3. Abraham Ortelius (1596)
    first put forward the hypothesis that continents ‘drift’
    In his work Thesaurus Geographicus suggested that the Americas were “torn away from Europe and Africa by earthquakes and floods”
  • 4. Alfred Wegener (1596)
    Continents had once formed a single landmass before breaking apart and drifting to their present locations
    First use the phrase “continental drift”
  • 5.
  • 6. Evidence that continents ‘drift’
    Similar plant and animal fossils are found around different continents shores, suggesting that they were once joined.
  • 7. Examples:
    Fossils of Mesosaurus, a fresh water reptile rather like a small crocodile, found both in Brazil and South Africa
    Fossils of the land reptile Lystrosaurusfrom rocks of the same age from South America, Africa and Antartica
  • 8. fossils of the Glossopteris, an ancient fern, are found in South America, Africa, Antarctica, India, and Australia.
    It was hypothesized that such a distribution could only come about if the continents were all part of the one super-continent.
  • 9.
  • 10. The complementary arrangement of the facing sides of South America and Africa is obvious, but is a temporary coincidence.
  • 11.
  • 12. Wegener noted that the rock sequences in South America, Africa, India, and Australia are very similar. Wegener showed that the same three bottoms layers occurred on each of the continents.
  • 13. The bottom layer, called tillite, was thought to be of glacial origin.
    The middle layer composed of coal beds, shale and sandstone contained Glossopteris fossils, as did the bottom tillite layer.
    The top most and youngest layer is lava flows. Such a strong similarity in the rock record of these localities, now separated by great geographic distance, lent credence to Wegener's notion of continental drift.
  • 14. The occurrence of glacial features in the geologic record of South America, Africa, India ,and Australia provides further evidence for the notion of continental drift. Glaciers affected all or part of these continents at the same time in Earth history.
  • 15.
  • 16. Rejection of Wegener’s theory
    One problem was that the a plausible driving force was missing.
    As late as 1953, Carey introduced the theory of plate tectonics thus the theory of continental drift was rejected by the physicist Scheiddiger