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How many oceans? - PowerPoint PPT Presentation

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How many oceans?. Continental Drift. Alfred Wegner 1912 German geophysicist. Super continent:. Pangea. Panathalassa. 2 sections: . Laurasia. Gondwanaland. Problem with Wegner’s theory:. Finally accepted in :. 1960. Why no one believed him?.

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continental drift
Continental Drift

Alfred Wegner 1912 German geophysicist

Super continent:



2 sections:



Problem with Wegner’s theory:

Finally accepted in :


why no one believed him
Why no one believed him?
  • Wegner said the continents could plow through the continental crust.
  • Said the continents moved because of the gravitational pull of sun and moon.
  • Said the spinning of the earth also caused continents to move.
mid ocean ridge
Mid Ocean Ridge

Post WW II b/c of sonar use to track submarines

Mtns. avg 1.5 miles high

Cmdr. Harry Hess leaves sonar on full time

Responsible for creating …..

evidence the cd occurred
EVIDENCE the CD occurred
  • Glacial Evidence:
    • 300 million year old Glacial remains found in India, Africa, Australia, S. America
    • Whole world covered with ice?

These continents used to be located

at the north and south poles

more evidence
More evidence
  • Palm tree fossils found in Arctic regions
  • Coral fossils found in present day cold climates
  • Maps of

continent locations

magnetic reversals
Magnetic reversals


Molten rock contains: MAGNETITE

types of ocean sediments 4
Types of ocean sediments: 4






Plate Movements

Divergent Boundaries

Convergent Boaundaries

continental margin
Continental Margin

Continental Slope:

Actual boundary

of the continents

Very steep angle

Continental Shelf:

Gentle angle

Sm. Pt. of Oceans

½ mile – 450 mile wide

VERY rich in sea life

Abyssal Plain:

Deep sea floor


Hills, guyots


Continental Rise:

Where the sediment

has accumulated

active vs passive margins
Active vs. Passive margins

Steep shelf, slope and there is no rise

Lots of Earthquake and volcanic activity

Ex. Western edge of S. American coast

Wide Shelf, gentle slope, long rise, lots of sediment

Geologically inactive b/c no plates are subducting

Ex. East coast USA


BBC: hydrothermal vents

  • BBC: underwater lake