Post on 01-Apr-2015
transcript
CONTINENTAL CRUST vs. OCEANIC CRUST
Solar Wind
Earth or Ocean
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?
1. Wegner said the continents could plow through the continental crust.
2. Said the continents moved because of the gravitational pull of sun and moon.
3. Said the spinning of the earth also caused continents to move.
Mid Ocean Ridge
Post WW II b/c of sonar use to track submarines
Cmdr. Harry Hess leaves sonar on full time
Mtns. avg 1.5 miles high
Responsible for creating …..
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
Fossil evidence
More evidence• Palm tree fossils found in Arctic regions
• Coral fossils found in present day cold climates
• Maps of continent locations
Magnetic reversals
Molten rock contains: MAGNETITE
animate
Sea floor spreading
Age of the sea floor confirmation
GLOMAR EXPLORER
Types of ocean sediments: 4Lithogenous
Hydrogenous
Biogenous
Cosmogenous
Ocean Sediment details
Project Nekton
HRE??
Continental vs. Oceanic
Divergent Boundaries
Convergent Boaundaries
Plate Movements
Transform Boundaries
Continental Margin
Continental Shelf:Gentle angleSm. Pt. of Oceans½ mile – 450 mile wideVERY rich in sea life
Continental Slope:Actual boundary of the continentsVery steep angle
Continental Rise:Where the sedimenthas accumulated
Abyssal Plain:Deep sea floorHas:Hills, guyotsvolcanoes
Active vs. Passive margins
Steep shelf, slope and there is no riseLots of Earthquake and volcanic activityEx. Western edge of S. American coast
Wide Shelf, gentle slope, long rise, lots of sedimentGeologically inactive b/c no plates are subductingEx. East coast USA
mid ocean ridge and hydrothermal vents
• BBC: hydrothermal vents
• BBC: underwater lake