Presentation on theme: "CONTINENTAL CRUST vs. OCEANIC CRUST Solar Wind."— Presentation transcript:
CONTINENTAL CRUST vs. OCEANIC CRUST
Earth or Ocean
How many oceans?
Continental Drift Alfred Wegner 1912 German geophysicist Super continent:PangeaPanathalassa 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
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: 4 Lithogenous Hydrogenous Biogenous Cosmogenous
Continental Margin Continental Shelf: Gentle angle Sm. Pt. of Oceans ½ mile – 450 mile wide VERY rich in sea life Continental Slope: Actual boundary of the continents Very steep angle Continental Rise: Where the sediment has accumulated Abyssal Plain: Deep sea floor Has: Hills, guyots volcanoes
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