continental crust vs. oceanic crust

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