Ocean Basins

Topography

One World Ocean

Four ocean Basins:What about the Southern Ocean?

Ocean Floor Topography

Earth’s Crust

Oceanic crust- more dense, newer, andcomposed of iron and

magnesium.Continental crust-less dense, older, and

composed of many materials- “granitic”

Trenches- Subduction zones

Mariana- 38,635, Tonga- 35,505, Japan- 34,626, Puerto Rico-30, 184 feet deep.

Abyssal Plains

• 3,000 – 6,000 ft. deep

• Flattest place on Earth

• Almost ½ of Earth’s surface

• Abyssal clay feels like “cold butter”

• Conditions: freezing and intense pressure.

Ocean SedimentsThree Catagories:

1. Lithogenous (terrigenous)• weathering of landLitho- rock

2. Biogenous:• Remains of organisms• More than 30% called “OOZE”• Bio- life

3. Hydrogenous: • precipitants of sea water• Hydro- water

Biogenous sediment

• Mainly protozoans• Composed of:

silica

calcium carbonate

radiolarians

Diatoms

Coccolithophores

Gene- origin/ beginning

Pacific Ocean Basin

Largest- 50% of the world ocean

Avg. depth- 13, 740 ft.• Contains most trenches• Fastest growing

ridge/rise• 1,000,s of islands• “Ring of fire” volcanos

that result from subduction.

East Pacific Rise

Dead-ends into Baha California.

Named by Magellan- PacificHe thought the waters were calm

Pacifia= peaceful

Underwater landforms-