sea-floor spreading. tubeworms have no mouth, eyes, or stomach ("gut"). their survival...

Sea-Floor SpreadingSea-Floor Spreading


Tubeworms have no mouth, eyes, or stomach ("gut"). Their survival depends on a symbiotic relationship with the billions of bacteria that live inside of them. These bacteria convert the chemicals that shoot out of the deep sea vents into food for the worm.

Sea-Floor SpreadingSea-Floor SpreadingSonar - a device that bounces sound waves off under-water objects and then records the echoes of these sound waves. The time it takes for the echo to arrive indicates the distance to the object.

Sea-Floor SpreadingSea-Floor Spreading Mid-Ocean RidgeMid-Ocean Ridge – the longest chain – the longest chain

of mountains in the world---these are of mountains in the world---these are divergentdivergent plate boundaries. plate boundaries.

Sea-Floor SpreadingSea-Floor Spreading Sea-Floor Spreading – Harry Hess in the 1960’s; the process that continually adds new material to the ocean floor while pushing older rocks away from the ridge

Ocean floor moves like a Ocean floor moves like a conveyorconveyor belt belt carrying continents with it. carrying continents with it.

New New ocean floorocean floor forms along cracks in forms along cracks in the ocean crust as molten material erupts the ocean crust as molten material erupts from the mantle spreading out and from the mantle spreading out and pushing pushing older rocksolder rocks to the sides of the to the sides of the crack. crack.

New ocean floor is continually added by New ocean floor is continually added by the process of the process of sea-floorsea-floor spreading. spreading.

Sea-Floor SpreadingSea-Floor Spreading1. Evidence from Molten Material – Rocks shaped like pillows(rock pillows) show that molten material has erupted again and again from cracks along the mid-ocean ridge and cooled quickly

http://www.youtube.com/watch?http://www.youtube.com/watch?v=gn_IW5Vsxawv=gn_IW5Vsxaw

Evidence #1: Molten MaterialEvidence #1: Molten Material

The submersible, Alvin, The submersible, Alvin, found strange rocks found strange rocks shaped like pillows or shaped like pillows or like toothpaste squeezed like toothpaste squeezed from a tube. from a tube.

Such rocks can form Such rocks can form only when molten only when molten material hardens quickly material hardens quickly after erupting under after erupting under water.water.

Sea-Floor SpreadingSea-Floor Spreading2. Evidence from Magnetic Stripes – Rocks that make up the ocean floor lie in a pattern of magnetized stripes which hold a record of the reversals in Earth’s magnetic field

Evidence #2: Magnetic Evidence #2: Magnetic StripesStripes

Scientists discovered Scientists discovered that the rock that makes that the rock that makes up the ocean floor lies up the ocean floor lies in a pattern of in a pattern of magnetized “stripes”. magnetized “stripes”.

They hold a record of They hold a record of reversals in Earth’s reversals in Earth’s magnetic field. magnetic field.

Earth's magnetic field comes from this ocean Earth's magnetic field comes from this ocean of iron, which is an electrically conducting fluid of iron, which is an electrically conducting fluid in constant motionin constant motion

Supercomputer models of Supercomputer models of Earth's magnetic fieldEarth's magnetic field..

Sea-Floor SpreadingSea-Floor Spreading3. Evidence from Drilling Samples – Core samples from the ocean floor show that older rocks are found farther from the ridge; youngest rocks are in the center of the ridge

Sea-Floor SpreadingSea-Floor Spreading Subduction – Process by which the ocean floor sinks beneath a deep-ocean trench and back into the mantle; this part of the ocean floor melts in the process

Sea-Floor Spreading: Sea-Floor Spreading: Subduction zoneSubduction zone

Deep-Ocean Trench – Occurs at subduction zones. Deep underwater canyons form where oceanic crust bends downward

http://www.wwnorton.com/college/geo/egeo/animations/ch2.htm

http://science.discovery.com/videos/100-greatest-discoveries-shorts-magnetic-field-reversal.html

http://www.youtube.com/watch?v=4LoiInUoRMQ&feature=fvw

http://www.youtube.com/watch?v=6CsTTmvX6mc

sea-floor spreading. tubeworms have no mouth, eyes, or stomach ("gut"). their survival...

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