Sea Floor Spreading Flashcards

1
Q

A chain of mountains found underwater

A

ridge

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2
Q

A device that bounces sound waves to determine distance and location

A

sonar

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3
Q

When sonar was first used

A

World War II

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4
Q

Scientist responsible for discovering mid ocean ridges

A

Harry Hess

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5
Q

Sea floor spreading begins here

A

Crack at mid ocean ridge

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6
Q

Evidence that supports sea floor spreading

A

Pillow-like rocks cooling quickly

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7
Q

Where the ocean floor eventually sinks

A

Deep ocean trench

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8
Q

When ocean crust sinks under continental crust

A

Subduction

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9
Q

Where are older rocks on the ocean floor found

A

Furthest from the crack

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10
Q

How long does it take subduction to occur

A

Millions of years

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11
Q

True or false: Continental crust also undergoes subduction

A

True

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12
Q

Which crust has high density

A

Oceanic Crust

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13
Q

True or false: Subduction changes the size and shape of oceans

A

True

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14
Q

Which ocean is currently in the process of subduction

A

Pacific

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15
Q

What do rocks in the ocean floor contain?

A

Iron

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16
Q

What lines up in the direction of Earth’s magnetic poles

A

Iron in rocks

17
Q

When was the last magnetic flip of the poles

A

450,000 years ago

18
Q

What is the main cause of subduction and sea floor spreading

A

Convection currents

19
Q

What is the layer of earth responsible for magnetic field

A

Outer core

20
Q

Which type of rock makes up the oceanic crust

A

Basalt