Sea Floor Spreading

Question 1

A chain of mountains found underwater

Answer 1

ridge

Question 2

A device that bounces sound waves to determine distance and location

Answer 2

sonar

Question 3

When sonar was first used

Answer 3

World War II

Question 4

Scientist responsible for discovering mid ocean ridges

Answer 4

Harry Hess

Question 5

Sea floor spreading begins here

Answer 5

Crack at mid ocean ridge

Question 6

Evidence that supports sea floor spreading

Answer 6

Pillow-like rocks cooling quickly

Question 7

Where the ocean floor eventually sinks

Answer 7

Deep ocean trench

Question 8

When ocean crust sinks under continental crust

Answer 8

Subduction

Question 9

Where are older rocks on the ocean floor found

Answer 9

Furthest from the crack

Question 10

How long does it take subduction to occur

Answer 10

Millions of years

Question 11

True or false: Continental crust also undergoes subduction

Answer 11

True

Question 12

Which crust has high density

Answer 12

Oceanic Crust

Question 13

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

Answer 13

True

Question 14

Which ocean is currently in the process of subduction

Answer 14

Pacific

Question 15

What do rocks in the ocean floor contain?

Answer 15

Iron

Question 16

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

Answer 16

Iron in rocks

Question 17

When was the last magnetic flip of the poles

Answer 17

450,000 years ago

Question 18

What is the main cause of subduction and sea floor spreading

Answer 18

Convection currents

Question 19

What is the layer of earth responsible for magnetic field

Answer 19

Outer core

Question 20

Which type of rock makes up the oceanic crust

Answer 20

Basalt