Sea Floor Spreading Presentation

Multiple Choice

What is the longest chain of underwater mountains called?

• Mid-ocean ridges

• Continental shelf

• Trenches

• Coral reefs

Multiple Choice

How did scientists map the mid-ocean ridges in the mid 1900's?

• Using sonar

• By diving

• With satellites

• By collecting rocks

Open Ended

Explain Harry Hess's theory of sea-floor spreading and how it adds new material to the ocean floor.

Multiple Select

Which of the following statements about sea-floor spreading are correct?

• It begins at the mid-ocean ridge.

• Molten magma rises and erupts.

• Older rock moves outward.

• It starts at the continental shelf.

Open Ended

What evidence supports the process of sea-floor spreading according to scientists?

Multiple Choice

What evidence supports the idea that Earth's magnetic poles have reversed themselves many times during Earth's history?

• The pattern of rocks or stripes is the same on both sides.

• Rock samples found closer to a ridge are older.

• Sonar devices detect magnetic reversals.

• Gravity pulls oceanic crust beneath trenches.

Multiple Choice

How does the age of rock samples change as you move farther from a mid-ocean ridge?

• They become younger.

• They remain the same age.

• They become older.

• They become denser.

Multiple Select

Select all statements that are true about the movement and aging of oceanic crust at mid-ocean ridges and trenches.

• New oceanic crust forms at mid-ocean ridges.

• Older oceanic crust is pulled down beneath trenches.

• Rock samples closer to ridges are older.

• Oceanic crust becomes denser as it cools.

Multiple Choice

Which device bounces sound waves off underwater objects and then records the echoes of these sounds?

• radar

• GPS

• satellite

• sonar

Multiple Choice

What is the name of the longest chain of mountains in the world that wind beneath Earth's oceans?

• Grand Canyon

• Sea-floor spreading

• Trenches

• Mid-Ocean Ridge

Multiple Choice

Which scientist suggested a process he called sea-floor spreading continually adds new material to the ocean floor?

• Alfred Wegener

• Albert Einstein

• Harry Hess

• Alfred Hess

Multiple Choice

Where does sea-floor spreading begin?

• Upper Mantle

• Mid-ocean ridge

• Inner Core

• shadow zone

Multiple Choice

What is pushing the magma upward towards the crust?

• Convection current

• Gravity

• Inertia

• Density

Open Ended

What is the process of sea-floor spreading? What is the evidence for sea-floor spreading? What happens at deep-ocean trenches?

Hotspot

There is seafloor spreading occurring at which spot?

Labelling

Label the diagram of Sea Floor Spreading

Drag labels to their correct position on the image

Young Crust

Old Crust