6 IS CH 3 L2

What is a mid-ocean ridge?

• A deep trench in the ocean floor

• A long chain of mountains rising from the ocean floor

• A flat area on the ocean floor

• A type of ocean current.

What did Marie Tharp and Bruce Heezen work on mapping?

• The ocean floor

• The moon's surface

• The Earth's core

• The atmosphere

Name three pieces of evidence that support the theory of sea-floor spreading.

• Ocean material

• Magnetic stripes

• Drilling samples

• All of the above.

In sea-floor spreading, where is new crust added?

• mid-ocean ridge

• ocean trench

• continental shelf

• volcanic island

The youngest rocks in the ocean are found near what feature?

• mid-ocean ridge

• ocean trench

• continental shelf

• volcanic island

At Location A, the crust is ______.

• newly formed

• older

• less dense

• more dense

What is the effect of subduction on Earth's oceans?

• It causes expansion

• It causes shrinking

• It causes no change

• It causes evaporation

The Atlantic Ocean is (expanding / shrinking / unchanged).

• expanding

• shrinking

• unchanged

• evaporating

How often is the ocean floor renewed due to subduction?

• Every 100 million years

• Every 200 million years

• Every 300 million years

• Every 400 million years