Seafloor Spreading and Plate Tectonics

Seafloor Spreading

​

How many layers of the Earth are there?

crust, mantle, outer core, inner core

Multiple Choice

How may layers of the Earth are there?

• 4

• 3

• 2

• 1

Multiple Choice

Which of the following is NOT one of the layers of the Earth?

• inner core

• subduction

• crust

• mantle

Multiple Choice

Which layer is found below the mantle?

• inner core

• outer core

• crust

Multiple Choice

Which layer is found above the mantle?

• inner core

• outer core

• crust

The crust is the ocean floor.

If you stand at the bottom of the ocean, you are standing on Earth's crust.

The crust is thin at the ocean floor.

* The crust is found under the ocean but is thin.

*It is about 3 miles from the top to the bottom of the ocean.

Multiple Choice

Deep beneath the ocean, the Earth's crust there is _______________.

• thick

• thin

Multiple Choice

The crust is under our oceans where it is more than ________ thick.

• 30 inches

• 10 feet

• 3 miles

What can be found at the bottom of the ocean floor?

*The longest chain of mountains in the world is called the mid ocean ridge.

*The mid ocean ridge is found at the bottom of the ocean.

Home

Open in new tab

Copy link

Multiple Choice

Where is the longest chain of mountains in the world found?

• North America

• South America

• ocean floor

Multiple Choice

How far along does the mid ocean ridge stretch?

• 10,000 miles

• 20,000 miles

• 40,000 miles

What is the mid ocean ridge?

• The massive mid-ocean ridge system is a continuous range of underwater volcanoes that wraps around the globe like seams on a baseball, stretching 40,390 miles.

• 90% of the ridge is found underwater.

Multiple Choice

The mid ocean ridge is a series of ____________ located under the ocean floor.

• earthquakes

• volcanoes

Multiple Choice

What percentage of the ridge is found underwater?

• 10%

• 60%

• 90%

What happens at the mid ocean ridge?

*Mid-ocean ridges occur along plate boundaries, where new ocean floor is created as the Earth’s tectonic plates spread apart.

*As the plates separate, molten rock rises to the seafloor, producing enormous volcanic eruptions of basalt. 

Multiple Choice

What happens as the plates separate?

• molten rock sinks down to the seafloor

• molten rock rises to the seafloor, producing enormous volcanic eruptions

Multiple Choice

True or False : Sea-floor Spreading adds new material to the ocean floor?

• True
• False

What is seafloor spreading?

• Seafloor spreading is when the magma rises to the ocean floor.

• Seafloor spreading begins at the midocean ridge.

• When the magma comes in contact with the ocean floor, it cools down and becomes a rock called basalt.

Multiple Choice

Sea-floor spreading begins at the

• Deep ocean trench

• Mid-ocean ridge

• Continent's edge

Multiple Choice

The ocean floor is made up of a rock called ______________.

• Granite

• Basalt

• Sulfur

Multiple Choice

The material that is rising up from the mantle to form new ocean crust is called?

• Lava

• Slate

• Magma

Multiple Choice

When looking at mid ocean ridges the oldest rocks are

• In the middle

• Found close to the rift zone

• Found far from the mid ocean ridges

Multiple Choice

Newer rocks are found _________________.

• In the middle

• Found close to the rift zone

• Found far from the mid ocean ridges

How often does seafloor spreading happen?

*It happens over and over again, as a recycling process.

*Older rock move away from the ridge and down a trench. (A trench is a long cut into the earth where the older rock goes back into the earth).

Multiple Choice

How often does seafloor spreading happen?

• once a year

• over and over again

• It only happened once.

Multiple Choice

A ______________is a long cut into the earth where the older rock goes back into the earth

• trench

• river valley