Seafloor Spreading

Seafloor Spreading

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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.

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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