Seafloor Spreading

In the Atlantic ocean, where is the youngest seafloor located?

• Towards the edges, near the eastern and western continents
• Towards the middle of the ocean
• Towards the north and south poles
• Young seafloor is located randomly throughout the ocean

How do scientists figure out the age of the seafloor?

• They research it from ancient sea maps that trading vessels would use in the 1700s
• They use the moon phases and eclipses to calculate the age
• They use seismographs and the depth as well as location of earthquakes to calculate the age
• They take drill ships to many locations in the oceans and collect, then date, rock samples. 

How is it possible for new crust to be formed without increasing the surface area of the Earth?

• Crust is recycled in subduction zones at the same time it is created at mid-ocean ridges

• New crust is underwater where it sinks

• New crust breaks more easily than old crust

• The oldest crust just breaks apart as the plates move

Scientists use ______ to map the ocean floor

• radar

• pulsar

• lidar

• sonar

The OLDEST seafloor is located

• closest to the mid-ocean ridge.

• farthest from the mid-ocean ridge.

• east of Hawaii

• west of California

Which of the following supports the theory of seafloor spreading?

• Correlation of rock layers

• Crustal slab pull

• Magnetic reversals recorded in rocks

• Continuous mountain chains

Seafloor spreading...

• creates new oceanic crust

• destroys or recycles crust

• creates new continental crust

• creates old crust

Rock at the mid ocean ridges...

• is the oldest rock on the earth.

• is older than continental rock.

• is younger than continental rock.

A change in Earth' s magnetic field is called a

• magnetic reversal

• subduction

• paleomagnetism

• slab pull

The zone where one plate slides under another is called the

• Convergent zone
• Subduction zone
• Transform zone
• Mantle zone