Plate tectonics

In sea-floor spreading, molten material rises from the mantle and erupts

• along the edges of all the continents.

• along mid-ocean ridges.

• in deep-ocean trenches.

• at the north and south poles.

The process by which the ocean floor sinks beneath a deep-ocean trench and back into the mantle is known as _______

• convection.

• continental drift.

• subduction.

• conduction.

Most geologists think that the movement of Earth’s plates is caused by _______

• convection.

• continental drift.

• subduction.

• conduction.

A place where two plates slip past each other, moving in opposite directions, is known as a _______

• transform boundary

• divergent boundary.

• convergent boundary.

• rift valley.

Scientists think that convection currents flow in Earth’s

• continents.

• mantle.

• lithosphere.

• inner core.

The place where two plates come together is known as a _______

• transform boundary.

• divergent boundary.

• convergent boundary.

• rift valley.

Below is a picture of sea-floor spreading. How are the ocean crusts moving?

• Converging

• Diverging

• Sliding

• No movement

Where would the oldest rock be found?

• L
• M
• N
• O

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

• Crust is destroyed at the same time it is created
• New crust is underwater where it sinks
• New crust breaks more easily than old crust

What are the two types of crust

• continental and oceanic
• ocean and upper
• lower and upper
• pizza and subway