Earth's Layers, Cont. Drift, Seafloor Spreading, Plate Tectonics

Tectonic plates consist of

• continental crust.
• oceanic crust.
• both continental and oceanic crust.

Magnetic reversals are recorded on the seafloor by

• Silver
• Aluminum
• Nickel
• Iron

Seafloor spreading occurs at divergent boundaries. Which statement best identifies the geologic process taking place at the point where seafloor spreading occurs?

• a trench is forming
• new crust is forming
• oceanic crust is subducting

Which movement of tectonic plates caused the rift valley to form?

• Two tectonic plates separated from each other.
• Two tectonic plates collided with each other.
• One tectonic plate slides under another.
• One tectonic plate slide past another.

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.

Old oceanic crust is more dense than new oceanic crust because it is

• hot.
• cold.

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

• transform boundary.
• divergent boundary.
• convergent boundary.

A collision between two pieces of continental crust at a convergent boundary produces a

• mid-ocean ridge.
• rift valley.
• deep-ocean trench.
• mountain range.

The Caribbean Islands and Japan were formed from a

• convergent ocean vs. ocean boundary.
• divergent ocean vs. ocean boundary.
• transform boundary.

The Andes Mountains were formed from a

• convergent ocean vs. continental boundary.
• convergent continental vs. continental boundary.
• transform boundary.