Plate Tectonics 2020

Most geologists rejected Alfred Wegener's idea of continental drift because

• they were afraid of a new idea.

• Wegener was interested in what Earth was like millions of years ago.

• Wegener used several different types of evidence to support his hypothesis.

• Wegener could not identify a force that could move the continents.

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

• gravity.

• Earth's magnetic field.

• convection currents in the asthenosphere.

• subduction.

What is Pangaea?

• the name of the supercontinent that existed a million years ago.

• another name for continental drift.

• the name of a German scientist.

• the name of an ancient fossil that existed a hundred thousand years ago.

The theory of ___________ was that all the continents were once joined as a single super-continent and have since drifted apart.

• subduction

• volcanic activity

• continental drift

• seafloor spreading

The geological theory that states that pieces of Earth's lithosphere are in constant, slow motion is the theory of

• subduction

• deep-sea trenches

• plate tectonics

• seafloor spreading

What is happening in this diagram?

• Two continental plates are diverging.

• The continental plates are creating a rift valley.

• Two continental plates are converging.

Describe what happens at a divergent boundary under the ocean.

• Convergent and transform boundaries form there.

• Oceanic crust subducts and a deep-sea trench forms.

• The crust is folded to form mountains.

• Seafloor spreading creates new land as magma rises.

When two plates come together is known as a ________________ boundary.

• rift valley

• divergent

• transform

• convergent

What kind of boundary is show in this diagram?

• convergent boundary

• divergent boundary

• transform boundary

What process is shown by the diagram?

• convergent boundary

• seafloor spreading

• transform boundary

• subduction