Earth Sciences: Plate Boundaries

Earth Sciences: Plate Boundaries

In the theory of plate tectonics, the earth's crust is broken into plates that move around relative to each other. As a result of this movement, three types of plate boundaries are formed: divergent, convergent, and transform boundaries.

Divergent Boundaries

Divergent boundaries are boundaries where plates pull away from each other, forming mild earthquakes and volcanoes as magma comes to the surface.

Convergent Boundaries

Convergent boundaries are boundaries where two plates are pushing into each other. They are formed when two plates collide, either crumpling up and forming mountains or pushing one of the plates under the other and back into the mantle to melt.

Convergent Boundaries

Convergent boundaries form strong earthquakes, as well as volcanic mountains or islands, when the sinking oceanic plate melts.

Transform Boundaries

The third type is transform boundaries, or boundaries where plates slide past each other, forming strong earthquakes. All of this crashing, banging, and erupting are one reason why the surface of the earth has such a variety of landforms and features.

Multiple Choice

Why does oceanic crust slide below the continental crust in a convergent boundary to create ocean trenches?

• Oceanic crust is more likely to crumble under the pressure.

• Oceanic crust is less dense and more likely to be pushed back into the mantle.

• Oceanic crust is more plentiful and more likely to be available to slide in a convergent boundary.

• Oceanic crust is more dense and more likely to be pushed back into the mantle.

Multiple Choice

Plate tectonics is the theory that the Earth's crust _____.

• moves around on the surface of the Earth in one piece.

• is stationary except for the continents that move through the ocean.

• is broken into pieces that move around.

• is broken into stationary pieces.

Multiple Choice

Which of the following statements BEST categorizes a transform boundary?

• It is tectonic movement as a result of mountain formation.

• It is tectonic movement as a result of building pressure, resulting in an earthquake.

• It is tectonic movement as a result of building pressure, resulting in an ocean trench.

• It is tectonic movement as a result of volcanic action.

Multiple Choice

What kind of plate boundary is shown in this picture?

• plates sliding past each other.

• a divergent boundary.

• a convergent boundary.

• a transform boundary.

Multiple Choice

Which of the following can be formed by a convergent boundary?

• Volcanic islands

• all of the choices

• Volcanic mountains

• Deep ocean trenches