Ch. 3 Plate Tectonics

Front

The lithosphere is broken into sections called _________, which float on top of the asthenosphere.

Back

plates

Front

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

Back

plate tectonics

Front

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

Back

convection currents in the mantle

Front

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

Back

cool

Front

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

Back

along mid-ocean ridges

Front

What is the layer of Earth that is made up of the crust and the upper mantle?

Back

The lithosphere.

Front

What is the semi-fluid layer beneath the lithosphere called?

Back

The asthenosphere.

Front

What process describes the movement of tectonic plates away from each other?

Back

Divergent boundaries.

Front

What is the process called when one tectonic plate moves under another?

Back

Subduction.

Front

What geological feature is formed at convergent boundaries?

Back

Mountains or deep ocean trenches.