A nearly level land area that was formed as a lakebed.

A nearly level land area that was formed as a lakebed.

A collection of islands in a sea.

The mass of rocks and finely ground material carried by a glacier, then deposited when the ice melted. This creates an mixture made up of many different types of rocks and other materials.

The location of a point on the Earth's surface that can be expressed by a grid reference such as latitude and longitude.

A volcano that is currently erupting, or has erupted during recorded history.

Height of an object in the atmosphere above sea level.

Fragments less than 2 millimeters (about 1/8 inch) in diameter of lava or rock blasted into the air by volcanic explosions.

The lowest level to which a stream can erode its bed. The ultimate base level of all streams is, of course, the sea.

A very large body of igneous rock, usually granite, which has been exposed by erosion of the overlying rock.