Line on a map joining places that are the same height above sea level

the change from liquid to gas

the time where earth's average temperature was lower than usual and glaciers spread

a sheet of ice that is attached to land, but floats on the ocean

A type of plant or animal

A cold region where the ground is deeply frozen; only the surface thaws in summer, allowing small plants to grow.

The average number of people living in a place, per square kilometre

A map of a small area