A plateau is high land that is flat on top, or gently rolling, not pointed like mountains or rounded like hills. In hilly or mountainous country, the bands of a soil and rock are folded, but in a plateau the "strata" are in flat layers. The water that makes streams on the top of a plateau cuts down in wide valleys with sides that are steep cliffs and a bottom that is quite flat. Valleys like this are often deep and very narrow. Some valleys like this are very deep and wide. They are called "canyons". Famous valleys of this type are the Grand Canyon in the United States and the Megalong Valley in Australia. 