* Coastal plains: These are flat, low-lying areas that are located near the coast. They are formed by the deposition of sediment by rivers, waves, and tides. Examples include the Atlantic Coastal Plain of the United States and the Great Plains of Australia.

* Interior plains: These are flat, low-lying areas that are located far from the coast. They are often formed by the erosion of mountains and plateaus. Examples include the Great Plains of North America and the Siberian Plain of Russia.