It's the Great Plains
plateau
what is a large,high,almost level area of land
Plain
plateau
A Plain
a plateau
a plateu
Brazil
The name given to a large area of level land on the Earth's surface is a plateau. A plateau also typically is elevated above the surrounding area. Such areas are also sometimes called tablelands.
A large level area high above the ground is called a mesa. Mesa is a Spanish word that means 'table'.
That I believe, would be the Earth's Crust.