Three of Mexico’s geographic zones cover parts of the state. The Mesa del Centro is in the center-west of the state, and mostly consists of small mesas with an average altitude of above sea level (ASL). A few elevations reach over . The Sierra Madre Oriental occupies the northeast of the state and includes the cities of Huasteca area. The topography of this area is rugged, with long mountain chains and narrow valleys. Elevations here range between and m ASL. The Trans-Mexican Volcanic Belt occupies about half of the state in the center and south. The area is mostly volcanic rock with peaks and mesas between and and valleys between and ASL.