A mesa is an isolated, flat-topped elevation, ridge or hill, which is bounded from all sides by steep escarpments and stands distinctly above a surrounding plain. Mesas characteristically consist of flat-lying soft sedimentary rocks capped by a more resistant layer or layers of harder rock, e.g. shales overlain by sandstones. The resistant layer acts as a caprock that forms the flat summit of a mesa. The caprock can consist of either sedimentary rocks such as sandstone and limestone; dissected lava flows; or a deeply eroded duricrust. Unlike plateau, whose usage does not imply horizontal layers of bedrock, e.g. Tibetan Plateau, the term mesa applies exclusively to the landforms built of flat-lying strata. Instead, flat-topped plateaus are specifically known as tablelands.
Gaoping District, Nanchong City, Sichuan Province, is located in the south of Nanchong City, Sichuan Province, east of the city, Hanzhu Anhan County, Sui Nanchong County, changed from Nanchong County to Municipal District in 1993, with an area of 806 square kilometers and a population of 600000 in 2013. it has jurisdiction over 8 streets, 10 towns and 1 township. Gaoping District is located in the northeast of Sichuan Basin, the east bank of the middle reaches of Jialing River, is a low mountain and hilly area, is a subtropical warm and humid monsoon climate area, Jialing River, Luoxi River, Wanjiahe, meandering River, Luojia River and large and small stream ditches are fan-shaped. In agriculture, citrus, bamboo, vegetable industry and "three" ten thousand mu modern agricultural industrial bases are developing well. It is a strong modern agricultural industrial base county in Sichuan Province, and a citrus base county (district) with advantages and characteristic benefits in Sichuan Province. Six villages and towns have entered the national modern agricultural demonstration.