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.
Nancheng is the deputy central city of Fuzhou planned by the Jiangxi provincial party committee and provincial government. it is a pilot county directly administered by the province, located in the middle of Fuzhou city, with an area of 1712 square kilometers, 10 towns and 2 townships, with a total population of 350000, an urban population of 184000 and a urbanization rate of 57.3%. In Nancheng County, there is a railway (Xiangxiang Railway), two highways (Fuyin Expressway and Ji-Guang Expressway) and three national highways (206 National Highway, 316 National Highway and Changsha Highway). The planned Tengqiao Civil Airport is 20 kilometers away from the county seat. Fuzhou to Nancheng expressway, Nancheng-Yihuang-Chongren-Fengcheng encryption highway is also being planned. The second batch of national agricultural products quality and safety counties.