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.
Nanqiao District, Chuzhou Municipal District of Anhui Province, the resident of Chuzhou Municipal Government, is located in the east of Anhui Province, at the junction of Jiangsu and Anhui provinces, in the southeast of Chuzhou, and in the west of the Yangtze River Delta. The district was established on January 18, 1993 and became one of the two municipal districts of Chuzhou. Nanzigu is Tangyi, with Dunqiu County behind it, which lays the embryonic form of the political district. As a new area of urban development, Nanfeng District is located in the transitional area from the coast to the interior, and is at the forefront of the development of Wanjiang River and eastward development. Nanfeng District is a member city of the Yangtze River Delta urban agglomeration, the core city of Nanjing metropolitan area, an important member city of Hefei economic circle, the Jiangbei gate of Nanjing, the northern wing city of national Wanjiang demonstration zone, and an important hub city in Jianghuai region. Since ancient times, it has been known as "the key to Jinling and the guarantee of Jianghuai", "both Wu and Chu, Qi Yue Huai Yang", "the prosperity of Confucian style,"