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.
Shuangta District, which belongs to Chaoyang City, Liaoning Province, is located in Chaoyang City in the west of Liaoning Province. It is located in the east of Nuluerhu Mountains and the western foot of Songling Mountains. It is a long pan in the Daling River Valley. It is the political, economic and cultural center of Chaoyang. It gets its name from the well-preserved North Pagoda of the Northern Wei Dynasty and the Southern Tower of the Tang Dynasty. Shuangta District is connected with the urban agglomeration in central Liaoning and the Liaodong Peninsula in the east, the Beijing-Tianjin-Hebei metropolitan area in the west, the Bohai Sea in the south and the hinterland of Inner Mongolia in the north. The center of geographical coordinates is 120 °27km east longitude and 41 °35 'north latitude. In 2015, Shuangta District has a total area of 500square kilometers and has jurisdiction over 4 townships (towns) and 11 streets with a total population of 404500. In 2015, the GDP of the whole region reached 13.33061 billion yuan.