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.
Yuping Dong Autonomous County is a county under the jurisdiction of Tongren City, Guizhou Province. The county is located between 108 °34 mi mi 109 °09 east longitude and 27 °28 mi mi 27 °31'N. The county is located in Xinhuang, Hunan Province in the southeast, Zhenyuan and Cengong in the west, Bijiang District and Wanshan District in the north, 36 kilometers from east to west and 42 kilometers from north to south, with a total area of 516.6 square kilometers. Originally known as Yuping County, it was founded in the fifth year of Yongzheng of the Qing Dynasty (1727). On November 7, 1984, with the approval of the State Council, Yuping County was abolished and Yuping Dong Autonomous County was established. In August 2019, it was selected as a pilot county for the construction of medical community in a compact county.