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.
Xisaishan District, which belongs to Huangshi City, Hubei Province, is located on the south bank of the middle reaches of the Yangtze River and in the east of Huangshi City. It is bordered by Diyuankou Town, Yangxin County in the east, Nanhu Township in the lower land area in the west, Sike Township and Wangren Town in Daye City in the south, Xishui and Qichun in the north, and Shengyang Port in Huangshi Port District in the northwest. The whole territory is 22.9km long from east to west and 9.945 km wide from north to south. As of 2012, Xisai Mountain area has a total area of 112.39 square kilometers, of which the urban area is 49.95 square kilometers, the suburbs are 62.44 square kilometers, and the population of the whole region is 258000. As of 2013, Xisaishan District has successively won the honorary titles of "National Scientific and technological Progress City" and "National Community Construction demonstration Zone". March 6, 2019, Central propaganda Department, Ministry of Finance, Culture and Brigade