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.
Datong Hui and Tu Autonomous County is under the jurisdiction of Xining City, Qinghai Province. it is located in the Hehuang valley in the east of Qinghai Province, the southern foot of Qilian Mountain, and the Beichuan River basin in the upper reaches of Huangshui River. it is a transitional zone between Qinghai-Tibet Plateau and Loess Plateau. It has a total area of 3090 square kilometers, has jurisdiction over 9 towns and 11 townships, with a total population of 453000 (2012). There are 26 ethnic groups, including Han, Hui, Tu, Tibetan, Mongolian, etc., and has twice been named "hometown of Chinese Folk Culture and Art" by the Ministry of Culture. In November 2019, Datong Hui and Tu Autonomous County was named as the national demonstration county of "Sihao Rural Road" and was selected into the second batch of water-saving society construction standard counties (districts).