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.
Youyu County is located in the northwest border of Shanxi Province, belonging to Shuozhou City, Shanxi Province. It is bounded by the ancient Great Wall in the north and northwest, adjacent to Liangcheng and Helinger County in Inner Mongolia, Zuoyun County, Datong City in the east, and Shanyin County and Pinglu District in the south. Youyu County is surrounded by mountains, high in the south and low in the north. The Cangtou River runs from north to south, with a width of 45.7km from east to west and 67.7km from north to south. It has jurisdiction over a provincial eco-cultural tourism development zone, four towns, six townships, one scenic spot and 288 administrative villages, with a total area of 1969 square kilometers and a total population of 115000 (total population at the end of 2017). Youyu County is rich in tourism resources, including Xiahukou Scenic spot, Youyu Spirit Exhibition Hall, Cangtou River Wetland Park and other tourist attractions. It has successively won "National AAAA tourist Scenic spot", "Chinese charm Town", and "the most worthwhile."