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.
Wusheng County, which belongs to Guangan City, Sichuan Province, the hometown of Deng Xiaoping, is located in the east of Sichuan Basin, the middle reaches of Jialing River, the southwest of Guang'an City, the junction of Sichuan and Chongqing provinces and cities, Yuechi in the east, Pengxi in the west, Hechuan in the south, and Nanchong in the north. The distance between east and west is 48.5km and the distance between north and south is 40.5km. It covers an area of 966 square kilometers with a total population of 848000 (2013). The county government is stationed in Yankou town. Wusheng is the hometown of Chinese folk art (bamboo silk painting curtain), the second largest Hui settlement in the Jialing River Basin, known as the "Jialing Pearl". Famous scenic spots "National key Cultural relics Protection Unit" Baomingsai, Yinshan Park. On October 22, 2018, Wusheng County was selected into the list of national pilot areas for the integration and development of primary, secondary and tertiary industries in rural areas in 2018. twenty