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.
Muchuan County, under the jurisdiction of Leshan City, Sichuan Province, is located in the southwest of Sichuan Basin, the triangle between Minjiang River, Dadu River and Jinsha River in the upper reaches of the Yangtze River. It is bordered by Yibin in the east, Pingshan County in the south, Shawan District and Jianwei County in the north, Ebian County in the west and Mabian County in the southwest. It covers an area of 1408 square kilometers with a population of 260000. The territory has fresh air, beautiful scenery, rich products and simple folk customs, with a forest coverage rate of 77.34%, known as "natural oxygen bar" and "green pearl". It is the pilot county of the national ecological civilization demonstration project, the national ecological demonstration area, the national key ecological functional area, the hometown of bamboo in China, the national greening model county, the national forestry science and technology demonstration county, and the best green eco-tourism county in China. On July 31, 2018, the Sichuan Provincial Government approved Muchuan County to withdraw from poverty.