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.
Weng'an is located in the southwest hinterland, is a national health county and China's ecological charm county, the national phosphorus chemical ecological production base, known as the "Asian phosphorus warehouse" reputation. Weng'an is an old revolutionary base. The Red Army passed Weng'an four times on the long March and held a historic monkey farm meeting in Weng'an, which Comrade Zhou Enlai called "the eve of a great turning point." Weng'an is the place of origin of life and the ancient city with thousands of years of civilization. Fossils of faunas from 610 million years ago have been found here, and they are the earliest fossils found so far. On December 25, 2017, the General Office of Guizhou Provincial Government issued the implementation Plan for Guizhou Province to accelerate the Construction of a New Type of urbanization with Mountain characteristics, which shows that the Guizhou Provincial Government supports Weng'an County to remove counties and cities.