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.
Anlong County is located in the southwest of Guizhou Province, the north bank of Nanpan River in the upper reaches of the Pearl River, with a total area of 2237.6 square kilometers. Anlong County is bordered by Ceheng County to the east, Xingyi City to the west, Longlin County to the south across the river, and Xingren County and Zhenfeng County to the north. There are Han nationality, Buyi nationality, Miao nationality, Tujia nationality, Dong nationality, Yi nationality, Gelao nationality, Shui nationality and other ethnic groups in Anlong County. Ethnic minorities account for 47.25% of the total population of the county, with 359000 permanent residents. In March 2019, it was on the list of the first batch of revolutionary cultural relics protection and utilization districts and counties. On April 24, 2019, the people's Government of Guizhou Province formally approved Anlong County to withdraw from the sequence of poor counties.