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.
Qiannan Buyi and Miao Autonomous Prefecture is an autonomous prefecture under the jurisdiction of Guizhou Province. it is located in the central and southern part of Guizhou Province, connected with Qiandongnan Prefecture in the east, Guangxi Zhuang Autonomous region in the south, Anshun City and Qianxinan Prefecture in the west, and Guiyang City in the north. It is located in the slope zone of the transition from Guizhou Plateau to Guangxi hills, with high terrain in the north and low in the south, and is located in the East Asian monsoon area. The state has a total area of 26197 square kilometers and has jurisdiction over two county-level cities, nine counties and one autonomous county, with a resident population of 3.2809 million in 2017. Qiannan Buyi and Miao Autonomous Prefecture was once an important passage of the Silk Road to the sea in the south, and it was also the old road from central Guizhou to Sichuan, Guangxi, Hunan and Yunnan. Aviation, railways, highways and river transportation crisscross in southern Guizhou. Qiu Hejia, governor of Liaodong and general soldier of Shanhaiguan, has emerged in southern Guizhou.