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.
Daozhen Gelao and Miao Autonomous County (Daozhen County for short) is an autonomous county under the jurisdiction of Zunyi City, named after Yin Daozhen, a scholar in the Han Dynasty. Daozhen County is located in the northernmost part of Guizhou Province and is the slope zone of the transition from Yunnan-Guizhou Plateau to Sichuan Basin. It is adjacent to Nanchuan District, Wulong District and Pengshui Miao and Tujia Autonomous County in Chongqing in the northwest and northeast. The southwest and southeast are bordered by Zheng'an County and Wuchuan Gelao and Miao Autonomous County respectively. 180 km to the south of Zunyi, 338 km to Guiyang and 160 km to Chongqing, it is the "joint" between the central Guizhou economic zone and the Chengdu-Chongqing economic zone and the bridgehead of opening up and cooperation between Guizhou and Chongqing. By the end of 2017, Daozhen County had jurisdiction over 1 street, 11 towns, 2 townships and 1 nationality township, with a registered population of 350900 and a resident population of 247300. 2019