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.
Xinlong County, which belongs to Ganzi Tibetan Autonomous Prefecture of Sichuan Province, is located in the middle of Ganzi Prefecture in Sichuan Province and the southeast edge of Qinghai-Tibet Plateau. It belongs to the contact zone between West Sichuan Mountain Plain and Hengduan Mountains. Xinlong County is connected with Luhuo County and Daofu County to the east, Yajiang County and Litang County to the south, Baiyu County to the west, Ganzi County to the north, Dege County to the northwest, and latitude 30 °23 to 31 °32 'and longitude 99 °37 to 100 °54' east. The terrain of Xinlong County is high in the north and low in the south. The highest elevation is 5992 meters and the lowest point is 2760 meters above sea level. Ganzi Xinlong Highway to the north of Xinlong County is connected with National Highway 317 via 100 kilometers. By the end of 2013, Xinlong County has an area of 9182.74 square kilometers and has jurisdiction over 1 town, 18 townships and 1 street office, with a total population of 49833. 2013