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.
Sangri County, which belongs to Shannan City, Tibet Autonomous region, is located in the southeast of Tibet Autonomous region and north of Shannan City, with a total area of 2633.62 square kilometers, one town and three townships, with a resident population of 15746 (2013). Sangri, which means "Tongshan" in Tibetan. The county is located in the southern foot of the Gangdise Mountains, the middle reaches of the Brahmaputra River valley, is a valley in southern Tibet, the geological structure is complex, the topography is mainly alpine valley, the temperature difference between day and night is large, and the climate is dry. It is rich in copper, limestone, marble, solar energy and hydropower resources. The main scenic spots are Dansati Temple, Waka Hot Spring, Dagu Canyon, Red Deer Nature Reserve and so on. Sangri County is the counterpart support county of Yueyang City, Hunan Province. Agriculture and animal husbandry is the economic base of Sangri County, which mainly grows highland barley, winter wheat, rape and other crops, and raises cattle, sheep and horses.