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.
Guoluo Tibetan Autonomous Prefecture is an autonomous prefecture under the jurisdiction of Qinghai Province. it is located in the southeast of Qinghai Province in China, facing Gannan Prefecture and Huangnan Prefecture to the east, Aba Autonomous Prefecture and Ganzi Prefecture to the south, Yushu Prefecture to the west and Haixi Prefecture and Hainan Prefecture to the north; all are above 4200 meters above sea level, with a continental climate of the plateau. The state has a total area of 76400 square kilometers and has jurisdiction over six counties with a total population of 205700 in 2017. There are Animaqing Peak and Nianbaoyu Peak in Guoluo Tibetan Autonomous Prefecture; Zaling Lake and Eling Lake, which are called Baihai Shenhu Lake in ancient times, and the historical story of Tibetan-Han marriage; there are famous temples, ancient temples and cultural landscapes such as Laga, Baiyu, Chalang and so on. Because of its special geographical location and natural environment, the whole territory of Autonomous Prefecture is listed in the ── "Sanjiangyuan" Nature Reserve, the largest nature reserve in the country. two hundred and one