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.
Gangcha County is under the jurisdiction of Haibei Tibetan Autonomous Prefecture of Qinghai Province, one of the key animal husbandry counties around the lake, located in the west of the state, the north bank of Qinghai Lake. The county government is stationed in Saliuhe Town, 110 kilometers away from Xihai Town, Haiyan County, where the state capital is located. By 2012, the total population of the county was 42000, of which ethnic minorities accounted for 72.5%, Tibetans accounted for 63.38%, as well as Han, Mongolian, Hui, Dongxiang and other ethnic groups. The area is 12000 square kilometers. Jurisdiction over 3 townships, 2 towns and 1 game. It was called Qiang Land in ancient times. The main rivers in Gangcha County are the Moeller River, the Kexai River, the Jiangcang River, the Shaliu River, the Bahaulan River, the Buha River, the Halgai River and the Gilmont River. It belongs to the continental climate of the plateau, with an average annual temperature of-0.6 ℃ and annual precipitation of 370mm. The main mineral deposits are coal, iron, copper, silver, uranium and so on. Pure animal husbandry county, herding Tibetan sheep