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.
Qumalai County is a county under the jurisdiction of Yushu Tibetan Autonomous Prefecture in Qinghai Province. it is located in the southwest and north of Qinghai Province. the county government is stationed in Yogai Town, 310 kilometers away from the state capital. It is located in longitude 92 °56 "97 °35" east and latitude 33 °36 "35 °40 'north. The land area is 47000 square kilometers, with a population of 32000 (2012). The population is mainly Tibetan, and it has jurisdiction over one town and five townships. The government is stationed in a new town. In 2012, Qumalai County completed a regional GDP of 453 million yuan (calculated at comparable prices), an increase of 9.4% compared with 2011. The total investment in fixed assets reached 490 million yuan, and the local general budget income reached 7.82 million yuan. Famous tourist attractions include the Monument to the Source of the Yellow River, King Gesar's landing on the platform, and Tibetan Buddhism.