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.
Golmud, a county-level city under the jurisdiction of Qinghai Province, is administered by Haixi Mongolian and Tibetan Autonomous Prefecture and is located in the central and western part of Qinghai Province and the hinterland of the Qinghai-Tibet Plateau. The topography of the area is complex and can be divided into two parts: the basin plateau and the northern foot of Tanggula Mountains. It is a typical plateau continental climate; the total area is 118954.18 square kilometers, with 5 streets, 2 towns and 2 townships; in 2017, there are 27 ethnic minorities with a resident population of 240494. "Golmud" is transliterated in Mongolian and translated as Gaolumsi, Guoliang and Garmu, meaning "a place with dense rivers". Golmud is a strategic fortress connecting Tibet, Xinjiang and Gansu and a transportation hub in western China. Qinghai-Tibet, Qingxin and Dunge highways meet here; the Qinghai-Tibet Railway has been opened to traffic; there are the headwaters of the Yangtze River and ten thousand