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.
Nie Rong County is under the jurisdiction of Naqu City, Tibet Autonomous region, located in the northern part of the Tibet Autonomous region, the southern foot of Tanggula Mountain, located in the hinterland of the Qinghai-Tibet Plateau and on the border with Qinghai Province. The terrain is high in the northwest and low in the southeast. The average elevation is about 4700 meters. The territory has undulating mountains and vertical and horizontal gullies, some peaks in the northwest are covered with snow all the year round, the relative height difference between the central and southern peaks is large, and the low mountains and hills are scattered with valleys. Nie Rong County has jurisdiction over 1 district, 9 townships and 173 villages. It covers an area of 14540 square kilometers, of which the available grassland area is 18 million mu. The financial revenue of the county reached 1.2 million yuan in 2003, an increase of 53000 yuan over 2002, with a total population of 30, 000 (2003). On February 6, 2019, the people's Government of the Tibet Autonomous region decided to withdraw Nierong County from the poverty-stricken county.