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.
Duolun County, which belongs to Xilingol League of Inner Mongolia Autonomous region, is located at the southern end of Xilingol League and the eastern end of the northern foot of Yinshan Mountain. Longitude 115 °30, longitude 116 °55, latitude 41 °45, longitude 42 °39'. It is connected with Zhenglan Banner in the west, Keshikten Banner in Chifeng City in the north, and Guyuan County, Fengning County and Weichang County in the south. The total area is 3863 square kilometers. In 2011, it was approved to build a central city by the government of Inner Mongolia Autonomous region and Xilingol League. County people's government in Duolun Nur town. It won the honorary title of famous historical and cultural town in China in 2008 and the honorary title of famous landscape tourism town with national characteristics in 2010. In September 2018, he won the title of "China Natural oxygen Bar". On April 18, 2019, the people's Government of Inner Mongolia Autonomous region decided Duolun County.