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.
Gucheng District is a municipal district under the jurisdiction of Lijiang City, Yunnan Province, which is located in the northwest of Yunnan Province, with a total area of 1255.4 square kilometers. Fuhui Road, Dayan Town, was established in December 2002. By 2018, Gucheng District has jurisdiction over 7 streets, 2 townships and 2 towns. In 2010, the population was 152300, including more than 10 ethnic groups, including Naxi, Han, Bai, Tibetan, Yi and Pumi, of which 120030 were ethnic minorities, accounting for 78.8% of the total population. The gross domestic product (GDP) of Gucheng District reached 8.31077 billion yuan in 2013, and the proportion of the three industries was 5.9, 40.5, 53.6. Gucheng District is the political, economic, cultural, scientific and technological, financial and information center of Lijiang. Since ancient times, it has been written by Naxi, Han, Tibetan, Bai and other ethnic groups.