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.
Liangdang County belongs to Longnan City, Gansu Province, located in the southeast of Gansu Province, northeast of Longnan City. Liangdang Ancient Road, Gudao, Qin Huiwen King years home Gudao County, the Northern Wei Dynasty Gudao County Liangdang County, named because of the territory of Liangdang River, after 1985 under the jurisdiction of Longnan area, Longnan City. Liangdang County has jurisdiction over 6 towns, 6 townships and 118 administrative villages, with a total area of 1408.73 square kilometers and a total population of 50429 (2010). Liangdang County, located in the Qinling Mountains at the junction of Shaanxi, Gansu and Sichuan, is known as "the defense of Qinlong and the silence of Bashu". It is located between 773-2738 meters above sea level, with a warm temperate continental monsoon climate, rich in light and heat, and abundant rainfall. The difference is significant. The territory has Qinling antelope, clouded leopard, forest musk deer and other rare animals, with Gan