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.
Hualong Hui Autonomous County is located in the transitional zone between the Loess Plateau and the Qinghai-Tibet Plateau in the east of Qinghai Province and in the south of Haidong City. Is a Hui-based multi-ethnic county, a total of Hui, Han, Tibetan, Salar and other 12 ethnic groups. The county people's government is stationed in Bayan Town, 75 kilometers away from the provincial government. Linping Highway, Lehua Highway, Asai Highway, Zaha Highway, Ping-An Expressway and Yanguan Highway run through the county. Hualong Hui Autonomous County has a total area of 2740 square kilometers and has jurisdiction over 3 towns and 18 townships. As of 2010, the total population is 229669. Located in the mountains and valleys on the north side of the Yellow River valley, the terrain tilts from northwest to southeast, and the Yellow River flows through the southwest and south of the county. It belongs to the eastern arid area of the Qinghai-Tibet Plateau, with an average annual temperature of 2.2 ℃ and annual precipitation of 470mm.