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.
Ledu District, the seat of Haidong Municipal Government in Qinghai Province, was established on May 12, 1969, and the district government is located in Haidong Street. It is located on the south side of the Huangshui River in the northeast of Qinghai Province, adjacent to Pingan District of Haidong City in the west, Minhe County in the east, Qingsha Mountain in the south and Huazhu County in the north, 95 kilometers away from the provincial capital Xining City and 115 kilometers away from Lanzhou City, the capital of Gansu Province. The total area of the region is 3050 square kilometers, including 111 administrative villages and 7 communities. At the end of 2011, there were 15 ethnic groups, including Tibetan, Qiang, Tu, Han and Hui, with a population of 360200, with the Han nationality accounting for the majority. On September 25, 2018, he won the honorary title of "2018 e-commerce into rural comprehensive demonstration county" of the Ministry of Commerce. In October 2018, it won the national integration of the primary, secondary and tertiary industries in rural areas.