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.
Huining County, which belongs to Baiyin City, Gansu Province, is located in the central part of Gansu Province, at the southern end of Baiyin City; the terrain is tilted from southeast to northwest, with undulating beams and ravines; it is a mid-temperate semi-arid climate with a total area of 6439 square kilometers. As of 2018, Huining County has 24 towns and 4 townships under its jurisdiction, with a resident population of 543900. Huining County is known as the "lock key of Qin long". As early as the Neolithic Age more than 5000 years ago, human beings lived and multiplied in the territory. Zuli County was set up in the third year of Emperor Yuanding of Han Dynasty (114BC), which has a history of more than 2100 years. In October of the 25th year of the people's Republic of China (1936), the three main forces of the Chinese Workers' and Peasants' Red Army successfully reunited in Huining, which was the turning point of the Chinese revolution. In 2018, Huining County realized the GDP (GDP).