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.
Qilihe District, Lanzhou District, located in the central and southern part of Lanzhou, is the central urban area of Lanzhou. Qilihe District is bordered by Chengguan District and Yuzhong County in the east, Lintao County and Yongjing County in the south, Xigu District in the west and Anning District in the north. It is shaped like an irregular palm, 21 kilometers long from east to west, 33 kilometers wide from north to south, with a total area of 397.49 square kilometers. Among them, the urban area is 25 square kilometers. The district has jurisdiction over 2 townships, 4 towns, 9 streets, 60 administrative villages and 77 communities. The total population is 571000, of which the rural population is 89600. By 2017, there were 44 ethnic minorities, including Hui, Mongolia, Tibet, Dongxiang and Uygur. In the area, there are scenic spots such as West Lake Park, Western Happy Park, Shifogou National Forest Park, Black Eagle Temple, Yunlin Temple, beef noodles and roast sheep with northern characteristics.