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.
Honggu District belongs to Lanzhou City, Gansu Province, located in the far suburbs of Lanzhou City, located in the middle of Gansu Province, was established in 1960, named because of the Honggu River east of Xiangtang Gorge, the geographical coordinates are 102 °50mm east longitude 102 °54' and 36 °19mm Met 36 °21' north, Xigu District to the east, Datong River to the west, Huangshui River to the south and Qinghai Minhe Hui Autonomous County and Yongjing County to the south, the loess mountains in the north adjoining Yongdeng County. It is located in the geometric center of the two provincial capitals of Lanzhou and Xining. In 2014, Honggu District has a total area of 567.66 square kilometers, with a total population of 150000 (2014), and has jurisdiction over three streets, three towns and one township. In 2014, Honggu District achieved a GDP of 10.528 billion yuan, an increase of 15.5% over 2013.