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.
Minle County, which belongs to Zhangye City, Gansu Province, is located at the northern foot of Qilian Mountain, the middle of Hexi Corridor, the southeast of Zhangye City, bordering Shandan and Yongchang counties in the east, Qilian County and Menyuan County in Qinghai Province in the south, Yugu Autonomous County in Sunan in the southwest, and Gansu District in Zhangye City in the west and northwest. The geographical coordinates are between 100 °22 °59 "~ 101 °13 °9" east longitude and 37 °56'19 "~ 38 °48" 17 "north latitude. It is 73.8km wide from east to west and 95.4km long from north to south, with a total area of 3678 square kilometers (2013). With a population of 230800 (2013), Minle County achieved a GDP of 1.658 billion yuan in 2007. Minle County has Haichao Lake Ecological Resort, Bandukou Ecological Leisure Tourism area and Nuniu.