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.
Hezhang County, which belongs to Bijie City, Guizhou Province, is located in the sloping zone of the East Yunnan Plateau from the upper reaches of the Wujiang River Beiyuan Liuchong River and Nanyuan Sancha River in the northwest of Guizhou Province to the Wumeng Mountain area with excessive mountains and hills in central Guizhou. It is located in the east longitude of 104 °10 °28 ampquotters105 °01 & #39;23", latitude 26 °46 °12 "~ 27 °28 & #39. It is 85.276 km long from east to west and 77.696 km wide from north to south, with Bijie and Nayong in the east, Weining in the west and Liupanshui in the south, Zhenxiong and Yiliang in Yunnan Province in the north, with an area of 3250 square kilometers and a total population of 798700 (2013). The government is stationed on Shuanghe Street. In 2013, Hezhang County completed a GDP of 6. 5%.