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.
Weishan Yi Hui Autonomous County (Weishan County for short) is located in the west of Yunnan Province and in the south of Dali Bai Autonomous Prefecture. The county seat is 391 kilometers east from the provincial capital Kunming and 53 kilometers north from the state capital Dali. Weishan County is connected with Dali City in the north, Midu County in the east, Nanjian and Fengqing County in the south, and Yangzhuang and Changning County in the west. As of 2013, Weishan County had jurisdiction over 6 townships and 4 towns, covering an area of 2266 square kilometers; by the end of 2017, the registered population was 321554. In 2017, the GDP of Weishan Yi Hui Autonomous County reached 5.753 billion yuan, an increase of 9.8%, of which the added value of the primary industry was 1.805 billion yuan, an increase of 6.2% over the same period last year, and the added value of the secondary industry was 1.791 billion yuan, an increase of 13.7% over the same period last year.