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.
Yongning County, which belongs to Yinchuan City, is located in the middle of the Yellow River diversion Irrigation area of Yinchuan Plain in Ningxia, facing the Yellow River to the east and Helan Mountain to the west. It is a suburban county of Yinchuan, the capital of Ningxia Hui Autonomous region, and is located to the south of Yinchuan City. It has jurisdiction over 5 towns, 1 township, 1 street and 2 state-owned farms, with a total area of 934 square kilometers and a total population of 230957 (2013). The government is stationed in Yang Wo Street. The Najia Mosque, the Great Wall of the Ming Dynasty, Li Jun Pagoda and other monuments are key cultural relics protection units in Ningxia Hui Autonomous region. In 2012, Yongning County completed a regional GDP of 7.645 billion yuan and local revenue of 1.362 billion yuan. In October 2017, Yongning County was named the National Garden County by the Ministry of Housing and Construction. In November 2017, Yongning County was awarded the "Top Ten quality Leisure Counties of 2017 in China".