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.
Changshu City, referred to as Yu, is named Changshu, a national historical and cultural city, because of "fertile soil and no flood and drought". Changshu is located in the south of the Yangtze River, known as the "blessed land in the south of the Yangtze River", is one of the birthplaces of Wu culture. Changshu, located in the south of Jiangsu Province, is a county-level city hosted by Suzhou. Changshu City is bordered by the Yangtze River in the northeast, Taicang in the southeast, Kunshan City and Xiangcheng District in Suzhou City in the south, Jiangyin City in the west and Xishan District in Wuxi City, and Zhangjiagang City in the northwest. Changshu under the jurisdiction of 8 towns, 6 streets, a total area of 1264 square kilometers, the territory of low-level, intertwined water network, located in the temperate zone, is a subtropical monsoon marine climate. Changshu culture belongs to Wu-Yue culture, and the people of Changshu belong to the people of Jiangsu and Zhejiang provinces. Changshu is an excellent tourist city in China and an international garden city.