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.
Changqiao District, which belongs to Suzhou City, Anhui Province, is located in the northeast of Anhui Province, bordering the three provinces of Jiangsu, Shandong and Henan. It was renamed from the former county-level Suzhou City in 1999. It is the only municipal district of Suzhou City, with a total area of 2868 square kilometers. Yuanqiao has a long history, it was the fief of the ancient "Sui Kingdom" in the Spring and Autumn period, and it was already a "gathering place of boats and cars and a thoroughfare in Kyushu" in the Qin and Han dynasties. After the opening of the "Tongji Canal" in the Sui Dynasty, it became a military town of "strangling and controlling the Huaihe River". Confucius practiced Zhou Li here; Min Ziqian, a high apprentice of Confucius and a sage of the Chinese nation, was born here; Bai Juyi grew up here until he became famous in Changan; Wang Ji, Han Yu, Su Shi, Yuan Mei and others left splendid poems; modern and modern cultural celebrities such as Mei Chunyi, Li Bairen, Yang Zaibao, Li Bingshu, and so on. This is the old uprising of Chen Sheng and Wu Guang Daze Township.