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.
Zichuan District, which belongs to Zibo City, Shandong Province, is located in the middle of Zibo City, bordering Boshan District in the south, Zhangqiu City in the west, Zhoucun, Zhangdian and Linzi in the north, Qingzhou in the east and Linqu and Yiyuan in the southeast. Between longitude 117o41 & #39;-118 °14 & #39;, 36 °22 & #39;-36 °45 & #39;, it is 49 km long from east to west and 42 km wide from north to south, with a total area of 960 square kilometers. Zichuan District has Pu Songling's former residence and Ma'anshan Anti-Japanese site as provincial key cultural relics protection units. The site of Dahe tragedy and the former site of "Great Han Dezhu" in Qing Dynasty are municipal cultural relics protection units. Places of interest include Su Xiang's Tomb, Yang Zhaita, Liaozhai Park, Zichuan Amusement Park and so on. As of 20