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.
Shuangyashan City is a prefecture-level city in Heilongjiang Province. Shuangyashan City is located in the northeast of Heilongjiang Province, with high terrain in the southwest and low in the northeast, and is located in the humid climate zone of the middle temperate zone. It has jurisdiction over 4 districts and 4 counties, with a total area of 22483 square kilometers and a total population of 1.423 million in 2017. Within 300 kilometers of Shuangyashan, there are Tongjiang, Fuyuan and other first-class ports to Russia, which are located in the core area where Heilongjiang Province opens to the Russian far East, and is an important node city for the construction of the "China-Mongolia-Russia Economic Corridor." It has a first-class national port-Raohe Port, the Raohe Sino-Russian Exchange Trade Zone and the Sida Sino-Russian International Trade Center have been put into operation, and the Sino-Russian International Cultural Logistics Economic and Trade Industrial Park is being constructed. to build an import and export processing base for Russia and a national trade distribution base for Russia. Successively opened Shuangyashan to Haba.