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.
Hunchun City, which belongs to Yanbian Korean Autonomous Prefecture of Jilin Province, is located in the east of Jilin Province and southeast of Yanbian Korean Autonomous Prefecture. Hunchun is bordered by Hunchun Ridge and Hassan District of Russia's coastal border region. The total length of the border is 246km. The southwest is bounded by the Tumen River and is adjacent to Hamgyong North Road of North Korea. The total length of the border is 139.5 km. The north is bounded by Laoyeling and adjoins Wangqing County, the northwest corner is connected with Tumen City, and the northeast is adjacent to Dongning City, Heilongjiang Province. It is between longitude 130o 03m 21 "- 130o 18m 33" east and latitude 42o 25m 20 "- 43o 30m 18" north, with a total area of 5145 square km. Hunchun is the only border city in China located at the junction of China, North Korea and Russia, because it is at the core of international cooperation and development in the Tumen River region.