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.
Longjing City belongs to Yanbian Korean Autonomous Prefecture of Jilin Province. Located in the east of Jilin Province, the southeast of Yanbian Korean Autonomous Prefecture and the eastern foot of Changbai Mountain, it is the forefront of Changji map development and opening up pilot area, an important part of the international cooperation of Tumen River region and the integration of Yanlong map. It is located in the southeast of Jilin Province, at the eastern foot of Changbai Mountain. The geographical coordinates are between 128 °54 °E and 129 °48'E and 42 °21 °N and 43 °24'N. Facing North Korea across the Tumen River in the southeast, the border is 142.5 kilometers long, bordering Yanji City and Tumen City in the northeast, Helong City in the southwest, and Antu County in the northwest. In 2015, Longjing City achieved a GDP of 4.03 billion yuan. As of 2014, Longjing had jurisdiction over 5 towns, 2 townships and 2 streets.