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.
Helong City, which belongs to Yanbian Korean Autonomous Prefecture of Jilin Province, is located in the southeast of Jilin Province, in the south of Yanbian Korean Autonomous Prefecture, at the eastern foot of Changbai Mountain, on the north bank of the upper reaches of Tumen River, bordering Longjing City in the east, Antu County in the west, Longjing and Antu cities and counties in the north, and the Democratic people's Republic of Korea in the south across the Tumen River. The population is 314995 (at the end of 2011), most of whom are ethnic Korean, accounting for 51.53% of the total population. It covers an area of 5068.62 square kilometers (2013). In 2015, Helong City achieved a GDP of 5.45 billion yuan. Helong City is known as the hometown of quot; song and dance & quot;, & quot; Jindalai hometown & quot;. In 1883, the Qing government and the Korean king