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.
Tengchong, a county-level city hosted by Baoshan City, is located in the southwest of Yunnan Province, connected with Longyang District in the east, Longling County and Lianghe County in the south, Yingjiang County and the Federal Republic of Myanmar in the west, and Lushui City in Nujiang Lisu Autonomous Prefecture in the northeast. The urban area is 606km away from the provincial capital Kunming, 200km away from Myitkyina in Myanmar and 602km away from Ledo, India. It is an important gateway and node for China to South and Southeast Asia. As of 2014, Tengchong City covers an area of 5845 square kilometers and has a border length of 148.075 kilometers. It has jurisdiction over 11 towns and 7 townships. In 2014, the total population (resident population) was 659900; in 2014, the regional gross domestic product (GDP) reached 13.34 billion yuan. Tengchong is a famous hometown of overseas Chinese.