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.
Longzi County, which belongs to Shannan City, Tibet Autonomous region, is located in the south of Shannan City, in the eastern part of the northern foot of the Himalayas, bordering Lang County and Jiacha County in the north, Menjiu County in the south, Luoyu County in the east and Cuomei County in the west, Cuona County in the southwest, Qusong County in the north, Nedong District in Shannan City in the northwest, and Milin County in the northeast. Its geographical location is 91 °53km east longitude, 93 °06km east longitude and 28 °07mm north latitude, with a total area of 10566 square kilometers and an actual control area of 8165 square kilometers. As of 2018, Longzi County has jurisdiction over 2 towns and 9 townships. By the end of 2017, the total population of Longzi County was 35858, with a regional gross domestic product (GDP) of 1.099 billion yuan, of which the added value of the primary industry was 64.185 million yuan and the second production was the second.