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.
Lixian County is located on the eastern edge of the Qinghai-Tibet Plateau and in the southeast of Aba Tibetan and Qiang Autonomous Prefecture. It is located at 30 °54km north latitude 31 °12km north longitude 102 °32m mi 103 °30' east longitude. It is bordered by Maoxian and Heishui in the northeast, Xiaojin in the southwest, Wenchuan in the southeast, Malkang and Hongyuan in the northwest, 202km away from the provincial capital Chengdu, 193km away from the state capital, and the county seat is 1888 meters above sea level. The geological structure of Lixian County belongs to the middle part of Longmenshan fault zone, with undulating mountains, an average elevation of 2700 meters, and a three-dimensional climate of mountain type, with more precipitation in spring and summer, short frost-free period in winter, annual rainfall between 650 ℃ and 1000 mm, and annual average temperature of 6.9 ℃-11 ℃ in the valley. Lixian County has great advantages in tourism resources. There is a natural ecological scene with beautiful scenery