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.
Sangzhuzi District: formerly known as Xigaze, also known as Nianmai, Sangzhuzi is now a municipal district under the jurisdiction of Xigaze City of Tibet Autonomous region, covering an area of 3700 square kilometers. Xigaze City is the second largest city in Tibet and a national historical and cultural city. Sangzhuzi District is located in the south of Tibet Autonomous region and the east of Xigaze region. Geography: in the northern foothills of the Himalayas, the Brahmaputra River runs from east to west, meandering 145 kilometers, and the Nianchu River converges with it. The climate is relatively mild, with obvious monsoon and arid plateau climate characteristics. The average annual temperature is 6.3mm ℃ and the annual precipitation is 400mm. History: during the Sakya dynasty in the eleventh century, there was an embryonic form of a small town. It has been more than 600 years since the founding of the city: Jiangqu Jianzan, the Great Szeto of Emperor Yuanshun, established the Palzhu Dynasty, with thirteen major ones, and the last one was called Sangzhu.