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.
Dingjie County belongs to Xigaze City, Tibet Autonomous region, located in southern Tibet, southern Xigaze City, the northern foot of the Himalayas, is one of the border counties of the Tibet Autonomous region. The area is 5461 square kilometers. Knot means "growing under the water" in Tibetan. Subordinate to Xigaze City, the county government is stationed in Jiangga. Dingjie County is located in the lake basin area at the northern foot of the Himalayas, with high terrain in the north and south and low in the middle. The climate is the plateau temperate semi-arid monsoon climate. In 2013, the total population of Dingjie County was 16000. In 2005, Dingjie County achieved a gross domestic product (GDP) of 83.85 million yuan, of which the added value of the primary industry was 34.66 million yuan, the secondary industry was 28.16 million yuan, and the tertiary industry was 45.51 million yuan. The per capita GDP is 6021.68 yuan. October 2018, Tibet