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.
Shulan City, which belongs to Jilin City, Jilin Province, is located in the north-central part of Jilin Province, with geographical coordinates of 43 °51 latitude 44 °38 'north latitude and 127 °45' east longitude. Jilin Province under the jurisdiction of county-level cities, entrusted to Jilin City escrow. It is bordered by Longtan District and Jiaohe City of Jilin City in the south, Jiutai City across the Songhua River in the west, and Wuchang City in Heilongjiang Province in the northeast. The city is 105km long from east to west and 77km wide from north to south, with a total area of 4557.05 square kilometers. With a total population of 656000 (2012), it has jurisdiction over 5 streets, 10 towns, 5 townships and 1 provincial economic development zone. In 2012, the gross domestic product of Shulan City reached 18.55 billion yuan. The first batch of national experimental and demonstration areas for sustainable agricultural development. In September 2018, in the sixteenth session