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The volcanic cluster of Datong, Shanxi province is a quaternary cluster with more than 30 volcanic cones scattered across the eastern part of the Datong Basin to the east, west, south and north. The volcanoes come in four categories depending on their shape – dome, shield, semi-circle, and horse's hoof. The dome-shaped ones are basalt lava flows without a volcanic vent, such as the one at Gushan Mountain. The shield-shaped ones, such as Xiaojiayaotou and Dazhuang are basalt volcanoes. Semicircular volcanoes are formed by lava that flowed from cracks. Basalt lava flows and volcanic debris laid under one another formed the horse–hoof-shaped ones, such as Dongping Mountain and Jinshan Mountain. Judging from the landform and lava, the Datong cluster was formed between the end of the Pliocene and the Late Pleistocene, with its north and east areas the earliest and the west area the latest.