Introduction to the Dongxuanguan Formation and Anqima Fossils: A set of conglomerate, fine sandstone, and mudstone rocks is exposed on the west slope of Fangshan Mountain. Geologically, it is called the Dongxuanguan Formation. It is similar to the Yuhua Stone produced in Nanjing. The Yuhuatai Formation is of the same age and was formed by the deposition of pebbles and silt in rivers at that time. Fossils have been found in this set of sandy conglomerates.