明成祖朱棣在修建紫禁城的时候从北京郊区西山、房山一带开采了很多石材,其中以故宫保和殿后一块采自房山的汉白玉制成的最大云龙图案石雕最为吸引游客;而注意到太和殿前的地板的游客就不多了,这些地板由产自北京西山寒武系的石灰岩拼成,其中很多石板表面可见长条状、扁圆状等的砾石,这就是地质学上通称的“砾屑灰岩”(flat-pebble conglomerate Ming dynasty Zhu Di in the construction of the Forbidden City from the Beijing suburb of Xishan, Fangshan area mining a lot of stone, of which the Imperial Palace Baohe Hall after a collection of white marble from Fangshan made the largest Yunlong stone carving patterns most attract tourists; and noticed There are not many tourists on the floor. The floors are made of limestone from the Cambrian Department of Xishan, Beijing. Many of the slates show gravel on the surface, such as long strips and oblate shapes. This is geologically known as “ Limestone ”(flat-pebble conglomerate