Three Gorges primarily famous for its scenery, the Three Gorges region is also historically and culturally important in China. Many settlements and archaeological sites are in danger of being submerged by the rising reservoir of the Three Gorges Dam. Due to the lithological conditions of its different regions, the valleys of the Three Gorges are narrow in some areas and broad in others. Most narrow valleys occur in regions where there is limestone, which is relatively hard and resists erosion. However, water can flow along deep vertical fractures, eroding underneath. As the limestone bed is gradually undercut, parts of it fall into
Three Gorges with terrain lowering gradually from south to north. The western and eastern parts of the area, between the southern mountains and Bashan Mountain (), in the north, are comparatively lower; and in the past, the river flowed to the east through the region. As the crust of the locality continued to rise, the river's erosion intensified, and the Three Gorges were carved. The natural beauty of the Three Gorges along the Yangtze River has been appreciated for hundreds of years. In the Northern Wei (北魏) dynasty, Li Daoyuan (郦道元) described them in his work "Shui Jing Zhu" (水经注), or the