Xiaonanhai Dam upstream from the Three Gorges Dam. Weng Lida, a former director of the water resources bureau at the Yangtze River Commission, said that senior China Three Gorges executives had succumbed to pressure from the Chongqing authorities. According to the "South China Morning Post", Chongqing's success in overcoming all major obstacles to the dam's construction is attributed to the personal intervention of Bo. The project was strongly opposed by environmentalists, who saw it as a "politically motivated decision". It was highly controversial due to the environmental impact, the high cost-benefit ratio, as well as the secretive decision-making process under Bo. A
Three Gorges the river along vertical fractures, forming precipitous cliffs. When the river flows through areas of softer sandstone and shale, which have less resistance to erosion, the erosive effect is increased, carving wide valleys. There are different theories on how the Three Gorges were formed, but geographers and geologists have generally reached a consensus, believing mountain folding in the east of Sichuan Province and the west of Hubei Province, including the Wu Mountains (), were the outcome of the Yanshanian movement () around 70 million years ago. The gorges run from southwest to northeast, then turn, and from west to east,