The Niagara Falls formation is a slow process that continues today. The annual freezing and thawing of the Niagara River still wears away at the rocks under the surface. Gradual erosion and periodic rockfalls steadily move Niagara Falls farther upstream. However, modern influences have caused the falls to wear away less quickly. Remedial work has been done to preserve the falls and the volume of water has been reduced by diversion for hydroelectric power.