What Is a valley that forms when water cuts into rock over time?

A valley that forms when water cuts into rock over time is known as a "river valley." This process, called erosion, occurs as flowing water removes soil and rock, gradually deepening and widening the valley. River valleys typically have a V-shape and are often characterized by steep sides and a flat bottom, shaped by the persistent action of the river over thousands of years. Examples include the Grand Canyon, which showcases the power of water erosion.