River valleys are low-lying areas formed by the erosion and deposition of sediment by rivers over time. They typically have a V-shape, with steep sides and a flat bottom where the river flows. These valleys can vary in size and are often fertile, making them ideal for agriculture and human settlement. The landscape of river valleys can include features like floodplains, meanders, and oxbow lakes. They play a crucial role in ecosystems, providing habitats for various plants and animals. Additionally, river valleys are important for transportation and can influence weather patterns in the surrounding regions.