A sedimentary basin is a low-lying area of the Earth's crust where sediments accumulate over time. These basins can form in various environments, such as river valleys, lake beds, or ocean floors. The weight of the accumulating sediments can cause the basin to sink further, allowing more layers to build up. Sedimentary basins are important for understanding geological history and are often rich in natural resources like oil, gas, and coal. They can also provide valuable information about past climates and ecosystems, as the layers of sediment often contain fossils and other geological records.