Much of Wyoming is covered with large basins containing different eco-regions, from shrublands to smaller patches of desert. Regions of the state classified as basins contain everything from large geologic formations to sand dunes and vast unpopulated spaces. Basin landscapes are typically at lower elevations and include rolling hills, valleys, mesas, terraces and other rugged terrain, but also include natural springs as well as rivers and artificial reservoirs. They have common plant species such as various subspecies of sagebrush, juniper and grasses such as wheatgrass, but basins are known for their diversity of plant and animal species.