Sand caves are natural formations created by the erosion of soft sandstone or other sandy materials. Over time, wind and water wear away the rock, creating hollow spaces and tunnels. These caves can vary in size and shape, often featuring unique formations like arches and pillars. Many sand caves are found in coastal areas or deserts, where the conditions favor the erosion process. They provide habitats for various wildlife and can be popular spots for exploration and photography. Notable examples include the Coyote Buttes in Arizona and the Great Sand Dunes in Colorado.