Drainage patterns refer to the arrangement of rivers and streams within a drainage basin. Common patterns include dendritic, trellis, radial, rectangular, and centripetal. Dendritic patterns resemble tree branches and form on uniform rock surfaces. Trellis patterns develop in areas with alternating hard and soft rocks. Radial patterns flow outward from a central high point such as a volcano or dome. Rectangular patterns occur where rocks are fractured, causing right-angle bends. These patterns provide valuable clues about the underlying geology and structure of the land.