Headward Erosion - Drainage Patterns Created By Headward Erosion

Drainage Patterns Created By Headward Erosion

Headward erosion creates three major kinds of drainage patterns: dendritic patterns, trellis patterns and rectangular and angular patterns. Dendritic patterns form in homogenous landforms where the underlying bedrock has no structural control over where the water flows. They have a very characteristic pattern of branching at acute angles with no common or similarly repeating pattern. Trellis patterns form in where the underlying bedrock where there is repeating weaker and stronger types of rock. The trellis pattern cuts down deeper into the weaker bedrock, and is characterized by nearly parallel streams that branch at higher angles. Rectangular and angular patterns are characterized by branching of tributaries at nearly right angles and tributaries which themselves exhibit right-angle bends in their channels. These usually form in jointed igneous bedrocks, horizontal sedimentary beds with well-developed jointing or intersecting faults. (Easterbrook, p. 149-150)

Four minor kinds of drainage patterns also can be created: radial patterns, annular patterns, centripetal patterns and parallel patterns. Radial patterns are characterized by flow of water outward from a central point, such as down a newly formed cinder volcano cone or an intrusive domes. Annular patterns form on domes of alternating weak and hard bedrocks. The pattern formed is similar to that of a bullseye when viewed from above, as the weaker bedrocks are eroded and the harder are left in place. Centripetal patterns form where water flows into a central location, such as in a karst limestone terrain where the water flows down into a sinkhole and then underground. Parallel patterns are not very common and form on unidirectional regional slope or parallel landform features. They are usually limited to a small, generalized area. (Easterbrook, p. 152)