GL102 Lecture Notes - Lecture 8: Head Of The Valley, Headward Erosion, Wind Gap
Document Summary
A graded stream has reached near equilibrium and maximum efficiency: no net erosion or deposition. The base level is the lowest level to which a stream can erode its bed. Some streams are very narrow compared to their valleys (misfit streams). This is because their valley was carved by a glacier. Many of canada"s streams do not fit their valleys because they occupy ancient spillways carved by former glacial meltwater streams. Occurs in arid regions where weathering is slow and rock is resistant. Streams primary work has been down cutting. As a stream approaches base level, less energy is for down cutting and more energy into lateral erosion. Stream energy is directed from side to side forming an erosional floodplain. If sediment accumulates in an existing valley, the valley floor broadens, forming a depositional floodplain. Deposits accumulate on the channel floor, act as obstacles, split the water flow. Complex network of diverging and converging flow paths.
