![]() The floor of the valley is narrow, and the valleys are reshaped. Here the velocity of the water is faster due to the steep gradient. First is the upper or the mountain course where the river originates.The course of a river comprises three distinct paths. The irregularities of the ground force the river to swing in great S-shaped curves forming horseshoe-like loops called meanders. ![]() A winding course develops as water flowing under gravity seldom flows straight for long distances. The rivers flow through almost a flat plane in the middle courses. Meanders are formed in the middle course of a river. As fast-flowing water erodes the outside of the pool and slow-flowing water deposits, various materials inside the pool meander begin to occur. The river now swings side to side, and the pools move to opposite sides of the relatively straight channel over time. Shallower parts of the river contain faster areas of water and larger stones. Deeper parts of the river contain slower water areas filled with fine sediments. River water flows around various obstructions such as stones and rocks, which results in different areas of slow and fast-moving water. The winding curve in a river results from erosional and depositional processes. The river’s been cutting, matching an uplift rate of the bedrock-basalt layer after basalt layer exposing themselves on the way up. ![]() The land has been lifting against the meander against the river. The river has been down there for millions of years. Entrenched meanders tell that the land is lifting against the river. A subtle curve is becoming a more exaggerated curve. The meanders got established when the area was flat. It undercuts the riverbank and forms a river cliff, whereas the water travels slower on the inside bend, causing deposition to create a slip-off slope. As the water flows through the meander, it travels faster on the outside bend creating erosion through abrasion and hydraulic action. Meander is a slight bend in the river, and water will continue to flow down the river’s long profile from the upper course to the low cost. The exaggerated curves also mean central Washington used to be flat. Humans can only develop these curves when an area is flat, like back east at the Mississippi. Eventually, the meander becomes so exaggerated that the curve is abandoned, forming an oxbow lake. As rivers age, they develop more and more exaggerated meanders. Continuous erosion on the outer bank and deposition on the inner bank forms a meander in the river, which will migrate downstream and change shape over time.Meanders are a feature of old age.Water moves slowly on the inside of the bend and the river deposits some load, forming a gently sloping river beach (also called a slip-off slope).The river erodes the outside bends through hydraulic action, corrasion and corrosion.This occurs on the outside of the bend and forms a river cliff. Water moving faster has more energy to erode.A corkscrew-like flow of water called Helicoidal Flow moves material from the outside of one meander bend and deposits it on the inside of the next bend.Once pools and riffles have developed, the river flows from side-to-side in a winding course.Riffles are areas of shallow water created by deposition of coarse sediment. Pools are areas of deep water and greater erosion (energy build-up due to less friction).This results in areas of slower and faster water movement. In a straight river channel pools and riffles will develop as water twists and turns around obstructions such as large boulders.
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