Geology And Geophysics

An Outline of River Landforms



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Movement of water, by means of erosion and geology along with climate, is responsible for creating river landforms. Their shapes reveal their ages. Young rivers have valleys in V-shapes and irregular depths. Mature rivers have long sloped valleys and meandering streams. Sluggish streams and oxbow lakes characterize older rivers. Deltas and floodplains are a couple of other examples of river landforms.

Process

Climate is responsible for forming river landforms. It is not a separate process but works in conjunction with erosion and geology. All three work together to make the formations found along a river. Rain and wind start the erosion process. Glaciation, volcanic eruptions, and earthquakes can further contribute to the erosion increasing the process. Areas with more rain and precipitation see many river landforms; while, in more arid places, the depths of the rivers may change as the dirt flows into the riverbeds.

Valleys and canyons

Erosion creates valleys, canyons and badlands. The constant action of ice forming and melting on a river changes the shape of the river. Rain falling on weak sand and dirt make paths called runoff. Runoff cuts its way down a mountain or hillside. As the runoff widens, it becomes a river. V-shaped valleys develop from flowing water. The shape the valley takes on depends on the size and speed of the river. Glaciers form U-shaped valleys. The Mt. Hood Wilderness is an example of a U-shaped valley. Canyons are deep river valleys. Arizona’s Grand Canyon is the most well-known canyon. Sandstone, shale and other stones form badlands when wind-driven rain and sand fall against their weak surfaces. Scoured and barren rocks characterize these lands.

Floodplains and deltas

Deltas form when rivers push debris down into already formed bodies of water. Deltas contain large amounts of sand and gravel. They form at the mouths of rivers and often connect to bays. San Francisco has a delta, as does the Gulf of Mexico. Parts of the area along the Missouri River are examples of floodplains. They stretch from the river all the way to the edge of a hill or mountain. Floodplains occur adjacent to mature and aged rivers. As floods and erosion continue along a river, floodplains can become terraces. Uplift is an important process for initiating a new cycle of erosion.

Rejuvenation

Conservation groups have started rejuvenation projects in some older streams and rivers. By digging debris from a slow-moving river and planting native plants along its banks, conservationists can make the river a valuable habitat for all wildlife. Sometimes dams have blocked areas and caused the river to stagnate. Removing the dam and diverting the river helps the river to heal and become a healthy home for fish and other creatures.

River landforms are those forms that occur adjacent to or in a river. Climate, erosion, deposits and geologic forces all contribute to the shape of the river. Time can change the shape of a river. Studies show that, if people change the shape of polluted and stagnant rivers, they can become productive and vibrant. Man has altered the productivity of some rivers. Careful planning can reverse the negative effect(s). 

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ARTICLE SOURCES AND CITATIONS
  • InfoBoxCallToAction ActionArrowhttp://www.thecanadianencyclopedia.com/articles/river-landform
  • InfoBoxCallToAction ActionArrowhttp://www.opb.org/programs/ofg/episodes/view/2106