3-2 Water erosion
Moving water is the major agent of the erosion that has shaped Earth's land surface. Erosion by water begins with the splash of rain.
Runoff is all the remaining water that moves over Earth's surface. When runoff flows in a thin layer over the land, it may cause a type of erosion called sheet erosion.
As runoff travels, it forms tiny grooves in the soil called rills. As the rills flow into one another, they grow larger forming gullies. A gully is a large groove or channel in the soil that carries runoff after a rainstorm. Gullies flow only after it rains.
A drainage basin is the land area from which a river and its tributaries collect their water.
Through erosion, a river creates valleys, waterfalls, flood plains, meanders, and oxbow lakes.
The flat wide area of land along a river is a flood plain. A meander is a looplike bend in the course of a river. An oxbow lake is a meander that has been cut off from the river.
RIVER SYSTEMS~ A tributary is a stream that flows into a larger stream. A drainage basin is the land area from the land area from which a river and its tributaries collect their water. A divide is the high ground between two drainage basins.
Deposition creates landforms such as alluvial fans and deltas. It can also add soil to a rivers flood plain.
An alluvial fan is a wide, sloping deposit of sediment formed where a stream leaves a mountain range. This deposit is shaped like a fan.
Sediment deposited where a river flows into an ocean or lake builds up a lanndform called a delta.
A deposit that hangs like an icicle from the roof of a cave is called a stalactitie. Slow dripping buids up a cone-shaped stalagmite from the cave floor.
Runoff is all the remaining water that moves over Earth's surface. When runoff flows in a thin layer over the land, it may cause a type of erosion called sheet erosion.
As runoff travels, it forms tiny grooves in the soil called rills. As the rills flow into one another, they grow larger forming gullies. A gully is a large groove or channel in the soil that carries runoff after a rainstorm. Gullies flow only after it rains.
A drainage basin is the land area from which a river and its tributaries collect their water.
Through erosion, a river creates valleys, waterfalls, flood plains, meanders, and oxbow lakes.
The flat wide area of land along a river is a flood plain. A meander is a looplike bend in the course of a river. An oxbow lake is a meander that has been cut off from the river.
RIVER SYSTEMS~ A tributary is a stream that flows into a larger stream. A drainage basin is the land area from the land area from which a river and its tributaries collect their water. A divide is the high ground between two drainage basins.
Deposition creates landforms such as alluvial fans and deltas. It can also add soil to a rivers flood plain.
An alluvial fan is a wide, sloping deposit of sediment formed where a stream leaves a mountain range. This deposit is shaped like a fan.
Sediment deposited where a river flows into an ocean or lake builds up a lanndform called a delta.
A deposit that hangs like an icicle from the roof of a cave is called a stalactitie. Slow dripping buids up a cone-shaped stalagmite from the cave floor.
Key ideasMoving waters is the major force of erosion that has shaped Earth's land surface.
A river may form V-shaped valleys, waterfalls, meanders, oxbow lakes, and flood plains. When a river slows down, it deposits some of the sediment load it carries, forming features such as alluvial fans and deltas. |
key termsRunoff
Rill Gully Stream River Tributary Drainage Basin Divide Flood PLain Meander Oxbow Lake Alluvial Lake Delta Groundwater Stalactite Stalagmite Karst topography |
Checkpoint questionsHow does an oxbow lake form?
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section review1. What is the major cause of erosion on Earth's surface?
2. Briefly describe five feautres formed by rivers and streams as they erode the land. 3. What are the results of deposition alond the course of a stream or river? 4. How can groundwater contribute to erosion? 5. Thinking Critically Comparing and Contrasting How is an alluvial fan similar to a delta? How is it different? |