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Questions and Answers
What percentage of running water is a significant agent in land surface degradation in humid regions with heavy rainfall?
What percentage of running water is a significant agent in land surface degradation in humid regions with heavy rainfall?
What type of flow occurs as a sheet on the land surface?
What type of flow occurs as a sheet on the land surface?
What happens to stream channels over time due to erosion?
What happens to stream channels over time due to erosion?
What is the result of continued erosion on hills and valleys?
What is the result of continued erosion on hills and valleys?
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What is the term for a lowland with faint relief formed by stream erosion?
What is the term for a lowland with faint relief formed by stream erosion?
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What is characteristic of the youth stage of a river?
What is characteristic of the youth stage of a river?
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What happens to rills and gullies over time?
What happens to rills and gullies over time?
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What is the term for a resistant remnant formed through stream erosion?
What is the term for a resistant remnant formed through stream erosion?
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Which of the following characteristics is unique to the Mature Stage of a river?
Which of the following characteristics is unique to the Mature Stage of a river?
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What is the primary mechanism of erosion in Corrasion or Abrasion?
What is the primary mechanism of erosion in Corrasion or Abrasion?
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In the Old Age Stage, what is the dominant process shaping the river landscape?
In the Old Age Stage, what is the dominant process shaping the river landscape?
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What is the primary difference between vertical corrosion and lateral corrosion?
What is the primary difference between vertical corrosion and lateral corrosion?
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What is the primary mechanism of Transportation involved in Traction?
What is the primary mechanism of Transportation involved in Traction?
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What is the characteristic feature of the landscape in the Old Age Stage?
What is the characteristic feature of the landscape in the Old Age Stage?
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Which of the following is NOT a type of erosion?
Which of the following is NOT a type of erosion?
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What is the primary mechanism of Corrosion or Solution?
What is the primary mechanism of Corrosion or Solution?
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Study Notes
Running Water as a Geomorphic Agent
- In humid regions with heavy rainfall, running water is a significant agent in land surface degradation.
- Running water has two components: overland flow (as a sheet on the land surface) and linear flow (as streams and rivers in valleys).
Erosional Landforms
- Vigorous, youthful rivers on steep gradients are associated with erosional landforms.
- Stream channels become gentler over time due to erosion, leading to increased deposition.
Depositional Forms
- Streams flowing over steep slopes lead to depositional forms on a small scale.
- Over medium to gentle slopes, streams contribute to larger-scale deposition.
Effect on Landforms
- Continued erosion reduces downward cutting and increases lateral erosion, transforming hills and valleys into plains.
- Sheet erosion by overland flow occurs on the land surface.
- Overland flow concentrates into narrow to wide paths, forming rills and gullies.
- Friction of flowing water removes materials from the land surface, leading to rill formation.
- Rills and gullies further deepen, widen, lengthen, and unite to form valleys.
Stages of Valley Development
- Early stages: down-cutting, removing irregularities like waterfalls.
- Middle stages: slower stream bed cutting and severe lateral erosion of valley sides.
- Valley sides are gradually reduced to lower slopes, forming a peneplain (lowland with faint relief).
Stages of River
Youth Stage (Erosion dominates)
- Few streams, poor integration, and shallow V-shaped valleys.
- Trunk streams may have narrow floodplains or none at all.
- Broad and flat stream divides with marshes, swamps, and lakes.
- Meanders may develop on broad upland surfaces, possibly entrenching themselves.
- Waterfalls, Georges, and rapids may exist in areas with exposed hard rock bodies.
Mature Stage (Transportation dominates)
- Plenty of streams with good integration, increasing water volume with the confluence of many tributaries.
- Vertical erosion slowly starts to replace with lateral erosion or erosion from both sides of the channel.
- River channel causes the gradual disappearance of its V-shaped valley (not completely).
- Trunk streams have wider floodplains, allowing for alluvial fans, piedmont alluvial plains, meanders.
- Flat and broad inter-stream areas, swamps, and marshes of youth disappear.
- Sharp stream divides with no waterfalls or rapids.
Old Age Stage (Deposition dominates)
- Few smaller tributaries with gentle gradients.
- Streams meander freely over vast floodplains with natural levees, oxbow lakes, etc.
- Broad and flat stream divides with lakes, swamps, and marshes.
- Landscape mostly at or slightly above sea level.
Erosion Types
- Corrasion or Abrasion: rock particles break off additional rock fragments through bouncing, scraping, and dragging.
- Vertical corrosion: acts downward.
- Lateral corrosion: acts on both sides.
- Corrosion or Solution: chemical or solvent action of water on soluble or partly soluble rocks.
- Hydraulic Action: mechanical loosening and sweeping away of material by the sheer force of river water itself.
Transportation types
- Traction: heavier and larger rock fragments like gravel, pebbles, etc. are forced by the flow of the river to roll along its bed.
- Saltation: fragments of rocks bounce and jump along the riverbed.
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Description
This quiz covers the role of running water in land surface degradation, including overland flow, linear flow, erosional landforms, and depositional forms.
