1. Section 2: Stream Development
Streams erode paths through sediment and rock, forming V-shaped stream valleys. K
What I Know W
What I Want to Find Out L
What I Learned

2. Essential Questions
What physical features are characteristic of stream development?
What is the relationship between meanders and stream flow?
How is the process of rejuvenation in stream development explained?
Stream Development
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3. Vocabulary Review New abrasion stream channel stream bank base level
meander
delta
rejuvenation
Stream Development
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4. Supply of Water Stream channels
The region where water first accumulates to supply a stream is called the headwaters.
Falling precipitation accumulates in small gullies at higher elevations and forms briskly moving streams.
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Stream Development

5. Supply of Water Stream channels
Moving water carves a narrow pathway into the sediment or rock called the stream channel.
Stream banks hold the moving water within them.
When small streams erode away the rock or soil at the head of a stream, it is known as headward erosion.
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Stream Development

6. Supply of Water Stream channels
The headward erosion of Stream A cuts into Stream B and draws away from its water into one stream, in a process called stream capture.
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Stream Development

7. Formation of Stream Valleys
The energy of a stream comes from the movement of water down a slope. The slope of a stream channel is called the stream gradient.
The gradient of the stream depends on its base level, which is the elevation at which it enters another stream or body of water.
Stream Development
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8. Formation of Stream Valleys
The height of a stream above its base level determines how much downcutting energy the stream will have.
Stream Development
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9. Formation of Stream Valleys
Meanders
A bend or curve in a stream channel caused by moving water is called a meander.
Water moving along the outside of a meander curve experiences the greatest velocity within the meander and erodes the side of the streambed.
Stream Development
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10. Formation of Stream Valleys
Meanders
Along the inside of a meander, the water moves more slowly and deposition is dominant.
After enough winding, it is common for a stream to cut off a meander and once again flow along a straighter path. The blocked-off meander becomes an oxbow lake, which eventually dries up.
Stream Development
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11. Add link to Animation from p. 234 here.
Meander Formation
Concepts In Motion
FPO
Add link to Animation from p. 234 here.
Stream Development
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12. Visualizing Erosion and Deposition in a Meander
The meanders of a stream are accentuated by differences in the velocity of water in the channel.
Stream Development
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13. Add link to Animation from p. 235 here.
Visualizing Erosion and Deposition in a Meander
Concepts In Motion
FPO
Add link to Animation from p. 235 here.
Stream Development
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14. Deposition of Sediment
When streams lose velocity, they lose some of the energy needed to transport sediment, and deposition of sediment occurs.
Stream Development
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15. Deposition of Sediment
Alluvial fans
Alluvial fans are fan-shaped, sloping depositional features that form when water flows down steep slopes onto flat plains.
Alluvial fans are composed mostly of sand and gravel.
Stream Development
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16. Deposition of Sediment
Deltas
The triangular deposit that forms where a stream enters a large body of water is called a delta.
Delta deposits usually consist of layers of silt and clay particles.
Stream Development
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17. Rejuvenation
During rejuvenation, a stream actively resumes the process of downcutting toward its base level.
This causes an increase in the stream’s velocity, and the stream’s channel once again cuts downward into the existing meanders.
Stream Development
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18. Review Essential Questions Vocabulary
What physical features are characteristic of stream development?
What is the relationship between meanders and stream flow?
How is the process of rejuvenation in stream development explained?
Vocabulary
stream channel
stream bank
base level
meander
delta
rejuvenation
Stream Development
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