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AIM: What is a stream/river?
Do Now: Where does the water come from that fills streams and rivers? Where do streams and rivers begin?
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I. Source of Stream Water
begin at higher elevations water comes from: Rain fall Glacial Melting Underground (especially when it has not rained for a while)
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start of the stream/river.
(Headwaters) Stream/River System start of the stream/river. Tributaries small streams Stream/River Bank sides of the channel bending and turning of a stream channel (wander). path the water follows. end of the stream/river
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II. Describing streams Discharge: Velocity: Gradient
The amount of water moving in the stream/river. Speed at which the water is moving Steepness of the land (formula in ESRT)
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*Due to there being more water
Source vs. Mouth Channel = Gradient = Discharge = Velocity = Channel = Gradient = Discharge = *Velocity = wide narrow gentle steep less greater less greater *Due to there being more water Gentle Gradient
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Aim: How do streams/rivers change the landscape?
Do Now: In your note books, explain how the velocity of a stream/river affects it’s ability to erode and deposit?
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What words would you use to describe this river?
I. Stream/River Flow flow describes the movement of water depends greatly on stream velocity, gradient and discharge.. What words would you use to describe this river?
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- The more velocity and discharge, the more erosion occurs.
II. Erosion - Streams/Rivers erode material in three ways: Solution: soluble minerals (can’t see) Suspension : floating in the middle (sands silts and clay) Bed Load: rolling along the bottom (pebbles cobbles and boulders)
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Bed Load- bouncing or rolling
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- Streams/Rivers abrade rocks as they flow.
- Sediments become rounder and smaller.
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Narrow V-shaped valley’s are created as streams/rivers erode away bedrock.
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- Take a worksheet from the back top bin
- Take out your ESRT and turn to page 6 * Each section counts by the place value listed at the beginning.
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- as stream/river velocity (speed) decreases sediments can no longer be carried.
III. DEPOSITION What size sediment will deposit first in the river? Why? Larger sediments are deposited (settle) near the headwaters (start) and smaller sediments are carried to the mouth (end). This causes the sediments to be sorted.
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What size sediments do you think make up the deltas and alluvial fans?
Deltas and Alluvial fans are an accumulation sediment at the mouth of a stream/river. What size sediments do you think make up the deltas and alluvial fans? Why?
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Describe velocity on the inside and outside of the bank.
On meandering streams, erosion occurs on the outside of the bank and deposition occurs on the inside of the bank. Describe velocity on the inside and outside of the bank. - Inside bank = slow velocity (deposition) - Outside bank = fast velocity (erosion) - Creates an Oxbow Lake
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Meandering River Cross Section
Copy Diagram
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At which letters does erosion occur?
At which letters does deposition occur? A and D 2) B and C A B C D
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Closure - In your Review books – Page 141-143 # 1-11 This must be finished for homework.
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