1. Characteristics of Straight, Meandering, and Braided Channels

2. Straight Channels Rare Low velocity due to low gradient (slope)
Bars = piles of sediment within the channel.
Rare because of constant deposition and erosion

4. Velocity in a straight river channel
Velocity is always greatest in the middle away from the banks and bed of the channel (area 4)

5. Meandering Channels Latin word for WANDERING.
Cutbank = outside curve of meander.
High erosion and velocity
Point bar = inside curve of a meander.
High deposition
Low velocity
This continual erosion and deposition causes the channel to move and bend across a river valley.
Creates a floodplain and Oxbow Lakes
Flat land next to a river that can floods.

6. Oxbow Lakes – lake formed when a meander of a river is cut off from the main channel

8. Braided Channels Low gradient End of a river
Usually happens at deltas.

10. Deltas Stream enters standing body of water.
Velocity drops and sediment is deposited.
They build outward from coastline.
Can only survive in low current and velocity.

13. The Stream Cycle
As a river erodes its banks and bed, it changes the landforms it passes though and alters its own course. The development of a river system is divided into three stages:
Youthful
Mature
Old
A river can become rejuvenated

14. Youthful Rivers V-shaped valley with steep sides
A youthful stream usually erodes its bed more rapidly than it erodes its banks.
V-shaped valley with steep sides
Waterfalls and rapids are common
Relatively few tributaries.
No Floodplain
Flat area next to a river that can flood
Somewhat straight channel
Steep gradient
Few pointbars
Youthful Rivers

16. Yellowstone River

18. Mature Rivers V-Shaped valley is not as deep Floodplain develops
Increased meanders
Gradient begins to reduce
Erosion is sideways instead of downward
Divides become rounded
Erosion and deposition at near equal rates
Pointbars and cutbanks develop

19. Old Rivers Land worn to nearly flat surface
No downward cutting taking place
Very low gradient
Rivers meander across extremely wide, flat flood plains
Natural levees may form
Oxbow lakes form

20. Oxbow Lakes

24. Rejuvenated Rivers
Uplift of Land (Lowering of Sea Level, sometimes greater stream flow) causes stream to speed up and cut deeper.
Stream valley takes on youthful characteristics but retains features of older stages as well.
Can happen at any point in the cycle.

25. Rejuvenation of an old-age landscape

26. Rejuvenation of an early mature landscape