1. The velocity of a stream or river determines
The size of the sediment it can carry
Example: What velocity would be required to transport
a small cobble (6.4 cm.) ?
The following chart shows how to get the answer

3. Intersects
Graph here
Answer= 175cm/sec

4. What is the largest size particle that
could be transported by a stream
with a velocity of 400 cm/sec?

5. Answer = boulders

6. Particles that are 1.5 cm. In diameter
would be which type of particle?

7. Answer = pebbles

8. As the gradient of a river becomes less,
the river enters the mature stage of it’s life
Yellowstone River

9. The river may start to braid and deposit sediment in the mature stage
Sand bar
The river may start to braid
and deposit sediment in the
mature stage

10. As the river becomes
old, it develops meanders

11. Large meander

12. Old meandering stream in Colorado

13. As a result: Erosion here As the stream curves It slows on the inside
And speeds up on the
outside,
Deposition
here
As a result:
Sand bar

14. High velocity
large sediment
carried
Low velocity
larger sediment
deposited

15. Red line shows the fastest velocity Deposition here Erosion here
Where the stream runs straight,
the fastest velocity is in the center
just below the surface

16. Meander bend on the River Conwy
Explain why there is more deposition at ‘A’ rather than at ‘B’.

17. In the process an oxbow lake is formed
Streams that develop very sharp meanders may
actually undergo cutoff a new channel is formed as shown

18. Oxbow lake
New channel

19. Sand bar
Oxbow lake
Flood plane

20. Profile of an old age river

21. When old age rivers reach the ocean or a lake, a delta
is formed as the river drops most of it’s remaining
sediment
Young delta
Mature delta
Old delta

22. New Orleans river Gulf of Mexico Mississippi delta as seen from
space shuttle
Gulf of Mexico

23. Nile River Delta
Nile River
Mediterranean Sea

24. As a river enters a still body of water (lake, or ocean)
it’s velocity slows to zero. As it does, it deposits the sediment load according to size.
This is known as horizontal sorting
Lake
Largest first
Medium next
Finest last

25. smallest
largest

27. Which particle would settle the fastest in still water?
Which particle would settle the slowest in still water?

28. It should also be noted that sediment A most likely
settled more quickly than sediment B
Sediment A and B are both round, and of the same
size. How can you account for the fact that
sediment A has settled mostly on the bottom?
Answer: Sediment A is denser than sediment B

29. Summary of deposition factors:
Size: larger sediment particles settle faster than smaller particles
Shape: rounder sediment particles settle faster that flat particles
Density: denser sediment particles settle faster than lower density
particles