1. World Geography 3202
Understand how running water acts as an agent of erosion and deposition. (Chapter 2)

2. 1.3.1 Define the term drainage basin. (p. 26)
Drainage Basin is the area of land drained by a river and its tributaries.
The Amazon Basin is the planet's largest body of fresh water with 1100 tributaries 17 of which are more than miles long. Many of the tributaries begin in Colombia and Peru.

3. Nile River Basin
The Nile river in Africa is the longest river in the world.
The green are on the map marks the Nile River basin.

7. 1. 3. 1/3. Describe the three stages in. the life cycle of a river. (P
Rivers change over time and seem to go through three stages:
1st Youthful rivers
2nd Mature rivers
3rd Old rivers

8. Young Rivers Usually found in highland or mountain regions
Steep slope (high gradient)
Small volume of water
Rapid flow of water
Rapid erosion
Narrow “V” shaped valley (usually erodes deeper not wider)
Water falls & rapids common

10. Mature Rivers Most high relief eroded Gentler slope
Many well developed tributaries
Broad flat river valley
Well developed flood plain
More lateral erosion than vertical
Meandering results

12. Old River Almost no slope Very little relief Elaborate meandering
Often swampy areas around river
Very muddy due to slow speed
Most susceptible to flooding because of large flood plain.

13. Red River

14. Late River Maturity Remember the stages are not distinct.
These changes occur over long periods of time.

15. 1.3.2 Describe two ways in which water erosion occurs. (P. 31)
Vertical erosion makes rivers deeper as is the case in young rivers
Lateral erosion makes rivers wider leading to the meandering of mature rivers.

16. 1.3.4 Define the term Delta. (P.32)
Delta is a low lying area at mouth of river
Deltas are formed by deposition of silt
Deposition occurs because river slows as it enters ocean or lake

17. 1. 3. 5. Distinguish among the terms arcuate
* Distinguish among the terms arcuate delta, digitate delta and estuarine delta. (P. 32)
Arcuate Delta is named from the curved shape of a bow.
Fan shaped
Example Nile Delta p. 32

18. Digitate Delta
Digitate Delta is a delta with long fingers of sediment reaching into the sea
Example Mississippi

19. Estuarine Delta p. 32
Estuarine Delta is formed when river runs into bay or estuary
Tidal mud flats form which can be seen at low tide
Sediment deposited from river outflow and from tidal inflow

20. Delta Similarities & Differences
Arcuate & digitate both flow into open ocean
All three allow river water to flow out
All have channels or distributaries cut into them by the river
Differences
Estuarine empties into a bay whereas other 2 empty into open water
Three different shapes

21. Video

22. 1. 3. 3. Examine evidence to determine the life cycle stage of a river
1.3.3 Examine evidence to determine the life cycle stage of a river. (P. 28 questions #5 & 6)
Evidence to look for
Slope of the river
Relief of the banks
Width of the valley
Meandering
Size of flood plain
Rapids or water falls

23. What stage is this river in?
Young
Water falls & rapids
Steep slope

24. What stage is this river?
Early maturity
Some meandering
However still some relief
Associated with mountain

25. What are the Stages in a River Cycle?
Youth
Rapid water movement
Rapids & water falls
High relief on banks

26. What kind of Delta?

27. What kind of Delta?

28. What Kind of Delta?

29. How are Deltas Formed
Deltas are formed from the deposition of the sediment carried by the river as the flow leaves the mouth of the river in smaller channels called distributaries.
Over long periods of time, this deposition builds the characteristic geographic pattern of a river delta.

30. Conditions Required to Form a Delta
1. The river must carry a large amount of sediments. 2. The waves or current along the coast must NOT be strong enough to remove the sediments deposited by the river, at least not faster than the river can deposit them. 3. The slope of the sea floor or lake at the river mouth must be gentle or flat.
Deltas often change in size based on ocean and river currents

31. How Deltas are Formed