World Geography 3202

1
World Geography 3202

• Understand how running water acts as an agent of
  erosion and deposition. (Chapter 2)

2
Introductory Terms / Information

• Tributaries are branches of a river that feed
  water into the larger river
• Rivers flow from high elevation to low elevation
• Rivers empty into the sea at sea level 0 ft
• Look for elevation legend, often color coded,
  symbols or contour lines.

3
Amazon River
What direction does the river flow? Where is the
high elevation? Where are the tributaries? Where
does the river begin?
4
Define the term drainage basin. (p. 26)

• Drainage Basin the area of land drained by a
  river and its tributaries.
• Try question 4 p. 26

5
Drainage Basin-Circled in red
6
Drainage Basin. (p. 26)

• The Amazon Basin is the planet's largest body of
  fresh water with 1100 tributaries 17 of which are
  more than 1000 miles long.
• Many of the tributaries begin in Colombia and
  Peru.
• WHY????

7
(No Transcript)
8
Nile River Basin

• The Nile river in Africa is the longest river in
  the world.
• The green area on the map marks the Nile River
  basin.

9
(No Transcript)
10
1.3.1 Describe the three stages in the life
cycle of a river. (P. 26)

• Rivers change over time and seem to go through
  three stages
• 1st Youthful rivers
• 2nd Mature rivers
• 3rd Old rivers

11
Young Rivers

• Usually found in highland or mountain regions
• Steep slope (high gradient)
• Small volume of water
• Rapid flow of water
• Rapid erosion
• More vertical erosion than lateral
• Narrow V shaped valley
• Water falls rapids common

12
(No Transcript)
13
(No Transcript)
14
Mature Rivers

• Most high relief is eroded
• Gentler slope
• Many well developed tributaries
• Broad flat river valley
• Well developed flood plain
• More lateral (?) erosion than vertical
• Meandering results

15
Late River Maturity

• Remember the stages are not distinct.
• These changes occur over long periods of time.

16
(No Transcript)
17
Old River

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

18
(No Transcript)
19
The Amazon- What stage??
20
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.

21
Youth Stage
Mature Stage
Old Age Stage
22
1.3.4 Define the term Delta. (P.32)

• Delta
• low lying area at mouth of river
• formed by deposition of silt
• deposition occurs because river slows as it
  enters ocean or lake

23
(No Transcript)
24
1.3.5 Distinguish among the terms arcuate
delta, digitate delta and estuarine delta.
(P. 32)

• Arcuate Delta
• Named from Latin word for curved in the shape of
  a bow.
• Fan shaped
• Example Nile Delta p. 32

25
Nile Delta
26
Digitate Delta

• Digitate Delta
• From Latin for finger
• Delta with long fingers of sediment reaching into
  the sea
• Example Mississippi

27
Mississippi Delta
28
Estuarine Delta p. 32

• Estuarine Delta
• 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

29
Sacramento River San Joaquin San Francisco Bay
Delta
30
Delta Similarities Differences

• Similarities
• 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

31
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

32
What stage is this river in?

• Young
• Water falls rapids
• Steep slope

33
What stage is this river?

• Early maturity
• Some meandering
• However still some relief
• Associated with mountain

34
What river Stage?

• Youth
• Rapid water movement
• Rapids water falls
• High relief on banks

35
(No Transcript)
36
(No Transcript)
37
(No Transcript)