Transcript Rivers and Geomorphology CGF3M

Rivers and Geomorphology
CGF3M
Rivers
1. Energy
2. Stages of River Development
3. Drainage Basins
4. River Patterns
5. Geomorphological Features
Energy
• Features due to erosion or deposition
depending on speed.
• Low energy/low speed = deposition
• High energy/high speed = erosion
Stages of River Development
A: Youthful/Upper Stage
B: Mature/Middle Stage
C: Old/Low Stage
Stages of River Development
A: Youthful Stage
• Steep, fast, straight, vertical erosion
B: Mature Stage
• Less steep, slower, meanders, horizontal
erosion
C: Old Age Stage
• Flat, slow, meandering, depositional
Drainage Basins
• Area in which all raindrops eventually
drain into the same river system, ocean, or
lake (catchment, watershed)
The Amazon Drainage Basin
Drainage Basins
• Tributaries: smaller rivers that drain into
larger rivers.
• Interfluves: pieces of higher land between
tributaries.
• Divide: higher ground
between drainage basins.
Drainage Basin
Drainage Patterns
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Main river = trunk
Tributaries = branches
Distributaries = roots
Drainage Patterns
• 5 Drainage Patterns:
– Dendritic
– Trellis
– Radial
– Deranged
– Rectangular
Drainage Patterns
Dendric Drainage Pattern
• Flow across level land, merging with other
rivers
• Resemble branching tree
Trellis and Rectangular
• Ground is made of folded bedrock, rivers
may follow a straighter course along the
softer bedrock, with hard rock on either
side.
• Often in mountainous areas.
• Trellis: one main trunk
• Rectangular: square pattern
Radial Pattern
• Landforms influenced by volcanoes and
cone-shaped hills.
• Streams radiate outward in all directions
from central zone
Deranged Pattern
• No distinct pattern noted
• Often lakes are found
throughout
• Glaciation has torn
the landscape leaving
this deranged pattern
Geomorphological Features
• Levees: sediments deposited in the
stream channel that contain the water.
(ridges).
Geomorphological Features
• Meander: sinuous back and forth sweep of
a river in old age.
• Meander scar: an oxbow lake that has
dried up leaving a dry hollow where the
river channel had been.
Geomorphological Features
• Oxbow lakes: an area of poor drainage
that occurs when a meander is cut off from
the main river channel, forming a lake.
Geomorphological Features
• Delta: depositional feature found at the
mouth of a river.
• River’s water reaches mouth of river and
the sediment is carried settles.
Geomorphological Features
• Estuary: the flooded mouth of a river
valley.