Erosion and Landscape Evolution

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Erosion and Landscape Evolution
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Anatomy of a Drainage System
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Youth

• V-Shaped Valley
• Rapids
• Waterfalls
• No Flood Plain
• Drainage Divides Broad and Flat, Undissected by
  Erosion
• Valley Being Deepened
• General Agreement on this stage, lots of examples

4
Maturity (Early)

• V-Shaped Valley
• Beginnings of Flood Plain
• Sand and Gravel Bars
• Sharp Divides
• Relief Reaches Maximum
• Valleys stop deepening
• General Agreement on this stage, lots of examples

5
Maturity (Late)

• Valley has flat bottom
• Narrow Flood Plain
• Divides begin to round off
• Relief diminishes
• Sediment builds up, flood plain widens
• River begins to meander
• Many geologists believe slopes stay steep but
  simply retreat.

6
Old Age

• Land worn to nearly flat surface (peneplain)
• Resistant rocks remain as erosional remnants
  (monadnocks)
• Rivers meander across extremely wide, flat flood
  plains

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3
Image produced from the OS Get-a-Map service.
Image reproduced with kind permission of the OS
and OS of Northern Ireland
Describe the physical features of the river and
its valley
8
5
What features identify this stretch of river as
part of its upper course?
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7
How would you know that this valley was not
carved by the river which flows in it today?
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8
Image produced from the OS Get-a-Map service.
Image reproduced with kind permission of the OS
and OS of Northern Ireland
Describe the physical features of the river and
its valley
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ox bow lake
broad, flat flood plain
gentle long profile
limit of tidal influence
meanders
river channel more than 8m
embankments/levees
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steep valley sides
many small tributaries
no flood plain
river channel less than 8m wide
steep long profile
river follows a relatively straight course