Characteristics of rivers Flashcards
Describe upland valley
V shape Steeper sides/steep long profiles Vertical erosion Narrow/non-existent valley floor Rapids, waterfalls, lakes.
Describe lowland valley
U shape Gentle long + cross profile Wider Lateral erosion Deposition Flood plain
Formation of waterfalls and gorges (Upper course)
river flows over more resistant rock, less resistant rock beneath
Rapid erosion of less resistant rock
More resistant rock not worn away as rapidly
force of the water erodes bottom of waterfall –> plunge pool
Eddy currents undercut hard rock, soft rock eroded
Collapse of overhanging hard rock
Waterfall retreats (to form gorge)
Gorge: deep, steep-sided valley
Formation of oxbow lakes and meanders (middle + lower course)
Outer bend eroded, faster flowing water, river cliff formed
Deposition, inside bends, water low velocity, slip off slope
Meander increases in size, narrow neck forms
Neck cut, water direct route, flood
Cut-off loop forms oxbow lake
Formation of floodplain and levée (lower + middle courses)
Flood occurs
Deposit material
Floodplain:
Meander cut their way through by lateral erosion
Fine material deposited on wide, flatter valley floor surrounding the river
Levée: Large, coarse sediment deposited next to the channel
Fourmation of a delta (lower + middle courses)
River meets still water from lake or sea and loses velocity
Deposition builds up
Delta gradually built out into the sea
Potholes (upper courses)
River flows over solid rocks
Eddie currents swirl stones around –> corrasion/abrasion
Hollows deeper + wider
Join together
Features upper course of river
Potholes
Interlocking spurs
Waterfalls
Gorges
Interlocking spurs (upper course)
Vertical erosion, travelling down hill
Winds + bends to avoid areas of hard rock
(spurs of land either side valley)
