Unit 1 C River Landscapes In The Uk Flashcards
What does the long profile of a river show
How the gradient changes of the different courses
What does the cross profile show
What a cross-section of the river looks like
Describe the upper course of a rivers gradient,valley and channel shape
- steep gradient
- V-shaped valley,steep sides
- narrow,shallow channel
Describe the middle course of a rivers gradient,valley and channel shape
- medium gradient
- gently sloping valley sides
- wider,deeper channel
Describe the lower course of a rivers gradient,valley and channel shape
- gentle gradient
- very wide,almost flat valley
- very wide,deep channel
Vertical erosion
- deepens river valley and channel making it v-shaped
- dominant on the upper course of river
- high turbulence causes rough,angular particles to be scraped along the river bed,causing intense downwards erosion
Lateral erosion
- widens river valley and channel during formation of meanders
- dominant in middle and lower courses
What is hydraulic action
The sheer force of the water breaks rock particles away from the river channel
What is abrasion
When eroded rocks picked up by the river scrape and rub against the channel,wearing it away
What is attrition
When eroded rocks picked up by the river smash into each other and break into smaller fragments.their edges get rounded off as they rub together.
What is Solution
When river water dissolves some types of rock
How do waterfalls form
- form when river flows over area of hard rock followed by area of softer rock
- softer rock is eroded more than hard rock creating a ‘step’ in the river
- as water goes over step it erodes more or the softer rock
- steep drop is eventually created which is called a water full
how are gorges formed
- hard rock is eventually undercut by erosion from waterfall and becomes unsupported and collapses
- collapsed rock are swirled around at food of waterfall where they erode softer rock by abrasion which creates a plunge pool
- over time more undercutting causes more collapses. The waterfall retreats leaving behind a steep sided gorge
What are interlocking spurs
- rivers aren’t powerful enough to erode laterally in the upper course as they have to wind around the high hillsides that stick out into their paths on either side
- The hillsides that interlock with each other as the river winds around them are called interlocking spurs
Meanders
- current faster on outside of bend because river channel is deeper (less friction to slow water down)
- so more erosion takes place in outside of bend forming river cliffs
- current is slower on inside of bend because river is shallower (more friction to slow water down)
- so eroded material is deposited on inside of bend,forming slip-of slopes
Formation of ox-bow lakes
- erosion causes outside bends to get closer
- until there’s only small bit of land left between bends
- river breaks through this land,usually during flood
- and the river flows along along the shortest course
- deposition eventually cuts off meander forming and ox-bow lake
What are flood plains
The wide valley floor on either side of a river which occasionally gets flooded
What are levees and how are they formed
Natural embankments along the edges of a river channel.formed during a flood when eroded material is deposited over whole flood plain.heaviest material deposited closest to river channel because it gets dropped first when the river slows down.over time deposits material builds up creating levees
What are estuaries and where are they found
Tidal areas where river meets the sea found at the mouth of a river
Features of estuaries
- land is closest to sea level
- river valley at its widest
- river levels rise and fall each day
What land forms are in the upper course
V-shaped valleys Interlocking spurs Rapids Waterfalls Gorges