Case Study River Tees Flashcards
Location?
North-east England
Background info?
Source in Penine Mountains - flows east towards North Sea
Upper course: river valley - shape?
V shaped valley as due to river’s high altitude it has large amount of GPE and uses this energy to erode downward (vertical erosion) creating narrow steep-sided gorge.
The sides of gorge collapse due to their own weight and due to weathering creating a v-shaped valley.
Upper course: valley - interlocking spurs?
River is forced to wind around hills because it does not have enough energy to remove them by sideways (lateral) erosion so instead creates interlocking spurs.
Upper course: landforms - waterfall?
- High Force waterfall and gorge formed (tallest in England at 21M).
- Made of cap of hard rock (Whinsill) and softer rocks below (limestone, sandstone and shale)
- Soft rocks eroded more quickly causing undercutting and hard rock overhangs, eventually collapsing due to gravity
- Waterfall retreats, creating a steep sided gorge
Upper course: Landforms - pot holes at Low Force?
- Pebbles of resistant Whinsill become trapped in hollows in river bed
- As river flows over these pebbles it forces them to swirl around and bedrock is worn away by abrasion making hollow wider and deeper
- These enlarged hollows are known as pot holes
Middle course: valley - shape?
- Wider, flat bottomed valley
- As river altitude decreases, the river has less GPE and so less vertical erosion occurs
- Instead river uses energy to erode sideways (laterally) and river valley gets wider w flat valley floor
Middle course: valley - bluffs?
River has enough energy to erode laterally and wear away hills that protrude into the river valley (interlocking spurs).
This leaves a line of hills on either side of the river valley known as bluffs.
Middle course: landforms - meanders?
- Near Barnard Castle
- Fast water on outside of bends in river erode rapidly (hydraulic action and abrasion) forming a river cliff
- Slower water on inside of bends deposits material forming a slip-off slop
- Bends in the river become more pronounced and sides of the river valley undercut, collapse and retreat so river valley becomes wider
Middle course: Landforms - floodplain?
- Near Barnard Castle
- When the river level rises, the surrounding land is flooded
- Sediment transported in suspension is deposited as the speed of the water flow decreases
- Every time the river floods, a new layer of slit is added to the floodplain
Lower course: valley - shape?
Very wide, flat-bottomed w bluffs. The river continues to erode laterally, widening the river valley.
Lower course: landforms - levees?
- When the river floods, the biggest, heaviest material is deposited first, closest to the original river channel
- Over time this builds to form a bank on either side of each channel known as a levee
- Depostion on the original river bed leads to it flowing above the height of floodplain
- When river now floods, it can no longer flow back into river
Lower course: Landforms - ox-bow lakes?
- Close to Yarm
- As meanders become more exaggerated due to erosion on outside and deposition on inside of bend, the meander neck narrows
- Eventually river breaks through the neck often during time of high discharge (flooding)
- Deposition in the entrance and exit to old meander results in it eventually being cut off as a crescent shaped lake called an ox-bow lake
- Over time this dries out due to evaporation