Rivers and Valleys Flashcards
What are the three main ways a river shapes the landscape?
Erosion, transportation and deposition.
What are the four ways a river erodes?
Hydraulic Action, Corrasion, Corrosion and Attrition.
What are the four ways a river transports materials?
Traction, Saltation, Suspension and Solution.
What are the characteristics of the upper course of a river?
The Landscape is steep.
Its main process is vertical erosion.
Its main features are V-Shaped Valleys, Waterfalls and Gorges.
What are the characteristics of the upper course of a river?
The Landscape is steep.
Its main process is vertical erosion.
Its main features are V-Shaped Valleys, Waterfalls and Gorges.
What is the formation of a V-Shaped Valley?
A river flows downhill quickly and erodes the landscape vertically. The river cuts a deep gash into the landscape using hydraulic action, corrasion and corrosion. As the river erodes downwards the sides of the valley are exposed to Freeze-thaw Weathering. This process loosens rocks and they fall into the river, this helps to produce steep valley sides. The rocks which have fallen into the river assist the process of corrasion which leads to further erosion. The river transports the rocks downstream. The process of attrition helps to break down rocks down and they become smaller and rounder. The river channel becomes wider and deeper creating a V-Shaped Valley between interlocking spurs.
What is the formation of a waterfall?
The river flows over bands of hard and soft rock. Softer, less resistant rock is quickly eroded by the processes of hydraulic action, corrosion and corrasion. The river undercuts the harder rock leaving an overhang of hard rock. The river erodes the softer rock below the waterfall by the process of hydraulic action and forms a plunge pool. The overhang of hard rock is unsupported and collapses into the plunge pool below. The waterfall moves back upstream and a gorge is cut into the landscape.
Land use in the upper course.
Hill sheep farming due to poor soils, steep slopes, cold weather, high rainfall and exposed hillsides.
Forestry due to thin soils and steep slopes, trees can live in harsh conditions.
Recreation and Tourism; sightseeing waterfalls, gorge walking, fishing and canoeing.
Hydro Electric Power can be generated in the upper course of a river due to high rainfall and steep slopes.
Land use in the upper course.
Hill sheep farming due to poor soils, steep slopes, cold weather, high rainfall and exposed hillsides.
Forestry due to thin soils and steep slopes, trees can live in harsh conditions.
Recreation and Tourism; sightseeing waterfalls, gorge walking, fishing and canoeing.
Hydro Electric Power can be generated in the upper course of a river due to high rainfall and steep slopes.
What are the main characteristics of the middle course?
Gently sloping gradient landscape.
Its main processes are lateral erosion and transportation.
Its main features are meanders, river cliffs and river beaches.
Explain the formation of a meander.
A river rarely flows in a straight line, it will bend around something in its course eg a tree or a hard rock. This results in areas of slower and faster water movement. The river contains areas of deep and shallow water, this causes the current to swing from side to side. The river flows faster on the outside and erodes the outside bends of the river channel, this forms a river cliff. The river flows slower on the inside bend of a river channel and deposits some of its load. This forms a river beach/slip-off slope. Continuous erosion on the outer bank and deposition on the inner bank forms a meander in the river. Overtime, meanders become larger and more distinct.
Land use in the middle course.
Dairy and Arable farming are both possible due to the more gentle sloping, soil is more fertile and the weather is warmer and drier. The flatter land makes it easy for cattle to graze.
Fishing for trout and salmon.
Recreation and tourism, building roads and railway systems to stages of the river. Campsites, B&B facilities are available to tourists.
What are the characteristics of the lower course?
Flat landscape.
Its main process is deposition.
Its main features are flood plains, ox-bow lakes and levées.
Explain the formation of an ox-bow lake.
The river is meandering across the valley and erodes laterally. The river flows faster on the outside bends and erodes a river cliff. The river flows slowly on the inside bend and deposits material forming a river beach/slip-off slope. Repeated erosion and deposition narrows the neck of the meander. During a flood or intense rainfall, the river will have the energy to erode and it cuts through the neck of the meander. The river flows on a new, straighter path and the meander is cut-off. The river deposits silt which seals of the ends of the meander and forms an ox-bow lake.
Explain the formation of a Levée.
The river flows on a flat flood plain in the lower course. The water is flowing slowly and deposits silt on the river bed. The build-up of silt raises the river above the flood plain. When the river floods, a lot of silt is deposited on the river banks. Regular flooding continues this build-up of silt at the sides of the river. The built up levées (natural embankments) usually protect the land from further flooding.
