The river has three different "courses", the Upper Course, Middle Course and Lower Course, each with their own different characteristics.
narrow with steep sides
flat with steep sides
flat floor, gentle sloping sides
flat with steep sides
flat with gentle sloping sides
waterfalls, interlocking spurs
meanders, floodplain, levees, ox-bow lakes
Processes shaping rivers
Weathering and mass movement are the main processes that shape river valleys.
In the cold winter months, when rain water enters a crack in a rock and freezes, the freezing process exerts pressure on the rock eventually causing it to break into smaller pieces.
Tree roots can penetrate cracks in rocks and split them apart
All rainwater is slightly acidic and this can dissolve some rocks, especially limestone and chalk.
Particles of soil slowly move down the sides of valleys due to gravity
The river erodes the valley sides making them steeper and increasing the downward movement of material. Heavy rainfall can trigger this movement.
Upper course landforms
In the upper course, there are a few unique landforms, mainly caused by erosion, which you are not going to find in the other courses of the river.
Thornton Force waterfall, North Yorkshire
Mudstone - Where rivers flow over bands of tocks with different resistance, the softer rocks will be eroded more quickly. The River Twiss flows over limestone rocks and meets a band of mudstone. The mudstone wears away more quickly, creating a step which gradually becomes deeper.
Overhang - Eventually the overhanging resistant rock will collapse, making the waterfall steeper. If this happens repeatedly, the position of the waterfall moves upstream, known as retreat.
Undercutting - The water flows down over the resistant rock but when it reaches less resistant rock underneath, it erodes it, cutting back into the rock and creating the overhang above.
Plunge pool - At the foot of the waterfall is where you'll find a plunge pool. It's an area of deeper water that has been created by the rapid erosion of the mudstone as the waters plunge down. The higher the waterfall, the greater the speed of erosion due to the higher speed the water is travelling at.
Lower course landforms
Unlike the upper course, the middle course has both erosion and deposition acting upon it, but by the lower course, the main process acting on it is deposition.
In a meander, the river swings from side to side and the force of it doing so directs the fastest current and greatest force of water against the outside of the meander, forming a steep bank called a river cliff. On the inside edge of the meander, the current is slower and deposition of sand takes place, creating a gently sloping bank called a slip-off slope.
Narrow neck of land is eroded
Narrow neck of land is cut through and water takes quickest route. An ox-bow lake is formed.
Deposition seals off old meander and ox-bow lake begins to dry up.
Causes and impacts of flooding
There are several different reasons as to why a river may flood, some of these are: