Rivers Flashcards
explain the formation of interlocking spurs
as the river erodes the steep V-shaped valley in the upper course, it winds and bends to avoid areas of hard rock. The vertical erosion due to gravity creates interlocking spurs, which jut out alternatively.
explain the formation of a waterfall
(high force waterfall, river tees)
In the upper course, a river will erode the softer rock as it flows over much more easily than the hard rock, forming steps in the long profile of the river. As the river flows over the step it plunges over, forming a deep plunge pool. Erosion through hydraulic action and abrasion will undercut the soft rock leaving a hard rock overhang. As the plunge pool expands, the overhang eventually collapses and the waterfall retreats. Over time, the retreating waterfall will leave behing a steep-sided gorge.
explain the formation of a meander
When a river goes around a bend, the water is thrown to the outside bend. this is where the water is flowing the fastest and therefore has the most energy. this causes erosion and the river bank is undercut through abrasion and hydraulic action. Where the pressure of the water, pushes air into the crack in the river banks and pebbles in the river get scrapped along the river banks both helping to erode it creating a river cliff. The river is deeper here. On the inside bend, the flow of the water is slower and the river has less energy. This causes deposition. This causes the river to be shallower on the inside bend creating a slip-off slope.
explain the formation of levees
They form along rivers that flow slowly, carry a large load and periodically flood. when a ribver floods, energy is immediately lost due to friction with the floodplain causing deposition of the river’s load. Coarser, heavier material (alluvium) requires more energy to be moved so is deposited first; finer material is carried further away. with successive floods, heavy material continues to be built up closest to the river creating natural embankments of silt along the river’s banks.
explain the formation of a floodplain
A floodplain is the wide, flat area next to the irver channel, especially in the lower part of the course. This is the natural area for water to spill onto when the river reaches the top of its banks. Lateral erosion, through abrasion and hydraulic action, widens the valley, taking away the interlocking spurs
