The river erosion processes involved in the formation of waterfalls are hydraulic action, abrasion and solution. Hydraulic action is the force of moving water on the land. Fast flowing water forces out looses rock and soil from the river bed and bank. Soft rock is eroded faster than hard rock (differential erosion) and overtime the bank will collapse. Abrasion is the wearing away of the river bed by its load. Stones carried by the river smooth the river channel deepening & widening it. Solution occurs when the river dissolves the soft rock over which it flows.
The erosion processes mentioned above to form waterfalls in the youthful stage of a river course. Waterfalls occur where a band of hard rock e.g. granite lies across a river bed, soft rock is eroded faster and GRADUALLY a fall forms in the river bed. Hydraulic action and abrasion combine to deepen the fall and a plunge pool forms at the base of the waterfall.
Water splashes against the back wall and erodes it by the process of solution. This splash back soon creates a cave or a hollow behind the waterfall. The overhanging piece of hard rock will eventually collapse and slowly the waterfall retreats up stream (head ward erosion).
Sometimes a steep sided gorge is formed if head ward erosion is very fast. The gorge in Niagara Falls is 11km long and up to 91m deep Description- What is it your trying to explain.
Example- An example of a waterfall or whatever.
Explanation- How they form and everything about them.
Processes- Processes that form them= Hydraulic action, abrasion, attrition etc. Diagram- Diagrams explaining the whole process.
Waterfall proper 30/30 Sample Answer The Irish landform that I have studied is the waterfall. Waterfalls can be found in Killarney such as the Torc Waterfall and in Wicklow, the Powers court falls. Waterfalls are a feature of river erosion which is commonly found in the youthful stage of a rivers course. In the formation of waterfalls processes such as hydraulic action, abrasion, eddying and solution are present. Waterfalls occur when a band of hard rock lies on a river bed, where the river bed is usually soft rock. Rapids form where the hard rock dips downstream/ upstream. As the river passes down over the hard rock hydraulic action is present. Hydraulic action, where force of moving water increases the erosive power and thus vertically erodes the soft rock. Differential erosion is where the river erodes the softer rock at a faster rate than the hard rock. Abrasion, where the river uses it’s broken off material to deepen and widen the vertical fall that formed, is present here. As the fall has been deepened, when the water comes down the speed will have increased which will strengthen the hydraulic action and abrasion.This in turn steepens the fall.Most erosion takes place at the base of the waterfall thus forming a plunge pool. Eddying is now present, where the swirling motion of the water and turbulence uses the load to widen the plunge pool. Eventually the waterfall will be undercut and will collapse as the back of the waterfall is eroded by spray. The waterfall has now increased in height.The collapsed rock is broken down by attrition and is transported downstream by solution, suspension, saltation and traction. Eventually the waterfall will retreat backwards by headword erosion and end its days as a Gorge. Waterfalls are usually formed on the upper stage of a rivers level. Sometimes waterfalls can be formed on the lower stage as a result of river rejuvenation due to a drop in river base level. Faulting can also lead to the formation of waterfalls. At a normal fault the land slips downwards, and if a river was flowing down this it will now have been changed. Waterfalls can also be found in Glaciated regions where hanging valleys occur. The world’s most famous waterfalls are Niagara Falls and Vitoria falls.
Physical environment: The Apennines are a mountain
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