The waterfall
A waterfall is a point where there is an interruption in the river profile and the water makes a vertical drop. It is normally found in the upper stage of the river.
Aasleagh falls near Killary harbour and torc waterfall county Kerry are well known waterfalls in Ireland.
Most waterfalls develop where the river meets a band of softer, less resistant rock after flowing over harder more resistant rock. As a result of differential erosion the water quickly erodes the softer rock by the processes of hydraulic action and abrasion
DIFFERENTIAL EROSION: The process where different rocks erode and different rates.
HYDRAULIC ACTION: the force of moving water on the land. Fast flowing water forces out loose rock and soil from the riverbed and banks.
ABRASION: wearing away the riverbed by it's load. Stones carried by the river scrape away and smooth the river channel as they move along, deepening and widening the river channel
As the water falls and hits the soft rock on the riverbed, it's energy cuts a deep hole called a plunge pool directly beneath the fall.
The falling water also begins to undercut soft rock of the waterfall, mainly by hydraulic action, creating an overhang. Over time the hard rock I deeply undercut, becomes unstable and eventually breaks off into the plunge pool.
This is repeated many times and result in head ward erosion of the waterfall. The waterfall gradually retreats upstream to form a steep sides gorge.
A waterfall is a temporary feature. Head ward erosion will eventually undermine all the resistant rock. The river will once again begin to develop a regular
Aasleagh falls near Killary harbour and torc waterfall county Kerry are well known waterfalls in Ireland.
Most waterfalls develop where the river meets a band of softer, less resistant rock after flowing over harder more resistant rock. As a result of differential erosion the water quickly erodes the softer rock by the processes of hydraulic action and abrasion
DIFFERENTIAL EROSION: The process where different rocks erode and different rates.
HYDRAULIC ACTION: the force of moving water on the land. Fast flowing water forces out loose rock and soil from the riverbed and banks.
ABRASION: wearing away the riverbed by it's load. Stones carried by the river scrape away and smooth the river channel as they move along, deepening and widening the river channel
As the water falls and hits the soft rock on the riverbed, it's energy cuts a deep hole called a plunge pool directly beneath the fall.
The falling water also begins to undercut soft rock of the waterfall, mainly by hydraulic action, creating an overhang. Over time the hard rock I deeply undercut, becomes unstable and eventually breaks off into the plunge pool.
This is repeated many times and result in head ward erosion of the waterfall. The waterfall gradually retreats upstream to form a steep sides gorge.
A waterfall is a temporary feature. Head ward erosion will eventually undermine all the resistant rock. The river will once again begin to develop a regular