rivers chapter 7. start on high, flow down low, creating features as they flow!
TRANSCRIPT
Youth Stage = Upper Course
Mature Stage = Middle Course
Old age Stage = Lower Course
Three stages of a river
The Work of Rivers
Processes of erosion:
1. Hydraulic Action
The force of the moving water causes erosion of the river bed and the banks of the river. The greater the speed and amount of water the greater the force.
The Work of Rivers
Processes of erosion:
2. Abrasion
The rivers load is bounced and dragged along the river bed causing it to scrape and deepen the course of the river.
The Work of Rivers
Processes of erosion:
3. Attrition
The rivers load is constantly colliding in the moving river water causing the load to break down into smaller pieces.
The Work of Rivers
Processes of erosion:
4. Cavitation
As a river flows over the uneven river bed air bubbles travel up to the top of the river, pop and send ripples out towards the river banks. These ripples gently erode the rivers banks.
The Work of Rivers
Processes of erosion:
5. Solution
Chemicals in the rivers water and rocks along the river course change the river chemically which reacts with and erodes various rocks along the way.
F.E.E.D
F: Feature (Name, erosion or deposition, stage it is found)
E: Explain with at least one or two processes explained
E: Three examples, one Irish
D: Clear 1/2/3 diagram/s to show how the feature is
formed.
Describing a feature
Youth Stage = Waterfalls
Mature Stage = Meanders and Oxbow Lakes
Old age Stage = Deltas
Three features we will study
A typical upper course V-Shaped valley with interlocking spurs, steep valley sides and active slope processes.
The diagram below shows the formation of interlocking spurs.
Interlocking spurs
Waterfalls are features of erosion usually found in the upper course (youth stage) of a river.
They are found in areas where a river is flowing over bands of hard and soft rock. The
hard rock is slower to break down but the river can erode the soft rock much quicker. A
band of hard rock lies on an area of soft rock. The river erodes the soft rock by the
processes of hydraulic action (the force of the moving water) and abrasion (the scraping
of the rivers load against the banks and bed). This causes a small notch to be formed into
the soft rock which is eroded further into a drop over which the water falls. As the water
falls over the drop there is a greater rate of hydraulic action and the rivers load also scrapes
and deepens a hole in the bottom of the waterfall. This hole is called a Plunge Pool. The
hard rock is slowly eroded and hangs over the edge called a Overhang. This is eventually
worn down by the river and is carried away as the rivers load.
f
e
Waterfalls
Angel Falls, Venezeula
Victoria Falls, Zimbabwe
Torc Waterfall, Killarney, Kerry
Examples
Waterfall
foe/sor=Feature of erosion….stage of river
(e) px2=Erosion, Process are hydrualic action and abrasion
Aoh/sr srw=Areas of hard/soft rock, soft rock weaker
Neisr=Notch eroded in soft rockRfovd=
River falls over vertical drop
pp@bow=Plunge pool at base of waterfall
Ucipp=Undercut collapses into plunge pool
Weu=Waterfall erodes upstream
Feature of Erosion and Deposition
Name
Found
Processes involved
Meanders and Ox Bow Lakes
Mature and Old Age Stage
Erosion and Depositon
F.E.E.D
F: Feature (Name, erosion or deposition, stage it is found)
E: Explain with at least one or two processes explained
E: Three examples, one Irish
D: Clear 1/2/3 diagram/s to show how the feature is
formed.
Describing a feature
F.E.E.D
F: Feature (Name, erosion or deposition, stage it is found)
E: Explain with at least one or two processes explained
E: Three examples, one Irish
D: Clear 1/2/3 diagram/s to show how the feature is
formed.
Describing a feature
Examples of deltas include:The River Nile, EgyptThe Mississippi River in Louisiana, USAThe River Shannon in Limerick, Ireland
Read Page 38-39
1. Name the river and the city of this case study?2. The city is between two physical areas…what are
they?3. How is the city protected from flooding?4. What did the President do to the amount of money
available for protection of the land?5. When did the disaster strike?6. What was the name of the hurricane?7. How many poor people could not leave the area?8. How many people drowned in this disaster?