Presentation on theme: "Stages of a River Stage:Upper Course 1. Source 3 4 2. Waterfall 3. V-shaped valley 4. Steep sided valley 5. Interlocking spur."— Presentation transcript:
Stages of a River Stage:Upper Course 1. Source 3 4 2. Waterfall 3. V-shaped valley 4. Steep sided valley 5. Interlocking spur
Stages of a River Stage: Middle Course 6. Gentle Valley Sides 7. Flood-plain 8. Meander
Stages of a River Stage: Lower Course 9. Ox-bow lake 10. Mouth
The hard rock above the plunge pool collapses and the waterfall moves back The river flows over areas of hard rock above soft rock The soft rock at the bottom of a waterfall is eroded more quickly to form a plunge pool The hard rock is undercut and becomes unsupported How a waterfall is formed. 1.1. 2 3.3. 4.4.
weathered material is used to erode the river channel further by abrasion erosion is mainly vertical Weathered material travels downslope to wards the river the steep slopes suffer from weathering river in its upper course has much energy so erosion takes place Formation of V-Shaped Valleys erosion by the river undercuts the slope making it unstable
Faster current Slower current Outside (river beach) ( river cliff) What happens on a River Meander? Deposition of Sand and shingle Erosion of bank and bed Inside FOE SID
In time the lake will evaporate or silt up When the river floods it has enough energy to erode a new channel across the meander The river meanders in its valley with erosion on the outside and deposition on the inside of the bend. Formation of an Ox-bow Lake 1. 2. 3. 4. The neck of the meander becomes narrower due to erosion on the outside of the bends. The old meander is separated from the river by deposition and is left as an ox-bow lake. 5.
Flat floodplain Layers of silt Deposited during floods Coarse material Forms natural levees Gentle valley sides How Flood Plain and Levees are formed Levees
How floodplain and levees are formed In the lower course of a river river overflows its bank There is a sudden loss of energy. The courser material is deposited first along the banks This forms levees. Silt is deposited over the flood plain as even more energy is lost during a time of Flooding. The finer material called silt is carried further by the flood water
CharacteristicsUpper CourseMiddle CourseLower Course Slope Width Depth Straightness Main work Valley width Type of load Load amount
Characteristics Slope Width Depth Straightness Load amount Main work Valley width Type of load usually steep narrow shallow winding little large/small angular erosion transportation quite steep quite wide quite deep meandering some medium/small rounded Transportation narrow gentle quite wide wide deep big meanders lots small+ rounded transportation deposition wide Upper CourseMiddle CourseLower Course