Biology and Geology 3. Secondary Education

1. UNIT8 Surface Processes FLUVIAL MODELLING Biology and Geology 3. Secondary Education

2. UNIT8 Fluvial modelling Upper course CLICK ON THE BUTTONS TO FIND OUT MORE Middle course Fluvial valley (V-shaped) Waterfall Lower course Gorges Fluvial terrace U-shaped valley Wider valley Meanders Delta Sediments Flood plain River mouth Biology and Geology 3. Secondary Education

3. UNIT8 UNIT8 UNIT8 UNIT8 UNIT8 UNIT8 UNIT8 UNIT8 UNIT8 UNIT8 UNIT8 Fluvial modelling Fluvial valley (V-shaped) In the upper course, the current is very fast and erosion is very intense. The river excavates the channel to a great depth, giving rise to narrow, V-shaped valleys. Biology and Geology 3. Secondary Education

4. UNIT8 Fluvial modelling Waterfalls They appear in areas where there are very sudden changes in the level of the terrain. Waterfalls form on slopes which have layers of rock which are harder than others. The current erodes the soft layer faster and the waterfall is created. Biology and Geology 3. Secondary Education

5. UNIT8 UNIT8 UNIT8 UNIT8 UNIT8 UNIT8 UNIT8 UNIT8 UNIT8 UNIT8 Fluvial modelling Gorges They are very narrow valleys with almost vertical walls. They are formed in areas with rocks which do not collapse easily and where the river excavates a very deep channel. Biology and Geology 3. Secondary Education

6. UNIT8 UNIT8 UNIT8 UNIT8 UNIT8 UNIT8 UNIT8 UNIT8 Fluvial modelling U-shaped valley These are very wide valleys, with a concave cross-section. They are formed because the river still erodes the bottom of the channel, but, at the same time, deposits large amounts of sediment when the river level rises. Biology and Geology 3. Secondary Education

7. UNIT8 UNIT8 UNIT8 UNIT8 UNIT8 UNIT8 UNIT8 UNIT8 UNIT8 UNIT8 UNIT8 UNIT8 UNIT8 UNIT8 UNIT8 Fluvial modelling Flood plain They are formed at the bottom of U-shaped valleys as the floor of the flood plain is created by the sediments deposited by the river when the river level rises. In these plains, the soil is very fertile and they are normally used to grow crops. Biology and Geology 3. Secondary Education

8. UNIT8 UNIT8 UNIT8 UNIT8 UNIT8 UNIT8 UNIT8 UNIT8 Fluvial modelling Fluvial terraces These terraces are formed in the flood plain, as the current excavates its own sediments. Biology and Geology 3. Secondary Education

9. UNIT8 UNIT8 UNIT8 UNIT8 UNIT8 UNIT8 UNIT8 UNIT8 Fluvial modelling Meanders These are bends formed by the river as the slope of the terrain diminishes. They are formed because the current always flows across the most steeply-sloping areas. Biology and Geology 3. Secondary Education

10. UNIT8 UNIT8 UNIT8 UNIT8 UNIT8 UNIT8 UNIT8 UNIT8 Fluvial modelling River mouth Very wide river mouths are formed when the marine currents prevent the deposition of the sediments carried by the river current. Biology and Geology 3. Secondary Education

11. UNIT8 Fluvial modelling Deltas These are river mouths where the marine currents are weak and do not prevent the deposition of sediments. The river deposits sediments over a large, fan-shaped area and forms different branches across it. Swamps and marshes form on the sediments deposited in the delta. Biology and Geology 3. Secondary Education