1. St. Michael’s RC School The Upper Course of a River

2. St. Michael’s RC School Processes of river erosion Hydraulic action Abrasion Attrition Corrosion

3. St. Michael’s RC School Abrasion/Corrasion This is the process by which the bed and banks are worn down by the river’s load. The river throws these particles against the bed and banks, sometimes at high velocity. Hydraulic Action This process involves the force of water against the bed and banks. Corrosion This is the chemical action of river water. The acids in the water slowly dissolve the bed and the banks. Attrition Material (the load) carried by the river bump into each other and so are smoothed and broken down into smaller particles. Processes of river erosion

4. St. Michael’s RC School Source of a River

5. St. Michael’s RC School river disappears from view hidden by this spur of land Upper Valley - River Conwy (near Mignant Moor) Landforms in the upper course V-shaped valleys and interlocking spurs Rapids Waterfalls

6. St. Michael’s RC School V-shaped valleys on OS map

7. St. Michael’s RC School Upper Course of River Tees

8. St. Michael’s RC School Waterfalls!

9. St. Michael’s RC School Waterfall formation

10. St. Michael’s RC School The waterfall retreats back forming a gorge (steep sided valley) Overhang becomes unsupported and falls into the plunge pool

11. St. Michael’s RC School High Force

12. St. Michael’s RC School

13. An example of a waterfall – Gulfoss, Iceland

14. St. Michael’s RC School Gulfoss is located in Southwest Iceland on the Huita River. Gulfoss has two ‘steps’ to its waterfall. These steps are made by basalt lava while the rocks between these layers are softer, sedimentary rocks. Its gorge is 70m deep and 3 km long! Gulfoss