Rivers

Question 1

Cross profile : upper course

Answer 1

Gradient - Steep

Valley - V-shaped, steep sided
Channel - Narrow, Shallow, Turbulent water
→ Due to vertical erosion by the river + weathering and mass movement of the valley slopes.

Question 2

Cross profile : middle course

Answer 2

Gradient - Medium

Valley - Wide + flat, Gently sloping sides
Channel - Wider, Deeper
→ Lateral erosion is dominant, eroding the valley sides. The rate of weathering increases on the softer rocks of the valley sides.

Question 3

Attrition

Answer 3

Eroded rocks smash into each other → break into smaller fragments = edges are round off as they rub together
Particle size decreases from source to mouth

Question 4

Solution

Answer 4

River flows over limestone or chalk → Rock slowly dissolved as it is soluble in slightly acid river water

Question 5

Traction

Answer 5

Large particle pushed along the river bed by the force of the water

Question 6

Saltation

Answer 6

Pebble sized particles bounce along the river bed by the force of the water → as one lands it dislodges another

Question 7

Suspension

Answer 7

Small particles carried by the water

Question 8

Solution

Answer 8

Dissolved chemicals derived from limestone + chalk

Question 9

Why do rivers deposit material?

Answer 9

• Volume of water decreases
• Velocity decreases
• Amount of eroded material in the water increases
• Water is shallower
• River velocity decreases as it reaches the mouth → interaction with tides + gentle gradient

Question 10

Upper course landforms

Answer 10

Erosion landforms → Interlocking spurs, waterfalls + gorges

Question 11

Middle course landforms

Answer 11

Erosion + deposition landforms → Meanders + oxbow lakes

Question 12

Lower course landforms

Answer 12

Deposition landforms → levees