- Describe the three things rivers do: erode, transport, deposit
- Explain the four types of erosion
- Link processes to landforms like waterfalls and meanders
Rivers at work
A river does three jobs with the material (load) it carries:
- Erosion — wearing away rock and soil.
- Transportation — carrying the eroded material downstream.
- Deposition — dropping material when the river loses energy.
Erosion is the wearing away of rock and soil by a moving force — here, flowing water — followed by removal of the material. (Weathering breaks rock up; erosion carries it away.)
Four types of erosion
- Hydraulic action — the sheer force of water crashing into banks, compressing air into cracks until rock breaks off.
- Abrasion — sand and pebbles carried by the river scour the bed and banks like sandpaper. The main erosive force.
- Attrition — rocks carried by the river smash into each other and wear down, becoming smaller and rounder downstream.
- Solution — acidic river water dissolves soluble rocks like limestone.
Landforms: erosion in action
Waterfalls form where a river flows over hard rock onto soft rock. The soft rock erodes faster (differential erosion), creating a step; the overhanging hard rock eventually collapses, and the waterfall retreats upstream, leaving a gorge.
Meanders form downstream where the river swings side to side. Water flows fastest on the outside of the bend, eroding it into a steep river cliff; slowest on the inside, depositing material as a gentle slip-off slope.
Top answers always connect the two: don't just describe a meander — explain it with erosion on the outside bend and deposition on the inside. Process explains pattern.
Practice
Hydraulic action (force of water), abrasion (scouring by load), attrition (rocks wearing each other down), solution (dissolving soluble rock).
Soft rock erodes faster, undercutting the hard cap rock; the overhang collapses, moving the waterfall's edge upstream and leaving a gorge.
Fastest water on the outside bend erodes a steep river cliff; slowest water on the inside bend deposits a gentle slip-off slope.
Quick check
Which erosion type works like sandpaper?
Deposition happens when the river…
The steep bank on the outside of a meander is called a…
- Rivers erode, transport and deposit — dominating in the upper, middle and lower course respectively.
- Four erosion types: hydraulic action, abrasion, attrition, solution.
- Waterfalls form by differential erosion and retreat upstream.
- Meanders: erosion outside the bend (river cliff), deposition inside (slip-off slope).