Use a two-question test. First, did material move? Second, what moved it? The answers sort every scenario into one of the three processes.
This lesson belongs to weathering and mass movement. The next lesson, explaining physical and chemical weathering under stated conditions, goes deeper on the first process.
What does each process mean?
| Process | Did material move? | What moves it? |
|---|---|---|
| Weathering | No, rock breaks in place | Nothing: weather and chemicals act on the rock |
| Erosion | Yes | Water, wind, ice or waves |
| Mass movement | Yes, downslope | Gravity, helped by water in the slope |
Worked example: four invented scenarios
Scenario 1. A granite boulder at the top of a hill has a network of cracks, and flakes of rock lie around it. Nothing has travelled far. This is weathering, because the rock is breaking where it sits.
Scenario 2. A river in flood carries gravel downstream and cuts into its bank. Material moves and the agent is water. This is erosion.
Scenario 3. After days of heavy rain, a section of a steep, bare hillside slides onto the road below. Gravity moved the soil, and rain made it heavy. This is mass movement.
Scenario 4. Tree roots push into a crack in a rock and widen it. The rock breaks in place, so this is weathering, more specifically biological weathering.
Writing the answer
State the process, then quote the clue, then give the reason. For scenario 3: “This is mass movement because the soil moved downslope under gravity, and rain added weight by saturating the slope.”
Each answer is one sentence, and the clue is always a phrase from the scenario.
The mistake that costs marks
The slip is to choose erosion for anything that looks like damage. A landslide looks destructive, so students write erosion. The question to ask is whether a carrying agent such as a river or wave did the moving.
The second slip is to call cracks in a rock “erosion”. Nothing was carried away, so it is weathering.
Check yourself
Classify this scenario and give the deciding clue: “Waves pick up pebbles and throw them against a cliff, wearing the rock surface away.”
Answer
It is erosion, specifically abrasion. The deciding clue is that waves carry pebbles and use them to wear the cliff, so a moving agent removes material.
What to study next
Go to explaining physical and chemical weathering under stated conditions, then check your clue-spotting in the claim, evidence and explanation revision desk.
If you want a teacher to give you fresh scenarios, see online one-to-one Geography tuition.