A process sequence is a chain of steps in which each step is caused by the one before it. It appears whenever a question says explain how, explain why, or account for.
It is the core skill of extended geographic explanations, and it works for rivers, weather, population, farming and any other topic.
How do you build the chain?
Start from the trigger and finish at the outcome the question names. Then fill the gap between them so that a reader could not ask “but how did that happen?” at any step.
- Name the trigger and the outcome in one line each.
- List the factors you know, in any order.
- Sort them into time order: what happens first, next, last.
- Write one sentence per step, and begin each with a link to the previous step (so, which means, as a result).
- Test each link by asking “does the first step really cause the second?”
A rough margin plan looks like this: trigger → step → step → outcome. It takes under a minute and prevents most list answers.
Worked example
Question: Explain how deforestation on a hillside can increase flood risk downstream.
Step 1, trigger and outcome. Trigger: trees are cleared from the slope. Outcome: more flooding in the valley below.
Step 2, factors. Fewer leaves to catch rain, fewer roots, bare soil, faster flow, more sediment, river channel fills.
Step 3, time order. Trees removed, then less interception, then less infiltration, then more runoff, then faster flow to the river, then higher peak flow, then flooding.
Step 4, write it out:
Without trees, fewer leaves intercept the rain, so more rain reaches the ground directly. Roots no longer open up the soil, which means less water soaks in.
As a result, more water runs over the surface and reaches the river faster. Sediment washed from the bare soil can also settle in the channel, so the river holds less water and overtops its banks sooner.
Step 5, test. Does less interception cause more rain on the ground? Yes. Does less infiltration cause more runoff? Yes. Does faster runoff raise the peak flow? Yes. The chain holds.
The mistake to watch for
Mistaken answer: “Deforestation means no trees. There is also more rain and soil erosion. The river floods.”
Every phrase here is a fact, but “also” only adds, and nothing says why bare soil leads to flooding. A marker cannot give credit for links that the student has left unwritten.
The correction is to replace each “also” with a cause: no trees, so less infiltration, which means more runoff, so the river rises faster.
Check yourself
1. Put these in a linked sentence chain: warm sea surface, strong evaporation, rising moist air, clouds form, heavy rain.
Show answer
A warm sea surface causes strong evaporation, so large amounts of water vapour enter the air. The moist air rises and cools, which means the vapour condenses and clouds form. As the clouds thicken, droplets grow heavy enough to fall as heavy rain.
2. The chain “More cars, so more fuel burned, so poor air quality” has a weak middle. What is missing?
Show answer
It does not say what the burning releases. A better link is: more fuel burned releases exhaust gases and particles, which build up in the air, especially in a congested city centre, so air quality falls.
3. Rewrite using links: “Heavy rain. Impermeable surfaces. Fast runoff. Flash flood.”
Show answer
Heavy rain falls on impermeable surfaces, so very little soaks in. This means most of the water runs quickly into drains and streams, which fill faster than they can empty, so a flash flood develops.
Where this leads next
Next, strengthen the chain with case evidence, then test yourself on the mixed practice set. The statistics and distribution explorer helps when your chain needs a figure.
If your chains keep breaking at the same step, our teachers can look at it with you in online one-to-one Geography tuition.