Key Idea: Topic 9.2 is about how extreme environments are physically shaped — and how to take a named landform and explain which process built it. It pulls together two contrasting cold/hot worlds: 9.2.1 — hot deserts: weathering breaks rock in place, wind (aeolian) action sandblasts and builds dunes, and rare but powerful water (fluvial) action carves wadis and lays down fans and playas. 9.2.2 — glacial & periglacial: moving ice plucks and abrades to carve corries, aretes and troughs, while in the periglacial fringe it is the freezing and thawing of water in permafrost (freeze-thaw, solifluction, frost heave) that does the work. This is an Option (Extreme environments), examined on Paper 1 — SL answers 2 options, HL answers 3 (same questions). Each option = a short structured question off a figure plus a [10] extended-answer essay (Examine / To what extent / Discuss).
🏜️ 9.2.1 — Hot desert processes and landforms
A hot desert is shaped by three families of process: weathering (rock broken in place), wind action (erosion by abrasion/deflation + deposition of dunes) and water action (rare flash floods that carve and deposit). Deserts look 'dry', but water still does a lot of the shaping. The data-response skill is reading a value off a figure — for example which dune type forms (sand supply + wind + vegetation) — then Explaining a named landform by its process chain.
Tip: Marks come from the process chain, not the name. Wind abrasion is strongest near the ground → it wears the base of a rock thin → a mushroom-shaped pedestal. A dune's type depends on sand supply, wind and vegetation — read it straight off the figure, then explain.
🏔️ 9.2.2 — Glacial and periglacial processes and landforms
Glacial landscapes are carved by moving ice: plucking (ice freezes onto rock and pulls it away) and abrasion (embedded rock grinds the bed like sandpaper) cut corries, aretes and U-shaped troughs. Periglacial landscapes are the cold fringe beyond the ice, underlain by permafrost. Here ice does not flow — the repeated freezing and thawing of water (freeze-thaw, solifluction, frost heave) builds the landforms. The corrie-aspect figure below is a typical Paper 1 stimulus.
[Diagram: geo-bar-chart]
Heat from drilling, buildings and warm oil thaws the frozen ground; the thawed soil subsides and loses strength, so pipelines fracture and foundations tilt. This is why Arctic infrastructure (e.g. the Alaskan oilfields, Siberian towns) is raised on piles, insulated or refrigerated — not because the frozen ground is simply 'too hard to drill'.
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Exam Tips
- Option C is on PAPER 1: a structured question off a figure PLUS a [10] extended answer per option (SL does 2 options, HL does 3 — same questions).
- Always pair the landform with its PROCESS CHAIN — naming alone scores little (wind abrasion near the ground → thin base → pedestal).
- Deserts: weathering = in place; wind builds dunes + pedestals/yardangs; water cuts wadis + builds fans/playas. Dune type = sand + wind + vegetation.
- Glacial = moving ice (plucking + abrasion → corries, aretes, troughs); periglacial = freeze-thaw of water in permafrost → patterned ground, lobes, pingos.
- Permafrost thaws when heated → subsidence → raised/insulated pipelines (NOT 'too hard to drill').
- On the [10] essay: develop two+ named landforms tied to processes, use NAMED places (Sahara, Death Valley, the Alps), weigh the processes, and end on a clear JUDGEMENT.