Wilson cycle

Long fault-bounded valleys and escarpments in Kenya's East African Rift, viewed from the ISS. — The East African Rift in Kenya: continental extension is an opening stage of a possible ocean-basin cycle. A rift does not inevitably become an ocean.

A suggested lesson sequence

Use these stages at your own pace. Pause for students to sketch, compare observations or lead part of the demonstration.

01
Observe
Choose Continental rift, then Young ocean. Locate the ridge and thin oceanic crust in Open ocean.
Open Observe
02
Tinker
Switch to Subduction begins and follow the slab. Compare Ocean closes with Continental collision and identify the root.
Open Tinker
03
Explain
How does subduction turn an expanding ocean into a closing basin?
Open Explain
04
Check
Choose an answer and explain your reasoning. Each question includes feedback.
Open Check

Rehearse with the model

The same scene and controls as the lab. Load it when you are ready; use Start projector for the full classroom view.

Before the lesson

Follow the opening and closing of an ocean basin and relate continental collision to the formation of mountain belts.

Open the model before the lesson and choose a view that makes the important feature easy to see. Drag to rotate, and use the on-screen controls to change one variable at a time. The Controls panel explains the available keyboard shortcuts.

Ask students to predict the result before you change a setting. Compare the new view with the starting state.

Guide the demonstration

Choose Continental rift, then Young ocean. Locate the ridge and thin oceanic crust in Open ocean.

Switch to Subduction begins and follow the slab. Compare Ocean closes with Continental collision and identify the root.

Discuss a common misconception

“Every ocean basin follows the same fixed timetable from opening to closure.” The Wilson cycle organises possible stages of rifting, ocean spreading, subduction and collision. Real basins differ in geometry, plate motions and duration, and some rifts stop developing. The framework helps interpret geological evidence without prescribing one schedule for every ocean.

Build the explanation

Continental rifting can open an ocean basin, while subduction can later consume oceanic lithosphere and bring continents together. Mountain belts can preserve evidence of oceans that have closed.

Switch to Subduction begins and follow the slab. Compare Ocean closes with Continental collision and identify the root.

The six stages organise possible tectonic changes; they are not a fixed schedule followed by every ocean basin.

Teaching notes

Use Pangaea as one example within a longer history of continental assembly and breakup.

Place Iceland at a divergent boundary rather than using it as an example of continental collision.

Connect the closing of an ocean with later mountain building while allowing for more complex histories in real regions.

Check understanding

Open Check for 4 questions. Ask students to explain their choice before revealing the answer.

Return to the opening photograph. Ask students to identify one visible feature and explain which part of the model helps account for it.

Look more closely

Use these observations to connect the vocabulary to features students can identify.

Rift

Read the definition

Passive margin

NOAA bathymetry map of the South Atlantic showing continental shelves and the mid-ocean ridge. — NOAA South Atlantic bathymetry. Colour represents seafloor depth, revealing continental margins, abyssal basins and the Mid-Atlantic Ridge.