Modelling divergent, convergent and transform boundaries and the features they build

The idea

Each boundary type produces a characteristic set of features, rift and ridge, trench and fold mountains, offset faults, which simple sand and card models reproduce under the same motions.

What you need

• a clear box with a board standing in one end and alternate flat layers of dry sand and flour, no more than half full (Earthlearningidea Himalayas in 30 seconds)
• the Continents in collision card model: stiff and thin card, paper serviettes, two small wooden blocks, paper clips, sticky tape (Earthlearningidea)
• the Transform faults model: stiff card about 25 × 35 cm with slits cut in it, two A4 sheets, ruler and pen (Earthlearningidea)
• camera or phone; world plate-boundary map (Geoscience Australia plate tectonics notes)

How to do it

1. Continental collision: push the board slowly into the sand and flour layers, stopping to photograph the folds and faults; measure the shortening.
2. Subduction: pull the card flap of the Continents in collision model down through the slot and record what happens to the serviette sediments and the two blocks.
3. Spreading and transform faults: pull the paper ocean floor up through the offset slits, draw stripes as it emerges and record where the ridge segments are offset.
4. Name a real example for each from the plate map (Himalaya, East African Rift, Alpine Fault) and note the topographic feature at each.
5. Tabulate boundary type, motion, faults formed, feature formed, example.

What you should see

The sand and flour layers buckle into folds, some overturned, then one set slides over the rest on a reverse fault and the surface rises (Earthlearningidea); in the subduction model the flap descends below the base, the blocks move together and the serviettes crumple between them; in the transform model the stripes on each ridge segment are offset where the slits step. The table matches the syllabus list: divergent boundaries give rift valley, mid-ocean ridge, normal and transform faults; convergent boundaries give mountain range, trench, reverse faults and folds.

What changes

This activity lists no variables to change, measure and keep the same.

Common misconceptions

Each of these ideas is wrong, and the activity is a chance to test it.

• Plates float on a sea of magma (the asthenosphere is solid rock that flows slowly).
• Continents move across the sea floor (plates carry both).

Safety card

Curriculum references

The NSW syllabus outcomes and Australian Curriculum v9 codes this activity supports. They are references, not a verified or complete curriculum alignment.

• Earth and Environmental Science Stage 6 Syllabus (2017), NESA; current, replaced by the 11–12 Syllabus (2025) from 2028EES11-9EES11/12-1EES11/12-2EES11/12-3EES11/12-4EES11/12-5
• Earth and Environmental Science 11–12 Syllabus (2025), NESA; to be implemented from 2028, not yet taughtEES-11-01
• Australian Curriculum v9No Australian Curriculum v9 code is listed.

Sources

The pages the author read to write this activity.

1. www.nsw.gov.au/education-and-training/nesa/curriculum/science/earth-and-environmental-science-stage-6-2017
2. www.earthlearningidea.com/PDF/83_Continents_in_collision.pdf
3. www.earthlearningidea.com/PDF/84_Transform_faults.pdf
4. www.ga.gov.au/education/classroom-resources/plate-tectonics-teacher-notes-and-student-activities
5. www.earthlearningidea.com/PDF/Himalayas_in_30_seconds.pdf