Teachers

A lesson for your classroom or geography club

Soil profile

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A measured field profile in Wuhlheide, Berlin. Colour and texture vary down the soil; horizon boundaries must be identified from field evidence.

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 the temperate profile and read its depth scale. Name O, A, Bw and C; explain why E and R are not compulsory.
Open Observe
02
Tinker
Compare the dark mineral surface in the Mollisol example. Switch to Oxisol and discuss gradual boundaries and intense weathering.
Open Tinker
03
Explain
How do the profiles show that a soil need not contain every possible horizon?
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

Identify the horizons in a soil profile and compare how water, organic matter and parent material influence their development.

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 the temperate profile and read its depth scale. Name O, A, Bw and C; explain why E and R are not compulsory.

Compare the dark mineral surface in the Mollisol example. Switch to Oxisol and discuss gradual boundaries and intense weathering.

Discuss a common misconception

“Every soil contains the same sequence and thickness of horizons.” Soil profiles develop through interactions among parent material, climate, organisms, relief and time. Some horizons may be absent, weakly developed or altered by erosion and land use. Colour helps describe a profile, but classification also depends on diagnostic properties and processes.

Build the explanation

A soil profile exposes horizons formed by organic inputs, weathering and material movement. Their colours and textures can provide clues, but not every soil contains every horizon.

Compare the dark mineral surface in the Mollisol example. Switch to Oxisol and discuss gradual boundaries and intense weathering.

The selected profiles are examples; identifying a soil order also requires diagnostic properties beyond a colour match.

Teaching notes

Compare the selected profile with other environments rather than presenting it as a universal sequence of horizons.

Distinguish surface topsoil from the underlying horizons and from the bedrock represented by the R horizon.

Connect a deeply weathered tropical soil with its formation conditions rather than equating it with peat.

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.

O horizon

Fallen leaves and organic litter beneath white beech trees in New South Wales, Australia. — White beech leaf litter at Carowiry Creek, New South Wales. Organic material on the forest floor stores carbon and provides material for decomposition.

Read the definition

A horizon

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Calciustoll near Ponce, Puerto Rico: a Mollisol with a roughly 30 cm mollic surface over a calcic horizon. Its parent material includes colluvium and weathered limestone.