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Geolens

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Soils & Rocks

Discover how rocks and soils change

Inspect rock textures and soil profiles, and compare the processes that break down, transport and transform their material.

An exposed soil profile beneath woodland at Wuhlheide in Berlin, with a measuring tape against the face.
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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 rounded specimen of augen gneiss with pale mineral eyes enclosed in dark, folded bands.
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Soils & Rocks

Rock cycle

Rocks can change through melting, crystallisation, weathering, deposition, burial and metamorphism.

An exposed soil profile beneath woodland at Wuhlheide in Berlin, with a measuring tape against the face.
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Soils & Rocks

Soil profile

A soil profile exposes horizons formed by organic inputs, weathering and material movement.

National Park Service soil scientists examine a freshly sampled soil profile and record its texture.
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Soils & Rocks

Soil texture triangle

Soil texture describes the proportions of sand, silt and clay.

Rounded remnants of granite emerge from loose weathered material in an exposed rock profile.
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Soils & Rocks

Weathering

Weathering changes rock in place.

Bare eroded soil with small gullies on a hillslope near Charters Towers, Queensland.
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Soils & Rocks

Soil erosion

Raindrops and flowing water can detach and carry soil.

Field photographs of red and black soils at different positions on the Addi Selam hillslope in Ethiopia.
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Soils & Rocks

Soil catena

Soils along a slope are linked by movement of water and sediment.