1. How Soils Form
Image: T. Loynachan
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2. Physical weathering breaks rocks into small mineral particles that accumulate on the Earth’s surface.
Images: Martin Miller, NRCS
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3. Chemical weathering dissolves and changes minerals that have accumulated on the Earth’s surface.
Images: National Cooperative Soil Survey, University of Nebraska
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4. Decomposing organic material from plants and animals mixes with accumulated soil minerals.
Images: NRCS, Soil Classifiers of Michigan
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5. Accumulated soil materials contain voids filled with air or water.
Image: T. Loynachan
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6. Continued physical and chemical changes over hundreds to thousands of years produce layers called soil horizons.
Image: National Cooperative Soil Survey
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7. The Formation of Soils
Image: T. Loynachan