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Earth Science
How Rocks Become Soil
Wind, Water, and Time
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Soil starts with rocks, but the change takes a very long time. Sun, rain, wind, ice, and living things help rocks crack and crumble into tiny pieces. These tiny pieces mix with old leaves and dead plants to make soil. Soil matters because many plants need it to grow.
Key Facts
- Weathering means rocks break into smaller pieces.
- Water can get into cracks in a rock and help split it apart.
- Wind can blow sand and rub rocks smooth.
- Plant roots can grow into cracks and push rocks apart.
- Soil is made from tiny rock pieces, water, air, and bits of old living things.
- New soil forms slowly, often over many years.
Vocabulary
- Rock
- A hard natural material found on Earth.
- Soil
- The loose top layer of Earth where many plants grow.
- Weathering
- The breaking of rocks into smaller pieces by nature.
- Pebble
- A small rounded piece of rock.
- Humus
- Dark material in soil made from old leaves, plants, and animals.
Common Mistakes to Avoid
- Thinking rocks turn into soil in one day. This is wrong because rocks break down slowly over a long time.
- Thinking soil is only dirt. This is wrong because soil also has air, water, tiny rock pieces, and bits of old living things.
- Thinking only rain makes soil. This is wrong because sun, wind, ice, plants, and animals can also help break rocks apart.
- Thinking plants do not help make soil. This is wrong because plant roots can crack rocks and old plant parts can mix into soil.
Practice Questions
- 1 A rock breaks into 5 pieces. Each piece breaks into 2 smaller pieces. How many smaller pieces are there now?
- 2 A class finds 12 pebbles and 8 handfuls of sand near a big rock. How many rock materials did they find in all?
- 3 Explain how a plant root can help a rock become part of soil.