Soil Layers worksheet for learning about soil composition and structure.

You’re looking at a classic soil profile diagram — a cross-section showing the different layers (or “horizons”) of soil from the surface down to bedrock. The task is to label each numbered layer using the correct terms from the word bank:
> Humus, Parent Material, Topsoil, Subsoil, Bedrock

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🔍 Step-by-Step Explanation:

Let’s go from top to bottom, matching each number with the correct soil layer.

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#### ✔ Layer 1 (Topmost layer)
➡️ This is the organic-rich surface layer, often dark in color, where decomposing plant and animal matter (like leaves and roots) accumulates.
✔️ Correct label: Humus

> *Note: Humus is the dark, organic material formed by decomposition. It’s part of the topsoil but specifically refers to the organic component.*

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#### ✔ Layer 2 (Just below humus)
➡️ This is the fertile, nutrient-rich layer where most plant roots grow. It contains a mix of minerals, organic matter, water, and air.
✔️ Correct label: Topsoil

> *Sometimes “humus” and “topsoil” are used interchangeably, but technically, humus is the organic part within the topsoil. In educational diagrams like this, they’re often shown as separate layers for clarity.*

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#### ✔ Layer 3 (Below topsoil)
➡️ This layer is richer in clay and minerals leached down from above. It’s less fertile and has fewer organic materials.
✔️ Correct label: Subsoil

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#### ✔ Layer 4 (Below subsoil)
➡️ This is the layer of partially weathered rock — the material that the soil above developed from. It’s not fully broken down into soil yet.
✔️ Correct label: Parent Material

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#### ✔ Layer 5 (Bottom-most layer)
➡️ This is the solid, unweathered rock beneath all the soil layers. It’s the foundation of the soil profile.
✔️ Correct label: Bedrock

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📝 Final Answer (Labeling):

| Number | Label |
|--------|----------------|
| 1 | Humus |
| 2 | Topsoil |
| 3 | Subsoil |
| 4 | Parent Material |
| 5 | Bedrock |

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🎨 Coloring Tip:

While not required for labeling, if you’re coloring:
- Humus: Dark brown or black
- Topsoil: Rich brown
- Subsoil: Lighter brown or reddish
- Parent Material: Gray or tan with rocky texture
- Bedrock: Solid gray or brown

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✔ You’ve now correctly labeled the soil layers! This understanding helps explain how soil forms over time through weathering and biological activity — from bedrock up to the living surface layer.