Soil profile diagram illustrating the different layers of soil, including organic matter, topsoil, subsoil, and bedrock, with labels for educational purposes.

Let's solve this step by step.

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Step 1: Understand the Soil Profile Layers

The soil profile is made up of several horizontal layers called horizons. Each layer has distinct characteristics:

- O – Organic Layer: Topmost layer, composed of organic material like leaves, twigs, and decomposed matter.
- A – Topsoil: Rich in humus and nutrients; where most plant roots grow.
- E – Eluviation Layer: Leached of minerals and organic matter; often lighter in color.
- B – Subsoil: Contains accumulated minerals leached from upper layers; less organic matter.
- C – Parent Rock: Partially broken-down rock material.
- R – Bedrock: Solid rock beneath the soil.

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Step 2: Match Labels to the Diagram

From top to bottom in the diagram:

1. Top layer (green) → O – Organic layer
2. Dark brown layer below O → A – Topsoil
3. Lighter layer below A → E – Eluviation layer
4. Layer with rocks and particles → B – Subsoil
5. Layer with larger broken rocks → C – Parent rock
6. Bottom solid rock layer → R – Bedrock

So, matching from top to bottom:
- 1st line → O
- 2nd line → A
- 3rd line → E
- 4th line → B
- 5th line → C
- 6th line → R

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Step 3: Answer the Questions

Now let’s answer each question using the correct letter codes.

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1. The ________ horizon is located above the bedrock and contains less humus, soluble minerals, and organic matter.

- This describes the subsoil (B), which lies above bedrock and contains leached materials.
- ✔ Answer: B

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2. The ________ horizon is mainly composed of organic materials such as dried leaves, grasses, small rocks, twigs, surface organisms and decomposed matter.

- This is the organic layer (O).
- ✔ Answer: O

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3. The ________ horizon is also called the humus layer.

- The topsoil (A) is rich in humus (decayed organic matter).
- ✔ Answer: A

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4. The ________ horizon is composed of nutrients leached from the O and A.

- The eluviation layer (E) is where nutrients are washed down from the O and A horizons.
- ✔ Answer: E

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5. The ________ horizon is very compact and is made of granite, basalt and limestone.

- This is the bedrock (R), which is solid rock.
- ✔ Answer: R

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6. The ________ horizon is devoid of any organic matter and is made up of broken bedrock.

- This is the parent rock (C) — partially weathered rock with no organic matter.
- ✔ Answer: C

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7. The soil profile extends from the ________ surface to the rock material.

- It starts at the organic surface, so it's the O layer.
- ✔ Answer: O

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✔ Final Answers:

1. B
2. O
3. A
4. E
5. R
6. C
7. O

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📌 Summary of Labeling (for the diagram):

From top to bottom:
- O – Organic layer
- A – Topsoil
- E – Eluviation layer
- B – Subsoil
- C – Parent rock
- R – Bedrock

This completes the task!