Year 8 Science · Unit 3 · Lesson 26

Soil Formation

Foundation Worksheet

Name

Date

Class

Learning Goals

Name the five soil horizons in order from the surface down to bedrock.
Describe the key features of each soil horizon.
Explain what soil is made of and approximately how long it takes to form.

Warm Up

Order the soil horizons

The five soil horizons are listed below in the wrong order. Number them 1–5 from the surface (1) down to bedrock (5). Then write a brief description of each horizon in the right-hand column.

Order (1–5)	Horizon	Brief description
	B horizon
	R horizon
	A horizon
	O horizon
	C horizon

Label the soil profile

Use the word bank to label each horizon on the soil profile diagram below. Write the correct horizon letter (O, A, B, C or R) next to each label line.

O horizon (leaf litter) A horizon (topsoil) B horizon (subsoil) C horizon (weathered rock) R horizon (bedrock)

Your Turn

True or False? Fix the false ones

Circle T or F for each statement. If the statement is false, rewrite it correctly on the line below.

Humus is made from ground-up rocks and provides minerals to soil.

Correct it:

Clay soils are the best soils for most plants because they hold lots of water and nutrients.

Correct it:

It takes about 100 years to form 1 cm of topsoil.

Correct it:

Australia's ancient soils are among the most nutrient-rich in the world because they have had so long to develop.

Correct it:

Show What You Know

1. Name the three main ingredients that combine to form soil. For each ingredient, state what it contributes.

Recall 3 marks

2. Explain why the A horizon (topsoil) is described as the most valuable horizon in a soil profile.

Recall 2 marks

Wrap Up

In one sentence, what was the main idea of this lesson?