MINERALS, ROCKS AND SOIL ACTIVITIES

HOW TO LOOK AFTER SOIL

Soil is essential for people.
This is because plants need soil to grow.
We need plants for food and for wood.
Plant roots help fix soil and prevent wind and water sweeping it away.
Plant leaves and branches protect soil from heavy rains.
For this reason, we must protect the plants that grow in soil.

SOIL IS MADE UP OF LAYERS

Soil is made up of three layers, each containing different materials:

• Topsoil: This top layer contains sand, clay, water, air and humus.
• Subsoil: This middle layer contains stones, sand, clay and some water.
• Bedrock: This bottom layer is made up of rocks, and contains very little water.

A: TOPSOIL; B: SUBSOIL; C: BEDROCK.
Photo from Wikipedia

HOW IS SOIL FORMED?

Soil is a mixture of many things.
It forms very slowly over a long period of time.
First, wind, rain and ice wear down rocks into smaller pieces.
Then, the action of animals and plant roots breaks the rocks into even smaller pieces.
Little by little, the pieces of rock mix with the remains of plants or animals.
These remains of living things turn into a dark mixture called humus.
The little pieces of rock mix with the humus to form soil.
There are different types of soils because they are formed from different mixtures of rocks and organic matter.

WHAT IS SOIL?

In many places, rocks are covered by a layer of earth, called soil.
Soil consists of stones, water, air, minerals and the remains of animals and plants.

USES OF MINERALS

Minerals can be used for:

• Construction materials. Gypsum is used to make cement and plaster.
• Obtaining metals. Iron is extracted from magnetite. Copper is obtained from chalcopyrite.
• Making jewellery. Diamonds, rubies and emeralds are used to make jewellery.

MINERALS IN ROCKS

Rocks in the Earth's crust are made up of minerals.
Here are some:

• Quartz: Quartz is very hard. It can scratch glass. It is translucent. It can be white, pink or grey. It is found in granite.

• Feldspar: Feldspar is hard. It is not shiny. It can be different colours: white, green or brown. It is found in granite and clay.

• Calcite: Calcite is soft. It can be scratched with a knife. It can be white, orange or yellow. It is found in marble and limestone.