Soil, Rocks and Minerals
Class 6 Science · Chapter 11: Nature's Treasures · NCERT Curiosity section 11.5
Learn
Soil looks ordinary, but it took a very long time to form. Rocks are slowly broken by heat, cold, rain and wind into smaller pieces, then into sand and fine particles. Rotting plants and animals add humus, making the soil fertile.
Plants grow in soil, and so almost all our food depends on it. Earthworms, insects and tiny living things live in soil and keep it healthy. A few centimetres of soil can take hundreds of years to form, but can be washed away quickly.
Rocks give us stone for building, and minerals hidden in rocks give us metals like iron, copper and aluminium, and also salt and mica. These are dug out by mining. They took millions of years to form and will not be replaced quickly.
Explore: how is soil made?
- Put the steps of soil formation in order.
Remember
- Soil forms from rocks over hundreds of years; humus makes it fertile.
- Rocks and minerals give us stone, metals and salt; they are limited.
Quick check
What makes soil fertile?
- Humus from rotting plants and animals
- Plastic waste
- Only big rocks
- Salt
Answer
Humus from rotting plants and animals. Humus adds nutrients and holds water.
Think about it
Why are earthworms called farmers' friends?
One answer
They make tunnels that let air and water into the soil, and their waste adds nutrients, making the soil loose and fertile for crops.
Practice
Practise with fresh questions at three levels (easy, medium, hard), some answered hands-on, with hints and worked answers. Get 4 of your last 5 right to finish the topic.