What is soil ? What are …

Soil is the upper layer of earth in which plants grow and is usually composed of a mixture of organic remains, clay, and rock particles.Soil is the upper layer of earth in which plants grow and is usually composed of a mixture of organic remains, clay, and rock particles.
Horizon-A: 
The topmost layer is dark in color, and contains the remains of dead plants and animals. This rotting matter is called humus.

1. This layer of soil is called topsoil or A-horizon.
2. It is made up of humus and minerals, and makes the soil fertile.
3. It is soft and porous, and can retain more water than the other layers.
4. Many tiny organisms, such as beetles, worms and rodents, live in the topsoil. The roots of small plants do not go down very deep and can be found in the topsoil. 

Horizon-B: 

1. The layer below the topsoil is called B-horizon or the middle layer.
2. The middle layer is less porous than the topsoil, and is, therefore, harder.
3. It contains more minerals as compared to the topsoil, but less quantity of humus.

 
Horizon-C:

It is not as compact as the two layers above it. This layer is called C-horizon.
It has cracks running through it.
It is mostly made up of rocks.
 
Bedrock: The bottom-most layer in the soil profile is called bedrock.
This is far more solid in composition than the other layers and is very hard. This layer consists of the parent rock.