(i)    A vertical section through different layers of the soil is called soil profile. 
(ii)    Each layer of soil profile differ in colour, depth, chemical composition. These layers are called “soil horizons”.

Figure: Soil Profile

•    Soil profile can be seen in recently dug ditch, during digging a well or laying the foundation of a building. 
•    Soil profile shows three main horizons : -  
     A-Horizon: - Uppermost, dark coloured, rich in humus and supports plants and many living organisms like worms, rodents, moles and beetles. Humus makes the soil fertile & provides nutrients to the growing          plants. This layer is generally soft, porous and can retain more water. It is also called top soil. 
    B-Horizon: - It is also called middle layer, which is generally harder and more compact, having less 
    amount of humus but more minerals. 
    C-Horizon: It is made up of small lumps of rocks with cracks & crevices, called third layer. Below this is bed-rock, which is hard and difficult to dig with a spade.
•    Soil profile can be observed by dissolving little soil in glass tumbler, three quarters filled with water. Each layer in glass shows different size of soil particles.
•    The rotting dead matter in the soil is called humus.