Due to the physical, chemical, and biological activities that take place during soil formation, well-developed layers of soil are formed, one below the other.
Typically, four distinct soil layers can be seen, distinguishable due to differences in colour and size of the particles. These layers are referred to as horizons.
A vertical section that shows the distinct layers of soil or horizons when we cut straight down into the soil is known as a soil profile.
A Horizon or Topsoil is the uppermost layer of soil.
It consists of fine particles.
It is rich in humus and therefore dark in colour.
It is soft, porous, and can hold water.
O layer which lies just above the topsoil is rich in organic matter.
B Horizon or Subsoil is rich in minerals and other materials, which seep down along with water.
It also contains compactly packed fine particles of soil.
C Horizon contains partly weathered pieces of rock.
It is usually characterized by cracks and crevices.
It is very difficult to dig beyond this layer.
R Horizon or Bedrock is the lowermost layer and mainly consists of the parent rock.
It undergoes weathering and starts forming the soil.
The properties of this rock greatly determine the composition of the soil.
