A distinct layer of soil, more or less parallel with the soil surface, having similar properties such as colour, texture and permeability, the soil profile is subdivided into the following major horizons:
A-horizon, characterised by an accumulation of organic material.
B-horizon, characterised by relative accumulation of clay iron, organic matter or aluminum.
C-horizon, the undisturbed and unaltered parent material. (Some soils have an E-horizon, characterised by leaching of organic and other material.)