It has vertical boundaries with the atmospheric-surface interface and the lower limit of root penetration.
Horizontal boundaries are established at the interface with water bodies, parent rock material, and human- made surfaces.
Soil is connected to the atmosphere, lithosphere, hydrosphere, and biosphere, so it is made up of solids, liquids, and gases.
The true soil is characterised by distinct horizons and the capability to support plants. Below true soil it is infertile regolith, derived from the underlying bedrock.
Polyhedron is the smallest distinctive division of the soil of a given area.
A pedon is’~a soil column extending down from the surface to reach a lower limit in regolith or bedrock.
A horizon is a distinguishable layer in the soil that has certain chemicals, and a distinct colour, texture, pH, and structure.
A soil profile is the vertical arrangement of horizons down to the parent material; this profile is most easily observed in an exposed roadcut in arid lands or at a construction site.