pedosphere

right|thumb|Cross-section illustrating the soil layer, showing the topsoil (A); [[regolith (B); and saprolite, a less-weathered regolith (C).]] The pedosphere () is the outermost layer of the Earth's crust that is composed of soil and subject to soil formation and erosion processes. It exists at the interface of the lithosphere, atmosphere, hydrosphere and biosphere. The pedosphere is the "stratum corneum" of the Earth's surface and only develops when there is a dynamic interaction between the atmosphere (air in and above the soil), biosphere (living organisms and associated organic matters), lithosphere (unconsolidated regolith and consolidated bedrock) and the hydrosphere (water in, on and below the soil). The pedosphere is the foundation of terrestrial ecosystems on Earth.

The pedosphere acts as the mediator of chemical and biogeochemical flux into and out of these respective systems and is made up of gaseous, mineralic, fluid and biologic components. The pedosphere lies within the Critical Zone, a broader interface that includes vegetation, pedosphere, aquifer systems, regolith and finally ends at some depth in the bedrock where the biosphere and hydrosphere cease to make significant changes to the chemistry at depth. As part of the larger global system, any particular environment in which soil forms is influenced solely by its geographic position on the globe as climatic, geologic, biologic and anthropogenic changes occur with changes in longitude and latitude.