These 3D photorealistic figures as well as 7 other figures, maps, and diagrams were created by TMF for Soil!, a primer produced by the Soil Science Society of America. The foreground of the far left figure shows the 6 horizons of a hypothetical soil profile. Starting at the upper dark brown horizon...

O-humus or organic
A-topsoil
E-eluviated horizon
B-subsoil
C-parent material
R-bedrock

The bottom right figure illustrates the different processes that change soil over time.