As is well known, a material horizonation occurs in the soil as a result of the action of the formation processes. Every horizon responds to a specific genesis, which is demonstrated by a distinctive micromorphology.

The micromorphology of a series of profiles of defined typologies are shown below (in accordance with the FAO Key of 1990). The similarities of a same type of horizon in different soils can be deduced in them (for example, horizon A, or horizon E, or the Bw, or the Bt, etc.) and the microfeatures of the different horizons in the same soil can be compared (horizon A with horizon E, or with Bt, etc., and with C or R) and the evidence of the different processes that are involved in the formation of every soil can be highlighted.