Morphological classification

The following subdivision in matrix° and intrusive° pedofeatures is not given in the "Handbook". It has been added by the author as experience has shown that in descriptions, and especially in interpretation, this distinction is most important. Based on their relation to the groundmass, five types can be distinguished, and based on their morphology seven types and many subtypes:




1. pedofeature still presenting the general characteristics of the groundmass, mostly, but not always, with a gradual transition to the groundmass: matrix pedofeatures°

Three subtypes are distinguished:

1.1. matrix pedofeatures recognizable because of a lower concentration of one or more components: depletion pedofeatures

1.2. other matrix pedofeatures recognizable because of a higher concentration of one or more components: impregnative pedofeatures

1.3. other matrix pedofeatures recognizable only because of a different fabric, (with exclusion of b-fabrics): fabric pedofeatures

2. pedofeatures non enclosing the groundmass, formed either in voids, or in the groundmass by accretion: intrusive pedofeatures°



1° not all impregnative features are pedofeatures, e.g. impregnative nodules may be inherited from the parent material (e.g. transported nodules). They are generally recognizable because the groundmass, to which the impregnation is superimposed, is different from the actual groundmass of the soil (e.g. coarse material shows a difference in nature, shape, size, proportions, sorting).

2° Only for intrusive pedofeatures a quantification (in volume %) can make sense for mineralogical or chemical calculations.


Morphological classification of pedofeatures as related to their fabric

According to their morphology, crystallinity and referred distribution pattern, a number of types may be distinguished.




1. Matrix pedofeatures

1.1. associated with the surface of peds, voids or constituents and occurring immediately at that surface: hypo-coatings

1.2. other matrix pedofeatures related to surfaces but occurring at some distance from the surface: quasi-coatings

1.3. other strongly elongated or undulating matrix pedofeatures unrelated to surfaces: intercalations

1.4. other matrix pedofeatures unrelated to surfaces: nodules


2. Intrusive pedofeatures

2.1. associated to surfaces of peds (*), voids (but filling them for < 90 %) or constituents: coatings

2.2. other intrusive features filling voids totally or partially: infillings

2.3. other intrusive pedofeatures unrelated to surfaces and voids, consisting of euhedral or subhedral single crystals or crystal intergrowths of pedogenic origin: crystals and crystal intergrowths

2.4. other strongly elongated and undulating intrusive pedofeatures unrelated to surfaces and voids: intercalations

2.5. other intrusive pedofeatures unrelated to surfaces and voids: nodules (*) ped surfaces have priority over void surfaces.


(*) If not recognized as such, fragments of pedofeatures will automatically key out as nodules; deformed pedofeatures may key out either as intercalations or as nodules.