The use of the virgule and the word ‘and’ in horizon nomenclature is used for combination horizons as you indicated. They indicate a relationship exists between soil materials for the two horizon symbols that they connect in becoming a combination horizon.
The virgule (/), or forward slash, is used between master horizon symbols when describing discrete, intermingled (and identifiable) pedogenic bodies of two different master horizons within a single layer. At least one of these intermingled horizons would show evidence of pedogenic features. Such would be the case when soil horizons are disturbed or mixed by cryoturbation, wind throw, burrowing animals, landslides, and some types of plowing or ripping activity. Basically, soil material from one horizon is displaced vertically to another horizon. The horizon topography would be described as broken. The materials are described together as a single soil layer for greater precision in defining the relationship between them, or for ease of description. An indication of the nature of the disturbance or cause should be noted for the pedon.
The word ‘and’ is most commonly used between master horizon symbols when describing multiple thin lamellae of illuvial clay (Bt - argillic horizon) separated by thin eluvial (E) horizons as a repeating pedogenic feature. It is not used for depositional stratification as in alluvial sediments or annual deposits such as varves. The case of using the word ‘and’, the individual lamellae, though rather thin, are visible and could be described and separated, but have been grouped together due to their common pedogenic origin and occurrence. The ‘and’ connector is not used simply as a means to reduce or simplify the number of layers described for a soil profile.
The virgule and the ‘and’ connector are used in combination horizons. They are not used in labeling bulk soil samples from more than one horizon such as might be done during sampling for laboratory analysis.
