Soils with an orthic A horizon and none of the subsurface horizons that distinguish groups 5-10 may still exhibit a degree of maturity in the form of colours associated with intense reduction, either in an E horizon associated with an intermittent, perched water table in which ferrolysis occurs with a predominantly lateral discharge of surplus water, or in a G horizon which reflects a more persistent and stagnant degree of wetness associated with more clayey textures or greater topographic confinement (as in wetlands).
Some mottling may be present but this is insufficient for the horizon to qualify as a plinthic B. Typically the E is bleached as a result of iron removal. This is most evident when the soil is dry. The archetype G has bluish-green or olive tints reflecting the presence of iron in a reduced state (Soil forms: Kroonstad, Katspruit, Constantia, Vilafontes, Kinkelbos, Cartref, Fernwood).