Strongly weathered red and yellow soils with thick (490-900 mm) humic Al horizons (Haplohumox and Palehumults) derived from sandstones and basic igneous rocks, and occurring near the east coast of Southern Africa, are described and discussed in terms of their distribution, morphology, texture, mineralogy, chemistry, genesis and classification. The high organic matter content (2-5%c) of the A l contributes significantly to a high pH-dependent negative charge, probably to poorer crystallinity of goethite and kaolinite and to the transformation of haematite to goethite. Varying proportions of kaolinite and gibbsite reflect different soil ages within these old landscapes. The yellow colour of aluminous goethite, the main pedogenic iron oxide, is masked in the A1 by organic matter and in red B2 horizons by haematite. Temperature may have influenced the broad pattern of occurrence of red and yellow B2 horizons. These soils need not, as previously suggested,

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Summary Considering the nature of soil and the ends which a classification must serve, principles are stated whereby a soil classification may be devised for application over extensive areas of varied soil composition. Naturally occurring bodies of soil, each with a high degree of homogeneity, are apparent rather than real individuals as their properties overlap to form a continuum. This continuum is multi‐dimensional because soil is characterized by numerous properties. The procedure of devising a classification is one of subdividing the continuum such that class boundaries accommodate, as far as possible, apparent individuals rather than of grouping like apparent individuals together. A classification may be used to locate the position of a profile in the continuum and so define its relationship with other profiles. It may also be used to indicate the soil composition of land by using soil classes on a map to show differences in the soil mantle. The latter procedure may best be regarded as land classification or soil mapping rather than soil classification; a class of land or mapped area seldom contains profiles belonging exclusively to a single class, whereas a soil class never contains profiles of another class. The soil form, a specific arrangement of diagnostic horizons, is introduced as a category above the series to facilitate the identification of soil profiles. Member series of a form are defined according to property variations within the diagnostic horizons of the form. It is suggested that a binomial system of profile nomenclature, using the form and the series, would have much to commend it.

The morphological, physical, chemical and mineralogical properties of eight prominent classes of soil developed in the coast aeolianites and sands of Natal are presented. These data and information on soil geography lead to the conclusion that: (i) losses of silica and bases and relative accumulation of iron (the ferrallitic process) have given rise to red and yellow kaolinitic materials; (ii) clay eluviation has given rise to coarse textured topsoils and to B2t horizons; and (iii) the hydromorphic process has caused grey colours in many sandy topsoils, plinthite development at some E/B horizon interfaces and gleying of some B2 horizons. In the soils on the older aeolianites, there is no evidence of either podzolization or the coarser textured topsoil being a younger geological deposit. The development of yellow soils in younger aeolianites may indicate a cooler climate than existed when red materials developed from the older aeolianites.