THE PEDOGENESIS OF SOME GIBBSITIC SOILS FROM THE SOUTHERN UPLANDS OF SCOTLAND

Abstract

Summary The mineralogy of ten profiles developed from hornfelsic rocks on the summit areas of the Merrick and Kells Hills has been investigated by X‐ray powder diffraction, thermal, infra‐red, and optical methods. The soil clays of the C horizons of all profiles contain 6 to 37 per cent of gibbsite but this mineral is not found in the A horizons. Optical observations reveal that gibbsite is associated with hematitic rock fragments which are considered to represent older soil material–i.e. are pedorelicts. It is suggested that the Merrick soils are polygenetic and consist of two soil stratigraphic units, recent pedogenic effects being superimposed on a basal horizon that has been strongly influenced by preglacial or interglacial weathering.