There are many areas throughout Britain where soil parent materials cannot be differentiated on the basis of solid geology alone, and difficulties are frequently experienced in classifying and mapping the soils. The object of this investigation was to study the parent materials and soils in a complex area of this kind.

The area selected is in north-east Scotland, and about half of it is covered by acid igneous and metamorphic rocks and the rest by sedimentary rocks of Old Red Sandstone age. The geology is complicated by three glaciations giving rise to diverse soil parent materials.

Five main groups of parent materials have been recognized, based on origin, texture and mineralogical composition. The first group consists of drift derived from acid igneous rocks and schists; the second of boulder clay from similar material plus an admixture of sedimentary rocks; the third of fluvioglacial deposits of varied textures; the fourth of conglomerate or thin drift from Old Red Sandstone rocks; and the fifth of boulder clay derived from Old Red Sandstone rocks where the influence of marls and shales in the drift is strong. Groups 1 and 5 are of major importance in this region and also elsewhere because of their widespread distribution. The others are more local.