As a pilot study of clay-mineral speciation due to vegetational differences, the distribution of clay minerals was studied in two soil profiles with 65-year-old stands of spruce and birch within Tönnersjöheden Experimental Forest. Dystric cambisols and orthic podzols were developed on till parent material. Principal minerals were quartz, potassium feldspars and plagioclases originating from metamorphic Proterozoic bedrock. Minor minerals were phylIosilicates and amphiboles. In the clay fraction of the till, the young soil profiles were characterized by smectite with accessory kaolinite in A2-horizon, vermiculite in B-horizon and chlorite in C-horizon. Weathering, detrital inheritance, transformations and neoformations of smectite and kaolonite are discussed.