Some Notes on Clay Minerals in Podzol Profiles in Fennoscandia

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Abstract
Montmorillonite is found to be a predominant clay mineral in the < 2/z fraction of the A2 horizon of podzol profiles in Fennoscandia, even when these are only 300 years old. Irt fractions between 2/~ and 20/~ vermiculite and. hydrobiotite predominate, but are rarely detected in the fraction coarser than 20/z. Vermiculite and hydrobiotite are also found in the finer fractions of the B horizon, but are only rarely detected in the C horizon where their presence is apparently due to contamination with inter- glacial or older products of weathering. The presence of kaolinite in some profiles is explicable in the same way. Samples from the A2, B and C horizons of podzol profiles de- veloped on freely drained sandy materials (< 5 per cent. clay) were selected. The parent materials date from the last glaciM age or are postglacial. The samples were dispersed with Calgon (Kilmer and Alexander, 1949) or with 0.1 N EDTA at pH 4 and a mechanical analysis carried out by the hydrometer method (Gandahl, 1952). The samples were fractionated by sedimentation into < 2ix, 2-6t~, 6-20t~ and 20-60/~ fractions, care being taken to avoid admixture of finer material with the coarser fractions. The fractions were flocculated with calcium chloride, washed with water, and dried. Some of the samples, especially those from the B horizons and from young profiles, were deferrated by the sodium dithionite-hydrochloric acid method of Mitchell and Mackenzie (1954). The samples were examined by usual X-ray diffraction methods as applied to clay minerals (Brindley,

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