Om våra kvartära lerors mineralogiska sammansättning

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Abstract
On the Mineralogical Composition of Swedish Quaternary Clays. The literature direetly deseribing Swedish Quaternary clays from a mineralogical point of view is very scanty. To some extent, supplementary data may be found in papers treating other clay problems and quite different geological questions, respectively. On the basis of such an incomplete material and some new data, the author gives a short account of the subject. As in Finland and Norway, illite appears to be the dominating clay mineral in Swedish Quaternary clays, both in Glacial and Post-Glacial types. Fur. thermore, kaolinite seems to occur. In western Seania (southernmost Sweden) montmorillonite minerals, derived from Triassic sediments, are probably to be found in Quaternary clays, while in eastern Scania kaolinite from Cretaceous deposits is supposed to play a greater röle. The data available support the assumption by some earlier authors of the material of Quaternary clays of Fennoscandia consisting largely of Tertiary and, to some extent, Mesozoie clay sediments, reworked and redeposited during the Ice Age. The high content of illite of Quaternary clays may be explained partly as a direct »inheritance» from Pre-Glaeial ones, and partly as derived from the alteration of their montmorillonite, under potassium fixation. Moreover it may be questioned whether the illite of Tertiary clays could, with regard to the climatic conditions during that period, really be formed primarily, viz. as a weathering product.

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