W sprawie metodyki badań składu głazowego moren
Abstract
SOME REMARKS CONCERNING METHODOLOGY OF STUDIES ON COMPOSITION OF TILL BOULDERS
Summary
The paper evaluates usefulness of principal methods of studies on composition of boulders in tills. The method of V. Milthers is shown to be unserviceable. It takes into account only 6-10 guide rocks and data obtained are not sufficient to determine actual quantitative relations between rocks derived from different parts of Fennoscandia. The method of J. Hasemann (considering the majority, i.e. about 200 guide rocks) is not widely spread as it requires too numerous comparative collections. It can be said that the method of K. Richter is the most promising one. It is based on calculations of the ratio of rapakiwi to the remaining crystalline rocks. However, application of that method requires more accurate definition of the concept of "rapakiwi", which was hitherto differently interpreted. It is proposed to supplement the characteristics of till boulders by the ratio between two principal groups of guide-rocks, namely: (1) anorogenic granites from the eastern Fennoscandia and accompanying porphyrs, and (2) Smaaland granites and porphyrs.
Summary
The paper evaluates usefulness of principal methods of studies on composition of boulders in tills. The method of V. Milthers is shown to be unserviceable. It takes into account only 6-10 guide rocks and data obtained are not sufficient to determine actual quantitative relations between rocks derived from different parts of Fennoscandia. The method of J. Hasemann (considering the majority, i.e. about 200 guide rocks) is not widely spread as it requires too numerous comparative collections. It can be said that the method of K. Richter is the most promising one. It is based on calculations of the ratio of rapakiwi to the remaining crystalline rocks. However, application of that method requires more accurate definition of the concept of "rapakiwi", which was hitherto differently interpreted. It is proposed to supplement the characteristics of till boulders by the ratio between two principal groups of guide-rocks, namely: (1) anorogenic granites from the eastern Fennoscandia and accompanying porphyrs, and (2) Smaaland granites and porphyrs.