Abstract

Mr M. Brown said the author's use of the term agmatite appeared to be inconsistent with the original intentions of Sederholm (1923, Bull. Comm. geol. Finlande 58) and also with that given by Mehnert (1968, Migmatites and the origin of granitic works. Elsevier). In the speaker's opinion many so-called agmatites are really examples of schollen structure and he entered a plea for greater care to be exercised in the use and application of nomenclature which refers to 'xenolithic' material in 'igneous' material.

Dr Tarney asked whether, in striving to emphasize the importance of Inverian events at Lochinver, the authors had played down the extent of Laxfordian activity, particularly in the vertical north limb of the Lochinver antiform? Since the structural and metamorphic characteristics of the Inverian and Laxfordian were very similar in the area, what criteria had the authors used to discriminate between features attributable to each event? In the speaker's opinion, although the Lochinver antiform itself was a major pre-dyke WNW–ESE structure, the excellent exposures around Achmelvich Bay demonstrated equally well that both dykes and gneisses had been involved in strong penetrative deformation in a zone over 500 m wide in places which followed the steep north limb of the antiform for many kilometres inland. It appeared that this steep limb of the antiform with the associated soft talcose picritic dykes following it for much of its length had been a weak zone exploited during the Laxfordian.

The speaker would, however, like to lend support to the authors

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