Abstract

Dr. G ilbert Wilson said how pleased he was to learn from this, and the accompanying paper read by Dr M. R. W. Johnson, that early phases in the deformation of the Moine Series could now be considered Precambrian in age. Twenty or thirty years ago such a view was held by perhaps three or four heretical workers in the Highlands; but most geologists in those days followed Peach and Bailey in confining the deformation and metamorphism of these rocks to the post Cambrian, Caledonian diastrophism. This was particularly so in Inverness-shire and Wester Ross, where the trends of the Moinian structures are roughly parallel to the strike of the Moine Thrust Zone. Further north in Sutherland, as Coles Phillips (Q.J.G.S.,93, p. 581, 1937) showed, the tectonic trends form a crescentic pattern which is convex to the NE, and gradually swings through SE and ESE until a dominantly easterly direction and sense of plunge are achieved in the area of A'Mhoine. There the linear structures such as rods and mullions, are parallel to the axes of asymmetrical, overturned and recumbent reclined folds. This means that the roughly north–south trend-lines shown on Dr Powell's and other maps of this northern area represent the strikes of the bedding of recumbent fold-limbs and not the axial trends of the prevalent tectonic structures, though these are disrupted by some late folding and faulting accompanied by retrograde metamorphism, which trend parallel to the strike of the Moine Thrust. The easterly trends in North Sutherland

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