On lineation and petrofabric structure, and the shearing movement by which they have been produced

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Abstract
The currently accepted view of lineation regards it as being perpendicular to the direction of shearing or “transport”. This conclusion appears to have been arrived at by petrologists mainly on two grounds: (1) the evidence obtained by Schmidt in the Leoben district of Austria and in the Tauern Mountains, and (2) the “argument from symmetry”. Sehmid's evidence is re-examined in this paper, and it is concluded that more data than he has given would be needed to make the inference convincing. The inconclusive nature of the “agrument from symmetry” has, on the other hand, been shown very clearly by schmidt himself. The contrary view that lineation is parallel to the shearing movement is certainly true with regard to one district in Norway, as has been demonstrated by Kvale. In several localities, in different countries, it has also been found that the direction of lineation is that of the longest dimensions of pebbles and larger fragments in distorted conglomerate. The possibility that the pebbles themselves are elongated at right angles to the shoaring, and the plane of distortion, is discussed in this paper, and reasons are given against it. it is therefore inferred that shearing and lineation are most probably parallel, according to present evidence. This conclusion, if accepted, will lead to a revision of present ideas of petrofabric structure, in particular about the formation of single quartz and mica girdles. The direction of shearing, or “transport”, must, in fact, be normal, and not parallel, to the plane of the girdles. It is claimed, however, that this type of diagram may be as well, or perhaps better, explained according to the writer's hypothesis.

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