Development of schistosity in flexural folds

An example of the development of axial plane schistosity close to a buckled competent band is described [from the Moinian (Precambrian) of the Scottish Highlands]. There is a difference in the degree of development of the schistosity on the convex and the concave sides of the fold arch. This is explained as due to variation in contact strain. A similar pattern has been produced experimentally and it is concluded that the axial plane schistosity in the example under consideration is a mechanical phenomenon and has developed perpendicular to the direction of maximum compressive strain.