Dr A. L. Harris said that he and Dr D. J. Fettes have worked in the Dalradian rocks to the northeast of the area that Dr Roberts has described. Between Aber-foyle and Dunkeld the Highland Boundary Fault appears to lie markedly oblique to the axial trace of the Aberfoyle Anticline (synform). Hence it is of interest that, in contrast, in Dr Roberts' area this axial trace lies approximately parallel to the Highland Border between Abeffoyle and Arran. Can one confidently follow the axial trace of the Aberfoyle Anticline through this ground and to what extent are the stratigraphical formations, within which it lies, of value in mapping its course? During fieldwork for the I.G.S. in preparation for the provisional edition of the Cowal (29) Sheet (1971) Dr G. C. Clark and the speaker recorded near
Rothesay slaty cleavage which faces up across cross-laminated beds. This observation suggests that in that district the early structures have been affected by later folds in a manner comparable to that noted at Callander, where slates occupy the core of a secondary synform around which the primary slaty cleavage is bent.
The Author stated in reply that there were difficulties in the following the axial trace of the Aberfoyle Anticline from Aberfoyle to Arran. However, since the Beinn Bheila Schists were inverted at their contact with the Dunoon Phyllites, and since the rocks southeast of the Dunoon Phyllites appear to be right way up, at least overall, it seems reasonable to locate the axial trace