Edinburgh Royal Society, November 2 E. B. BAILEY and W. J. McCALLiEN: Perthshire tectonics; Schiehallion to Glen Lyon. E. M. Anderson's stratigraphy has been confirmed, with minor additions. The Dalradian boundary has been shown to be a slide affected by considerable over-folding. This over folding has brought into one and the same district Dalradian with and without a Blair Atholl component. Other slides include the Schiehallion slide, as spectacular as any thrust in the North-West Highlands. Large-scale inversion is a commonplace in the district. Often the older Blair Atholl Series is found downfolded into the younger Perthshire Quartzite Series. The Loch Tay inversion extends fifteen miles across the strike. All the big recumbent folding and refolding is towards the southeast.