Reports and Proceedings — Geological Society of London. 381 



The following communications were read : — 



1. "Interference Phenomena in the Alps." By Mrs. Maria M. 

 Ogilvie Gordon, D.Sc, Ph.D., F.L.S. (Communicated by Sir 

 Archibald Geikie, D.C.L., Sc.D., Sec.E.S., P.G.S.) 



In former papers ^ the authoress pointed out that, while the 

 leading axis of the Alpine mountain system extended in an east and 

 west direction, and it was generally accepted by Alpine geologists 

 that Alpine areas had endured horizontal compressive stresses in a 

 north-and-south direction, her own studies of Alpine geology had 

 led her to the conclusion that there had also been cross deformation 

 throughout the whole region, including both plicational and over- 

 thrust effects ; and that this cross deformation had been induced in 

 relation to horizontal pressures which had acted from the Hungarian 

 Basin westward over Alpine areas. In a quite similar way, radially 

 directed horizontal pressures had acted round the northern, eastern, 

 and southern periphery of the Hungarian Basin, and had originated 

 the deformational systems of the Carpathian Mountains. 



On the Alpine side of the Hungarian Basin, owing to the resisting 

 character of the previously plicated rocks composing the Palseozoic 

 Alpine chain, the ancient chain had been broken up by the east-and- 

 west compression into a series of cross segments or fault blocks, and 

 there had been a general westward crush of the series. The leading 

 cross segments named by the authoress were — (1) the Western Alps, 

 (2) the Engadine, and (3) the Styrian Alps.^'^' Overthrust effects 

 had been produced not only at the western margins of the segments, 

 but also in some- cases at the eastern margins, e.g. notably in the 

 Western Alps and at the Judicarian Fault in the Eastern Alps. 

 Further, these same cross segments in the Central Alps had been, 

 from their first initiation, interrupted on the north and south by 

 ancient leading east-and-west faults, in relation to which sagging or 

 downthrow movements took place towards the Central Alpine band, 

 and overthrust movements occurred in opposite directions. 



The present paper, so far as it deals with the general structure of 

 the Alps, was completed in April, 1905 ; but, acting on the advice 

 of Sir Archibald Geikie, the authoress has since endeavoured to 

 strengthen her line of argument by taking as a type the series of 

 structural changes undergone in the largely igneous mountain - 

 massive of Bufaure in the Dolomites, and elucidating the successive 

 phases from the point of view of histoi'ical geology. 



After describing in detail the geology of the Bufaure Massive, the 

 authoress discusses the structural relation of the Western Alps and 

 the Engadine to one another and to the whole mountain system. 

 From the particular arrangement of overthrusts, as well as from the 

 distribution of the igneous intrusions in the Western Alps and in 

 the Engadine, the authoress concludes that these were areas wher©^ 



1 M. M. Ogil\ie Gordon: (1) " Torsion- Structure in the Alps," Nature, 

 September 7th, 1899, vol. Ix, pp. 443-446; (2) "The Crust-Basins of Southern 

 Europe," Seventh International Geographical Congress, Berlin, 1899 (Proceedings 

 of the Congress, part ii, pp. 167-180, pi. vii) ; and (3) " The Origin of Land-Forms 

 through Crust-Torsion," Geogr. Journ., vol. xvi (1900), pp. 457-469. 



