1854. SHARPE STRUCTURE OF MONT BLANC. 11 



it from a spot near the sources of the Mseander, where that river 

 bursts forth in the market-place or agora of Celsense, as described by 

 Strabo, evidently after a subterranean course under the mountains, 

 the river having previously disappeared at the foot of the hills in a 

 more elevated plain on the N.E. side of the mountains. 



The two specimens show both in lithological appearances and or- 

 ganic character a very remarkable resemblance. Even the species of 

 Nummulite appears to be the same, thus affording another link in 

 that vast chain of nummulitic formations which extend almost from 

 th«. west of Europe to the northern provinces of India. In the 

 Varna specimen Mr. T. R. Jones has made out an Orbitoides (Orbi- 

 tolites of some authors), which is probably identical in species with 

 the Orbitoides dispansus of Persia and Scinde. 



November 15, 1854. 



Francis Galton, Esq. was elected a Fellow. 



The following communications were read : — 



1. On the Structure q/*MoNT Blanc and its Environs. 

 By Daniel Sharpe, Esq., F.R.S., F.G.S. 



[PI. I.] 



Mont Blanc has been represented by Professor James Forbes, in his 

 admirable work on the Alps, as consisting of a mass of stratified 

 granite, in which the strata are arranged in the form of a fan with 

 one vertical axis running through the whole chain : on both sides the 

 granite is stated to overlie a great formation of limestone, its beds 

 dipping under the granite in perfect conformity with the strata 

 of the granite itself, and a similar conformable superposition of gra- 

 nite upon limestone is stated to occur in the Montague de la Saxe on 

 the east of Mont Blanc * . 



The section given by Professor Studer adopts the above views 

 with the following modifications : instead of granite, the chain is 

 stated to consist of protogine flanked by gneiss and metamorphic 

 slates, the beds dipping under these are described as black limestone 

 and slate, and the Montague de la Saxe as felspar-slate f. 



There are two apparent anomalies in these statements which stand 

 in contradiction to the general experience of geologists elsewhere : 

 1st, the alleged conformity of stratification between the crystalline 

 and the secondary rocks ; 2nd, the superposition of the granite or 

 protogine upon the latter. It is of such vital importance to the pro- 

 gress of geology that we should have correct views upon these points, 

 that no apology is needed for a re-examination of the evidence on 



* J. Forbes, Travels through the Alps of Savoy, chap, xi., and Topographical 

 sketch, No. 3. 



t Studer, Geologic der Schweiz, vol. i. p. 168 to 176, and Section, p. 175. 



