CIV PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



elevations of land at distinct times, succeeded by periods of repose, 

 he considers that there would result from the sudden action various 

 irregular deposits due to geological currents thus produced, some of 

 these deposits having never been subsequently submerged, while others 

 have been so during one or more geological periods ; and that during 

 the succeeding periods of tranquillity there would be formed a variety 

 of irregular deposits, marine, flu^do-marine, and terrestrial, such as 

 beaches, banks and bars, deltas, alluvions of rivers and torrents, 

 glacial accumulations, the sand-hills of coasts and deserts, the fallen 

 fragments from mountains and inland cliffs, &c. 



M. FrapoUi then describes the subhercynian rocks of this class, 

 dividing them into the accumulations of four different and successive 

 epochs. The first he refers to a great elevation subsequent to the 

 deposit of the cretaceous series, and which he supposes may coincide 

 with that preceding the deposit of the eocene rocks. To the denu- 

 dation and debacle attending this elevation he attributes the dispersion 

 of the angular blocks of quartz rock in the district. The second is 

 thought due to an elevation corresponding with that by which the 

 western Alps were thrown up, and from it resulted deposits of which 

 ])ebbles from the Hartz form a large portion. During the period 

 following this elevation, the Hartz is inferred to have remained above 

 water, deposits from terrestrial and marine causes, acting upon the 

 land, being then effected, and the climate differing little from its 

 present state. The next is referred to the Arctic epoch. A rupture 

 on the north-west of Europe is inferred, followed by the dispersion of 

 the third of these accumulations. The subhercynian district was 

 then, it is supposed, invaded by detritus from the north, this detritus 

 thrown especially upon the northern and north-western flanks of the 

 hills, and covering previous deposits. During the period which 

 followed, an arctic climate is considered to have prevailed, and the 

 leJim of the district to have been accumulated. A fourth dispersion 

 is supposed to have then been effected by a movement which pro- 

 duced the final emergence of the subhercynian district. The 

 period following this is the present or modern, in which the accumu- 

 lations of the class noticed have been effected and are now taking 

 place. 



In a communication on the environs of Chamonix, Savoy, M. Favre 

 remarks that the pot-stone {jpierre ollaire) and the granite veins 

 occur in bands parallel to the contact of the crystalline slates and 

 protogyne, and that along the whole of the line, on the north-Mcst 

 flank of the chain of Mont Blanc, the same phsenomena are presented, 

 and in the same manner. He affirms that on this flank there are 

 several parallel bands of serpentine and potstone. With respect to 

 the Vallorsine conglomerate, he observes, that with associated sand- 

 stones and slates it constitutes the anthraxiferous formation of the 

 Alps, by which term he does not mean to refer it to any particular 

 geological age, but simply to state that in this group the Alpine 

 anthracite is found. M. Favre says, that while in the district noticed 

 this group occurs beneath the belemnitic limestone, it nevertheless 

 passes into it geologically, at the junction of the deposits, by alter- 



