C PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



5. Silurian series, including the Tilestone. 



5. System of Westmoreland and the Hundsriick. 



(Direction, at the Binger Loch, W. 31" 30' S. and E. 31° 30' N.) 



6. Devonian series. 



An additional note is appended respecting the prolongation of the 

 systems of the Ballons, of Westmoreland and the Hundsriick, and of 

 the Cote d'Or into distant countries, especially into North America, 

 the Russian dominions and China. 



M. Favre communicated observations on the relative positions of 

 the rocks in the western Alps of Switzerland and of Savoy, in which 

 he noticed, — 1. the crystalline rocks ; 2. the metamorphic rocks ; 3. 

 the Vallorsine conglomerate ; 4. the Jurassic series ; 5. the cretaceous 

 deposits, divided into («) Neocomian, (b) first rudiste zone, (c) Al- 

 bian rocks, gault and greensand, and (d) the Seeven limestone of 

 M. Studer; and, 6. the nummulitic limestone. The cretaceous de- 

 posits are stated to rest unconformably on the Jurassic series, and at 

 the Diablerets the nummulitic limestone reposes on the green sand, 

 the fossils of the two rocks being mingled. M. Favre notices a bed 

 of coal in the nummulitic deposits sufficiently thick to be worked in 

 the chain of the Titlis and other localities, and considers that the 

 nummulitic rocks are independent of the cretaceous series on which 

 they rest. The Macigno is then noticed, and it is inferred that both 

 it and the nummulitic limestone are alike independent of each other 

 and of the cretaceous series. 



M. d'Archiac read an extract of a memoir on the fossils of the 

 nummulitic rocks of the environs of Bayonne and Dax, in which he 

 refers to the fossils from Biaritz sent to him by Mr. Pratt, and those 

 from the arrondissement of Dax by M. Delbos. Of the 209 species 

 determined and obtained from the departments of the Landes and 

 Basses-Pyrenees, 1 28 are only yet known as local, 1 are found in 

 the nummulitic beds of Corbieres and the Montague Noire, 12 in 

 other parts of Europe, 48 in lower tertiary deposits, 22 in the middle 

 tertiaries, and 4 species in the chalk, 3 oysters among these last being 

 found in the lower group of the nummulitic rocks which rests directly 

 on the chalk of the district. 



In his researches on the crystallization of the granitic rocks, M. 

 Durocher refers to the remarks of M. Scheerer on his previous labours 

 on the same subject, and supposes that a mass containing in combi- 

 nation silica, alumina, alkaline and earthy bases, potash, soda, some- 

 times lithia, with a little lime, magnesia, the oxides of iron and 

 manganese, as also minute quantities of hydrofluoric acid and even of 

 boracic acid, would separate into quartz, mica and felspar when suffi- 

 ciently cooled. The solidification taking place according to the re- 

 lative tendency of the minerals to crystallize, the felspar would 

 crystallize sooner than the quartz. The solidification of the silica he 

 considers would not be instantaneous, the substance behaving like the 

 vitreous bodies, and remaining long in a viscous state. Thus the 

 crystallization of the granite would not be in the order of fusibility 

 of the component minerals. 



