140 Reports and Proceedings — 



conglomerates ; and Baltzer distinguishes between the old nucleus and the younger 

 shell (slates) of the Central-massif. They are kneaded and pressed into one another. 



" II. The genuine Mesozoic deposits follow, sometimes conformably, sometimes 

 unconformably. In places they have become crystalline and schistose (schiefrig 

 krystallinisch) ; but they never occur as a constituent of the Central-massif, but always 

 accompany the Mesozoic deposits, or are intercalated as ' Mulden ' in, and especially 

 between, the Central-massifs. They are never termed ' Crystalline-schists ' in the 

 geological sense of the word, at the most only in its petrographical sense. 



" The latest literature on these things is, above all : — 



" Baltzer. ' The Aar-massif and a part of St. Gothard-massif.' ' Beitrage zur 

 geol. Karte der Schweiz. 24th Lieferung, 1888. 



" Grubemnann (Prof. Dr.). ' The Sedimentary " Mulde" of Piora.' 



" Baltzer furnishes in the volume above cited some excellent work on the above 

 rocks indicated under I., and gives a drawing of the Calamite-like trunk from 

 Guttanen. Grubeumann does the microscopic work in connection with the Mesozoic 

 formations belonging to II., which have never been referred, by us, to the crystalline 

 schists, or to the Central-massif. 



" Result. 



"Much of what have been regarded as genuine crystalline schists in the Alps 

 is Palaeozoic. 



" The crystalline metamorphosed Mesozoic rocks always occur as sedimentary 

 deposits, and have never been termed "crystalline schists" in the stratigraphical 



II.— Feb. 5, 1890.— W. T. Blanford, LL.D., F.R.S., President, in 

 the Chair. — The following communications were read : — 



1. "The Variolitic Rocks of Mont-Genevre." By Granville A. J. 

 Cole, Esq., F.G.S., and J. W. Gregory, Esq., F.G.S., F.Z.S. 



The following conclusions were arrived at by the authors as the 

 result of their observations : — 



The gabbro or euphotide south of Mont-Genevre is associated with 

 serpentines, which were originally peridotites, and were not derived 

 from the alteration of the gabbro. These coarsely crystalline rocks 

 probably form a considerable subterranean mass, but have little 

 importance at the surface. 



They were broken through by dykes of dolerite and augite-ande- 

 site, and are now overlain by a great series of compact diabases and 

 fragmental rocks, which has no direct connexion with the gabbro. 



The variolite of the Durance occurs in situ as a selvage on the 

 surfaces of contact of these diabases among themselves, as blocks in 

 certain fragmental rocks, which are regarded by the authors as tuffs, 

 and occasionally as a selvage to the diabase dykes. 



This product of rapid cooling was originally a spherulitic tachy- 

 lyte, and has become devitrified by slow secondary action. Variolite 

 thus stands in the same relation to the basic lavas as pyromeride 

 does to those of acid character. 



The eruptive rocks in the Mont-Genevre area are probably Post- 

 Carboniferous, but their exact age cannot at present be determined. 



There are several other areas of similar variolitic rocks among 

 both the Alps and the Apennines of Piedmont and Liguria. 



The best modern representatives of the conditions that produced 

 these rocks are to be found in the great volcanoes of Hawaii, and 

 there is nothing either in their fundamental characters or in their 



