426 Geological Society. 



observable between the Eifel and the Hundsruck, the upper Silurian 

 flagstones being highly fossiliferous, but much contorted and dis- 

 turbed and altered in their mineral condition ; the banks of the 

 Moselle offer the finest proofs of such disturbances. The fossils 

 found in the quartzose rocks of the Hundsruck prove this mountain 

 chain, which is a prolongation of the Taunus, to be, like it, of Silu- 

 rian formation. 



In the Hartz, the authors traced the same succession of mineral 

 masses, each characterized by their peculiar fossils ; and, if possible, 

 in still more dislocated positions. In one section, however, they 

 point out a tolerably regular descending order, from the mining 

 tracts of Clausthal, Avhere the beds are the equivalents of the car- 

 boniferous strata (floetzlehrer sandstein of the Germans) down to 

 limestones charged with Devonian types ; but in other parts, as 

 near Goslar, the still older Silurian rocks occur upon the flanks of 

 the Brocken, and overlie the Devonian schists ; whilst it is shown 

 that the granite of the Brocken Avas in a molten condition after the 

 formation of these old rocks, fragments of which full of shells are 

 found included in this Granite. Other sections show that the chain 

 has subsequently been heaved up " en masse," and all the secondary 

 strata on its northern flanks set on edge, and in some instances in- 

 verted, from the Muschelkalk and New red sandstone to the Green- 

 sand inclusive. The authors believe that the last great dislocations 

 of the Hartz may be due (as suggested by Von Buch) to the erup- 

 tion of the Porphyry, which on the southern and south-eastern limits 

 of the tract is associated with the newest Coal strata and the oldest 

 beds of the New red system (Rothe todte liegende). 



The Thuringerwald is considered to exhibit the same succes- 

 sion of the older strata as the Rhenish provinces and the Hartz, the' 

 central masses being equivalents of the Silurian and possibly of 

 the Upper Cambrian group ; but the authors, having passed ra- 

 pidly over these parts, attach importance only to their observations 

 on the southern limits of that region, near the foot of the Fich- 

 telgebirge, Avhere they indicate a clear descending series, from the 

 true Mountain-limestone with large Producti into lower fossiliferous 

 limestones and slaty rocks, the fossils of Avhich have been elabo- 

 rately described by Count Miinster, and which they place in the 

 parallel of the Devonian system. 



The authors express their very great obligations to Mr. Lonsdale, 

 whose intiniate knowledge of the Devonian fossils has enabled them 

 to speak with confidence, and whose advice has often dispelled ob- 

 scurities which must ever attend the elimination of the order of 

 succession of rocks which have been sO extremely dislocated, and in 

 many instances so much altered. They also acknowledge the valu- 

 able cooperation of their friend M. de Verneuil, who accompanied 

 them during a portion of the time devoted to this laborious survey, 

 and to whose intimate acquaintance with the older fossils they are 

 largely indebted ; and who, uniting with his countryman M. d'Ar- 

 cliiac, Mill describe the Mollusca of these regions as a sequel to the 

 geological memoir of the authors. 



