248 Professor Sedgwick and Mr. Murchison on the 



these directions. We examined some lodes of excellent quality six to seven feet wide, which were then 

 worked by the English German Mining Company. We were conducted to them by our intelligent coun- 

 tryman M. Petherwick, to whom we owe our information ; and we have no doubt that these mines might 

 be worked to great profit, even in a country where the forests alone supply the necessary fuel, were the 

 land-transport shorter and less expensive. Up to this moment they have never been followed to any 

 great depth ; and are merely worked by horizontal galleries driven on their bearing through the sides 

 of the steep hills which they intersect. Lead ores also occur in this district, but they are in much less 

 abundance than those of copper*. 



Devonian Rocks of the Lahn. {Schaalstein, S^c.) 



The Devonian limestones are again exhibited in broad irregular bands on both 

 banks of the Lahn, occupying, here and there, a long elliptical area, of which the 

 major axis extends (in a north-easterly direction) from a point beyond Wetzlar to 

 a point on the Lahn a few miles below Dietz. The transverse axis may be placed 

 near Hadamar, and is not more than eight or ten miles in length. Within this 

 tract we can no longer distinctly trace the links which connect these rocks with 

 the superior or carboniferous deposits, the Flotzlehrer sandstein and Posidonia 

 schists not having been detected in union with them. But the whole system is 

 surrounded by older strata of grauwacke ; and hence, as seen on the map, it ap- 

 pears to be disposed in a great broken trough or basin. The existence of such a 

 trough is, however, by no means indicated by the concentric dip of the surround- 

 ing strata ; for on the greater part of all the transverse sections there is a pre- 

 vailing dip to the south-east, which gives the calcareous series, on the south side, 

 the appearance of plunging, not merely under the grauwacke, but also under the 

 whole chain of the Taunus. In short, we conceive the Lahn limestones to occupy 

 what, in a subsequent part of our paper, we call an inclined trough or basin. 



The chief depositary strata in this shattered trough consist of limestone, some- 

 times associated with shale, but for the most part interstratified with vast expan- 

 sions of " schaalstein." Besides these laminated deposits, igneous rocks of many 

 varieties, from true eruptive porphyry in mass, basalt, greenstone, to slaty por- 

 phyry and bedded traps, are apparent at the surface. Iron ore is also very gene- 

 rally diffused, and here and there is worked. The limestones, though occasionally 

 flat-bedded dark-coloured compact or earthy, for the most part are thick-bedded, 

 in a highly crystalline condition, and are largely quarried as ornamental marbles f. 

 There is perhaps no stronger indication of the great chemical changes to which 

 the strata have been subjected than the numerous mineral springs which burst 



* M. Petherwick, at the time of our visit, was just beginning to use small steam-engines ; and the 

 introduction of a few Cornish miners had given a new spirit to the enterprise. 



■j- Many of these marbles, in their colours, their structure, and their fossils, are tlie exact counterpart 

 of the marbles of South Devon. 



