282 Professor Sedgwick and Mr. Murchison on the 



Among the slate rocks of the Rhine the cleavage planes usually hang to the south- 

 east, and keep their direction and inclination even among masses which are vio- 

 lently contorted. Hence any one assuming the cleavage planes for beds would not 

 only form erroneous conclusions about the dip, but also most exaggerated notions 

 of the thickness of the formations. Now in one or two places on the north flank 

 of the Taunus, though the slate beds dip south-east, the inclination of the cleavage 

 planes is reversed to the north-west : and hence, without very careful observation, 

 we might be led to suppose that the quartzites of the chain rose from beneath the 

 slates ; which (if our views be correct) is a conclusion directly contrary to fact. 



But it may be objected, that if the rocks of the Taunus and Hundsriick be mem- 

 bers of an ascending section commencing from the old slates of Caub, we ought 

 also to find corresponding rocks in the ascending sections on the other side of the 

 old Rhenish slates ; otherwise there must be a want of symmetry in the sections 

 on the opposite sides of the central system. We admit the force of the objection ; 

 and we reply, that there are very fine quartzites in the ascending sections from 

 the left bank of the Moselle towards the Eifel (for example in the Grunen-Wald 

 north of Wittlich), and consequently that the ascending sections are not without 

 mineralogical symmetry. Again, we found similar masses of crystalline quartzites 

 associated with trappean rocks^, on the right bank of the Rhine, and rising out at 

 various points between Limburg and the Taunus*. If such masses have been pro- 

 duced by the action of igneous rocks on the more arenaceous slates, we have no right 

 to look for their symmetrical arrangement on any corresponding sections. In short, 

 we regard the structure of the Hundsriick and the Taunus as due to a long-continued 

 action from below ; which first lifting up their beds and twisting them, while in a 

 softer state, into most violent contortions, gradually mineralized them and changed 

 them into what they now are. Nor has the activity of these subterranean causes 

 yet entirely ceased. The phaenomena we have described may be regarded as the 

 effects of their early and intense activity ; while the hot springs of Wisbaden and 

 the bubbling fountains of Schlangenbad, Langen-Schwalbach, and Nieder-Selters 

 give indications of their feeble and expiring eflTorts in this mineralized region. 



But our evidence does not end here ; for we found Silurian fossils, from the 

 quartzites of the Hundsriick, in the museum of Tr^vesf. We afterwards crossed 

 to the eastern side of the chain, near Berkenfeld ; and, through the kindness of 

 M. Booking, were directed to some quarries (immediately above Abentheur and 

 Ringenberg) among fine vertical masses of quartz rock containing many organic 



» PI. XXIII. iig. 9. 



t We were indebted to Professor Stelninger for the knowledge of this fact, and for much interesting 

 information respecting all the formations in the basin of the Moselle. He has since published a geolo- 

 gical map of all the country between the Saar, the Moselle, and the Rhine. 



