270 GEOGNOSY OF THE APPALACHIANS. [XIII. 



and states as a reason for that opinion, that they are connected 

 by certain beds of intermediate lithological characters with 

 strata of undoubted Cambrian age.* These, however, as he 

 admits, present great local variations, and, after carefully scan- 

 ning the whole of the evidence adduced, I am inclined to see 

 in it nothing more than the existence, in this region, of Cam- 

 brian strata made up from the ruins from the great mass of 

 pre-Cambrian schists, which are the crystalline rocks of Angle- 

 sea. Such a phenomenon is repeated in numerous instances in 

 our North American rocks, and is the true explanation of many 

 supposed examples of passage from crystalline schists to un- 

 crystalline sediments. The Anglesea rocks are a highly inclined 

 and much contorted series of quartzose, micaceous, chloritic, 

 and epidotic schists, with diorites and dark-colored chromifer- 

 ous serpentines, all of which, after a careful examination of 

 them in the collections of the Geological Survey of Great 

 Britain, I consider identical with the rocks of the Green 

 Mountain or Huronian series. A similar view of their age is 

 shared by Phillips and by Sedgwick, in opposition to the 

 opinion of the British survey. The former asserts that the 

 crystalline schists of Anglesea are " below all the Cambrian 

 rocks " ; t while Sedgwick expresses the opinion that they are 

 of " a distinct epoch from the other rocks of the district, and 

 evidently older." J 



Associated with the fossiliferous Devonian rocks of the 

 Ehine is a series of crystalline schists, similar to those just 

 noticed, seen in the Taunus, the Hundsriick, and the Ardennes. 

 These, in opposition to Dumont, who regarded them as belong- 

 ing to an older system, are declared by Rb'mer to have resulted 

 from a subsequent alteration of a portion of the Devonian 

 sediments. 



Turning now to the Highlands of Scotland, we have a simi- 

 lar series of crystalline schists, presenting all the mineralogical 



* Geol. of North Wales, pp. }45, 175. 



+ Manual of Geology (1855), 89. 



Geol. Journal for 1845, 449. 



Naumann, Geognosie, 2d edition, II. 383. 



