XIII. ] GEOGNOSY OF THE APPALACHIANS. 269 



The crystalline strata to which the name of the Huroniau 

 series has been given by the Geological Survey of Canada, have 

 sometimes been called Cambrian from their resemblance to cer- 

 tain crystalline rocks in Anglesea, which have been imagined 

 to be altered Cambrian. The typical Cambrian rocks of Wales, 

 down to their base, are, however, uncrystalline sediments, and, 

 as pointed out by Dr. Bigsby in 1863,* are not to be confounded 

 with the Huronian, which he regarded as equivalent to the 

 second division of the so-called azoic rocks of Norway, the 

 Urschiefer or primitive schists, which in that country rest un- 

 conformably on the primitive gneiss (Ur gneiss), and are in their 

 turn overlaid unconformably by the fossiliferous Cambrian 

 strata. This second or intermediate series in Norway is char- 

 acterized by eurites, micaceous, chloritic, and hornblendic 

 schists, with diorites, steatite, and dark-colored serpentines, 

 generally associated with chrome j and abounds in ores of cop- 

 per, nickel, and iron. In its mineralogical and lithological 

 characters, the Urschiefer corresponds with what we have 

 designated the second series of crystalline schists. It is, in 

 Norway, divided into a lower or quartzose division, marked by 

 a predominance of quartzites, conglomerates and more massive 

 rocks, and an upper and more schistose division. Macfarlane, 

 who was familiar with the rocks of Norway, after examining 

 both the Huronian of Lake Superior and the crystalline strata 

 of the Green Mountains, had already, in 1862, declared his 

 opinion that both of these were representatives of the Nor- 

 wegian Urschiefer, t thus anticipating, from his comparative 

 studies, the conclusions of Bigsby. 



The crystalline rocks of Anglesea and the adjacent part of 

 Caernarvon, which have been described and mapped by the 

 British Geological Survey as altered Cambrian, are directly 

 overlaid by strata of the Llaiideilo or Upper Cambrian division, 

 corresponding to the Trenton and Hudson River formations. 

 If we consult Ramsay's report on the region, it will be found 

 that he speaks of the lower rocks as " probably Cambrian," 



* Quar. Jour. Geol. Soc., XIX. 36. 

 t Canadian Naturalist, VII. 125. 



