de a Ce et ee ee ee ee ey 
yet 
GEOGNOSY OF THE APPALACHIANS. 477 
Cambrian rocks were not Silurian, instead of maintaining Sedg- 
wick’s name, which with the progress of paleontological study is 
assuming a great zoological importance, devised the name of 
Taconic, as synonymous with Lower Cambrian ;* although, as we 
have seen, there is as yet no paleontological evidence to identify 
any portion of the Taconic strata with the well-defined Lower 
Cambrian rocks of our eastern shores. 
The crystalline infra-Silurian strata, to which the name of the 
Huronian series has been given by the Geological Survey of Cana- 
da, have sometimes been called Cambrian from their resemblance 
to certain rocks in Anglesea, which have been looked upon as al- 
tered Cambrian. The typical Cambrian rocks of Wales, down to 
their base, are however uncrystalline sediments, and, as pointed out 
by Dr. Bigsby in 1863,7 are not to be confounded with the Huron- 
ian, 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 unconformably on the primitive 
gneiss (Urgneiss),and are in their turn overlaid unconformably by 
the fossiliferous Cambrian strata. This second or intermediate 
series in Norway is characterized by eurites, micaceous, chloritic 
and hornblendic schists, with diorites, steatite and dark colored 
serpentines, generally associated with chrome ; and abounds in ores 
of copper, nickel and iron. In its mineralogical and lithological 
characters, the Urschiefer corresponds with what we have desig- 
nated the second series of crystalline schists. It is, in Norway, 
divided into a lower or quartzese division, marked by a predomi- 
nance of quartzites, conglomerates and more massive rocks, and 
an upper and more schistose division. Macfarlane, who was fami- 
liar with the rocks of Norway, after examining both the Huronian 
of Lake Superior and the crystalline strata of the Green Moun- 
tains, had already, in 1862, declared his opinion that both of these 
were representatives of the Norwegian Urschiefer, į thus anticipa- 
ting, from his comparative studies, the conclusions of Bigsby. 
The crystalline rocks ọf Anglesea and the adjacent part of 
Caernarvon, which have been described and mapped by the British 
Geological Survey as altered lowest Cambrian, are directly over- 
laid by strata of the Llandeilo and Bala divisions, corresponding 
Ls in 6 deel RO S 
* Emmons, Geol. N. District of New York, 162; and Agric. of New York, L 49. 
t Quar. Jour. Geol. Soc., XIX, 36. 
į Canadian Naturalist, VII, 125. 
