200 THE CANADIAN NATURALIST. [May 



above described have been formed. They have simply been produced 

 where no tumultuous motion was at hand thoroughly to incorporate 

 the material of the greenstone with that derived from the softened 

 fragments, but where a steady continuous motion, always in the 

 one direction, drew out the materials of the different slates into 

 long bands side by side with each other. It thus seems to us 

 reasonable, and quite compatible with a scientific interpretation of 

 the facts above given, to explain the origin of by far the greater 

 number of the above enumerated Huronian rocks upon a purely 

 igneous theory ; and it has occurred to us that many of the in- 

 stances of local metamorphism, recorded by geologists, in which the 

 contact of an igneous rock caused the silicification or lamination 

 of another, might be capable of thorough explanation in a manner 

 similar to that in which we have tried to account for the origin of 

 the breccias, conglomerates, siliceous greenstones and banded slates, 

 which constitute such a large part of the Huronian series. 



The Huronian series, whatever its mode of origin may have 

 been, must undoubtedly be regarded as an independent geological 

 formation. It has been represented as being " a mixture of the 

 St. Alban's group of the upper Taconic with the Triassic rocks of 

 Lake Superior, the trap native-copper bearing rocks of Point 

 Keeweenaw, and the dioritic dyke containing the copper pyrites of 

 Bruce mine on Lake Huron" * but surely such a description 

 is based upon a misconception of Sir W. E. Logan's views on the 

 subject. Until its discovery by Sir William, the Huronian formation 

 was unknown to geologists as a separate and independent system, and 

 even now it is only in comparatively few countries besides Canada 

 that it has been shown to exist. On a former occasion, in the 

 columns of the Naturalist f I endeavoured to shew that the 

 Azoic schists of Tellemarken, in Norway, were almost identical 

 in lithological characters with the Huronian rocks, and Dr. J. J. 

 Bigsby % shortly afterwards insisted upon the fact of their being 

 the same formations. Dr. Bigsby is of opinion that the Huronian 

 also occurs on the Upper Loire, in France, and that it is a totally 

 distinct formation from the Cambrian, with which it has hitherto 

 been customary to associate it. The Huronian forms part of 

 what Naumann calls the primitive slate formation. 



* Marcou; The Taconic and Lower Silurian Rocks of Yermont and 

 Canada. 



t Vol. vii, p. 113. 



X Quart. Journ. Geol. Soc. Vol. xix, p. 49. 



