98 THE CANADIAN NATURALIST. [Vol. ix. 



" geology which are required to explain the previous theory of 

 " the structure." But we must not imagine that such a simple 

 explanation could not possibly have occurred to Sir W.E. Logan, 

 and that his introduction of those '• almost impossibilities" was 

 unnecessary. I am inclined to think that the phenomena which 

 Sir William worked so indefatigably and so loyally to explain, 

 remain to this day as tangible as ever, and that Mr. Selwyn's new 

 theories afford no solution of the problem. 



2. Mr. Selwyn maintains the igneous origin of many of the 

 crystalline rocks of his second division, and especially of the 

 " diorites, dolerites and amygdaloids " which occur in connection 

 with certain copper ores. This is another view I have often 

 maintained, and I might readily quote passages from my papers 

 giving the authority of Naumann and others in support of it. 



3. Mr. Selwyn particularly insists upon this point, " that the 

 " fact of crystalline rocks (greenstones, diorites, dolerites, felsites, 

 " norites, &c.) appearing as stratified masses and passing into 

 " schistose rocks, is no proof of their not being of eruptive or 

 " volcanic origin." This is a principle of very wide application, 

 and cannot in my opinion be controverted. In my paper on 

 the Acton mine, dated 28th October, 1862, 1 described a striking 

 instance in support of this very point. I said, " Between the 

 " cupriferous limestone and the underlying shale, there is often 

 " intruded a fine grained greenstone, which sometimes forms 

 " very considerable and irregular masses ; sometimes intersects 

 " the limestone strata, and often presents a peculiar banded 

 " structure, resembling more that produced by igneous flow than 

 " that due to deposition from water." Further, when discussing 

 the origin of eruptive and primary rocks in January, 1864, I 

 insisted upon the view now brought forward by Mr. Selwyn, and 

 gave an explanation of it in the following words : '' The instances 

 ** of a similar modification of structure among the greenstones are 

 " very numerous, and they are even more important as shewing 

 " more clearly the cause of this structure among igneous rocks. 

 *' The diorites usually occur in the form of veins, irregular masses 

 '• and layers. The veins sometimes exhibit the following re- 

 " markable phenomena : In the middle they consist of granular 

 '^ diorite, and at the sides of slaty diorite or hornblende schist, a 

 '^ gradual transition being generally observable from the granular 

 " to the schistose rock. The cause of these phenomena may 

 " most reason ablv be souo^ht for in the circumstances attending 



