AN^SriVERSART ADDRESS OF THE PRESIDENT. 83 



t 



The Upper Laurentian of Sir W. Logan has often of late years 

 been distinguished by the name of Norian, I have examined this 

 in one district only. The gneisses are peculiar, not the least remark- 

 able being that designated anorthosite-gneiss by Sir W. Logan, which 

 is largely developed. Besides these, there is the great series of 

 gabbros, often containing huge compound crystals of labradorite 

 together with hypersthene. Attempts have been made to claim 

 these rocks, which have an enormous development nortb of the 

 St. Lawrence, as of stratified origin ; but for this I can see no valid 

 reason. These " norites," where I have seen them, are as truly 

 and characteristically igneous rocks, macroscopically and micro- 

 scopically, as the gabbros of the CuchuUin Hills in Skye, for which 

 a similar origin has been asserted. The one hypothesis has proba- 

 bly no better foundation than the other. Possibly some of the 

 gneisses may be only crushed and recrystallized igneous rocks : but 

 before I speak confidently on this, I must study them more thoroughly 

 than I have yet been able to do. I saw, indeed, a crystalline limestone 

 which may indicate sedimentation, but of this I speak doubtfully, 

 as there was no continuous exposure, and the rock was very full of 

 woUastonite, pyroxene, and garnet. In one place, however, I met 

 with a well-defined quartzite. Considering that some of the rocks 

 most conspicuously associated with this series are of igneous origin, 

 and are possibly not even contemporaneous, that others are dubious, 

 and that the rest (so far as I have seen them) differ varietally rather 

 than specifically from those below, I think it unfortunate that a title 

 founded upon the first-named should have been chosen for the 

 group ; and I doubt much whether anything has been gained by 

 departing from the old appellation of Upper Laurentian. 



The Huronian series, placed next in order by common agreement, 

 is one of extreme difficulty. I examined a section of considerable 

 extent in the field, and many specimens in museums, besides study- 

 ing a small collection from Georgian Bay, a typical locality of Sir W. 

 Logan, for which, together with some specimens from the Huronian 

 of Newfoundland, I have to thank Sir W. Dawson. Before my 

 visit to Canada, I could never understand what was meant by 

 the term Huronian ; I cannot say I am much wiser since my re- 

 turn. I believe, in short, that the name at present includes rocks 

 in very different stages of mineralization, and belonging to widely 

 separated epochs. The first rock assigned to Huronian which I 

 saw (a short distance west of Wahnapitae on the C. P. R.), to quote 

 the words of my note, " has a rather flaggy bedding, is much jointed, 

 is rather gritty to the touch, and consists mainly of fine-grained 

 quartz and felspar, having but little mica, though now and then 

 thinnish bands of a fissile mica-schist occur." Its structure ar.d 

 appearance reminded me of the more typical members of the " eastern 

 gneiss" in Glen Docherty (Scotland). This resemblance is confirmed 

 by microscopic examination. It is a fine-grained quartzose gneiss, 

 exhibiting traces of a clastic structure, which, however, is more 

 probably a record of subsequent crushing (followed by cementation) 

 than of original constitution. 



