386 Canadian Record of Science. 
GEOLOGICAL NOTES. 
By Sir J. Wittram Dawson, LL.D., F.R.S. 
The following notes, made in my recent sojourn in the 
South, may be of interest to some readers of the Recorp: 
I.—The Classification of the Oldest Rocks. 
Much controversy has raged over the age and arrange- 
ment of the older rocks of the Scottish Highlands; and 
ever since I had an opportunity to talk over the subject 
with my old friend and fellow-student, Prof. Nicol, of Aber- 
deen, I have felt that the matter was not in a position for a 
detailed comparison of these rocks with the clearly defined 
series worked out by Logan in Canada. Quite recently, 
however, I have read in the new American “Journal of 
Geology,” an article by the distinguished -head of the 
Geological Survey of Great Britain, in which he gives, 
avowedly for the benefit of those ‘engaged in the study of 
the oldest rocks of North America,” a summary of the 
latest conclusions on the subject. From this I deduce the ° 
following general statements : 
1. The older group of the Highlands is not the whole of 
the Lewisan group of Murchison, the Laurentian of Logan, 
but only the lower part of it—the Ottawa group of the 
Canadian Survey, and this holding probably a larger pro- 
portion of intrusive igneous matter than is usual in Canada. 
He mentions, however, certain rocks of Loch Maree in 
Ross-shire which, so far as mineral characters go, may 
represent a portion of the Upper Member of the Laurentian. 
No doubt when he has time to examine the Western Islands 
he will find there the Upper or Grenville series as well; so 
at least specimens from these islands would seem to indi- 
cate. JI may mention here that recent examinations by Dr, 
F. D. Adams seem to have confirmed the conclusion that 
the Upper Laurentian of Logan is mainly composed of 
igneous material erupted in the latter part of the Lanren- 
tian period, so that in the typical Ottawa region only two 
bedded members exist, the Ottawa group and the Grenville 
