SECTION IV., 1883. [ee lela TRANS. Roy. Soc. CANADA. 
I.—On the Geology of Lake Superior. 
By A. R. C. Srtwyn, L.L.D., FRS. President of the Section. 
(Read May 22, 1883.) 
In annual presidential addresses, it is customary to review the progress which has 
been made during the year in research and discovery, in the several departments of science 
with which the members of the section of the Society are occupied. To do this, however, 
would be a task which I feel I could very inadequately perform. Therefore, I propose on 
the present occasion to depart from this custom and to address you on a subject in which 
I feel at home and which I may, therefore, hope, notwithstanding its being purely geolo- 
gical, to make more interesting and suggestive than I could make any general remarks I 
might be able to bring before you on matters which I have not myself practically studied. 
The subject, then, to which I propose to call the attention of the section is one respect- 
ing which much difference of opinion has prevailed in the past, and which is still giving 
rise to considerable discussion. It is also one which several members of our Society, 
besides myself, have personally more or less investigated, and the consideration of it may 
therefore, I hope, prove interesting and give rise to a discussion by which important facts 
may be elicited, or which will help to explain some of the problems presented and 
stimulate further inquiry. I refer to the geology of the Lake Superior region. It is unne- 
cessary and, indeed, the time at my disposal would not suffice, to do more than mention a 
few of the various opinions that have been held and published by those who have pre- 
ceded me in this investigation. 
So various, indeed, are those opinions that they cover almost every reasonable, and 
some, perhaps, unreasonable suppositions. It, therefore, nowremains for future observers 
to endeavour to ascertain by closer and more careful investigation and study of the facts 
on the ground, which of all these various opinions stands on the broadest foundation, not 
of theory and supposition, but of facts and observation. 
In 1877, Professor Irving briefly stated the facts as then known to him respecting 
the Wisconsin older rocks as follows : 
1. The existence of an older gneissic and granitic series—Laurentian. 
2. The wnconformable superposition upon this of a second crystalline series—Hwronian. 
3. The superposition upon the Huronian in probable unconformity of the great “ Ke- 
weenian” series with a thickness of several miles. 
4. The existence of a series of horizontal sandstones, resting unconformably upon the 
the “ Keweenian” and holding the organic forms of the Potsdam sandstone. 
This succession corresponds, in the main, with that given by Logan for the north 
shore, in the Geology of Canada, 1863. But it differs in the unconformable relations assigned 
to the Laurentian and Huronian, and also in the probable age of the groups of strata, 
which, together, form Logan’s Upper Copper-bearing rocks, and which have been divided 
by Hunt into Animikie, Nipigon and Keweenian, with the suggestion that Animikie and 
