224 W. E.. Logan on the Rocks of Canada. 
At day break on the 28th we retraced our steps down the rug- 
ged mountain, rejoined the baggagemen, broke up the camp, and, 
by a forced march, regained the confines of the woods before 
dark. This was on Saturday, and here we rested on the Sab- 
bath. On Monday, by hard travelling for twelve hours, we 
reached Hilo, found all well, and felt rewarded an hundred fold 
for our toil of eight days 
March 6.—The fire has not yet reached the shore, and it may 
not. It is winding in the woods, filling our atmosphere with 
smoke, and sending down showers of ashes, charred leaves, etc. 
The great furnace in the mountain is still in terrible blast. No 
decrease of activity, but rather an increase, 
Old Kilauea is as dosy as ever. She has taken no interest in 
our exciting scenes, and seems to feel no sympathy with her fiery 
sister of the hills. 
Art. XXVI—On the Rocks of Canada; by Messrs. W. E- 
Loean and J. W. Satrer.* 
1: On the Age of the Copper-bearing Rocks of Lake Superior 
and Huron, and various facts relating to the Physical. struc- 
ture of Canada. By W. E. Logan, F.R.S. & G.S., Director 
of the Geological Survey of Canada. 
_ In the present paper it is my purpose to place before the Associa- 
tion, in as a condensed a form as possible, one or two of the main 
features of the physical structure of Canada, ascertained in the 
progress of the Geological Survey now carried on in the country, 
under my direction, by the authority of the Provincial Government. 
With the exception of the drift, the country is composed © 
rocks, none of which are newer than the carboniferous e ° 
The general geographical distribution of these rocks, as far as 
ascertained and as connected with the physical structure of the 
bordering states of the American Union on the one hand, and the 
sister British provinces on the other, is represented on the map 
which is displayed to view. we 
One of the points to which it is my wish to draw attention 1S 
the age of the copper-bearing rocks of Lake Superior and Huron, 
as determined by the evidences collected on the Canadian sur 
vey ; and another, the differences that exist in the structural com 
- dition of the western and eastern parts of the province. 
The rocks on the north shore of Lake Superior consist of red- 
dish granite and syenite, which in ascending order pass into mr 
caceous and hornblendic gneiss and allied forms. ‘These are SUC 
ceeded by chloritic and partially talcose slates, which become 1 
terstratified with obscure conglomerates with a slaty base, aud 
* From the Proceedings of the British Association for 1851. 
a a. 
