1852.] OF THE ROYAL INSTITUTION. 157 
fire. (Large sketches were exhibited representing the lofty basaltic 
country about Fort William, and the softer hill-scenery of Black 
Bay.) 
With the exception of the Fur trading stations, there are no white 
settlements on the north shore: — and this from its general bar- 
renness. At the Peek River, soil was imported in bags with which 
to raise a few potatoes. 
The Fauna and Flora of Lake Superior are semi-arctic — or sub- 
alpine. Professor Agassiz has treated of both in his late valuable 
publication on this lake. He found twenty-three new species of fish, 
and states that Lake Superior constitutes a special ichthyological dis- 
trict. The reason of this evidently lies in the coldness and extreme 
purity of the water, its slow departure towards the ocean, and the 
absence of weedy bays, and of lime rocks. 
It would seem that some portion of its animal life are waifs and 
strays from grand geological periods long passed away — as we see 
in its herrings, minnows, and the new genus Percopsis. Connected 
with this subject, Prof. Agassiz conjectures that much of North 
America was dry land when the rest of the world was under water ; 
and that thus its physical condition was less altered than elsewhere. 
Dr. Bigsby was inclined to believe this, for had Canada been as long 
under water as other large tracts, we should probably have had in 
some part of its vast extent, a member or two, at least, of the meso- 
zoic rocks; but there is no such thing — not a single relic of lias, 
oolite, or chalk, in the extraordinary heaps of débris which overspread 
these countries. 
Geology.* The rocks of Lake Superior have been arranged under 
three principal heads, as follows : — 
1. The Metamorphic. —Greenstone, chloritic, talcose, clay and 
greenstone slates, gneiss, quartzite, jasper, rock and saccha- 
roid limestone. 
2. The Aqueous. — Calciferous sandstone, Cambrian sandstone 
and conglomerates. 
3. The Igneous. — Granite, Sienite, Trap, in various states. 
The place and extent of these rocks having been pointed out on a 
map, Dr. Bigsby stated that the geological system of Lake Superior 
is a consistent and closely connected whole, forming a beautiful and 
easily read example of geological action in moulding the surface of 
our globe. 
The lake may best be presented at once to the mind as a trough 
or basin of Cambrian (or Silurian) sandstone, surrounded, and 
framed as it were, by two orders of rocks, in the form of irregular 
and imperfect zones; the inner consisting of trap, with its conglo- 
merates; and the outer, of metamorphic, flanking igneous rocks. 
* This branch of the subject was illustrated by numerous coloured Diagrams, 
and specimens of native copper, and of the rocks of the lake, 
