Geology of Lake Superior. 57 



dense forests, often mountainous, as at the Huron, Bohemian, and 

 Porcupine Mountains. The scene is dark with the verdure of 

 northern evergreens, and is here and there diversified with small 

 clearings, and the smoke of distant mines ascending among the 

 uplands. The bays are often deep, full of little iron-stained streams ; 

 and the promontories stretch for miles into the lake. 



The eastern and northern shores are different — more naked, 

 steeper, ever abounding in dome- shaped hills, or in ridges, rising 

 by steps, scantily covered with trees either stunted or scorched with 

 fire. (Large sketches were exhibited representing the lofty basaltic 

 country about Fort- William, and the softer hill-scenery of Black 



Ba y-). 



With the exception of the Fur trading stations, there are no white 

 settlements on the north shore ; and this from its general barren- 

 ness. At the Peak 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 offish, 

 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 debris which overspread 

 these countries. 



II. Geology. 



The rocks of Lake Superior have been arranged under three prin- 

 cipal 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, Syenite, 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 



