288 
THE GEOLOGIST. 
formation ; but as yet no fossils have been discovered in them. How- 
ever, from their position and analogies, they must be associated with 
the equivalents of our " Longmynd, " or "Bottom Rocks," or Lower 
Cambrian of Sedgwick. 
The schists on the borders of Lake Superior are of a bluish colour, 
and enclose beds of chert, with bands of limestone, the fissures of which 
are often filled with anthracite. They are often covered with a con- 
siderable thickness of trap, upon which are superimposed extensive 
layers of white and red sandstone, passing into a state of conglomerate, 
and inclosing pebbles of quartz and jasper. Beds of red argillaceous 
limestone are found interposed with these sandstones, which are often 
cut through and overlaid by a second sheet of diorite, exTiibiting a 
columnar structure. 
The corresponding rocks on the northern shore of Lake Huron have 
a more vitreous aspect, and conglomerates are more abundant than at 
Lake Superior. Great masses of intercalated diorite occur ; and 
besides these, and of subsequent date to the intcr-stratified diorites, 
there are two sets of dykes of the same mineral, and a third of granite, 
of a period intermediate between the last two. 
The Huronian formation has been traced over a distance of 450 miles 
around the Lakes Huron and Superior, and throughout its extent metal- 
liferous veins occur (of later origin than the volcanic eruptions), which 
have been as yet little worked, but which, from the proximity of the 
coal-fields of the neighbouring State of Michigan, must become, at some 
future period, a source of great riches to Canada. The well-known 
Bruce" and " Wallace" mines are in this formation. Metalliferous 
veins also occur in the Laureutian rocks. 
In the accompanying map of the remnants of the primeval lands in 
North America, the regions coloured pink are the remains of the first 
dry land — the old gneissic territory or Laurentian formation of the 
American geologists. The spaces coloured green are fragments of the 
primeval sediments on its shores — the equivalents of our " Longmynd" 
or "Bottom-rocks" — the "Huronian formation" of Logan. 
In our progress we shall add sedimentary formation after formation, 
iintil in the end will be produced a perfect map of the present geological 
conditions of such part or parts of the globe as the acquired knowledge 
of the day will permit us satisfactorily to attempt ; and by this simple 
