48 TRANSACTIONS OF THE CANADIAN INSTITUTE. [VoL. VI. 
In tracing the origin of the basin of Lake Superior, we must go back 
to a very early period in the history of the solid earth. It appears to 
have begun with a depression in the original crust, even before the 
deposition of the oldest Huronian rocks, and probably before any water 
at all rested upon the heated surface of the globe. The great basin of 
Hudson’s Bay is an example of a still larger depression in the first 
formed crust, which has persisted to the present day. 
The vast Archatan region of North America, embracing perhaps one- 
third of its area, and which formed the nucleus of the continent around 
which the land has grown by the addition of one formation outside of 
another, has a general elliptical outline and extends from the north 
of Greenland in the far northeast to the State of Missouri in the 
southwest. 
The depression of Lake Superior and that of Hudson’s Bay and its 
connecting waters to the northward are within this ellipse. The earliest 
clastic deposits from the primeval sea might be looked for in these 
hollows and in the corresponding levels around the primitive nucleus of 
the continent, and hence, in these situations we find the Newer Laurentian 
and the Huronian systems largely developed and followed by the 
fossiliferous formations while the higher grounds or those more distant 
from these depressions as well as from the general periphere, consist 
almost entirely of the oldest gneiss which appear to be all modified 
from a granitic magma. The Huronian series, made up to a great 
extent of igneous rocks, are very largely developed to the south and 
west of Lake Superior in the States of Michigan, Wisconsin, Minnesota 
and Dakota, as well as throughout the country lying to the northwestern, 
northern and northeastern sides of the lake. During the succeeding 
Lower Cambrian period, the region of Lake Superior was the site of 
great outpourings of igneous matter, which formed the diorites, diabases, 
melaphyres, gabbros, amygdaloids, etc., of the Animikie and the 
Nipigon series. Between the Huronian and the older Cambrian 
periods, a vast interval of time elapsed, of which but little record has 
been left in the Lake Superior region. The upturned edges of the 
highly disturbed Huronian rocks were denuded down to a nearly level 
surface, and upon them were deposited the horizontal and undisturbed 
beds of the Animikie and Nipigon or the older Cambrian system, which 
have remained unaltered to the present day. The masses of granite of 
greater or less extent, which cut the Huronian and sometimes the 
Laurentian rocks around Lake Superior may have been erupted during 
this long interval, as we do not find them intersecting the Cambrian or 
any of the still newer strata, although they are themselves cut by dykes 
