Geology of Lake Superior. 43 
Finally, at a period subsequent to the deposition of the 
shell limestones, another great convulsion appears to have oc- 
curred, probably of diluvial origin, one effect of which ap. 
pears to have been a rushing current of water from the north 
east. Such a current has, almost certainly, passed over the 
face of the country ; strewing the south-west sides of the 
lakes, and the whole country to the south west, with diluvium, 
and boulders of the rocks now in sie on their northern bor- 
ders. 
Tlie same great agent appears té have bronght the Boulders 
of old sliell Imestoné from the vicinity of Hudson’s bay, to 
have carried the agates of the lake Superior amygdaloid far to 
the south west, and the nalive copper from the vicinity of 
that lake down the valley of the Mississippi. 
We have now completed our endeavours to give an outline 
of the geology of lake Superior. The task which we have as 
signed to ourselves has been executed, we are fully conscious, 
with a degree of ability very far short of our inclination to for- 
ward or ouradmiration of the science to which the subject 
we have treated belongs. Yet, there is this consolation and 
hope left to us.—lIt is, that his efforts can scarcely be entirely 
useless, whoadds but one grain to the heap of information, 
where the object to be attained is so noble, and so perfectly 
worthy of the best efforts of the human mind. 
Arr, I1.—Memoranda respecting colouring mate- 
rials produced in Canada, By William Green, 
Esq. 
Tuis country produces various substances fit for the use of 
artists as pigments. 
In the parish of VAncienne Lorette and in that of St. Au- 
gustin near Quebec, there exists in alluvial soilatthe depth 
of three feet a horizontal stratum of fine yellow clay, 
a This 
