REVIEWS—GEOLOGICAL SURVEY OF CANADA. 463 
band obliquely crosses in succession the terminal edges of all the divisions which 
have been described on the south-east side of the river to the middle of the upper 
slate conglomerate, its relation to which has already been pointed out. 
“At the point which has been mentioned on the south side above the exit of 
Thessalon Lake, the chert band proceeding north-westward enters the lake, but 
some uncertainty exists as to the position at which it leaves it, On the north-east 
side of the peninsula of Otter-tail Lake, there is at the base of the chert band a 
bed of a red and yellowish fine grained sandstone. A similar bed is seen at the 
upper end of Thessalon Lake with a bed of yellowish chert resting on it, and it is 
probably here that the band again enters upon the land; but the dip at the spot 
is irregular, and the band has not been traced beyond it. There is no doubt, from 
the sequence of the rocks beneath the band, that it is equivalent to the one over- 
lying the white quartzite on Salter’s side-line; and should it, on farther investiga- 
tion, be found to continue westward from the upper end of Thessalon Lake, then 
the south-west dipping chert band which faces the first described one, would 
necessarily occupy a higher stratigraphical ‘place, and would prove the continuance 
of the fault which no doubt reaches Salter’s side-line. The extent of this down- 
throw is not quite certain, but it appears to me it cannot be less than 1500 feet at 
this part. 
“The rock which would lie between these two chert bands is seen in a hill 
forming a point north of the south-west corner of Thessalon Lake. It oceupies 
three quarters of a mile across the stratification and consists of white quartzite. 
A dip of eighteen degrees would give to this a thickness of near 1500 feet, to 
which, if 200 feet be added for the upper chert band, the dislocation would appear 
to approach even 1700 feet on Salter’s side-line. 
“The downthrow, however, if the dislocation result from a vertical movement, 
must be progressively much greater to the south-east, for the chert band termi- 
nating near the upper fall against the middle of the upper slate conglomerate, 
would there shew a displacement equal to the whole volume of strata between, 
which, according to the thicknesses given in the list of strata, would be 9,320 feet 
additional, or upwards of 11,000 feet, * * * * The examination of the 
area connected with the Mississagui has not yet been sufficiently extended to 
determine the relation between the copper-bearing veins of the Grand Portage 
and the physical form to which they are subordinate. The veins of the lower 
part of the river are evidently related to the anticlinal existing there. Those of 
the south part of Echo Lake aiso belong to an anticlinal; so do those of the Bruce 
and Wellington mines; and it would almost appear as if the importance of the 
metalliferous indications rose with the sharpness of the fold. But whatever be 
the cause of the dislocations in which metalliferous minerals are secreted, it would 
seem to be a probable suppositicn that in a metalliferous district the greater the 
dislocations the gieater the chances of valuable metalliferous lodes. If this be 
the case, the great dislocation of the valley of the Thessalon would become in- 
vested with much importance. But though there is no doubt whatever that it is 
a master fault, it would, I fear, be a somewhat expensive affair to prove or dis- 
prove that it is a master lode, for although the proximate position of it has been 
more or less examined for upwards of fifty miles. uever in any place have I been 
