DIKES AT SILVER ISLET. 379 
tion-product, and sparse apatite, complete the resemblance between this 
rock and the finer orthoclase-gabbros of the Keweenawan. 
The dikes appear also to cut the overlying sandstone for some little 
distance beyond Silver Islet Landing, but as to whether they have actually 
filled fissures in the sandstone, or have had the sandstone deposited around 
them, I did not satisfy myself. At Silver Islet Landing, for instance, one 
narrow dike was noticed cutting the slate, and the overlying chert-conglom- 
erate and sandstone. On one side of the dike the junction of the sandstone 
and slate is twenty feet higher than on the other, which fact might point 
either to unconformity or to faulting on the line of the dike. 
So far, then, as I have been able to learn by original observation, and 
by reading in the light of the observations the accounts of others, the 
Animikie rocks of the Pigeon River-Thunder Bay region consist of a 
great series, probably upwards of 10,000 feet in thickness, of quartzites, 
which are often arenaceous, quartz slates, argillaceous or clay slates, mag- 
netitic quartzites and sandstones, thin limestone beds, and beds of a cherty 
and jaspery material. With these are associated, in great volume, and in 
both interbedded and intersecting masses, several types of coarse gabbro- 
and fine-grained diabase, all of the types being well known in the Kewee- 
naw Series. 
Any one familiar with the descriptions of the Thunder Bay region by 
Logan, Macfarlane, and Bell, will see at once that in the statements of the 
last paragraph I have departed widely from the conclusions of these geol- 
ogists as to both the thickness and composition of the Animikie Group. 
Their descriptions are, however, misleading on these points, being based 
almost exclusively upon what is seen on Thunder Bay, which lies where 
only a relatively small thickness is exposed, and where the rocks sometimes 
come nearer to being “sandstones and shales”—the terms used by them— 
than elsewhere. Logan, moreover, evidently took as Huronian that part 
of the Animikie Group which occupies ‘the coast for a distance of ten 
miles immediately below the mouth of the Kaministiquia River on the 
north side, leaning in a narrow strip against the gneiss of the older series.”* 
Bell includes these rocks with the rest of the Animikie Group, where, as I 
have indicated above, they unquestionably belong. 
1 Geology of Canada, p. 63. 
