THE LOWER HURONIAN. 369 



It will thus he seen that the Cacaquabic granite massive is an intrusive 

 of younger age than the Knife Lake slates, but older than the Keweenawan 

 gabbro. 



INTERESTING LOCALITIES. 



At only two places has the granite been found showing its relations to 

 the adjacent sediments. One of these places is 700 paces north, 650 paces 

 west of the southeast corner of sec. 1, T. 64 N., R. 7 W., south of Caca- 

 quabic Lake, where the sediments are cut by dikes of the granite. The 

 other point is just back of the southwest shore of Cacaquabic Lake south 

 of a large granite island. Here the porphyritic form of the granite cuts 

 the adjacent conglomeratic sediments. 



Still other dikes occur in the southeast corner of sec. 1, T. 64 N,, 

 R. 7 W., on the hills north of the small lake in which the four sections 

 which meet at this place have their corner. 



VARIOUS ACID DIKES. 



Certain acid dikes, to which reference has already been made, are 

 found cutting through the various formations of the district, but can not 

 be directly connected with any of the large eruptive masses. They are 

 presumed to be of Lower Huronian age, and the evidence for this will 

 be given on another page, yet it is possible that some of them may 

 be of Keweenawan age, although if there are any Keweenawan dikes 

 included among them, they can not be recognized as such on account of 

 lack of evidence. They are not of sufficient interest or importance, how- 

 ever, to warrant a description of the individual dikes; consequently an 

 attempt will be made to give merely a general idea of their characters. 



DISTRIBUTION. 



The distribution of these dikes will be seen on the maps in the accom- 

 panying atlas, on which they are marked with the same symbol and the 

 same color as that used for the Giants R-ange, Snowbank, and Cacaquabic 

 granites. In most cases the exposures of these dikes are small, so that in 

 many instances it is practically impossible to state absolutely that they are 

 younger than the rocks near them. This presumption, however, is 



MON XLV— 03 2i 



