ARE THE "BATHOLITHS" OF THE HALIBURTON- 



BANCROFT AREA, ONTARIO, CORRECTLY 



NAMED ? 



W. G. FOYE 

 Harvard University 



The large areas, composed essentially of banded red gneiss, 

 which are found throughout the Haliburton-Bancroft area have 

 been called by Adams and Barlow "batholiths." 1 These appear 

 on maps of this region as circular or oval masses more or less com- 

 pletely surrounded by sediments or schists of sedimentary origin. 

 The stratification of these sediments follows in strike the boundaries 

 of the adjacent gneiss. Moreover, within the gneissic areas are 

 layers of amphibolite or gray gneiss which conform in dip and 

 strike to this same boundary. The gneissic areas, therefore, may 

 be described as domes of red granite gneiss containing gray gneiss 

 and amphibolite in layers striking concentrically to points more or 

 less fixed within the mass and dipping quaquaversally at angles 

 which vary from 37 to 45 . 



In his earlier writings, F. D. Adams stated three views as to 

 the origin and method of emplacement of the "Fundamental 

 Gneiss." 



1. The Fundamental Gneiss may be the remains of a primitive crust 

 which was penetrated by great masses of igneous rocks and subjected to suc- 

 cessive dynamic movements. The Grenville series may be an upward con- 

 tinuation of the Fundamental Gneiss under altered conditions, marking a 

 transition from a primitive crust to normal sediments. 



2. The Grenville series may be considered as distinct from the Funda- 

 mental Gneiss and reposing on it unconformably, being a highly altered series 

 of clastic origin; the Fundamental Gneiss having some such origin as sug- 

 gested above or being an older intrusive series of still more highly altered 

 sediments. 



3. The fundamental Gneiss may be considered as a great mass of eruptive 

 rock which has eaten upward and penetrated the Grenville series, while the 



1 Geol. Surv. Can., Mono., VI (1910), 12. 



783 



