32 Canadian Record of Science. 



amphibolites now occur might have been bands of the 

 limestone especially favourable to the passage and action 

 of the exhalations and solutions accompanying the magma, 

 while where there are now the pyroxene gneisses, there 

 were, before the intrusion, bands of the limestone which 

 were less permeable,and in which, therefore, the addition o 

 material was smaller and the transformation less complete- 

 On this ground also, the presence, close to the contact, of 

 bands of comparatively unaltered limestone would be due 

 to the fact that they were particularly impermeable to the 

 metamorphosing agents. 



Coming now to a consideration of the true character of 

 the so-called inclusions, there are found to be two possible 

 explanations of that question also. Either these dark 

 streaks and patches are basic secretions of the molten 

 magma itself, or they are, in reality, fragments of the 

 limestone series which have been detached and floated off 

 from it. 



_ The increasing approach of the rock of these masses to 

 granitic structure and composition from the contact 

 inward, the often-times sudden change from the true rock 

 of the batholite to these highly basic streaks, their 

 increasing basicity and angularity of form near the 

 contact — in fact, the field relations generally, as well as 

 the microscopic characters, favor the idea that they are 

 actual fragments of the limestone series, included by the 

 granite magma, and by it still more highly metamorphosed 

 than their parent rocks, though possibly in a somewhat 

 different way. The same conclusion has been reached in 

 some similar occurrences. 1 



If this be the case, however, it may be pertinently 

 asked why it is that although the rocks at the contact 

 contain a basic feldspar and pyroxene and scapolite, those 



1 cf . Lacroix on the Pyrenees ; see Adams, F. D., " The Excursion to the Pyrenees 

 in Connection with the Eighth International Geological Congress," Jour. Geol., 1901, 

 Vol. IX., pp. 31-32. 



