PHYSIOGRAPHIC HISTORY OF NORTHEASTERN ONTARIO 201 



in these mountain regions, and nowhere else in the continent, 

 except, of course, in the Precambrian Shield. 



This conjunction of batholithic intrusions with mountain 

 systems is no new observation. It has been long noted and there 



Legend 



I I 



Sodiments not hiyMy fotdeef 



Granitic cores of exisnnp tnountatns 



Other mountam-buitt 



Precambrtan area 





Fig. I. — Map of North America to show the distribution of bathoHthic intrusions 

 in relation to mountain-building. 



has been much speculation as to the nature of the association — 

 whether the compression and upheaval of the earth's crust caused 

 the igneous invasions or whether the latter were causes or mere 

 concomitants of mountain-building. Nor has the analogy between 



