REPORT OF TEE CHIEF ASTRONOMER 791 



SESSIONAL PAPER No. 25a 



and thick limestones, was invaded by the Kruger body. Whether or not the 

 older ultra-basic intrusives, cutting the Anarchist series near Kruger mountain 

 and visibly contacting with the alkaline body, were also significant factors in 

 .its genesis cannot be decided. There is clearly a chance that the heavy limestones 

 in the Anarchist series were more important. The separation of the malignitic 

 and foyaitic facies of the Kruger body is best explained as a differentiation in 

 place. 



In general, therefore, it may be said that the alkaline magmas of the Forty- 

 ninth Parallel section all originated in regions of heavy sedimentation, and 

 that thick limestones occur in the stratified series cut by the alkaline bodies. 

 All these associations are new illustrations of a very general rule applying to 

 the known occurrences of alkaline rocks. The rule is quite independent of any 

 petrogenic theory. Its explanation through the syntectic-differentiation theory, 

 wbereby a genetic connection is found between the relatively rare alkaline rocks 

 and the vastly more abundant subalkaline rocks, seems to be worthy of special 

 attention. 



