242 



Canadian Record of Science' 



of this rock exposed in the quarries on the mountain side, 

 and it is always vertical, showing that the movement of 

 the rock was upward through the pipe, and not outward 

 and horizontally over the pulaskite, as it would have been 

 in the case of a laccolite. Furthermore, in several cases 

 when the fluidal arrangement is very distinct and has a 

 somewhat banded character, as shown in Fig. 6, due to the 



Fig. 6. — Andose in quarry on Mount Johnson, showing vertical flow 



structure. 



alteration of somewhat more feldspathic portions of the 

 rock with others richer in iron-magnesia constituents, a 

 strike can be made out on horizontal surfaces, and this 

 strike curves around the mountain, following its marginal 

 outline, as shown in the map, Fig. 2. 



It is thus clear that Mount Johnson is a neck in its 

 most typical form. A cross-section of the mountain is 





