REPORT OF THE DIRECTOR I917 IO9 



parallel to stream lines in magmatic currents which continued to 

 maintain more or less the same relative movements during the 

 progress of crystallization which they followed during their intrusion. 

 During the later stages of consolidation of the magma the satellitic 

 dikes of hornblende syenite, hypersthene syenite, hyperite, grano- 

 syenite and granitic veins were intruded along cracks caused by 

 crystallization and cooling in the now partially crystallized viscous 

 mass; or sheets of similar materials were forced in along the already 

 existent foliation planes as sills, and suffered the same degree of 

 metamorphism as the rocks inclosing them. 



The next stage in the history of this mass witnesses the rise of 

 external compressive forces to a dominant position and a high degree 

 of magnitude in controlling the progress of crushing. Under the 

 influences of these intense stresses the growing meshwork of crystals 

 in the rocks of the Diana mass were ground against one another, 

 broken, strained and pulverized wmile the still liquid quartz was 

 smeared out into long, narrow, flat leaves. That portion of the 

 mass along the northwest received the stresses at their maximum 

 and suffered crushing and pulverization to the highest degree. The 

 crushing resulted in a coarser granular type as the Croghan mass is 

 approached and ceases abruptly at the border of this mass. This is 

 possibly to be explained by the assumption that this body was 

 intruded later than the Diana mass and was still molten and only 

 slightly crystallized when the latter body consisted of a very coarse, 

 openwork, crystal aggregate with only quartz and pneumatolytic 

 materials filling the interstices. The medium equigranular character 

 of the Croghan mass and the presence of occasional sharply defined 

 bands or dikes of rock similar to the latter in the adjacent Diana 

 body are indicative of such a succession. Within this mass 

 (Croghan) then, the lateral compressive forces already partially 

 spent and dissipated in the small but potent still liquid portion of 

 the Diana mass served merely to produce an orientation, growth 

 and segregation of the minerals along lines at right angles to them, 

 the mineral boundaries still being due to intergrowth in the normal 

 process of crystallization and not to crushing. But even within the 

 Diana mass the compressive forces could not overcome the influence 

 of the previous primary foliation and banding, offering as the latter 

 did potential surfaces along which movement was easiest and parallel 

 to which it actually took place. This follows from the fact that 

 foliation and banding are always parallel. If the rock had not 

 been partially liquid it is difficult to see how the compressive forces 



