PETROGRAPHICAL EVIDENCE IN SOUTH INDIA. 241 



other features which characterise so many of the charnockite masses, 

 show that deformation has occurred whilst the magma was still in a 

 plastic condition, and one accompaniment of such deformation would 

 in all probability be the production of a granulitic structure in which 

 groups of granules would represent the break-up of larger individuals 

 of the same species. If this be accepted, we have a simple explana- 

 tion for, not only the granulitic structure, but also for the constant 

 tendency there always appears to be for the minerals to present 

 themselves in groups of like kind. This feature has been noticed in 

 many of these ancient, foliated igneous rocks, in the elaeolite-syenite 

 for instance of Coimbatore. 



Phenomena resulting from the crushing of a solid rock and struc- 

 tures resulting from deformation during the process of consolidation 

 are not, however, distinguishable from one another with sufficient 

 certainty to permit dogmatic conclusions on this score. It is difficult, 

 if not impossible, to distinguish between the granulation of con- 

 stituents already formed and the formation of crystals from many 

 centres due to disturbance of the molecules during crystallization. 

 Probably in all cases of movement during the process of consolida- 

 tion, the ultimate phenomena are the combined result of these two 

 processes acting simultaneously. 



( 123 ) 



