On the Norian or "Upper Lcmrentian" Formation. 291 



from the movement in one direction of a mass, whose 

 colored ingredients are irregularly distributed, and espe- 

 cially concentrated in some places (see fig. 1). The more 

 or less rounded spots where the colored ingredients are 

 abundant, became pulled out into irregular, ill-defined 

 streaks, and parallel to these run portions of the rock, 

 which still contain large numbers of the fragments of 

 plagioclase crystals. 



The most probable explanation of these phenomena is 

 that the movements were caused by pressure. 



1. When the rock was still so far beneath the surface 

 of the earth, and so weighted down by the overlying beds 

 that breaking and shearing with the movement of the 

 resulting masses was impossible. The alterations in the 

 character of the mass were probably induced very slowly, 

 the constituents were granulated, and the small broken parts 

 moved one over another. This granulation progressed 

 with the duration and intensity of this movement to a 

 certain point. Such a motion would present certain 

 resemblances to that of a very tough pasty mass. 



2. While the rock was still very hot and perhaps even 

 near its melting point. This would explain why pyroxene, 

 which, according to the experiments of Fouque and 

 Michel-Levy, represents the stable form of the molecule at 

 a high temperature, is not easily changed into amphibole, 

 which represents the more stable form at a low tempera- 

 ture, as is usually the case in crushed and pulverized 

 rocks. It is perhaps owing to the same cause that no 

 saussurite is formed ; still, the conditions necessary to the 

 formation of these minerals are so little known that 

 opinions on this point cannot be ventured upon as yet. 



The Anorthosite Beds Interstratified with the Gneiss 

 and Alternating with it. 



We find in many places in the neighbourhood of the 

 Morin area, as was already mentioned, anorthosite bands 



