

Petrographieal Relations of Laurentian Limestones. 35 



rocks was due to the intrusion of igneous material into 

 true sediments, which thereby received the addition of an 

 immense amount of material, the metamorphism having 

 been intense, and essentially metasomatic. This process 

 he calls granitization, and the original sediments are said 

 to be granitize. In a later paper, l he describes the three- 

 fold manner in which this result was accomplished : — 



1. By injection of molten granitic material between 

 and around the fragments of the more or less shattered 

 margin of the penetrated rock, and as thin layers along its 

 foliation or lamination planes — lit par lit. This causes 

 intense metamorphosis of the rock and gives to it a granitic 

 character. 



2. By action of heated mineralizing solutions carrying 

 the essential elements of quartz and feldspar. In some 

 manner, which he does not make very clear, these solu- 

 tions penetrate the altered rock and cause the quartz and 

 feldspar to crystallize through it. 



3. By actual solution of the penetrated rock in the 

 granite magma. 



A number of workers on the geology of Mont Blanc 

 record similar conclusions. 2 Their belief 3 opposed to the 

 supposition of Suess that granite fills great cavities in the 

 crust of the earth which have resulted from tangential 

 stress, thus giving rise to batholites — is that " the granite 

 magma first rises aloncr lines of fracture in the crust. Its 



© © 



presence leads to a heating of the rock into which it is 

 injected, and its intrusion accompanied by a circulation 

 intense of mineralizing fluids, probably rich in alkalies. 

 These produce at first a transference of quartz from one 



1. "Contribution, a 1'etude du Granite de Flamanville, et des granites Francais en 

 general." Hull, des Services dela Carte Geol. de la France. No. 36, Paris, 1S93. 



2. Duparc, L. and Mrazec, L., " Nouvelles Recherches sur le Massif du Mont Blanc," 

 Archives de Sci. Phys. et Nat., 1895, Vol. XXXIV. 



Duparc, L., " Le Mont Blanc au point de vue geologique et petrographique ", ibid 

 1896. 



Vallot, J., and Duparc L., " Sur un synclinal schistieux ancien f ormant le coeur du 

 massif du Mont Blanc ", Comptes Dendus. March, 1896. 



3. Duparc and Mrazec, loc. cit. 



