302 MESOZOIC ROCKS IN THE LEPONTINE ALPS. [Aug. 1 894, 



sets of facts. The association of quartz-schists with the marble 

 was a fact which told strongly against its Jurassic age, though the 

 occurrence of a double series of the marbles and their repeated re- 

 appearance to the west did look like interstratification. At Rocca 

 Bianca in the Cottians there are saccharoidal limestones in com- 

 paratively unaltered phyllites, and calcareous masses appear to be 

 liable to more thorough alteration than the argillaceous beds in 

 which they may occur. 



The Author said that he quite agreed with Dr. Gregory as to the 

 comparative ease with which metamorphism took place in limestone. 

 Still he thought it highly improbable that a true saccharoidal 

 marble would be interstratified with a phyllite. He quoted cases to 

 show how mistakes might arise, and said that, though his experience 

 was very large, he had never seen an instance of such inter- 

 stratification. 



