Yol. 57.] IN FOEFAESHIEE AND KINCARDINESHIRE. 345 



Prof. Bonnet expressed his sense of the value of the Authors 

 paper, which was quite in accordance with the speaker's own ex- 

 perience. He had himself seen greenstones reduced to a condition 

 apparently as fissile as some of those on the table, and the bringing 

 together in apparent sequence and in a narrow zone of rocks differ- 

 ing much in age, reminded him of one or two cases in the Alps, 

 where it was often extremely difficult to fix the exact position of a 

 thrust-plane because of the crushing in its vicinity. This, he had 

 observed, always produced very great efi'ects near the junction of 

 two rocks differing much in hardness. The crushing near a fault 

 had often misled observers into supposing a transition to exist 

 from crystalline schists into phyllites. The difficulty was caused 

 by the fact that in the former the minerals were reduced in size, 

 and there might also be a minute secondary development of mica ; 

 while in the latter much minute mica (supposing the rock argillaceous) 

 was produced as a consequence of the pressure. So on the one side 

 there was a ' level ling-down,' on the other a ' levelling-up," which 

 occasionally made the two rocks very like one another. He thought 

 it highly probable that Palaeozoic rocks would occur in lenticles in the 

 Central Highlands — indeed he believed that the late Dr. Hicks had 

 identified Torridon Sandstone. Mesozoic rocks occurred in that way 

 in the Alps ; and he was more sanguine than Sir Archibald Geikie 

 that in such cases the newer rocks would be identified with 

 certainty. 



The President and Mr. E. P. Oldham also spoke, and the Author 

 replied. 



