162 THE CANADIAN NATIJ31ALIST. [Vol. 



Vlll.. 



THE METAM0RPHI8M OP ROCKS. 



By Prof. T. Sterry Hukt. 



The various changes which rocks undergo un^er the infiuence- 

 of wat«r, air, and various gases, and their changes fn molecular • 

 structure, were briefly noticed, and the use of the name of meta- 

 morphic rocks, as now generally applied to esystattine strata,, 

 considered. While some geologists had supposed that many or 

 these, such as gneisses, green-stones, serpentines, talcose, an(J 

 chloritic rocks were igenous products, more ©^r less modified by 

 subsequent chemical precesses, others maintained that they were- 

 formed by aqueous sedimentation, and subseqtieiitly cryst^illized.^. 

 This was taught by Hutton, and when, early m tl^» century, the- 

 crystalline rocks of the Alps were shown to re&t «pon uncrystal- 

 line fossiliferous strata, it was suggested that the OTcrlying crys- 

 tallines were newer rocks, which had undergone a metamorphismi- 

 from which those directly beneath had been exempted. This^ 

 notion spread until the great crystalline centre of the Alps was; 

 considered to be in part of secondary and even of tertiary age.. 

 The history of the extension of this notion to Germany, to the- 

 British Islands, and to New England, was then sketched, and it 

 was shown that similar crystalline rocks from supposed strati- 

 graphical evidence came to be referred to formations of very 

 ^iflferent ages in palaeozoic or more recent geologic trine. The 

 author then detailed the course of study by which he had been* 

 led to question this notion ; he showed that there was, according: 

 to Faure, no longer any evidence in the Alps in support of the 

 "view above noticed, that Sedgwick in England and Nicoll in> 

 -Scotland had rejected the views of the palaeozoic age of the crys- 

 talline schists regarded by Murchison as Cambrian and Silurian ;; 

 and finally gave the observations by which he (the speaker) had 

 satisfied himself that the crystalline rocks of the Green Moun- 

 tains and the White Mountains, and their representatives alike 

 in Quebec, New Brunswick, and in the Blue Ridge, were more 

 ancient than the oldest Cambrian or primordial fossiliferous 

 strata. He showed how folding, inversion, and faults had alike, 

 in the Alps and in Scotland, led to the notion that these crystal- 

 line rocks were in many cases newer than the adjacent fossilifer- 

 ous strata, and mentioned that the subject would be furtber 

 Illustrated by a paper on the geology of New Brunswick. 



