. 5 



NOVA SCOTIA. 



375 



" 3rd. The unconformjxble contact of the gokl-Learing scries with the Lau- 

 rentiaii gneiss, showing the absence of the intermediate gneissoid series, or the 

 Huronian." (I. c, p 474.) 



See also Am. Jour. Sci., 1870, (2) XLIX. pp. 347-355; K pp. 132- 



134, 417-422. 



In order that the conclusions of Prof. Hind uiay properly be regarded 

 as proved, it is neceasary that the age of the gold-bearing strata sup- 

 posed to be Lower Silurian or Cambrian should be ascertained, and also 

 that the origin of the rocks in question, and their actual, not supposed, re- 

 lations to one another be clearly made out, he having apparently detcr- 

 mhied the order of superposition by the dip of tlie foliation. Mr. Hind 

 expressly states that his supposed Silurian strata are more altered 

 bearing andalusite crystals ~ near the so-called Huronian rocks than 

 at a distance from them. Dr. Dawson regards the so-called gneiss of 

 Prof. Hind as granite, and states that it is intrusive in the gold-bearing 

 strata and Oriskany rocks. Certainly more credit should be given to 

 Dr. Dawson's assertion than to Prof. Hind's negative evidence. (Supple- 

 ment to Acadian Geology, 1878, pp. 84, 85.) 



Mr. Selwyn states regarding this granitic region : 



" I have examined it in all the above-named districts, and tjie impression I 

 at present have, is that it is strictly of an indigenous character, and neither an 

 old granitoid gneissic series of Laurei'itian age, nor an intrusive mass. Dr. 

 Dawson has shown (Acadian Geology, 1868) that in different parts of its 

 course it comes successively into contact witli Lower Silurian, Upper Silurian 

 and Devonian rocks, and the manner in which these sedimentary strata are 

 affected at the lines of contact scarcely leaves room to doubt the posterior ori- 

 gin of the granite ; but whether as an intrusive mass, or by the metamorphism 

 in sitd of tlie stratified rocks, (in part by a process of molecvdar re -arrangement 

 of their original component particles,) is perhaps uncertain." (Geol. of Can- 

 ada, Heport of Progress, 1870-71, p. 2G5.) 



Whatever the origin of the granite may have been, evidence of that 

 orighi ought to be obtained from an investigation of the relation of that 

 rock to the adjacent ones. Dr. Dawson's statements prove most clearly 

 the eruptive intrusive character of the granite in question, the evidence 

 consisting not only in the induration of the rocks with which the gran- 

 ite comes in contact, but also in its sending tongues and dikes into 

 them. Mr. Selwyn does not furnish any evidence to sustain his views, 

 which seem to be the natural result of an effort to solve problems with- 

 out a sufficient petrographical examination of the rocks concerned. As 

 we have before repeatedly remarked, such metamorphism i7i situ as is 

 here demanded needs to be proved, before it can be admitted. 





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