VIC IN ITT of EDINBURGH. 423 



tend my obfervations fo widely, as to embrace the facls refpect- 

 ing thefe rocks. One remark I mail, however, hazard in 

 this place, refpecting an effential difference between veins of 

 granite and thofe of greenftone. The former feem to be of 

 fimultaneous formation with the great body of that rock, to 

 which they may generally be traced, and, fo far as I have hither- 

 to obferved, are never found to cut it. Veins of greenftone, on 

 the other hand, I have never feen connected with the great beds 

 of that fubftance; they traverfe thefe juft as they do every 

 other kind of rock, and confequently are in all inflances of a 

 poflerior formation. I am aware, that thefe ideas are ve- 

 ry much at variance with certain received opinions. I there- 

 fore wifh to be underflood as fpeaking folely upon my own 

 experience.. 



I have now to mention the well-known included mafs of. 

 fandftone. Along the edge of the flrata, a number of inflances 

 occur on Salifbury Craig, affording the moft unequivocal marks 

 of difturbance \ but it prefents only one example^ of a mafs to- 

 tally enveloped in the fubflance of the greenftone *. 



This fpot has been the fcene of much controverfy, between 

 contending geologifls. While the Huttonian confiders it as a 

 moft incontrovertible proof of violence and of heat, the Werne- 

 rian contends, that there is nothing in the leaft extraordinary in 

 the appearance, and aflerts^that the fuperficies of the apparently 

 included mafs, is no more than the fection of fome part of the 

 flratum, which, if traced, would be found to conned; with the 

 reft ; that it had been enveloped in the fluid menftruum of the 

 greenftone, when in this elevated pofition ; and that the rock be- 

 ing 



* Since this paper was fent to prefs, others have been obferved in different 

 parts of the rock. 



