84 M. Keilhau''s Theory of Granite^ and other Rochs. 



abnormal rocks, but somewhat thicker than it, we see transi- 

 tions from compactness to crystalline structure which have pro- 

 ceeded farther ; and finally, again in others occurring under 

 the same relations, but which are a couple of feet in thickness, 

 we find masses that present a perfect crystalline granular trap, 

 which, in these places, represents the common greenstone. From 

 the trap-rocks there are transitions through petrographical inter- 

 mediate links in the less and less considerable beds to the finest 

 granular masses in the thinnest bed, all of which are distinct ; 

 and between what has been last mentioned and the common hard 

 slates, there are found intermediate rocks sufficient to complete 

 the suite. In other places, where bed-like masses of the usual 

 greenstone occur between strata of clay-slate and calcareous 

 clay-slate, there are found small thick beds of a rock having an 

 intermediate character between clay-slate and greenstone ; but 

 so far as our observations have hitherto gone, the range of beds 

 which exhibits the different shades of transition, is not so com- 

 plete here as in the other peculiar example of trap, nor are 

 these beds so thin as to preclude to the same degree the ad- 

 mission of the hypothesis of the lateral injections. 



The transitions from the granite of our territory to certain 

 primary strata must likewise be briefly noticed. I confess that 

 no geological phenomenon has struck me so much as this, that 

 I found places where the boundary between the granite and 

 the primary gneiss had entirely disappeared, where the nature 

 of the rock changed completely from the characteristic type of 

 the one rock to that of the other ; so that at first I despaired 

 of the possibility of finding any explanation. As to what re- 

 gards the facts in this case, the relations are precisely the same 

 as in the transitions from the same granite to the fossiliferous 

 state. For the most part we find at the boundary ramifica- 

 tions of the massive rock branching into the primary strata ; 

 but sometimes, though rarely, transitions occur. That these 

 transitions bear testimony against the eruption theory, in the 

 same manner as the transitions between the granite and \M 

 newer strata, requires no further explanation ; but, in passingj 

 we may remark, how extremely important this same fact is 

 an argument against Neptunism. It appears that some of th( 

 supporters of this doctrine have endeavoured to explain th« 



