90 0?i the Transition Rocks of the Cataraqui. 



conspicuous place, and we already know that terebratulse have been 

 discovered in greenstones, associated with carbonate of lime,* which, 

 however, according to Conybeare, is not very important, as he as- 

 serts that shells have been found in recent and decided lavas, at the 

 points where they have flowed into the ocean. f 



Trunks, branches and twigs, silicified, or penetrated with wood 

 stone, it is well known, occur in a rock called secondary porphyry, 

 but to which some geologists assign an older date, and there is some 

 reason to believe, that even in transition granitic masses, the organic 

 remains of a former world are yet to be seen. J 



But as the object of the prolegomena of the present essay is to 

 analyze remarkable facts concerning these granitic aggregates and 

 other rocks of the transition class, we shall go on to develop the re- 

 ceived opinions of the most eminent writers, regarding associations, 

 which the philosophers of the present day consider as decidedly newer 

 than those first created. 



It may, however, be necessary, before we proceed further on so inter- 

 esting a research, to explain our own views on the nature of the term 

 transition ; a term, we are well aware, highly objected to by many 

 very learned men. But unless either that word, or some other near- 

 ly equivalent is employed, how is it possible to detail ideas concern- 

 ing those extensive formations which so evidently occurred when the 

 planet we inhabit was undergoing, as it were, a new birth, and its 

 oceans were beginning to teem with animate beings. The term itself 

 may be objectionable in a philological, as well as in a geogonic point 

 of view, but it is preferable, in our opinion to any other, hitherto 

 offered ; and although it does not fully imply the notions which it is 

 intended to convey, of the vast changes gradually occurring, during an 

 indefinite period on the surface of the globe, yet it is sufficiently ex- 

 planatory, at least, of the difference which certainly exists between 

 the newest of the ancient, and the oldest of the more recent fami- 

 lies of rocks, and as such, we adopt it. 



* By M. Weaver, in Ireland, in a trappose rock. 



\ It will be recollected that the Huttonians always ascribe the origin of these 

 rocks to submarine volcanos, acting when the ocean still covered the surface of the 

 districts in which they are found. 



t Jamesojv says that petrified shells have been found in secondary trap rocks, as 

 secondary greenstones and also in the slaty rock, (slaty compact felspar,) frequently 

 associated with it. 



