iSlS.] ON THE FORMATION OF ROCK^. ^4J 



emanate ^ud rest, as an eternal foundation ? or is it 

 only a link of those changes, tlie circle and recurrence 

 of whose action is lost in the immensity of time ? We 

 know nothing ; we may form theories and systems 

 without end, and perhaps one system is as good as ano- 

 ther ; but still we must recur to the humiliating truth, 

 we know nothing. 



Between the rocks of the third class, called primi- 

 tive, and the rfx)ks fif the first class of positive Neptu- 

 nian origin, the great line of distinction is the aban^ 

 dance of remains of animals and vegetables in the first 

 class, and the total absence o£ them in the third class : 

 this third class is similar to the second class or volca- 

 nic origin, in being without any remains of organic 

 matter. 



The first and third classes differ from the second 

 class or volcanic, by being intersected by metallic 

 veins, and repositories of metallic substances ; wiiere- 

 as the se<:ond class has no metallic veins, or any me- 

 tallic deposits in it. The lowest granite approaches 

 to the volcanic in being without metallic veins, or me- 

 tallic deposits. 



The result of this investigation would appear to be, 

 that all the rocks caUed alluvial, secondary, and tran- 

 sition, are of Neptunian origin ; either by the evidence 

 of our senses, or by a strict antl direct analogy with 

 those formed daily under our eyes. That another spe- 

 cies of rocks whicli cover and overlay the former, 

 whose origin is either strikingly evident to our sense.s 

 by the eruptions of active volcanoes, or by a strict and 

 direct analogy, are evidently of volcanic origin, though 



Vol.1. Dd 



