-338 ON THE F0R3kL\TI0N OP ROCKS. [August, 



is nearer the rocks of undisputed Neptunian ori^ 

 gin than the gneiss ; and perhaps only differs in 

 the total absence of the remains of organic matter, 

 with which the limestones of Neptunian origin are 

 filled. 



Clay Slate is a rock which corresponds with the 

 rocks of Neptunian origin, in its mode and regularity- 

 of stratification : it does not differ very much in its 

 structure and external appearance from the Clay Slate 

 of transition. It having no remains of organic mat* 

 ter in it, while the slates of undisputed Neptunian ori- 

 gin contain both vegetable and animal remains, pre- 

 vents the analogy from being direct, and leaves it in 

 doubt. 



Serpentine has a regular, and rather extensive stra- 

 tification, similar to the rocks of Neptunian origin ; 

 but in its structure or external appearance, it does not 

 ^gree with any. It is likewise without the remains of 

 any organic matter, which prevents it being classed 

 by direct analqgj^ with the Neptunian, and leaves it in 

 doubt. 



It would appear that Serpentine is more liable than 

 any other rock, to change its form and external cha- 

 racter, by the agency of the common elements of rain, 

 &c. &c. and in many instances the changes are visi- 

 ble, where it appears to be sheltered from the v/cather, 

 as its mutation into every species of asbestus, amian- 

 thus, and all the variety of fibrous rocks of the mag- 

 ^esian class," At a place called Bauldisscio, at the- 



