HUTTONIAN THEORY. 



49 



h 



bn one fide of thejiip continue parallel to thofe 

 on the other ; in othtr cafes, the ftrata on each 



another, though 



iide become 



d to 



one 



their identity is Hill to be recognifed by th 

 poifeffing the fame thicknefs, and the fame 



ternal 



harad 



Thefe Jbifl 



are 



ften 



f 



great extent, and mufl be meafured by the quan- 

 tity of the rock moved, taken in conjundion 

 with the diftance to which it has been carried. 

 In fome inilances, a vein is formed at the plane 

 of the ftiift or flip, filled with materials of the 

 kinds which will be hereafter mentioned ; in 

 other inilances, the oppofite fides of the rock 

 remain contiguous, or have the interval between 

 them filled with foft and unconfolidated earth. 

 All thefe are the undeniable effeds of fome great 

 convulfion, which has fliaken the very founda- 

 tions of the earth ; but which, far from being a 

 diibrder in nature, is part of a regular fyflem, 

 effential to the conflitution and economy of the 

 globe. 



The produdiion of the appearances now de- 

 fcribed, belongs, without doubt, to different pe- 

 riods of time ; and, where flips interfed one ano- 

 ther, we can often diflinguifh the lefs from the 

 more ancient. They are all, however, of a 

 date poflerior to that at which the waving and 

 undulated forms of the flrata were acquired, 

 as they do not carry with them any marks of 



D 



the 



