Mh HOPKINS, ON RESEARCHES IN PHYSICAL GEOLOGY. 57 



materially fron. that which was originally given to it, by the move- 

 ment to wh,ch the formation of the principal fissures n.ust be referrll 

 The rule would probably be more applicable immediately after this 

 hrst elevation, than after the modifications in tl,e position of the 

 mass, which may possibly have been produced by subsequent ones. 



alikl'th'" ^ °^^^'-^'-V'"* '''^ ^^" "^^ parallelism, winch characterizes 

 ahke the phenomena of anticlinal lines, faults, mineral veins, &c., is to 

 be traced, according to the view we are taking of the sub ect, to the 

 ^me origm; VIZ. the formation of the tM^o great systems of fissures, 

 which have been shewn to be, under certain simple conditions the 

 necessary effects of the elevatory force to which tLy have bTe; re 

 ferred. The term para/Mi.n, therefore, when used as characterizing 

 systems of any of the above phenomena, must be equally regarded 

 as subject in its interpretation to the exceptions or modifications 

 pointed out in the last paragraph. In fact, if the extent of the mass 

 be comparatively small, and its boundary irregular, this property would 

 cease altogether to characterize the phenomena. If the elevated mass 

 be of great superficial extent, partial irregularities in its boundary will 

 have no appreciable effect on the directions of the fissures; and thou<.h 

 wo remote fissures of the same system might, in such case, (as appears 

 from the preceding paragraph), be inclined at any angle to each other 

 a..y two adjoining fissures would in general be approximately parallel 

 The law of parallelism, however, in the strict acceptation of the term 

 could only hold through the whole extent of the elevated mass in thJ 

 case above considered of a rectilinear elevation of indefinite lenoth In 

 <^he^ cases, the law must be subject .to the modifications indicated 



58. If the approximate accuracy of our assumptions be allowed 

 as applied to the crust of the globe, it appears, from our investiga: 

 tions that an elevated range characterized by continuous systems of 

 longitudinal and transverse fissures, referrible to the causes to which 

 we have been assigning such phenomena, could not be produced bv 

 successive elevations of different points, by the partial action of an 

 elevatory force. It has been shewn (Art. 46j that in such elevations 

 Vol.. VI. Part I. jj 



