DISLOCATIONS OF STRATA. 97 



depths; on the contrary, the very nature and multi- 

 plicity of their disturbances, argue, not only for their 

 own limited extent, but show how similar causes may 

 have equally limited the subterrene extent of strata 

 in other places, where, either the appearances are not 

 so obvious, or hare not been so perfectly investi- 

 gated. 



It is not unusual to meet with a long succession of 

 alternating strata, following each other with a com- 

 mon, though variable inclination. According to the 

 rules above laid down for computing the original 

 depth of such strata, or the access which we thus gain 

 within the earth, we might conclude that we had 

 penetrated far beneath it. Yet we might here be 

 easily deceived. If it be imagined that a horizontal 

 series was elevated at different points in succession, 

 so as to preserve such a consecutive disposition as 

 may aptly be represented by the teeth of a saw, it is 

 plain that a very small number of original strata would 

 give rise to a great series of inclined ones, and that 

 we might form a very false conclusion respecting the 

 real nature of such a series. It is probable, from 

 some appearances occurring on the west coast of 

 Scotland and among the neighbouring islands, that 

 this is actually the case in that tract; and we are 

 thus also easily led to explain that repeated succession 

 of a very limited number of strata in consecutive 

 order, which is found among the islands in question. 



Of unconformable Strata, 



The next case of contrariety in the relative po- 

 sitions of strata, is of much greater interest; as 

 affording evidence of some of the most important 

 changes which have occurred on the surface of the 



VOL. I H 



