130 ON THE FLEXURES &C. OF ROCKS. 



producing complicated contortions, and more espe- 

 cially in those cases where they are limited to one 

 stratum out of many, or to one part of a mass while 

 the other appears undisturbed. Yet amidst the innu- 

 merable marks of discordant and repeated changes 

 exhibited on the surface of the earth,, all bespeaking 

 the frequent renewals of disturbances, acting also 

 perhaps through periods. of time of which we can 

 form no notion, it is not easy to imagine any change 

 in the forms of flexible strata which these may not 

 have produced. This is not the only case in geology 

 in which we must be content to admit of varying 

 effects from a varying cause ; without thinking it 

 necessary to reject the general principle, merely 

 because we cannot apply it to every minute particular 

 which is included in them. 



