72 CHARACTERS OF STRATA 



a rock of this character; a natural consequence re- 

 sulting from the mode in which these rocks were 

 formed, and often very conspicuous at the junctions 

 of the primary strata with granite. 



There is another case in which strata cease to be 

 consecutive, without being in all parts unconforrnable 

 to those on which they lie. In the usual reversal of 

 position, the upper series may be conceived to lie on 

 the elevated edges of the inferior one ; although, even 

 in such cases as this, one part of the upper series 

 may be conformable, while the other is reversed, in 

 consequence of irregularities in the position of the in- 

 ferior strata, or from the superior being so deposited 

 as, in some places, to lie on the edges, and, in 

 others, on the planes of the inferior beds. This is 

 easily understood. In the case above alluded to, an 

 effect of a contrary kind takes place ; or every stratum 

 in an upper series, touches a single bed of the lower ; 

 the edges of the former abutting against the planes of 

 the latter. It is easy to comprehend how this may 

 happen. It is a necessary consequence of the depo- 

 sition of a horizontal series upon an inclined one, 

 and occurs, as a matter of course, in the recent depo- 

 sitions of lakes that are contained in cavities among 

 the usual primary or secondary strata which are so 

 rarely horizontal. That is a simple and intelligible 

 case ; and it is here also easy to see, that, in another 

 part of such a deposit, a very mixed and uncertain 

 collision must take place among the edges of the 

 superior and the inferior strata. In nature, this 

 happens on a much greater scale, and is often a 

 source of difficulty to geologists; to whom, if impro- 

 perly viewed or reasoned on, it presents appearances 

 of disturbance which have never existed. It is a 

 necessary result in those extensive deposits which 



