Ill 



distinguish strata from the pseudo-strata, or 

 already mentioned. In these, recourse must be 

 had to those characters on which the distinction 

 was originally founded, which are the follow- 

 ing. 



In some places the pseudo-strata pass into the 

 irregular masses which they generally accompany ; 

 or else they become irregular in some part. This 

 occurrence does not take place among real strata, 

 except in the solitary instance of limestone, else- 

 where mentioned, where the presence of organic 

 remains is a sufficient criterion of the stratified 

 nature of the rock. 



Pseudo-strata do not maintain an invariable 

 parallelism to the real strata which they accom- 

 pany. When above, they meet them obliquely ; 

 or the base of the pseudo-stratum is in contact with 

 different strata of the inferior series. When in- 

 termixed, they either present similar irregularities, 

 or, being parallel in one place, they intersect in 

 another. 



Veins are found to proceed from pseudo-strata 

 as they do from irregular masses, and to penetrate 

 the adjoining strata. No veins proceed from real 



