332 ON THE DEPOSITS CALLED TERTIARY 



marine, or fresh, or alternating, will form the more 

 interesting of the tertiary formations, separated from 

 the ocean and elevated above it. 



Marine or fresh water lakes have been drained 

 or filled ; and, in this case also, there may be al- 

 ternations. Such completed deposits may have also 

 been disturbed by volcanic elevations, thus associating 

 them to the last division.* And this is the second, and 

 only other division of the proper tertiary strata : unless 

 as we subdivide it into marine and fresh. This division 

 also is of any age, from the most remote times of the 

 emerged land to our own day : but the former is ex- 

 clusively antient. 



These comprise the more rigid tertiary formations. 

 But the association between the first class and those 

 described in the last chapter is intimate, as they may 

 not also be often distinguishable. In the mean time, 

 the cause and the facts being proved in this case, and 

 not so clearly in the other, it may be as well for the 

 present that they should be kept separate. 



The alluvial aestuaries of the present ocean, however 

 distant from the sea now, must be entirely rejected 

 and referred to the alluvia. To distinguish these, 

 there is required, in practice, that geographical tact 

 and knowledge which have distinguished leaders of 

 armievS, but rarely geologists. They seem to have 

 forgotten its necessity. In the account of Glen Roy, 

 I have given a practical illustration of that indispen- 

 sable necessity in the explanation of Geological ap- 

 pearances. 



We finally see how the facts of the last chapter, 

 bearing on the present, explain the mysteries of the 

 last revolutions of the Earth, and that they are but the 

 continuation of the former actions on which every- 



