AND FRESH-WATER FORMATIONS. 321 



that country, in believing that there is none of that 

 mystery which was stated in the original report. 

 Under such a view it might have been an inland 

 saline lake, but it might also have been an aestuary 

 of the ocean. In either case, it is explained on the 

 principle of elevation, under the reasoning applied 

 to the Subapennine formations. 



If this explanation be thought doubtful, in that case, 

 there can be no doubt as to the instance in the Isle of 

 Wight. The vertical position of the chalk is, here, an 

 incontrovertible proof of elevation, of a partial nature, 

 posterior to its original emergence. It is the case 

 of Italy on a limited scale : and thence the conclusion 

 is, that aestuaries, as well as basins, not only must 

 have been elevated, but that one or both actually have 

 been so. 



Thus we not only prove the possibility of such 

 greater elevations as I originally suggested, but are 

 also provided with a solution for many cases ; of 

 which there may be more than this, and under many 

 varieties, yet to be discovered. The condition of 

 modern Italy proves that the relative level of the sea 

 and land are changing, even in recent times ; as its 

 antient one, already recorded, proves far greater 

 changes of the same nature. There is not merely 

 variation, but vacillation of level ; and I shall hereaf- 

 ter show that this is a common occurrence in many 

 places. Thus then might tertiary deposits, whether 

 in lakes or aestuaries, have undergone such vacillations, 

 and to great extent, in those antient times in which 

 volcanic action seems to have been more powerful 

 than it now is : and, in this way, we find the means 

 of explaining any condition of these tertiary deposits 

 that can be imagined, and among others, such, for 



VOL. i. Y 



