Considerations connected with the Glacier Theory. 43 



tity of rain in the Alps northwards from the termination of 

 the Adriatic Sea, exceeds several times that of any other part 

 of Europe, it will be evident on what accidental circumstances 

 such an increase may depend.* 



In conclusion, it still remains for me to discuss a subject 

 connected, in many respects, with this matter, viz. that of 

 geological periods, of which five have lately been generally 

 adopted. These I have in my Lethiia designated by the names 

 Carboniferous, Saliferous, Oolitic, Cretaceous, and Molasse (Koh- 

 len, — SalZj — Oolith, — Kreide^ — and Molasse-perioden.) This 

 Period edifice, the offspring of limited observations on con- 

 tracted surfaces, already totters in all its supports ; but, never- 

 theless, it is still necessary to sustain it and to bolster it up, as 

 the erection of a new and better one is probably not so easy, 

 and as the old one still affords us a welcome point of departure. 



The refrigeration theory of the earth does not admit the 

 assumption of an interrupted cooling by successive grada- 

 tions, or even (as Agassiz supposes) an undulation of cool- 

 ing of the whole earth by simultaneous elevations and depres- 

 sions. Thus neither refrigeration nor any other given cause 

 affords us the power of assuming sharp boundaries between 

 different periods, or of adopting the consequences which 

 are thus deduced, and especially in regard to their ani- 

 mals and plants. These undoubtedly became changed, but 

 that in a continuous and gradual manner. We must, on the 

 contrary, whatever theory of the formation of the crust of the 

 earth we may follow, admit that the Neptunian strata, which 

 we arrange into groups, formations, and periods, could not, 

 individually, have been deposited simultaneously in an unin- 

 terrupted manner, and with similar mineralogical characters 

 over the whole surface of the earth ; that rather a number of 

 local modifications in the formation of strata, caused by the 

 relations subsisting at that time between the land and water, 

 must have occurred, which were every^vhere different; that 

 there were also many strata here and there destroyed, and 

 that, consequently, no petrographical or geological character 

 available for the distinction or separation of groups of strata 

 could extend to the whole surface of the earth. Neither, there- 

 , ... 



* Sec the Pktfsikalitchcr Atlat of Berghaus. 



