144 PROFESSOR ANSTED, ON THE 



It would be extremely difficult to lay down the limits of this bed 

 with accuracy, although the thickness cannot be any where very great ; 

 I could not discover a single spot where the dip could be taken, but as 

 the whole seems to have undergone a change of position by disturbances 

 connected, doubtless, with the uplifting of the mountain chain, no single 

 observation of this kind, even if it were made, could possess much value 

 in the way of determining the mass of the deposit. 



On the other hand, the thickness of the Molasse, although equally 

 difficult to determine, must be enormous, and if calculated in the ordi- 

 nary way, allowing for its being repeated once or twice by faults, will still 

 appear almost incredible. Extending across the valley of Switzerland for 

 nearly five and twenty miles, and inclined often at angles varying from 

 15 to more than 50 degrees, rising sometimes into hills four thousand feet 

 above the sea-level and more than two thousand above the general level 

 of the country, we cannot escape the conclusion that it is a mass of 

 vast thickness, even after making every allowance for the effects of dis- 

 turbance. 



I am inclined, however, to think that much of this appearance of enor- 

 mous thickness is owing to the deposit having been formed on a consider- 

 able slope, and not on a horizontal or nearly horizontal plain, and that thus 

 its almost uniform inclination is not owing entirely to disturbances of 

 the substratum, but also to the circumstances of deposition. If we imagine 

 the formation to have been commenced when the level of the valley 

 of Switzerland was below that of the sea, and that sandbanks rapidly 

 formed on a shelving coast at some distance from the shore, were gradually 

 raised by successive small elevations, and afterwards when the general level 

 of the land was above that of the sea, that the elevations had gone on 

 from time to time till the present state of things was produced, we 

 should have very similar phenomena presented to view, viz. an enormous 

 mass of sandstone, appearing to possess a dip that would multiply its real 

 thickness tenfold, and ranges of hills at some distance from the former 

 coast-line. 



The main difference between the Nagelfluhe and the Molasse, consists 

 in the mechanical difference between a coarse conglomerate and a fine sand- 

 stone, but interstratified with the Molasse there occur here and there beds 



