LECTURE X. 277 



geologists^ in opposition to my opinion^ ascribe even tlie dilu- 

 vium to still acting forces. Reference lias been made to pre- 

 sent agents^ only in another form than mine ; the origin of the 

 sandbank of Moulin-Quignon has been ascribed either to the 

 action of floating iceblocks stranded in the Somme creeks, or 

 to the various level-changes of the general mass of the conti- 

 nent. It does not seem to me justifiable to assume such grand 

 phenomena for the explanation of such small efiects, but I 

 must be permitted to observe^ that, if the sandbank of Moulin- 

 Quignon really owes its origin to either of these two different 

 phenomena, it manifestly does not, in my opinion, belong to 

 the real diluvium. 



" It is equally manifest that if this same sandbank of Moulin- 

 Quignon is the product of a mixture of the elements of the grey 

 and the red diluvium, it cannot belong to the grey diluvium, 

 which is the proper alpine diluvium, and which, I agree with 

 Cuvier in considering as corresponding to the extinction of the 

 fossil elephant and as preceding the apparition of man, 



"Attempts have, nevertheless, been made to prove that I 

 am wrong in distinguishing the gravel of Moulin-Quignon, as 

 well as many other deposits of flint, sand, and loam upon the 

 platforms of Picardy, from the Alpine diluvium, and my views 

 have been criticised because I very simply had recourse for the 

 formation of these deposits to thunderstorms, frost and snow 

 as the acting causes. I shaU oppose to these critics a few 

 ciphers. 



" 1 . The sandbank of Moulin-Quignon lies, according to Bou- 

 cher de Perthes, thirty meters above the level of the Somme, 

 near AbbeviUe, consequently thirty-nine meters above the level 

 of the sea. At a distance of less than two kilometers there are 

 spots which, according to the map, have an elevation of sixty- 

 one, sixty-three, and sixty-seven meters ; at a distance of less 

 than three kilometers there is one spot eighty meters, and at 

 five kilometers are spots one hundred meters high. Taking 

 into consideration the difference of elevation in proportion to 

 distance, it will be found that the declivities from these points 

 towards the sandbank of Moulin-Quignon all exceed the hun- 

 dredth or 0, b4' 22", 58, that is to say that this fall is ten times 



