Geological Society. 3 1 3 



At our former Anniversary I ventured to affirm, that our diluvial 

 gravel was probably not the result of one, but of many successive 

 periods. But what I then stated as a probable opinion, may, after the 

 Essays of M. de Beaumont, be now advanced with all the authority of 

 established truth : and among the many obligations we owe to this 

 accomplished observer, I may mention the new and instructive views 

 he has given us of the origin of the great masses of old detritus lying 

 scattered over the lower regions of the earth. We now connect the 

 gravel of the plains with the elevation of the nearest system of moun- 

 tains j we believe that the Scandinavian boulders in the North of 

 Germany are of an older date than the diluvium of the Danube ; and 

 we can prove, that the great erratic blocks, derived from the granite 

 of Mont Blanc, are of a more recent origin than the old gravel in 

 the tributary valleys of the Rhone. That these statements militate 

 against opinions, but a few years since held almost universally 

 among us, cannot be denied. But theories of diluvial gravel, like 

 all other ardent generalizations of an advancing science, must ever 

 be regarded but as shifting hypotheses to be modified by every new 

 fact, till at length they become accordant with all the phenomena of 

 nature. 



In retreating where we have advanced too far, there is neither com- 

 promise of dignity nor loss of strength ; for in doing this, we partake 

 but of the common fortune of every one who enters on a field of in- 

 vestigation like our own. All the noble generalizations of Cuvier, 

 and all the beautiful discoveries of Buckland, as far as they are the 

 results of fair induction, will ever remain unshaken by the progress of 

 discovery. It is only to theoretical opinions that my remarks have 

 any application. 



Different formations of solid rock, however elevated and contorted, 

 can never become entirely mixed together ; and the very progress of 

 degradation commonly lays bare all the elements of their structure. 

 But diluvial gravel may be shot off from the flanks of a mountain 

 chain, during a period of elevation, and become so confounded with the 

 detritus of another period, that no power on earth can separate them : 

 and every subsequent movement, whether produced by land floods or 

 any other similar cause, must continually tend still further to mingle 

 and confound them. The study of diluvial gravel is, then, not only 

 one of great interest, but of peculiar difficulty and nice discrimina- 

 tion : and in the very same deposit, we may find the remains of 

 animals which have lived during different epochs in the history of the 

 earth. 



Bearing upon this difficult question, there is, I think, one great 

 negative conclusion now incontestably established that the vast 

 masses of diluvial gravel, scattered almost over the surface of the 

 earth, do not belong to one violent and transitory period. It was in- 

 deed a most unwarranted conclusion, when we assumed the contem- 



fossils conforming both to the secondary and tertiary type. I must, however, 

 add, in justice to the author, that his observations on the changes of or- 

 ganic forms, are casually thrown out, here and there, and do not seem to form 

 any essential portion of his theory. 



N.S. Vol. 9. No. 52. April 1831. 2 S poraneity 



