526 Progress of Geological Science. [Nov. 



are uniformly favorable to such a theory — on the sea they are as steadily oppos- 

 ed to it ; observations of the temperature of springs in all parts of the world are 

 invited to solve this question*. 



It is now generally acknowledged, that the formation called diluvial gravel, and 

 supposed to have reference to the epoch of the deluge, is not the result of one, 

 but of many successive periods. The essays of M. Beaumont have established 

 this point beyond dispute, although it militates against opinions, but a few years 

 since held almost universally as indisputable. 



" We now connect the gravel of the plains with the elevation of the nearest 

 system of mountains ; 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 Mount Blanc, are 

 of a more recent origin than the old gravel in the tributary valleys of the Rhone. 



" 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 phsenomena of nature. 



" In retreating where we have advanced too far, there is neither compromise of 

 dignity nor loss of strength ; for in doing this, we partake but of the common for- 

 tune of every one who enters on a field of investigatio n 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 pro- 

 gress 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 one period of elevation, and become so 

 confounded with the detritus of another period, that no power on earth can sepa- 

 rate 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 discrimination ; 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 conclu- 

 sion now incontestably established — that the vast masses of diluvial gravel, scat- 

 tered almost over the surface of the earth, do not belong to one violent and tran- 

 sitory period. It was indeed a most unwarranted conclusion, when we assumed 

 the contemporaneity of all the superficial gravel on the earth. We saw the clear- 

 est traces of diluvial action, and we had, in the Mosaic history, the record of a 

 general deluge. On this double testimony it was, that we gave a unity to a vast 



* The prevailing practice of boring for water affords an easy method of ascertaining 

 the temperature of the ground of different depths, free from the dubious results of 

 mines:— thus Magnus has found from borings near Berlin, the temperature of the air 

 being 49" 1' the heat of the ground was as follows : 



at 675 feet, temperature 67.7, giving for one degree, 36.3 feet. 

 516 do. 63.9, 34.7 do. 



392 do. 62.8, 28.5 do. 



