444 Mr. De la Beche's Sketch of a Classification 



Stratified Rocks. — Group 1, {Alluvial) sQ&ms at first 

 sight natural and easily determined ; but in practice it is often 

 very difficult to say where it commences. When we take 

 into consideration the great depth of many ravines and 

 gorges which appear to originate in the cutting power of ex- 

 isting rivers, the cliffs even of the hardest rocks which more 

 or less bound any extent of coast, and the immense accumu- 

 lations of comparatively modern land, as for instance, those 

 great flats on the western side of South America, there is a 

 difficulty in referring these phtenomena to the duration of a 

 comparatively short period of time. Geologically speaking, 

 the epoch is recent; but, according to our general ideas of time, 

 it appears to be one that reaches back far beyond the dates 

 usually assigned to the present order of things. Man and 

 the monkey tribe seem to be the most marked new creation of 

 this epoch. I would by no means be supposed to deny that they 

 may not have previously existed, but at present the mass of 

 evidence is against their prior appearance. There seems, 

 indeed, no good reason why man and the monkeys should not 

 have lived as well as the bears and hytenas at periods ante- 

 cedent to this epoch ; but until the remains of the two former 

 be found in rocks proved to be formed previous to this period, 

 it cannot be affirmed that they did*. The animals now existing, 

 considered as a mass, appear to differ specifically from those 

 whose remains are found entombed in the various rocks, 

 gravels, clays, &c. formed previously to the existing order of 

 things. There are indeed a few exceptions to this observa- 

 tion, but the body of evidence seems to render a new creation 

 presumable. 



Group 2. {Diluvial) QomT^v'ises those gravels so commonly oc- 

 curring in situations where actual causes could not have placed 

 them, but where, on the contrary, such causes tend to destroy 

 them. The most extraordinary feature of this group is the 

 distribution of those enormous blocks or boulders found so 

 singularly perched on mountains, or scattered over plains far 

 distant from the rocks from whence they appear to have been 

 broken. Many valleys appear to have been scooped out of 

 horizontal or nearly horizontal strata at this epoch ; the force 

 which excavated them having acted often upon strata shat- 



* Should such observations as those lately made on the caverns of the 

 department of the Gard by M. dc Christol {Annah's des Alinc.t 1829) be 

 multiplied, and should it be always shown that human bones and pottery 

 are, as is stated to be the case, in these caverns, really of the same date as 

 the hya;na's bones, dung, &c. with which they are mixed, — we can scarcely 

 refuse to admit that man existed previous to the alluvial epoch; sup- 

 posing it in all cases proved that these cavern remains are of the same date 

 as those considered of the diluvial period. 



lered 



