GEOLOGICAL TOPICS. 



371 



these flints, all worked in the same manner, although for different purposes. 

 " Eor the most part there is a general resemblance of form, which is ordinarily a 

 flat oval, of which the upper part or thick end is smooth, remaining in its 

 primitive state, while the sides and point are sufficiently sharp to have permited 

 their use without recourse having been liad to grinding. 



"Others resemble a dagger (poignard) ; and some have the form of a triangular 

 pyramid, of which the fastenings (aretes) are very irregularly hollowed out by 

 the conchoidal chippings of the flint. The figures we have given will convey the 

 form of these productions of so remote an age ; their medium size is ten or twelve 

 centimetres in their greatest diameter. There are others in wliich this dimension 

 is only eight centimetres, and some in which it is twenty-four centimetres. 



" When one has seen some of these stones, they can be recognized immediately 

 as belonging to the diluvium. Those which M. Boucher de Perthes has found 

 in the same deposit at Abbeville have a like form and are worked in the same 

 manner. I could not say what has been their use ; and on this subject every 

 hypothesis ought to be carefully excluded, and we should content ourselves 

 with stating the facts in all their simplicity." 



M. E. de Marsy also published a work on this subject entitled "Kapport 

 sur I'ouvrage de M. Boucher de Perthes ayant pour titre, 'Des Monuments 

 Celtiques et Antediluviens' " (12mo., 1855). 



M. de Perthes now devotes a chapter of his book to " the erratic blocks, 

 flints, and animal debris transported by ice." 



" This may at first appear foreign," he says, " to the subject of this book, 

 but one wiR soon see why I insert it, and how transportation by ice has con- 

 tributed to the formation of some deposits, and consequently to the com- 

 mingling of obj ects brought from many and often distant points. Hence one ought 

 not to be astonished at finding in the diluvium debris of various origins, or 

 bones of animals which have not inhabited the same lands, and even of the 

 arms, signs, and instruments of stone worked by men who lived perhaps in 

 very different countries. 



" How the ice has been able to transport the boulders, the bones, and the dif- 

 ferent detritus which compose these tertiary layers and analogous deposits 

 I will now try to explain by the ideas which struck me for the first time 

 when 1 traversed the glaciers of the Alps, and since when I have seen on the 

 peaks of the Pyrenees, on Etna, and other mountains those masses of snow of 

 which the origin is lost in the night of Time, for if the superficial layers melt 

 and are renewed, the snow beds below remain always the same. In what 

 mamier, then, were those first snow beds formed ? Why have they not 

 amiually disappeared like those which have followed them ? 



"It may be thought that at different epochs there have succeeded 

 without interruption, during periods of more or less duration, violent 

 storms of snow, of which the consolidated masses have at certain points over- 

 topped the trees, filled up valleys, and enshrouded mountains, the earth for 

 a great part of its surface presenting an immense plain over which there 

 reigned but one season — winter. 



" This snow has consolidated and maintained itself throughout a vast period 

 of time ; at this hour even it has not entirely disappeared, we see its remnants 

 in our glaciers. 



" It was the melting of the snow of the plain and on the slopes of the moun- 

 tains which produced a last deluge. But before this deluge swept the earth, 

 it is possible that entire families, especially of the herbivora — deprived of food, 

 since it was buried under ihat icy sheet — had been annihilated ; or if they were 

 not suddenly destroyed, the alteration of climate would have arrested their re- 

 production. One can comprehend that from this snowfall, and from its con- 

 tinuancCj there would have resulted a great refrigeration of the atmosphere 



