ICE ACTION. 369 



been the same as now. Nor would the supposition, after all, 

 account for the phenomena. We should but fall from Scylla 

 into Charybdis. Around the blocks we see no evidence of 

 violent action ; in the section at Joinville, the grey sub-angular 

 gravel passed under the large block above-mentioned, with 

 scarcely any traces of disturbance. But a flood which could 

 bring down so great a mass would certainly have swept 

 away the comparatively light and movable gravel below. We 

 cannot, therefore, account for the phenomena by aqueous 

 action, because a flood which would deposit the sandstone 

 blocks would remove the underlying gravel, and a flood which 

 would deposit the gravel would not move the blocks. The 

 Deus ex machina has not only been called in most unne- 

 cessarily, but, when examined, turns out to be but an idol 

 after all. 



Driven, then, to seek some other explanation of the diffi- 

 culty, Mr. Prestwich falls back on that of floating ice. Here 

 we have an agency which would satisfactorily explain all the 

 difficulties of the case. The " packing" and propelling action 

 of ice would also account for some irregularities in the arrange- 

 ment of the beds, which are very difficult otherwise to under- 

 stand. Nor is it the physical evidence only which points to 

 an arctic climate during the period now under consideration ; 

 the fauna, as we have already seen, tells the same tale. 



But though the presence of the sandstone blocks and the 

 occasional contortions of the strata are in perfect accordance 

 with the view of Mr. Prestwich, that the gravels have been 

 deposited by the rivers, our second difficulty still remains 

 namely, the height at which the upper-level gravels stand 

 above the present water-line. We cannot wonder that these 

 beds have generally been attributed to violent cataclysms. 



M. Boucher de Perthes was always of this opinion. " Ce 

 coquillage," he says, " cet elephant, cette hache, ou la main 



2 B 



