2 2 2 PREHISTORIC E UROPE. 



spherical form. It is trie same, M. de Cossigny remarks, 

 with the smaller fragments. Sharp splinters abound, and 

 even the most minute debris is made up of little flakes and 

 splinters, pointed and cutting. These fragments, he has no 

 doubt, have been derived from the breaking and flaking of the 

 larger flints, and as they are never reduced to the state of 

 sand, he is of opinion that they cannot owe their origin to the 

 action of impetuous torrents of water. The clay is not exactly 

 plastic, but dry, and rather hard than unctuous to the touch. 

 M. de Cossigny thinks it has been deposited in the interstices 

 between the stones by the muddy water derived from the wash 

 of strata, the demolition of which supplied the flints. He is of 

 opinion that the accumulation cannot possibly be the result of 

 torrents, currents, or the waves of the sea, and he likewise 

 shows that it cannot owe its origin to chemical action, after the 

 manner of the " pipes," which are so frequent a phenomenon in 

 Cretaceous regions, and which, as Mr. Prestwich and others have 

 shown, are due to the percolation of acid water dissolving the 

 chalk, and thus forming pipes and funnels into which the over- 

 lying sand, gravel, etc., gradually sink. Eejecting these and 

 other explanations, M. de Cossigny has not hesitated to suggest 

 that the phenomena of the clay with flints may be the result of 

 glacial action — that it may be the moraine profonde which col- 

 lected between the ice and the superjacent rocks all the material 

 produced by the grinding of the glacier — the clay that envel- 

 opes the shattered stones being perhaps no other than a ooue 

 glaciaire. He points out that the appearances presented by 

 the clay with flints are just such as would result from the action 

 of a glacier, and that the absence of striae from the flints is not 

 any real objection to this view. All the circumstances were 

 unfavourable for striation, — the homogeneity and equal hardness 

 of all the stones which came into contact, their tendency to 

 give way or flake immediately under pressure, their surfaces 

 often rough and irregular with concavities and knobs that were 

 obstacles to slipping. M. de Cossigny enters into further 

 details to show that all the physical features presented by 



