The Scottish Naturalist. 253 



water being sharply defined, and retaining its position unchanged 

 for a long period of time ! However absurd this conclusion 

 may be, it is forced upon us if we admit the hypothesis at 

 present under review. For we must remember that the floating 

 ice is supposed to have melted whenever it came into contact 

 with the warm current. The erratics occur up to a certain 

 boundary-line, where they are concentrated in enormous num- 

 bers, and south of which they do not appear. Here, then, large 

 and small floes alike must have vanished at once ! Certainly a 

 very extraordinary case of dissolution. 



If we dismiss the notion of a warm ocean-current for that of 

 a warm wind, we do not improve our position a whit. Where 

 did the warm wind come from ? Not, certainly, from the ice- 

 laden seas to the east. Are we to suppose, then, that it flowed 

 in from the south or south-west ? If so, we might well ask how 

 it came to pass that in the immediate proximity of such a very 

 warm wind as the hypothesis demands, great snow-fields and 

 glaciers were allowed to exist in Wales? Passing that objection, 

 we have still to ask how this wind succeeded in melting large 

 and small masses of floating ice with such rapidity that it pre- 

 vented any of them ever trespassing south of a certain line? It 

 is obvious that it must have been an exceedingly hot wind ; and 

 that, just as the hypothetical warm ocean-current must have 

 suddenly dived under the cold water coming from the north, so 

 the hot wind, after passing over the surface of the sea until it 

 reached a certain more or less well-defined line, must have risen 

 all at once and flowed vertically upwards into the cold regions 

 above. 



Thus, in seeking to escape from what he doubtless considers 

 the erroneous and extravagant views of " land-glacialists," Mr 

 Mackintosh adopts a hypothesis which lands him in self-contra- 

 dictions and a perfect " sea of troubles " — a kind of chaos, in 

 fact. In attempting to explain the drifts of Western England 

 and East Wales, he has ignored the conditions that must have 

 obtained in contiguous regions — 'thus forgetting that " nothing 

 in the world is single," and that one ought not to infer physical 

 conditions for one limited area without stopping to inquire 

 whether these are in consonance with what is known of adjacent 

 districts, or in harmony with the existing phenomena of nature. 



I have so strongly opposed Mr Mackintosh's explanation of 

 the sudden termination of the northern erratics in the neigh- 

 bourhood of Wolverhampton and elsewhere, that perhaps I 



