2 4 o PREHISTORIC EUROPE. 



water derived from the melting of that ice-sheet in Northern 

 Europe, would find its way by underground channels along the 

 natural slope of the ground into the Polar Ocean and the basins 

 of the Baltic and the North Sea. The phenomena of the till 

 have disclosed the fact that streams and torrents flowed under- 

 neath the ice, the general course of which, however much it 

 might be influenced by the obstruction of the overlying ice, 

 would nevertheless tend to follow the inclination of the ground. 

 There would thus be many large sub-glacial streams and rivers 

 running in directions quite opposed to that of the mer de glace. 

 The sub-glacial representatives of the Messen and the Dwina, 

 for example, would flow directly into the Arctic Ocean ; those 

 of the Diina, the Nieman, the Vistula, the Oder, and other 

 North German rivers, would go by way of the Baltic and the 

 North Sea, as would also those of Sweden, Southern Norway, 

 and East Britain. And thus I would infer that the water 

 escaping into North Germany from the ice-sheet, however 

 actually copious it might be, would yet be relatively small in 

 amount. It would in fact be derived chiefly from the superficial 

 melting of the ice-sheet. It is quite true that there would be 

 an abundant flow of water all over the surface which would 

 tend in the direction of the ice-flow ; but much of it we may 

 suppose would disappear in crevasses, or into such great holes 

 as Nordenskiold observed in the inland-ice of Greenland. 1 So 

 far as we know from observation, the quantity of water pouring 

 from the surface over the terminal front of the Greenland ice is 

 much less considerable than that discharged by such glacial 

 rivers as the Mary Minturn described by Kane. 2 This river 

 flows all the year round, but becomes greatly swollen in 

 summer. The superficial streams, on the other hand, are sealed 

 up at night in summer, and in winter they vanish entirely. 

 Then, again, we must remember, that the water flowing upon 

 the mer de glace would be distributed in myriads of little 



1 Geological Magazine, vol. ix. p. 360. 



2 Arctic Explorations : The Second Grinnell Expedition in Search of Sir J. 

 Franklin, vol. i. p. 97. 



