92 HOBBS— CHARACTERISTICS OF THE [April 22, 



The position of a surface moraine which stretches in a sweeping 

 arc from the lower edge of one of Dalager's Nunataks to a similar 

 point upon its neighbor, indicates a complete parallel between the 

 motion of the ice and the water at the Neu-Haufen dyke, the rock 

 debris of the deeper ice layers being here brought up to the surface. 

 Study of the Scandinavian inland-ice of late Pleistocene times 

 throws additional light upon the nature of this process. Flowing 

 from a central boss near the head of the Gulf of Bothnia, the 

 ice pushed westward and escaped through narrow portals in the 

 escarpment which now follows the international boundary of 

 Sweden and Norway. This constriction of its current has been 

 appealed to by Suess to account for the interesting glint lakes 

 which to-day lie across this barrier and extend both above and 

 below the former outlets of the ice.*^ Lakes which have this origin 

 he has described under the term scape colks. Perhaps if examined 

 more carefully we should find that the bringing up of the englacial 

 debris to the surface of the ice, is only partially due to the inertia 

 of motion in the ice. With the more rapid flow of the ice within 

 the constricted portion, the basic portions, shod as they are with 

 rock fragments, accomplish excessive abrasion upon the rock bed. 

 This is in accord with Penck's law of adjusted cross sections in 

 glacial erosion. Where the ice channel broadens below the nunataks, 

 the abrasion again becomes normal so that a wall develops at this 

 place in the course of the stream. 



Here, therefore, a new process comes into play due to the 

 peculiar properties of the plastic ice, a process which has been illus- 

 trated in the formation of drumlins beneath former continental 

 glaciers, and has been given an experimental verification. Case 

 has shown that parafiin mixed with proper proportions of refined 

 petroleum, and maintained at suitable temperatures, can be forced 

 by means of plungers*** through narrow boxes open at both ends. 

 It was shown in the experiments that an obstruction interposed at 

 the bottom and in the path of the moving paraffin, forced the 

 bottom layers upward, and this upward movement continued beyond 



" Suess, /. c, pp. Z37-3A6- 



*^ E. C. Case, " Experiments in Ice Motion," Jour. Geo!., Vol. 3, 1895, pp. 

 918-934. 



