120 HOBBS— CHARACTERISTICS OF THE [April 22, 



glacier tongue would open an outlet for this lake to the sea at a still 

 lower level. Souvenirs of these events would be left in a series of 

 parallel shore lines ascending in step-like succession to the head of 

 the fjord (see Fig. 39). Suess has used this illustration to solve the 



5ea Level. 



Fig. 39. Diagram showing arrangement of shore lines from marginal 

 lakes to the northward of the Frederikshaab ice tongue, if its front should 

 retire past the outlet of the lower lake. 



vexed problem of the scter, the abandoned shore lines of Norway 

 which have this peculiarity of arrangement. ^°* 



The famous " parallel roads " of glens Roy, Glaster and Speen 

 in the Scottish Highlands, which have in similar manner vexed 

 geologists but which were finally given a satisfactory explanation 

 by Jamieson,^°^ find here a living model. Still later a nearly identical 

 example from Pleistocene times has been supplied from the Green 

 Mountains to the eastward of Lake Champlain."*^ 



About the Cornell tongue of the inland-ice of Greenland are 

 many marginal lakes situated where the border drainage has been 

 blocked by the glacier itself. These lakes have been described by 

 Tarr, who says •.^"'^ 



In its passage down the valley, betw^een the ice and the land, the 

 marginal stream finally enters the sea. During its passage it now and then 

 encounters tongues of ice, and for a distance flows along them, and finally 

 beneath them, where the glacier edge rests against a moraine, or the rock 

 of the land. Again it falls over a rock ledge as a cascade, or even a grand 

 waterfall ; and every here and there it is dammed to form a marginal lake. 



^"^ Besides the Jakobshavn ice tongue, there is another lake confined in 

 like manner to the Tasersuak. (Ed. Suess, "The Face of the Earth," Vol. 

 2, pp. 346-363.) 



^"^ Thomas T. Jamieson, On the parallel roads of Glen Roy and their place 

 in the history of the glacial period. Quart. Jour. Gcol. Soc, Vol. 19, 1863. 

 pp. 235-259. 



^"^ Because here the ice similarly blocked the natural outlet. 



"" R. S. Tarr, " The Margin of the Cornell Glacier," Am. GcoL, Vol. 20, 

 1897, pp. 150-151. 



