THE LAST GREA T BA L TIC GLA CIER 337 



sentation to show the " unnaturalness" of my classification. 

 Such graphic representations, however, unless they are con- 

 structed on sound principles, are apt to express rather the views 

 of the draughtsman than the actual facts of nature. Dr. Keil- 

 hack's diagrams are, in my opinion, constructed on a wrong 

 principle, and were I to draw similar diagrams they would show 

 a different result. But as my critic would probably be no more 

 satisfied with my graphic representation than I am with his, I 

 prefer to give one constructed a year or two ago by an indepen- 

 dent authority — Dr. Du Pasquier, whose recent untimely death 

 every student of glacial geology must deplore. For purposes of 

 comparison Dr. Keilhack's diagrams are also given. 



Alps (Keilhack). 



I I r 



II H 1 



III. I 1 



IV I 1 



North Europe (Keilhack). 

 11^ 1 



II. I 



III. I 



IV. I ■ 1 



Alps (Du Pasquier). 



X. \ 1 



Y 1^ ^ 



Z I ^1 



z I 1 



The first thing that strikes one in comparing Dr. Keilhack's 

 representation of the Alpine glacial system with that given by 

 the eminent Swiss geologist is the discrepancy between the lines 

 representing the last three glacial stages (II, III, and IV of Keil- 

 hack ; Y, Z, Z\ of Du Pasquier) . Dr. Keilhack obtained his lines 

 by simply measuring the length of individual glaciers on the north 

 side of the central Alps, but Du Pasquier has followed a differ- 



