GLACIAL EROSION AND TRANSPORTATION. 255 



M. E. Collomb has made some interesting calculations 

 . . . based upon the observations of MM. Dolfus and Desor on 

 the Aar Glacier in 1844 and 1854. These glacialists found 

 that the amount of water discharged from this glacier between 

 the 2uth of July and 4th of August averaged 1,278,738 cubic 

 metres daily — the minimum being 780,000 cubic metres, and 

 the maximum 2,100,000 cubic metres. The area occupied by 

 the glacier is estimated at fifty-two square kilometres. Now, 

 supposing that the old glacier of the Rhone (the area of which 

 M. Collomb estimated at 15,000 square kilometres, but which 

 is actually under the truth) discharged its water at the same 

 rate, it must have yielded a daily supply of 605,000.000 

 cubic metres. But if it be true, as all the facts would lead us 

 to believe, that in the summers of the Glacial period more heat 

 was received directly from the sun, then the daily discharge 

 from such a glacier must have been greatly in excess of that 

 amount. 



. . . MM. Dolfus and Desor found that a litre of water 

 from the Aar Glacier contained 0*142 gramme of fine mud ; so 

 that, according to Collomb's estimate of the area and daily dis- 

 charge of the ancient Rhone Glacier, the wate^ escaping from 

 the latter must in summer time have transported 86,000,000 

 kilogrammes, or about 8,50C tons (English) per diem — an esti- 

 mate which, considering the circumstances already referred to, 

 is probably much under the actual truth. 



According to Helland, the quantity of mud in the rivers 

 that issue from the glaciers of Greenland is very variable, as 

 may be seen from the table given by him, which is as follows : 



River of the glacier of Jakobahavn July 9, 1875 



Alangordlek " 10, 



Uardlek " 17, 



Tuaparsuit. . . . August 6, 



Umiatorfik " 20, 



Assakak " 21, 



Rangerdlugssuak " 11, 



Grammes of 

 mud in 1 cubic metre 

 of water. 

 104 



u 



(( 



a 



U 



u 



u 



M 



(( 



II 



u 



(1 



(1 



2,374 

 723 



678 



75 



208 



278 



Similar observations by the same geologist on the water 

 issuing from the snow and ice-field of Justed alsbraeen likewise 



