330 CLIMATIC CONDITIONS OF THE GLACIAL EPOCH. 



extraordinary diminution in their size ; with some of them it is not only 

 retreat, it is catastrophe. The amazing reduction of the high ice-mark calls 

 for special observation. What is the cause of it? Whether, as Mr. Stephen 

 suggests, the glaciers are indignant at the increased rush of tourists, and 

 retire sulkily into their hidden fortresses, or whether the enormous reduction 

 in the acreage of Alpine forests causes a drier atmosphere, and consequently 

 a diminished snow-fall, I shall leave for you to determine."* 



The diminution or increase in thickness of any glacier during a given 

 period is much less easily determined than any corresponding change in its 

 length. M. Fayot stated that up to 1876 the average diminution of the 

 Chamouni y-laciers in leno-th was about 1.000 meters, and in thickness about 

 100 meters. 



The glaciers of the Bernese Oberland appear to have begun their decrease 

 later than those of Mont Blanc, as did also the glacier of the Rhone, which is 

 said by C. Dufour to have commenced its recession about 1855 or 1856.1 As 

 far as known to the present writer, up to the end of last year the recession 

 had become imiversal throughout the Alps, and there were nowhere decided 

 indications of a change to an advance. 



That the recession of the glaciers is not confined to the Alps, but is also 

 most decidedly manifested in both the Pyrenees and the Caucasus, is a state- 

 ment in regard to which the evidence, although not as full as in the case of 

 the Alps, is sufficiently convincing. In reference to the Pyrenees, M. Trutat, 

 a member of the French Alpine Club, writes as follows : " In 1809, Charpen- 

 tier measured the elevation above the sea-level of the foot of the Maladetta 

 glacier, and found it to be 2,286 meters. In 1876, I repeated this measure- 

 ment, and found the terminus of the ice to be at the elevation of 2,550 

 meters, thus proving the fact of the recession of the glacier amounting to 

 a vertical distance of 274 meters in sixty-seven years." $ 



M. Trutat adds to this observation the following remai'ks : '• Pour ma 

 part, depuis que j'explore les Pyrenees, je vols, pour ainsi dire, les glaciers 

 fondre sous nies yeux, et dans la vallee du Lys, et dans la region de I'Oo le 

 retrait est effrayant.''^ 



* Journal of tlie Alpine Club, Vol. X. ji. 260. 



t liulletiu lie la Societe Vaudoise (les Sciences NatuivUes, Serie 2, Tome XVII. pp. 4'2'2- 425. 



t Annuaire du Club Alpin Fran^ais, Annee Troisieme, p. 483. 



§ Professor C. Dufour says, after speaking of "the general retrograde movement which has become the rule in 

 all the Alpine regions : " " In 1878, at the Scientific Congress in Paris, 1 had the opi>ortuuity of conversing on this 

 subject with several French sivan/x, and learned from them that the glaciers of the Pyrenees were in the same 



