534 TRANS. OF THE ACAD. OF SCIENCE. 



occasional blossoms through a thin covering of snow. In 

 these few observations was mainly comprised all the definite 

 information derived from my first visit to the snowy range 

 at its lower slopes. 



Subsequently, however, as practice improved my climbing 

 abilities, and I was enabled to scale the highest summits and 

 look down on snow fields, and ice-girt lakes, the question 

 came up: Where is the snow line? At what determinate 

 line do the regular winter-snows increase beyond the power 

 of the succeeding summer's sun to dissolve, thus leaving a 

 constantly-accumulating mass to give origin to glaciers? In 

 pursuing this investigation I climbed repeatedly to the high- 

 est summits within reach, attaining elevations of 13,000 to 

 14,000 feet above the sea. Still the same general features 

 were observable, vegetation, indeed, becoming scant, but never 

 entirely wanting, even at the highest elevations ; no perma- 

 nent snow deposits of which it could be said that they must 

 necessarily increase from year to year. The fact of the 

 largest bodies of snow being met with in depressions, which, 

 when filled up to a certain point, remained nearly stationary, 

 and did not accumulate by drifting more than the average 

 heat of summer could dissolve — the entire absence of any- 

 thing like glacier phenomena — soon satisfied my mind that 

 the true "snowline" as understood in European countries 

 was not reached, at least in this particular region. 



Being thus fairly divested of all preconceived notions, I 

 was in a proper frame of mind to apply the facts at hand to 

 account for the phenomena to be explained. And now came 

 up distinctly the problem, to explain the persistence of snow 

 through the warm summer months, in this mountain district, 

 lying below the true snow line. Here, then, note first, an 

 uneven surface, variously exposed to the direct action of the 

 sun's rays, on which there is an average annual precipitation 

 in the form of winter snow, which, it regularly spread over 

 the entire surface of the ground, would disappear in the warm 

 season sufficiently early to allow the maturing of its ordinary 

 vegetation ; but owing to the surface irregularities it cannot 

 be thus evenly spread, and furthermore, the light character of 

 this alpine snow renders it peculiarly liable to be acted on 

 by the fierce winds sweeping over these open wastes, driving 

 into sheltered hollows, and piling the wintry product in huge 

 drifts, especially abundant in the upper valleys. 



As a direct consequence of these conditions we find snow 

 accumulated in all the natural recesses, while the more ex- 

 posed peaks and ridges are comparatively but thinly covered ; 

 hence, when the lengthening days and the more direct rays 

 of the summer sun exert their melting power on these wastes 

 of wintry snow, the thinner portions yield first to its influ- 

 ence, and as the protruding rocks and exposed darkened 



