70 PROCEEDINGS OF THE ACADEMY OF [IS88. 



same region to lie at a general elevation of 8-9800 feet, above 

 which storms were of only exceptional occurrence, and the atmos- 

 phere usually clear and serene. These observations as to feeble 

 precipitation were further confirmed by Dollfuss, who found that 

 on the Theodule Pass (10,800 feet) the total precipitation for the 

 six winter months amounted to onl}^ 7^ feet of snow. On the St. 

 Gothard, on the other hand, at an elevation almost exactly 4000 

 feet lower, nearly the same quantity fell in a single day. Agnin, 

 on the Grimsel (G150 feet) Agassiz found the winter snow-fall to 

 amount to 57^ feet. While, therefore, the highest Alpine summits 

 generall}' appear to be buried in an almost unfathomable thickness 

 of snow, there can be but little doubt that in actual fact this thick- 

 ness is but very moderate. This is proved by the circumstance 

 that under exceptional conditions the snow covering may almost 

 completely disappear as a result of a single season's melting. Thus 

 in September, 1842, the Ewigschneehorn was completel}^ dismantled 

 of its cap, and in 1860-1862 a whole series of the usually snow- 

 clad peaks showed only patches of snow. During the same period 

 the Stralech (11,000) feet could be crossed without the traveler 

 encountering a single patch of either hard or Soft snow (Reclus). 

 With these facts before us, we have good grounds for doubting 

 whether any extraordinary accumulation of snow, unless with a 

 much warmer climate, could take place in the region of the far 

 north (with a descending cloud line) on elevations of very great 

 magnitude. Granting, however, the possibility of a huge polar 

 glacier tending southward, some singular facts are brought out by 

 a calculation of its rate of progression. Allowing an average 

 rate of one foot per day. which is about that of the average Alpine 

 gl.'icier, it would necessitate for a glacier starting from about the 

 sixty-fifth parallel of latitude a period of no less than 25,000 years 

 for it to have reached the line of its terminal extension, the terminal 

 moraine. But with such an infinitesimal slope as such a glacier 

 must neoessarily have had, it ma}' be questioned whether its rate 

 of progression would have been more than one-fifth or even one- 

 tenth of that which has been here given it. At the average rate 

 of two and one-half inches daily, 125,000 years would have been 

 reqtiired for its southerly' progression, a period that would neavl}' 

 tide over the interval between the periods of greatest eccentricity 

 indicated by astronomers. 



Professor Lewis remarked that arguments drawn from meteoro- 

 logical conditions as they now exist will not in all cases applj' in 

 considering the glacial epoch. The distribution of land and water 

 was so different in glacial times that meteorological conditions 

 must also have been different. He instanced facts which he had 

 observed in the valley of the Delaware and elsewhere, indicating 

 a depression south of the glaciated area, which produced a greater 

 water surface in the glacial epoch, and therefore dirterent meteoro- 

 lo"ical conditions. He remarked also that it was uiisafe to found 

 arguments upon any close analogy between the conditions of local 



