34 



PEOF. E. HULL, ON GENEVA AND CHAMOUNIX 



stillness which characterize the Alpine climate in winter to the 

 present day, these fogs rested upon the belt of everlasting snow 

 above the forest line, fed it, kept it much broader than it is now, 

 and brought it down much nearer to the forest edge. The quantity 

 of snow-ice thus accumulated during those distant ages was bound 

 to diminish in a ratio proportionate to the reduction of the ancient 

 forest area. What produces glacier-ice is an accumulation of 

 moisture in an atmosphere which is below freezing-point. 



Page 23. Glaciers move at a quicker rate in summer because 

 their reaches are then more uniformly subjected to a temperature 

 above freezing-point of the air. That increase of speed appears to 

 be in exact proportion to the shrinkage, and corresponds to a release 

 from pressure all over the mass, a consequence of the melting 

 process (both static and mechanical), non-existent in winter. Any 

 deep sub-glacial melting which may take place in winter is im- 

 mediately cancelled, as a mechanical agent, by re-freezing on 

 reaching the air. 



Page 24. Leaving aside the universal geological agents, it is clear 

 that the shrinkage and growth of glaciers in the Alps is partly the 

 result of man's interference with nature. The observations of 

 M. Vallot, as to the probable speed of glacier shrinkage within 

 historical times, have, for a complement, similar conclusions as to 

 the rapidity of glacier growth. In illustration of this oscillation 

 we have the local tradition, for instance, as to the Theodul pass 

 from Zermatt into Italy. The people say it was open to horse 

 traffic 1,300 years ago. That it had long ceased to be thus open 

 was so evident that the contrary statement became incredible. 

 But, this year, the pendulum has so far swung back, that mules 

 have been led across the iced watershed with success. 



I assign that swinging of the pendulum entirely to the action of 

 man. The Alps entered within the area of civilization in the 

 times of Julius Caesar, 58 B.C. Switzerland was then, from times 

 immemorial, a forest land. A process of systematic deforestatioii 

 began and developed during 500 years. 



The climate, from a comparatively damp climate, became 

 a comparatively dry climate, and as the process progressed, its 

 ratio of effectiveness grew naturally at a much quicker pace. The 

 glacier world shrank enormously, and Italy was laid open to the 

 incursions of northerners. These northerners destroyed civilization 

 in the Alps and elsewhere, as we all know (from the Channel, from 

 the Danube, from the lihine, to the Mediterranean). From A.D. 500 

 to A.D. 800 or 900, an enormous spontaneous re-afibrestation of the 

 Alps took place, in the absence of man, in the absence of all commerce 

 and industry. The glacier world re-gaiu'^l the lost ground, and 

 most of the passes were closed up again. The economic history of 

 the Swiss peo])le makes its influence felt next. 



From the fifteenth century, they drove back, unceasingly, the 



