i6 



GLACIERS OF THE CANADIAN ROCKIES AND SELKIRKS. 



amount is in excess of the normal, although it may fall below for some particular 

 year of the series. This damp phase of the cycle is followed by a series of 

 years during which the total amount of precipitated moisture is less than the 

 normal for this number of years, although it may be in excess for some 

 particular year. Based upon the meteorological data from 321 stations 

 distributed over Europe, Asia, Africa, Australia, North and South America, 

 Bruckner discovered the length of the cycle to be 35.5 years, 1 the 

 dry phase averaging slightly longer than the damp one. At neighboring 

 stations the cycles may partially overlap and, in the case of coast regions, the 

 phases may be completely reversed, as recognized by Bruckner. Coincident 

 with the damp phase there is a general reduction in temperature, an increase 

 in the level of lakes and rivers, a rise in the ground-water level, a halting or 

 advance of the front of glaciers. The following table shows at a glance such 

 data as are available along these lines, compiled from publications of Heim, 

 Richter, Bruckner, and Hess. The glacial data refer mainly to the Alpine 

 region. Constructed for any particular region the figures would necessarily 

 differ more or less from those given. So far as the United States is concerned 

 the dry phase through which we have just passed appears to have closed and 

 we are entering upon another series of damp years. In the Canadian region 

 under study the damp phase seems to have started about three or four years 

 earlier than in the Great Lake region and the preceding dry phase about as long 



before. 



TABLE III. 



PERIODIC OSCILLATIONS OF CLIMATE, WITH THEIR EFFECTS UPON LAKE LEVELS 



AND ALPINE GLACIERS. 



Klima-Schwankungen sett 1700, Edward Bruckner, Wien, 1890, pp. 133-193. 



