260 THE FOREST LANDS OF FINLAND. 



of the water having been much greater formerly than it is 

 now ; and greater depth in such cases implies greater velo- 

 city ; and greater velocity implies greater power. From 

 what the flow now is, carrying off only the drainage of the 

 rainfall in the higher lying basin, we may imagine what it 

 must have been, when it was carrying off the meltings under 

 an elevated temperature of glaciers formed of the accu- 

 mulated snows of the glacial period. 



Marine engineers employed in the construction of break- 

 waters and like undertakings have made us acquainted 

 with the fact of stones tons in weight being displaced and 

 tossed about by the waves during a storm. Here such 

 masses must have been moved by the river's flow ; and 

 from this we may again imagine what must have been 

 the mass of waters pouring down from the melting 

 glaciers, and this not by a steady, constant flow, but alter- 

 nating with this at times another phenomenon of glacial 

 action. 



There is a phenomenon well known in Alpine regions : 

 the debdcle, or outburst of water resulting from the melting 

 of snow pent up in some secondary valley, to which free 

 passage has been suddenly given by the melting of the 

 icy barrier. A characteristic example is one furnished by 

 the glacier of Gietroz. 



At the bottom of the valley of Bagnes, one of the 

 branches of the Drause, at sixteen kilometres, or about 

 twelve miles from Chadles, there rises vertically a high 

 wall of rocks surmounted by the glacier of Gietroz. The 

 moving mass protrudes itself, projects beyond the support, 

 and falls at the foot of the precipice ; the broken fragments 

 congeal anew and form a cone-shaped glacier, which pushes 

 before it its moraines. What ensues must be given in 

 the narrative of Guide Joanne : ' In those years in which 

 avalanches are very frequent the heat of summer does not 

 suffice to melt a quantity of ice equal to what the moun- 

 tains cast down. The enormous block which then forms 

 a bridge on the Drause becomes always larger and larger, 



