﻿MM. SCHLAGINTWEIT ON THE ALPS. 



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earth ; of the influence of glaciers on the destruction of rocky mate- 

 rials, the formation of sand, the transport of shingle, land- and 

 mountain-slips, and the movement of great masses of debris. 



The results arrived at from the study of these and other numerous, 

 allied and subordinate subjects, connected with aqueous and atmo- 

 spheric erosive agencies, appear to be : — 1. The influence of the 

 masses of "firn " and glaciers on the Alpine streams is not confined 

 to the increase, but extends also to the various distribution of the 

 water : — 2. At a certain depth all of the larger lakes have nearly 

 constant temperatures, connected with the maximum density of the 

 water : the vertical distance of this stratum from the surface varies 

 according to the mass of the water, the form of the lake-basin, and 

 the season of the year : — 3. The velocity of the mountain streams in 

 comparison with the rivers of the plains, is not in the same mass 

 greater than their inclination, while their mass is considerably less : — 

 4. A maximum velocity in the regular course of many rivers in trans- 

 verse valleys is frequently between 7 and 1 1 Paris feet per second. 

 Their velocity, however, is at other places so considerable, that they 

 have always force sufficient to move small shingle : — 5 . The quantity 

 of matter held in suspension in glacier-brooks and all Alpine streams is 

 usually very great, and exceedingly increases their eroding power : — 

 6. By erosive action the bed of a river maybe very deeply excavated 

 in the hard rock : such channels reach their utmost development in 

 the more inclined ravines ; they remain, hovever, confined to the 

 valley-bottom, and have no important influence on the formation of the 

 ravine itself : — 7. The sudden evacuation of vast reservoirs of water 

 participates very considerably in the phsenomena of erosion and trans- 

 port of rocks. Owing to the velocity and power of these floods, it 

 results that the volume of rushing water is far surpassed by the mass 

 of rocky material washed down and deposited about at different 

 places : — 8. The formation of earthy detrital matter [Erdkrume] by 

 mechanical disintegration and chemical decomposition of rocks, pro- 

 ceeds rapidly at the highest summits. Its accumulation, however, and 

 the covering up of neighbouring flat areas, are prevented by the steep 

 declivities and the isolated situation of such points : — 9. Vegetation is 

 always highly essential for the fixing of earthy matter on the inclined 

 sides of mountains ; hence, at great heights, and in the absence of 

 the growth of grass, the occurrence of humus, even on slightly in- 

 clined spots, is but very occasional and isolated: — 10. In the Alps, 

 particularly in the case of the crystalline slate rocks, the composition 

 of the earth and its physical properties are very favourable to vege- 

 tation. Its proportion of humus is very considerable, even at great 

 altitudes: — 11. The glaciers not only aid in producing superficial 

 changes by the transport of their moraine-masses, but also by giving 

 rise to an immense quantity of fine sand, which can usually be carried 

 far away by the rivers : — and lastly, 12. That the loosening of great 

 masses of rock by the weather and water cause vast land- and moun- 

 tain-slips ; and the streams traversing the bottoms of the longitudinal 

 valleys, owing to these fan-shaped, wide-spread masses of rubbish, 

 are subject to frequent and considerable variations in their course. 



