GLACIERS. 



walks in safety over a surface nearly uni- 

 form, and not so perfectly polished as 

 that of ponds and rivers suddenly and 

 violently frozen. The absence of trans- 

 parency, the various marks of air bub- 

 bles, and the general roughness, so per- 

 fectly resemble the congelation of snow, 

 when half restored to fluidity, that M. de 

 Saussure was immediately led to form the 

 following probable theory of the forma- 

 tion of the glaciers. 



Snow is constantly accumulating in the 

 recesses or depths of the mountains, dur- 

 ing nine months of the year, by the usual 

 fall of moisture, and the descent of vast 

 masses borne down by their weight from 

 the precipices and crags above. Part of 

 this is necessarily reduced to water by 

 slight thaws and casual rains, and being 

 frozen in this state, the glacier is com- 

 posed of a porous opaque ice. 



The upper glaciers, Mr. Coxe subdi- 

 vides into those which cover the sum- 

 mits, and those which extend along the 

 sides of the Alps ; the former originate 

 from the snow frequently falling, and con- 

 gealing into a firm body, though not be- 

 coming actual ice, which the brilliancy 

 of the projections has induced some phi- 

 losophers to suppose it. M. de Saussure, 

 having /explored Mont Blanc, ascertained 

 that me top was encrusted with ice, 

 \vhich might be penetrated by a stick, 

 covering a mass of snow on the declivi- 

 ties, so chilled and dry as to be incapable 

 of coherence. 



The sides of the Alps support a conge- 

 lation of half dissolved snow, which is 

 different from the pure snow of the sum- 

 mits and the ice of the lower glaciers. 

 Two causes operate to produce this ef- 

 fect ; the first is the descent of water 

 from the higher regions, where a dissolu- 

 tion of the snow sometimes occurs ; and 

 the second arises from the more favoura- 

 ble situatian of these parts for reflecting 

 the rays of the sun, and the consequent 

 melting of the snow. From hence down- 

 wards the ice adhering to the cavities 

 becomes gradually more solid by the 

 freezing of the snow-water, then nearly 

 divested of that air, which in the less dis- 

 solved portions renders the ice, formed 

 from it, porous, opaque,and full of bubbles. 

 Considerable difference of opinion has 

 prevailed amongst philosophers, whether 

 the masses of ice and snow in these 

 regions of endless winter increase, de- 

 crease, or remain nearly stationary ; Mr. 

 Coxe seems inclined to think they vary in 

 their size ; that gentleman observes, that 

 the glacier of Montanvert is generally 



bordered with trees ; near the base of this 

 vast body of frozen matter the ice is ex- 

 cavated into an arch,perhaps one hundred 

 feet in height, whence the Arveron rushes 

 with impetuosity and in a large sheet of 

 water. As he approached the ice he 

 passed through a forest of firs, those 

 near the arch were very ancient and about 

 eighty feet high, the trees between them 

 and the glacier were evidently younger, 

 from the inferiority of their size and 

 other intrinsic marks ; others, still less, 

 had been enveloped by the ice, and many 

 were thrown down ; arguing from this 

 gradation in the appearance of the firs, 

 he concludes that the glacier has origi- 

 nally extended to the full grown ancient 

 trees, and, dissolving, 'young ones have 

 grown on its former site, which have 

 been overturned by a fresh increase of 

 ice. 



Thisinference seems almost conclusive, 

 but it is still further supported by the fall 

 of large pieces of granite, called moraine 

 by the inhabitants, which, borne along by 

 the ice,sinks through it as it dissolves, and, 

 falling into the plain, form a border along 

 its extremity ; those have been urged 

 forward by the pressure of new ice, and 

 extend even to the place occupied by the 

 large firs. 



Exclusive of these circumstances, Mr. 

 Coxe discovered, that the glacier of Grin- 

 delwald had diminished, at least, 400 

 paces between the dates of his two visits 

 in 1776 and 1785 ; and in the valley ,of 

 Chamouny, the Muraille de Glace, which 

 he had described as forming the border 

 of the glacier of Bosson, in 1776, no long- 

 er existed in 1785, and young trees had 

 grown on the site of the edge of the 

 glacier of Montanvert. 



In opposition to the evidence thus ad- 

 duced, it is argued that the operations ob- 

 servable in the vallies, arising from the 

 concentration of solar heat, form no data 

 for judging of those on more elevated 

 situations, where, it is asserted, a greater 

 quantity of snow falls and becomes ice 

 than can possibly be dissolved annually ; 

 and experience proves, beyond doubt, 

 that mountains have been covered, pas- 

 sages obstructed, pastures and habita- 

 tions destroyed by the ice, within the me- 

 mory of man. In replying to these argiir 

 ments, the result obtained is extremely 

 satisfactory. The rain and sleet falling 

 during summer not only thaws the ice 

 and snow, but forms various channels in 

 it, the water descending must wear and 

 carry along part of the frozen sides and 

 depths, and prepare the way for separat- 



