S-i Remarks on i/ie Formation of Alluvial Deposites. 



degrees of size and coarseness, according to their proximity to 

 the centre of action, the apex of the cone, or to the middle of 

 some principal stream. 



^dly. The melting of Alpine stiows and glaciers. In winter 

 the torrents and rivers, which flow immediately from tl:e snows 

 and glaciers of the Alps, are nearly dried up. I saw them in a 

 state of vigorous action, and often remarked the peculiar thump- 

 ing sound of the boulders, which they drive along so as to keep 

 up an almost constant cannonade *. These stones are invisible, 

 in consequence of the opacity of the water, until, by its subsi- 

 dence, it displays their chiselled and whitened surfaces through- 

 out its bed. --ttft 



Wily, The breaking up of ice in rivers. In regions of such 

 a temperature as to contain rivers which freeze in winter, their 

 breaking up advances the progress of their alluvium, both be- 

 cause the pieces of ice cut away the banks, and because they 

 collect in certain parts, so as to keep back the water. Last 

 winter, at Winnengen, a short distance above Coblentz, the Mo- 

 selle, being hemmed in by the accumulation of its broken ice, 

 rose 20 feet in an hour and a-half. Having overcome this bar- 

 rier, it carried away 300 yards of the road between Layen and 

 Mosel-weiss. In the Rhine, debacles are produced by the same 

 cause. Through certain spaces of the river's course, where the 

 stream is narrow, deep, and strong, the ice floats downwards. 

 It stops where the bed becomes broader, and the current conse- 

 quently more shallow and more languid. The broken pieces, 

 for the most part reared upon their edges, and crowding over 

 one another, rise to the height of many feet, and are consoli- 

 dated by the freezing of the water, which they intercept. At 

 the commencement of a thaw, the water, coming from above, 

 quickly accumulates, in proportion as the ice is disposed to 

 yield. It then breaks the dykes, and rushes forward with tre- 

 mendous force, overflowing the plains, breaking down the banks, 

 and carrying along immense quantities of mud, sand, and 

 stones. 



• Sir T. D. Lauder, in his last work, gives an exact idea of the smnd 

 to which I refer, when, in a similar case, he remark.s that the stones were 

 muffled by the water. 



