\52 



The Glacial Theory. 



ness of M. de Saussure's conclusion, that the motion and 

 decay of glaciers are occasioned by the radiation of heat 

 from below, whereas it is necessary to the proposed theory, 

 that their waste should be extended or thrown out laterally, 

 like rain or hailstones from the eaves of a house. The first 

 results of enquiries on the glaciers of Roseulaui, and of Aar, 

 as well as of the Grimsel, convinced M. Agassiz, that the 

 little water which flows from beneath the glaciers is chiefly 

 from springs, often if not generally, thermal. That it is in 

 too small quantity to allow of the conclusion, that it is de- 

 rived from the melting of the glaciers, and besides the lower 

 surfaces of these are always composed of congealed mud 

 and stones, so that water derived from the melting of the 

 lower surfaces of glaciers would be thick and turbid, while 

 the water of springs is clear 5 and as that which he has seen 

 to flow from beneath glaciers, presents this last property, 

 M, Agassiz concludes, that it cannot be derived from them, 

 but from springs. Again, the structures of glaciers, M. Agas- 

 siz and his companions found to be lamellar, grooved inter- 

 nally by numerous channels and deep pools, produced by 

 the melting of the snow on the surface, and that these pools 

 and channels by freezing, in their turn, produce a dilatation 

 externally in the glacier, as well as a gradual movement 

 downwards on the face of the rocks. The downward move- 

 ment occasions the grooved and polished surfaces on the 

 surface of the rocks, over which the glaciers pass in the 

 moraines, already noticed, ( Cal, Jour, Nat. Hist. vol. II, 

 p. 449,^ while the dilatation carries the blocks and stones, 

 which are congealed within it, gradually towards its project- 

 ing eaves, on approaching which they are cast down in the 

 form of moraines. We pass over the lively picture which M. 

 Agassiz and his friends afford of their living on the glaciers 

 during the time they were engaged in their observations. The 

 Hotel des Neuchatelois is the pompous name bestowed on a 

 cabin twelve feet long, six broad, and four high, situated on 



