on the Rocks in the Environs of Edinburgh, 305 



of sand, which must be encased in the ice as the diamond 

 wherewith the glazier cuts glass is fixed at the end of a 

 handle, or as a precious stone is infixed into the bezel of a ring. 

 Thus is it that the existing glaciers mark the existing rocks 

 upon which they glide. All the travellers who have visited 

 the glaciers of the Aar, of Grindelwald, of Rosenlaui, &c., 

 have been able to collect many pebbles and detached gravel 

 projecting from the ice in which, they were enveloped. But 

 the question here occurs, do these pebbles remain imbedded 

 in a floating ice-block when it is detached from a glacier ? 

 This has never been demonstrated. And in truth we may 

 afiirm, that it is at the inferior surface of the GLACIER,— 

 at that part of it which still reposes upon the sand, — that 

 these pebbles are numerous. We have moreover observed 

 that when this part of it reaches the sea, it melts and disap- 

 pears, and consequently all the pebbles, and even the large 

 blocks, fall down as fast as the bed in which they are con- 

 tained passes into the liquid state. Hence, then, I have 

 never perceived pebbles beneath the glaciers of Spitzbergen 

 whilst examining their inferior surface at low tide, when the 

 interval between the water and the ice has been about three 

 feet apart. When, then, a part of the glacier comes to be 

 detached, falls into the sea, and becomes a floating iceberg, 

 it has ceased to have any pebbles at its inferior surface. As it 

 respects those at the upper surface, they adhere but slightly, 

 because pressure has not forced them into the ice. But it 

 may be alleged that this mode of the formation of floating 

 icebergs is not the only one, — that it occurs, indeed, at Spitz- 

 bergen, where the temperature of the sea is, in summer, 

 somewhat above 32° Fahr., but is not the same everywhere ; 

 and the voyagers who have traversed Baffin's Bay in search 

 of the unfortunate Sir John Franklin, have observed in these 

 regions that glaciers entered the sea without being melted 

 thei'eby, and are carried along its bottom. In these cases, it 

 is maintained that the floating icebergs may carry pebbles 

 incased in their inferior surface. This no doubt is true. 

 But then, not content with the hypothesis that the lowlands 

 of Scotland were submerged in the ocean to the depth of 

 VOL. L. NO. C— APRIL 1851. U 



