CLOUDS AND RIVERS, ICE AND GLACIERS. 



115 



an ideal Table. The oblique lines represent the direction 

 of the sunbeams, and the consequent tilting of the table 

 here shown resembles that observed upon the glaciers. 



291. A pebble will not rise thus : like Franklin's 

 single bit of cloth, a dark-coloured pebble sinks in the 

 A spot of black mould will not rest upon the sur- 



ice 



face, but will sink ; and various parts of the Glacier du 

 Geant are honeycombed by the sinking of such spots of 

 dirt into the ice. 



292. But when the dirt is of a thickness sufficient to 

 protect the ice the case is different. Sand is often 



washed away by a stream from the mountains, or from 

 the moraines, and strewn over certain spaces of the 

 glacier. A most curious action follows : the sanded 



