CLOUDS AND RIVERS, ICE AM) GLACIERS. 105 



266. The same remarks apply to various portions of 

 the Mer de Glace. At certain places the inclination 

 changes from a gentler to a steeper slope, and on cross- 

 ing the brow between both the glacier breaks its back. 

 Transverse crevasses are thus formed. There is such a 

 change of inclination opposite to the Angle, and a still 

 greater but similar change at the head of the Glacier 

 des Bois. The consequence is that the Mer de Glace at 

 the former point is impassable, and at the latter the 

 rending and dislocation are such as we have seen and 

 described. Below the Angle, and at the bottom of the 

 Glacier des Bois, the steepness relaxes, the crevasses 

 heal up, and the glacier becomes once more continuous 

 and compact. 



§ 40. Marginal Crevasses. 



267. Supposing, then, that we had no changes of 

 inclination, should we have no crevasses? We should 

 certainly have less of them, but they would not wholly 

 disappear. For other circumstances exist to throw the 

 ice into a state of strain, and to determine its fracture. 

 The principal of these is the more rapid movement of 

 the centre of the glacier. 



268. Helped by the labours of an eminent man, now 

 dead, the late Mr. AVm. Hopkins, of Cambridge, let us 

 master the explanation of this point together. But the 

 pleasure of mastering it would be enhanced if we could 

 see beforehand the perplexing and delusive appearances 



