CL0UI6 AND RIVERS, ICE AND GLACIERS. 55 



becomes evident that we have here the source of the 

 lateral moraines. 



138. But how are the medial moraines to be ac- 

 counted for ? How does the debris range itself upon the 

 glacier in stripes some hundreds of yards from its edge, 

 leaving the space between them and the edge clear of 

 rubbish ? Some have supposed the stones to have rolled 

 over the glacier from the sides, but the supposition will 

 not bear examination. Call to mind now our reasoning 

 re£fardin£ the excess of snow which falls above the 

 snow-line, and our subsequent question, How is the 

 snow disposed of. Can it be that the entire mass is 

 moving slowly downwards ? If so, the lateral moraines 

 would be carried along by the ice on which they rest, 

 and when two branch glaciers unite they would lay 

 their adjacent lateral moraines together to form a medial 

 moraine upon the trunk glacier. 



139. There is, in fact, no way that we can see of dis- 

 posing of the excess of snow above the snow-line ; there 

 is no way of making good the constant waste of the 

 ice below the snow-line ; there is no way of accounting 

 for the medial moraines of the glacier, but by supposing 

 that from the highest snow- fields of the Col du Geant, 

 the Lechaud, and the Talefre, to the extreme end of the 

 Glacier des Bois, the whole mass of frozen matter is 

 moving downwards. 



140. If you were older, it would give me pleasure to 

 take you up Mont Blanc. Starting from Chamouni, we 



