GLEN ROY, IN SCOTLAND. 
55 
them away or scatter them along the bottom 
of the valley. That this is actually the case is 
seen in the lower course of the valley of the 
Rhone, where there are no transverse moraines, 
while they are frequent and undisturbed in the 
upper part of the valley. This is no doubt 
owing to the fact, that, when the main glacier 
had already retreated considerably up the val¬ 
ley, the lateral glaciers from the chains of the 
Combin and the Diablerets still reached the 
valley of the Rhone at a lower point, and 
barred the outlet of the waters from the gla¬ 
ciers above. A lake was thus formed, which, 
when the lower glaciers retreated up the lateral 
valleys, swept away all the lower -transverse 
moraines, and formed the flat bottom of Mar- 
tigny. In this case, the moraines were totally 
obliterated ; but there are many other instances 
in which the materials have been only broken 
up and scattered over a wider surface by cur¬ 
rents. In such remodelled moraines, the gla¬ 
cier-mud has, of course, been more or less 
washed away. We have here a blending of the 
action of w^ater with that of the glacier; and, 
indeed, how could it be otherwise, when the 
✓ 
colossal glaciers of past ages gradually disap- 
