108 



ISLAND LIFE 



PART I 



are termed roches mcnotonnSes, from their often having the 

 appearance at a distance of sheep lying down. 



Now these two phenomena are actually produced by 

 existing glaciers, while there is no other known or even 

 conceivable cause that could have produced them. When- 

 ever the Swiss glaciers retreat a little, as they sometimes 

 do, the rocks in the bed of the valley they have passed 

 over are found to be rounded, grooved, and striated just as 

 are those of Wales and Scotland. The two sets of phe- 

 nomena are so exactly identical that no one who has ever 

 compared them can doubt that they are due to the same 

 causes. But we have further and even more convincing 

 evidence. Glaciers produce many other effects besides 

 these two, and whatever effects they produce in Switzer- 

 land, in Norway, or in Greenland, we find examples of 

 similar effects having been produced in our own country. 

 The most striking of these are moraines and travelled 

 blocks. 



Morai7ies. — Almost every existing glacier carries down 

 with it great masses of rock, stones, and earth, which fall 

 on its surface from the precipices and mountain slopes 

 which hem it in, or the rocky peaks which rise above it. 

 As the glacier slowly moves downward, this dShris forms 

 long lines on each side, or on the centre whenever two 

 glacier-streams unite, and is deposited at its termination 

 in a huge mound called the terminal moraine. The de- 

 crease of a glacier may often be traced by successive old 

 moraines across the valley up which it has retreated. 

 When once seen and examined, these moraines can always 

 be distinguished almost at a glance. Their position is 

 most remarkable, having no apparent natural relation to 

 the form of the valley or the surrounding slopes, so that 

 they look like huge earthworks formed by man for pur- 

 poses of defence. Their composition is equally peculiar, 

 consisting of a mixture of earth and rocks of all sizes, 

 usually without any arrangement, the rocks often being 

 huge angular masses just as they had fallen from the sur- 

 rounding precipices. Some of these rock masses often rest 

 on the very top of the moraine in positions where no other 

 natural force but that of ice could have placed them. 



