CHAP. VII.] 
THE GLACIAL EPOCH. 
105 
that could have produced them. Whenever 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 phenomena 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 evi- 
dence. Glaciers produce many other effects besides these two, 
and whatever effects they produce in Switzerland, 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. 
A GLACIER WITH MORAINTS. 
Moraines . — 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 
