24 
GLACIAL PERIOD. 
that these accumulations on either side of this 
and other Swiss lakes are ancient lateral mo¬ 
raines, we have it in their connection with 
walls of a like nature at their lower end, where 
we find again transverse moraines barring their 
outlet, and also in the continuity of long trains 
of fragments of similar rocks extending side 
by side across wide plains for great distances 
without mixture. From the beginning of my 
investigations upon the glaciers, I have urged 
these two points as most directly proving their 
greater extension in former times, and more 
recent researches constantly recur to this kind 
of evidence. All our lakes would be filled with 
loose materials, had their basins not been shel¬ 
tered by ice against the encroachments of 
river-deposits during the transportation of the 
erratic boulders to the farthest limits of their 
respective areas. All the continuous trails of 
rocks derived from the same locality would 
have been scattered over wide areas, had they 
not been carried along, in unyielding tracks, 
like moraines. On a small scale the waters of 
the Rhone and of the Arve recall to this day 
such a picture. There are few travellers in 
Switzerland who have not seen these two riv- 
