CHAPTER VIII 
RIVERS AND LAKES 
ON THE DIRECTIONS OF RIVERS 
In the last chapter I have alluded to the 
wanderings .of rivers within the limits of 
their own valleys; we have now to consider 
the causes which have determined the direc- 
tions of the valleys themselves. 
If a tract of country were raised up in 
the form of a boss or dome, the rain which 
fell on it would partly sink in, partly run 
away to the lower ground. The least in- 
equality in the surface would determine the 
first directions of the streams, which would 
carry down any loose material, and thus 
form little channels, which would be gradu- 
ally deepened and enlarged. It is as difficult 
for a river as for a man to get out of a 
groove. 
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