196 
THE AGE OF THE WYE. 
Now if no yards of cliff are worn at the rate of an inch in 
64^ years, while 1073 are worn at the rate of an inch in 129 
years, the rate of wear over the whole cliff of 1183 yards will 
he at the average rate of an inch in 118 years. Then, as 300 
yards, or 10,800 inches, have been worn at the rate of an inch 
in 118 years, the time required will be 1,274,000 years ; and, as 
all the figures have been taken at a minimum, this is, therefore, 
the smallest figure that can be calculated to represent the present 
Age of the Wye.” 
In conclusion, I may say that this subject has naturally been 
present to my mind for many years past. I have always 
observed the evidences of wear in other streams, whether large 
or small, that came under my notice, and to my mind they all 
bear equal testimony to the vast length of time during which 
they must have been performing a similar operation. If we 
regard the comparatively sluggish Thames, which appears to 
wear its banks so very slowly, and has yet accumulated a wide 
margin of alluvium all along its course, or if we look at any other 
stream that I have ever seen, they all tell the same tale ; but in 
no other case that I know of do the elements exist for making a 
definite, though approximate, calculation of the actual period of 
time required for the work that has been done. 
The Wye happens to run through a district of the old red 
sandstone which is subject to a slow but equable and constant 
rate of wear j ust suited to our purpose. If the rate of wear had 
been slower it could hardly have been measured, and if it had 
been faster the river would have worn for itself such a breadth of 
alluvium that the stream would frequently have failed to reach 
its marginal cliffs, as its “ bends ” descended through the 
alluvium, and the chief requirements for a definite calculation 
would thus have been wanting. Thus it is that the conditions 
under which the Wye runs down its course through the Boss 
