64 Joty—An Estimate of the Geological Age of the Earth. 
account our uncertainty in many particulars attending these corrections, and as 
to the constancy throughout the past of solvent denudation, and bearing in mind 
that any approximation to a correction for marine denudation must be attended 
with this same uncertainty, but that the latter correction will undoubtedly be 
subtractive, we think that it is at least justifiable to claim that our present 
knowledge of solvent-denudation of the Earth's surface points to a period of between eighty 
and ninety millons of years having elapsed since water condensed upon the Earth, and rain 
and rivers and the actions continually progressing in the soils began to supply the 
ocean with materials dissolved from the rocks. 
CORRIGENDA. 
Pages 34 & 85—WNote in reference to the calculation respecting the neutralisation of free hydrochloric acid :— 
The effect of the aluminium should also be taken into account. This would reduce the 
estimated percentage of acid neutralised in the formation of sodium chloride, and so raise somewhat 
the estimate of geological time. 
The margin of error assumed in the final estimate of geological time must, however, cover the 
oversight, but leaving the balance of probabilities in favour of a duration more nearly 90 than 80 
millions of years. 
Page 61, third line from top—/or Erdstollen read Erbstollen. 
Page 66, eighth line from top—/or part read past. 
