JoLY — An Estimate of the Geological Age of the Earth. 59 



rise to 54:3 parts.* This is the atmosphere actually concerned with the destruction 

 of Felspars, &c. 



The existing soils of a considerable part of the northern hemisphere are due to 

 the glacial effects of older Quaternary times. However, in the loess of China, 

 Europe, &c., the adobes of America, and similar clays, surface deposits are found 

 which may well have been represented in the remote past. In these we find 

 alkali joercentages comparable with the sedimentary soils, the potash ranging from 

 1'03 to 2"13, the soda from 0-57 to 1-63. The state of comminution is also 

 remarkable. t 



The interesting evidence of Pre-Pal neozoic granitic decay described by 

 Dr. R. Bell of the Canadian Geological Survey, and referred to by Merrill, J 

 should be referred to by those interested in the question, although, as 

 not being of a quantitative nature, the evidence does not, save for its general 

 teaching, concern us here. Other cases of evidence for Pre-Cambrlan denudation 

 are mentioned in the same treatise. Mr. Merrill concludes : — 



"These, and other illustrations that might be given, point unmistakably to 

 the identity of geological ^^rocesses and correspondence in results since the 

 earliest times, even did not analogy and the thousands of feet of secondary 

 rocks furnish us safe criteria upon which to base our inferences." 



Aj^proaching finally the question as to whether a correction on the Geological 

 Age of the Earth previously arrived at is fairly due — according to our lights — on 

 the score of the greater mass of detrital sediments now reposing on the land areas 

 compared with those of the earliest times, we have, as we have seen in these very 

 sediments, rocks of a physical character which forbids us to pronounce, in many 

 cases, on the relative effectiveness of igneous and sedimentary rocks, as con- 

 tributing to solvent denudation. We have also factors of both earlier and later 

 times acting to accelerate solvent denudation. Of these, the least speculative is 

 the influence of vegetation which is a post-Early-Palseozoic factor mainly. Again, 

 the land uplifted from the primeval ocean, after the free acids were for the most 

 part neutralised, was, we must infer, overlain with insoluble siliceous residues. 

 To make any deduction or addition is not warranted. There appears no good 

 reason to suspect that our broad Uniformitarian principles are leading us into con- 

 siderable error where, more especially, such disturbing causes as we are compelled 

 to recognize are both of positive and negative signs. But the whole consideration 

 should undoubtedly lead us to widen the margin we allow for error in our estimate 

 of Geological Time. 



* Merrill, loc. cit., p. 178. f Merrill, he. cit., p. 330. % Loc. cit., pp. 275, 276. 



