Joty—An Estimate of the Geological Age of the Larth. 59 
rise to 548 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, &e., 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 percentages 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-Paleeozoic granitic decay described by 
Dr. R. Bell of the Canadian Geological Survey, and referred to by Merrill, 
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-Cambrian 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 processes 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.” 
Approaching 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-Harly-Paleozoic 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. { Merrill, doc. cit., p. 380. { Loc. cit., pp. 275, 276. 
