SOME ASPECTS OF GEOLOGIC TIME 



By H. S. SHELTON, B.Sc. Lond. 



PART I.— GEOLOGIC PROCESSES AND GEOLOGIC 



TIME 



It is a fact of common knowledge that the opinion of men of 

 science on the much-vexed question of geologic time is in a 

 state of flux. Recent criticism and discovery have completely 

 shattered the theories of Lord Kelvin. The collateral methods 

 of Prof. Joly (on sea salt) and of Prof. Sollas (on the thickness 

 of sedimentaries) have been subjected to trenchant criticism. 1 

 A new method has arisen in the estimates of the amount of 

 helium accumulated in radioactive deposits. 2 A few words of 

 introduction are, therefore, desirable, to set forward my own 

 point of view. I would, therefore, say that, in my opinion, no 

 single one of the methods, which, until a few years ago, were 

 regarded by men of science as valid, and, within reasonable 

 limits, final, is of any value whatever. 3 My own opinion is that 

 geologic time is vastly greater than the geologist, since the days 

 of Lord Kelvin, has thought probable. But the opinion does 

 not greatly matter for the purposes of this essay. Here we are 

 suggesting various methods of attacking our problem. If the 

 suggested methods, or other new methods, confirm the con- 

 clusion of the present-day geologist, the labour will not be 

 wasted. If, after careful study, they establish an entirely 

 different order of time, their necessity will be all the more 

 certain. For, even if present-day views and methods are 

 mistaken, it does not follow that the problem is insoluble. 



1 See my article in the Contemporary Review, February igu. 



2 See particularly papers by Prof, the Hon. R. J. Strutt in the Proceedings of 

 the Royal Society. 



3 I have dealt with them individually in the following papers, in addition to the 

 one already mentioned : " On the Tidal Retardation of the Earth " {New Quarterly, 

 November 1909) ; " The Age of the Earth and the Saltness of the Sea " {Journal 

 of Geology, February — March 1910); "Secular Cooling as an Illustration of the 

 Methods of Applied Mathematics" {Journal of Philosophy, September 1, 1910) ; 

 " The Age of the Sun's Heat" {Contemporary, June 1913). 



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