EARTH'S PROBABLE AGE.
Professor Sollas, in "The .Age af the Earth," 'deals with -various estimates derived from various lines" of investigation. The earth may be regarded in the light of a clock, by examining which the skilful •watchmaker can generally tell with fair accuracy when it was last wound up. We know that the speed of the earth's rota-, tion is steadily diminishing, and we ; can calculate backwards to/find out when it must have consolidated ia its present shape under the physical laws which affect the form of rotating bodies of iiqmd. The' earth is losing heat, and, by- -calculating the rate at which this goes on, we can make a fairly close guess at the .timei wheir it must have "been eo hot as to be liquid throughout The sun is steadily contracts ing, and the comparatively modern theory which shows that this contraction ■. keeps ttp the solar emission of heat, enables us" .0 calculate just how long the' sun has been capable of vivifying the earth. Sir George Darwin has- shown us how to measure* the time which has elapsed, since the moon was 'torn, away- from the earth by the strain of too quick-; rotation. By such methods we can estimate the time which has elapsed siace, tbe earth, solidified, and, noae of these estimates has anything in common with, the vast, indefinite ages of the early geologists. Thus, Sir George Darwin estimates that about 56 million years have elapsed since the moon came into existence. Lord Kelvin estimates *hat 20 to 40 million years have elapsed since the surface of the earth began to consolidate.. The recent discovery of lie nnivers-jality of radio-activity has somef what upset this calculation -by introducm S a possible new factor. But there is no dour 4 whatever that the whole age of the earr Jk, since its surface began to be subiK ttd to the moulding influences of what! ™ r * call geological agencies, cannot be morel Afttt SO or 60 million years. Professor] .collas shows that all the best moderates-1 tm\a&s,bf the earth's be brought: into fair ogrtement. Probably tiie strayed: rocks, which represent the work of r&JSural agenfcies still in-operation, have takete "something like 26 million years to fo'fln, and | ifc is within this period that we Sh'ust place | the development of life on the
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Bibliographic details
Timaru Herald, Volume LXXXIII, Issue 12978, 18 May 1906, Page 3
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386EARTH'S PROBABLE AGE. Timaru Herald, Volume LXXXIII, Issue 12978, 18 May 1906, Page 3
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