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Show - Age Of The Earth Told 4 , cjiflilio announcement of the mar'-velous mar'-velous discovery of radium, some of our Ideas concerning thr cosmic-aspect of our earth have undergone revolutionary revolu-tionary changes. No single conception concep-tion lias experienced more fundamental fundament-al evolution that has taken place In the doctrine of the secular cooling of the globe, that the physicists have so long assumed, and to which they have so long tenaciously held. That the earth Is a self-cooling globe, Is an Idea that no one, until very recently, even fancied. The recognition of radioactivity radio-activity In matter has changed all. Itegardlng the age of the earth, the physicist now not only admits that his former estimates of 10,000,000 to 20,000,000 of years are much too small, but he Is willing to grant the geologist geolo-gist hU fullest measure of time. He M even goes further, and Is willing to M give the geologist ten times his claim 9 for the span of terrestrial existence. 9 Speaking of the newly discovered H radio-active properties of matter, Geo. H Darwin, in his lecent presidential ad-a ad-a dress before the British Association for I the Advancement of Science, makes the statement that they show that concentration of matter is not the only source from which the sun may draw Its heat. He further says, regarding re-garding the evolutionary hlstorj of the earth, that now "It docs not seem unreasonable to suppose that from 500,000,000 to 1,000,000,000 jcars may have elapsed since the birth of the moon. Such an estimate would not seem extravagant to geologists, As far as my knowledge goes," 1 should say that pure geology points to some period Intermediate between 50,000,000 to 1.00,000,000 years, the upper up-per limit being more doubtful than the lower. The determination of our earth's age is one of the triumphs of modern geological science The length of the time which has elapsed since life began be-gan on this globe, and the most ancient an-cient clastic rocks we know of were deposited, n.ay be greatly In excess of 160,000,000 j ears Geology's estimate Is surely not too great; but Is, In all likelihood, much too small From "The Age of Our Karth," by C. II. Keycs, In the Review of Reviews for April. |