THE EARTH'S AGE.

Wairarapa Age, Volume XXVIX, Issue 8139, 14 May 1906, Page 3

THE EARTH'S AGE.

Speculations about the age of the ' oartb are always interesting, bat it' is futile, we suppose, to expect ■■ that the estimates of scientists will •■ ever agree. Reviewing a work •of Professor Sollas* on the subject, tbe "Spectator" summarises the position very conveniently. There ■ are various LINES OF INVESTIGATION open to the man who desires, to compute tbe age of tbe planet. Tbe eartb may be regarded in the light * of a dock, by examining which the skilful watchmaker oan generally tell, with fair accuracy, when it was last wound up. We ■ know that the speed of the EARTH'S NOTATION is steadily diminishing, and by roalculating baokwards it is possible to find out when it must have conaoli dated in its present shape under tbe physical laws which affect the form of rotating bodies of liquid. The earth is losing heat, and, by calou- . lating the rate at which this goes on, scientists can make a rairly close guess at the time when it must have been so hot as to be liquid throughout The sun ia steadily contracting, and tbe comparatively modern theory, which shows that this contraction keeps up the SOLAR EMISSION of heat, enables [scientists to calculate just how long the sun has been capable of vivifying the eartb, Sir George Darwin, again, has shown how to measure tbe time which has elapsed since tbe moon was torn away from the earth by the strain of too quick rotation. "By such methods," saya the 'Spectator,' "we oan estimate the time which has

ELAPSED SINCE THE EARTH solidiflad, and none of those est! mates 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 oame Into existence. Lord Kelvin estimates that 20 to 40 million years have elapsed since the surface of the earth began to consolidate. But there is no doubt whatever that the WHOLE AGE OB THE EARTH, since its surface began to be subjected to the moulding influences of what we call geological agencies, oan net be more than 50 or 60 million years. Professor Sollas, dealing with the geological estimate, says that the stratified rooks have taken about 26 million years to form, and life on the earth has been developed within this period.