WEGENER THEORY

Evening Star, Issue 21709, 2 May 1934, Page 12

WEGENER THEORY

DRIFTING CONTINENTS NEW SUPPORT FOUND A crucial test of the Wegener theory of drifting continents is the comparison of longitude measurements at any one place over a sufficiently long period of time (says the ‘ Manchester Guardian’). The most favourable series of measurements is that which has been carried out at intervals during the last century on Sabine Island, in East Greenland. The longitude of Sabine Island was first determined by Admiral Sabine in 1823. It was again measured in 1870 by the astronomers of the Germania Expedition, and in 1906 by a Danish expedition under J. P. Koch. Comparison of the positions thus obtained led Wegener to postulate a westerly drift of Greenland of about thirty metres a year. In an attempt to settle the question the Norwegian Government, at the request of Professor K. Wegener, the brother of Alfred Wegener (who recently lost his life in Greenland), sent out Hans S. Jelstrup to determine the longitude of Sabine Island with the aid of the latest instruments, the most modern methods, and with the great advantage over previous workers of being able to use electrically-controlled chronometers and wirelessed determinations of time. The results of Jelstrup’s work have just been published.

In the writer’s opinion they prove indubitably a'’movement of Greenland towards the west. Taking the Germania observations of 1870 as the most accurate of the older measurements, Jelstrup finds an apparent displacement of 615 metres to the west in the sixty-two years between 1870 and 1932, " which amounts to a drift of ten metres a year in the direction demanded by the Wegener theory,: According to Jelstrup, the older observations are subject to a systematic! error of at least plus ’or minus eightythree metres, his own to an error of plus or minus twenty-two and a-half metres; but it is probable that tha real error, systematic and accidental,of the older measurements may amount to a few hundreds of "metres. Nevertheless, after minute examination of tha; sources of error, Jelstrup is convinced, that the positional difference obtained by him (615 metres) is much greater than the sum of all possible errors ia the measurements. That is to say, there is a true drift towards the west in Greenland in the sense predicated by Wegener, but of much smaller amount than was supposed by him. As Wegener showed,comparisons of the two successive pairs of observations up to Koch’s expedition of 1906 both give drifts towards the west; and the fact that Jelstrup’# new and extremely accurate' measurements are consistent with this result provides valuable confirmation of Wegener’s views. Making all allowances for sources of error in his own -and the older observations, Jelstrup finds that a'longitudinal difference in the position of Sabine Island between 1870 and 1932 of 250 metres must be ascribed to real displacement in accordance with the Wegener theory. A total of 250 metres in sixty-two years amounts to an annual drift of 13.2 ft, or a mile in 400 years. If the mean distance of Greenland from Europe is estimated at 2,000 miles it has taken 800,000 years to effect the present separation of the, two land masses. This figure is in approximate agreement with estimates of the date of the Glacial Epoch, subsequent to which Wegener places the separation of Greenland from northwestern Europe,