POLARITY OF EARTH

Press, Volume XCVII, Issue 28702, 27 September 1958, Page 15

POLARITY OF EARTH

Reversal TheoryDiscussed

Magnetism fixed in rocks had provided the clue to a theory that periodically the earth’s magnetic field reversed itself; in other words, the North Pole became the South Pole and vice versa. Dr. Trevor Hatherton told a meeting of the mathematics and physics section of the Royal Society’s Canterbury branch. Dr. Hatherton is the head of the Dominion’s Antarctic research programme. He said that the conclusion of polarity reversal had been forced on scientists when rocks were found in various parts of the world with magnetic fields of different direction to the present magnetic field of the earth. By assessing the age of the rock, fields of different ages could be calculated.

The polarity -reversal —expounded by a New Zealander, Dr. E. I. Robertson, in his Ph.D. research in 1948—occurred “every half million years.” That, however, was a “primitive estimate.”

With the discovery of magnetism direction in rocks, polar and continental drift experts became interested, Dr. Hatherton said. It was obvious that rock under the South Pole would show a vertical direction of magnetic field; yet such direction had been found in focks of India, South Africa and Australia. This would appear to show that these places were once at the South Pole—perhaps 200 million years ago. “We are working on these rocks at various ages to see if we can get a story of this continental movement out of the directions of magnetisations,” he said.