The World Does Move

Northern Advocate, 3 June 1939, Page 5 (Supplement)

The World Does Move

This is a very wobbly world, taking everything into account, writes R. W. Hudson, in the “Adelaide Chronicle.” The classic example of inanimate wobblincss is of Italy’s famous Leaning Tower of Pisa.

The tower was built about 500 years ago. It tipped over during construction, and has apparently been on the wobble ever since. Its movements remained undetected until recent years, when they were revealed by a delicate instrument known as the inclinometer. This device detected some astonishing things. During one month the tower moved north, and then began to move south. It continued moving south for three months, when the movement towards the north started again. And all the time it was, in addition, persistently moving eastward. Small as these movements are, if something had not been done a few years ago, the Leaning Tower of Pisa might, by now, have fallen. In 1932 Mussolini determined to put a stop to its wobbling by ordering it to be underpinned by 1000 tons of cement, which were injected into the foundations through 36 holes, none more than two inches in diameter. Always a business man, the dictator fully realised tourists would not bother to visit the spot if the tower collapsed. Now it attracts large numbers of foreigners every year.

Fisa’s unique building is not the only one in the world which is standingon very unsteady feet. America’s huge 555 feet Washington Memorial is far from rock like. It stands on a thick ciay sponge buried deep beneath its foundation. The sponge is shrinking and the building is sinking with. it. Kcnigsberg, in Prussia, has a famous thirteenth century cathedral. If it keeps on subsiding at the present rate much of it will be under the ground in time to come. In 600 years it has sunk five feet. In Leningrad is another cathedral. formerly St. Isaac's, now a Soviet “Godless Museum.” It is reported to be sinking badly. Some cf the most interesting discov-

DRIFTING CONTINENTS AND BUILDINGS GIVE STRANGE; PICTURE OF OUR PLANET

eries have been made regarding certain of London’s historic buildings. Cracks in the Tower of London about a quarter of a century ago intrigued the scientists, who kept them under observation. They proved to be merely settlement cracks; but while watching them the scientists discovered that the buildings were actually moving—a seemingly incredible happening with such gigantic masses of brick and masonry.

A special pier was built into the subsoil and a series of observations conducted over a long period of years. One of the discoveries made is that the Salt Tower is moving towards the Thames at the rate of a half a millimetre a year. It says much for the at curacy of modern scientific instruments that such a minute distance can be detected.

The quay wall is continually moving, too, but unlike the Salt Tower, it is moving away • from the Thames. In 10 years it has moved back .2 of an inch, and at the same lime sunk .3 of an inch. Every time the tide comes up it pushes back the wall two or three hundredths of an inch, and the wall moves out again with the receding tine. Similar movements have been detected at the •County Hall, Westminster.

St. Paul’s Cathedral is steadily sinking at three points, and it has also tilted over a little from north to south. The east end has sunk more than the west end. Before Waterloo Bridge was demolished, engineers had taken observations, and these revealed it sank at high tide and rose at low tide, due to the weight of the water. The fact that the bridge was settling rapidly was one of the reasons that compelled action to be'taken with regard to it. One of the piers had sunk no less than 28 inches in just over a century, and was five inches out of plumb. Another had sunk over a foot and: several six inches. Even the behaviour of the Bank of England, with its seven-inch subsidence during the past three-quarters of

a century, cannot vie with the alarming fact that England is sinking to, sea level at the rate of nine inches every century. Some have put this theory forward to account for disastrous floods in Norfolk, saying that the North Sea is finding it easier to break through the lowering sea defences. Frequent huge falls of cliff along the East Coast, anything from 30,000 to 250,000 tons collapsing at a time, seem to bear out the geologist’s

contention. The evidence seems conclusive that the level of high tide 2000 years back was at least 15 feet lower relative to the land surface than it is at present. What was once dry land subsided to form the North Sea. If the present rate of sinking continues much of Eastern England is doomed to vanish beneath the billows to join lost Dunwich, Cromer, Orford, and a dozen other long-lost ports and towns which once flourished between Durham and Kent.

Perhaps the most astonishing thought of all about this wobbly world is that possibly not even the continents are stable. It is probable they are all floating about on an enormous “ocean of reck,” forming the earth’s molten, interior. Some famous geologists are coming round to the belief* that originally the land surface was one huge piece. Then Australia broke away in the south, and America slipped away westwards; the latter, it is contended, is still withdrawing.

The late Dr. Wegener was the most brilliant exponent of the drift theory. To put it to the test, the Norwegian Government commissioned the scientist Jelstrup to ascertain the position of Sabine Island, Eastern Greenland, as accurately as was humanly possible. Electrically controlled chronometers, wireless determination of time, aind every device science could produce, were 'used. It cannot be denied that the results indicated the island to be 300 yards further west than in 1870,' so apparently bearing out Wegener’s theory. "■