NEW GEOLOGICAL FEATURE

Hokitika Guardian, 17 June 1931, Page 2

NEW GEOLOGICAL FEATURE

EARTHQUAKE EPFECTS. BEDS INTACT IN UPLIFTED A BE A. WELL'iA'GTON, June 13. The Murchison earthquake of 1929 has been supplanted .in popular interest to u large degree by the more remit upheaval in ilawlos Bay. But to geologists, who have by no means ceased their ' investigations into the pioblems it presented, the Murchison earthquake is still of great interest-. I here are some features connected with it which at present can only be tentatively explained.

As some of these features recurred in the Hawkes Bay earthquake, an adequate explanation of what happened, from a geological point of view, at Murchison will help in solving the geological problems connected with the Hawkes Bay earthquake. The tttucly of the problems was advanced a stage further when, to the geological section of the Wellington Philosophical Society, Mr M. Ongley, of the Geological Survey Department, read a paper on “The Whitecliffs Uplift.”

Maps gnd photographs, made and taken by Mr Ongley and by Mr N. R, Carter, of the Public Works Department, showed a eroseeiut-imfipeci area of sen-floor, two miles long and a quarter of a mile wide, elevated up to 100 feet above the sea level, with much faulted and broken country /ringing the shattered and faulted talus fan that lonned what is known as Llewellyn’s farm. Behind this was new talus shaken from the spurs by the earthquake, and at the hack the slightly scarred Cliff 1200 feet high. The whole, said Mr Ongley, was different from anything previously described, and required explanation.

He explained why he ruled out the theory of broken earthquake waves that of buckling accompanying land slides, that of the swelling of overloaded ground, or that of debrmational landslides. Instead, he offered for criticism a tentative explanation that the momentum of the high earth-block, on being transferred to the eroded coast block, was sufficient to flake off and turn up a wedge of the floor. Upon the withdrawal of the thrust of the earth block, the unsupported wedge collapsed along tension faults. A photograph was shown of the front of the Mohaka (Hawkes Bay) uplift showing the beds intact, a feature which was characteristic of the Whitecliffs uplift. Such a feature had not previously been described in any geological literature available, commented Mr Ongley. The paper was followed by an interesting discussion, some present not being inclined to accept Mr Qngley’s theory without further ovideneo,