SEA LEVELS IN N.Z.

Press, Volume XCIX, Issue 29373, 28 November 1960, Page 4

SEA LEVELS IN N.Z.

Findings Of Survey Examination ot ancient deposits of sea-shells reveals fluctuations in sea level around New Zealand of nearly 10ft, according to a recent bulletin from the Department of Scientific and Industrial Research. The bulletin reports on the findings of Mr J. C. Schofield of the New Zealand Geological Survey. “Geomorphology,” says the bulletin, “has been hitherto primarily a study of erosion, but it is now considered that constructional landforms can supply much information relating to river control, coastal protection, and sea-bed reclamations. “Part of the D.S.I.R. investigation shows that the sea-level of New Zealand about 2000 B.C. was seven feet higher than at present; the level fell to one foot below present sea level around 700 B.C. but rose five feet in the next 200 years; the present sea level is rising steadily and has doubled its rate of rise in the last 25 years.

“Mr Schofield concludes that the present rise, which is attributed to the world-wide recession of glaciers, is probably only a minor fluctuation because the sea level has been relatively stable for 2000 years. » “His study, in the Auckland area, of sediments deposited in the last 4000 years, and especially of those sandy ridges formed on clay by sea-water movement (known as Chenier plains) has indicated that many present day coastal and esturial districts were under water around 2000 B.C. “The depth and variety of marine deposits, and the manner of their formation, provide a means of studying constructional landforms which can be used to interpret sea fluctuations. By using radio-carbon methods various samples have been dated with an accuracy within 2.5 per cent. Glently sloping low coastal land is best suited for such studies because the different shoreline benches are more distinctive. “It is not generally known that prolonged cycles of rainy weather do not raise the sea level but cause ft to become lower; too much precipitation brings lower temperatures, which cause greater glaciation in the mountains and polar regions especially in the northern hemisphere.