PREHISTORIC NEW ZEALAND

Nelson Evening Mail, Volume LXI, 17 January 1928, Page 6

PREHISTORIC NEW ZEALAND

IECTURE TO TEACHERS' •SI!IIER.SCiO©)L

BY DR. MARSHALL

ILLUSTRATED BY LANTERN SLIDES

Before a crowded hall at the. School of Music last, night a most fascinating lecture on "Prehistoric New Zealand was delivered by Dr. P. Marshall, M.A., D.Sc, F.R.G.S., (Ex-Professor of Geology, Otago University). The hitter half of the lecture was illustrated by a number of lantern slides of photographs taken at various places in New Zetiland, and they served to illustrate in a practical manner how the volcanic, and other natural phenomena have carved the land mass wo know as New Zealand into its present shape. i Dr. Marshall wished first of all to impress his hearers with the fact, that the periods of time dealt with by the geologists were almost impossible for the human mind to grasp. It was only when hundreds of thousands or millions . of years wee spoken of that the geologists felt any interest. Mankind, alter summing up its written, legendary and other forms of historical data, had not been on the earth in its present form for more than 100,000 years. For the purpose of reading the history of New Zealand by geological methods it was necessary to insist upon the doctrine - of uniformity, that is that similar processes went on in the past as were going on.now. All students of geology. ,wero\ agreed that at various times in the history of the earth there had been . great glacial, periods. About 200,000 years agoj for instance, the northern half of Europe was covered with a huge ice cap, and about the same time many of New Zealand's valleys were filled with great rivers of ice. This had led people to, think that the world which was known to have once been molten was becoming cooler, but the speaker said that a constant lowering throughout the year of the temperature of New Zealand by only 5 degrees would result in a -reappearance of those old glaciers in the lower valleys. The documents,to be read in discovering a country's early history were the configuration of the land and a study had to be made of the various hills and valleys and how they had been formed. Volcanic action had been blamed for far more twisting of the earth's surface than was actually due to it. This was an example of the frailty of the human mind in not getting a .true perspective of a vokanic disturbance. For instance, the Tawawhera eruption in 1895 blew a hole 'in the earth's surface five miles long, 1£ miles wide, and 100 feet deep. People were over-impressed with^.this, display of energy, not knowing, or at least not realising that the rivers of New Zealand produce as great a disturbance in the earth's surface every year. Rivers worked steadily—day in and day out—and neyer stored up energy for centuries as did volcanoes. Earthquakes, too, were commonly held to be one of the chief factors in changing the earth's surface, but they, too, were hardly ever responsible for more tlian a _ comparatively slight change. An earthquake Was a fracture of a portion of the outside surface of the earth. Some such as the Japanese earthquake in 1922 and the land movement "in Wellington in 1855 had produced great effects, but such cases were isolated. Dr. Marshall stated that earthquakes usually had nothing to do with volcanic action. An example .of mankind's indifference to natural phenomena was the fact that in Auckland the Domain cricket and football ground was laid out in the crater pf an'extinct volcano, and those cricketers now using it would be astonished and annoyed if that volcano went on, as it was supposed to go on.

Of much more importance in finding out the past was the study of the fossils that were embedded in the rocks. These fossils were the regains representing ar.imals and plants that lived on the earth-in past time's. They had been collected and studied with considerable care by geologists, and mankind accordingly 'had considerable, knowledge of What had taken place on the face of the earth through past time. There was always, as' Dr. Tillyard had previously told the students, a progress from the simple to the complex—a continual evolution. There had been a development of humanity from less developed and less intelligent forms of life, and this development could be traced in the fossils. The Cambrian period, about 500 million years ago, was the age of shellfish Before lonsr the first vertebrates kind of fish. A further development of these vertebrates soon took place, and the amphibians resulted. Am other 50 million years brought about an extraordinary development of reptilian life. There' were reptiles that walked, swam and flew. Flying dragons were not uncommon, and some of the giant reptiles were 85 feet in length. There was a tremendous reptilian life on practically all the countries of , the earth. Then suddenly tnis great mass of reptiles disappeared. Why, it could not be said. There was no evidence of a sudden change of climate or a sudden outbreak of disease, but it had been suggested that, as the reptiles were egg-laying, their destruction was brought about through theneggs being eaten by the more intelligent and mobile mammals which had now evolved. Dr. Marshallsaid he : believed a similar happening had caused the moa to disappear from New Zealand. The eggs were found and eaten by the Maoris, thus quickly exterminating" the giant birds. As soon as the reptiles had gone the mammals began to develop and they reached an extraordinary variety in shape, size and abundance. The maximum of this mammalian development was reached about 200,000 years ago, and the modern, tigers, elephants, and hippopotami were direct but feeble descendants of some of the much healthier group of great beasts that roamed the earth at that time. Were reptiles doomed to extinction? That might be so and the conjecture at once arose: What animal will take the mammal's place?

"Our idea of prehistoric New Zealand, then," said Dr. "is to be based on a study for comparative purposes of the work that is being done now by streams and glaciers and by the study of fossils."

Dr. Marshall showed a series of lan- ( tern slides illustrating the salient fen-1 hires of New Zealand's geology, and also giving striking examples ol sea and stream erosion. Amongst the slides were a number of local views for many of which Dr. Marshall said he was indebted to Mr Davies of the Cawthron Institute. Several slides of the. Boulder Bank and Mackay's Bluff showed pictorially the origin of the stone as explained by Dr. Marshall in a. previous lecture. Examples of glacial and volcanic actior were also thrown on the screen, and a number of microscopic photographs of dunnite and other rocks, all of which contained much information that could be interpreted by the geologist.