Address delivered by the president / Julius Haast.

  • Haast, Julius, 1822-1887.
Date:
1874
Catalogue details

Licence: Public Domain Mark

Credit: Address delivered by the president / Julius Haast. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    I fans, namely, those of tho Waimakariri, Rakaia, Ashburton, and Rangitata, with smaller rivers having their sources in the front ranges run- ning between them ; the Belwyn between tho Waimakariri and Rakaia fans, the Northern Ashburton between those of the Rakaia and of the Ashburton—Northern Hinds ; and the Southern Hinds between the latter and the Rangitata fans. The gravel formation of these fans, where they remained undisturbed, does not warp, as Captain Hutton assumes, round the spurs of the hills at the same level that it has at the river gorges, but has a steady fall towards the small streams flowing between the fans of the two large glacier torrents ; however, in some instances, this has been concealed by detritus from the moun- tains, or by re-arrangement of the original river beds on the surface of the upper t ortion of the plains when the glaciers retreated. But, I may add, the general outlines are neverthe- less clear and distinct. In my geological notes on the Malvern Hills (Reports of Geological Explorations during 1871-72, Wellington, 1872, pages 33-36), I have given an illustration of this. I have shown how the great Rakaia glacier, having also an outlet by the upper course of the river Selwyn, covered with its gravel deposits the lower eminences forming the Malvern Hills, west of the dolerite range, and had its outlet in a N.E. direction in the neighbourhood of Little Raceoourse Hill, thus throwing doubtless the bed of the Waimakariri more to the north. When this glacier outlet ceased to flow and to deposit any more boulders and gravel in the district alluded to, the Waimakariri soon began to remove the alluvial beds, thus formed by the Rakaia branch, until harder rocks upon which they were reposing were reached. This fact alone, I trust, will prove that a detailed examination of all physical features in that portion of the country is re- quisite to enable us to understand the some- times complicated nature of the fluviatile beds, and that my explanation of the formation of the Canterbury plains is not a mere hypothesis, but based upon a great number of observa- tions made during a number of years. Captain Hutton, in the same paper, observes : — It is so universally acknowledged amongst geologists, that river terraces prove elevation that it is quite unnecessary to go over again such well trodden ground, and he brings for- ward a formidable array of scientific authori- ties in support. However, nobody over doubled his statement, but he forgets that there is still another and important agency by which terraces are formed, and which not only in New Zealand, but in many other mountain- ous regions, has been the principal if not sole cause of their formation, namely, the retreat of the river sources to higher and more dis- tant regions. In my different reports, already cited, I have treated* of that subject at length, and shown why and how rivers with less velocity do gradually lower their beds, so that I need not repeat myself here. But a stili more formidable objection to Captain Hutton's hypothesis presents itself :—If the Canterbury plains were of marine origin, the beds of which they are composed would have pre- served some traces of it; but although we have clear sections, several hundred feet high, in almost every river, their fluviatile charac- ter is unmistakeable. The boulders, shingle, gravel, sand, and ooze are all deposited as a river torrent would place them, according to their form and size, and according to the greater or less amount of water being brought down. The-peculiar character of surf shingle is nowhere exhibited, but all the pieces of stone have the subangular form so peculiar to river shingle. Marine fossils are missing throughout. Moreover, if elevation had taken place during the postpliocene or glacier period, Banks Peninsula would certainly show this most conspicuously, but what does a close exa- mination of that interesting, isolated, volcanic region reveal to us ? We observe no trace of marine action, except the results of a slight oscillation of about. 20 feet, by which the Pe- ninsula has been raised, after undergoing pro- bably a similar submergence. It is true, that its lower portion, in several localities up to 800 feet, is covered more or less with silt—a fine loam—which in many instances is a true slope deposit, partly derived from the dec im- position of the rocks in situ, or partly brought down from higher regions by running water. Moa bones and pieces of small land shells have been found in these deposits, of which there are many splendid sections to be exa- mined, but nowhere the least sign of marine life could be detected in them. This fact alone shows that the emergence theory has not the least foundation ; on the contrary, from the nature of these silt beds and their partial denudation, we might con- clude that the Peninsula has undergone a depression since they were deposited. Had a