Fifth Meeting: 14th September, 1909.
Professor J. H. Scott, M.D., in the chair.
Papers.—1. “Notes on some Rocks from Parapara, Bluff Hill, and Waikawa,” by J. Allan Thomson; communicated by George M. Thomson, F.L.S.
The author describes in detail six specimens from Parapara, furnished by Dr. Bell, Director of the Geological Survey, the object being to test the rival theories of assimilation or absorption, as propounded by Levy and Lacroix, and of differentiation, supported by Rosenbusch. The investigation serves chiefly to draw attention to the question, as the phenomena observed admit of either interpretation. A through chemical examination of the rocks would be required to settle the problem.
The rocks from the Bluff were collected along the shore on the south and west of Bluff Harbour. The relative ages of these different rocks—fine grained banded hornblende schists, and dark and light diorites—the mode of origin of the foliation, whether
arising during or after consolidation, the origin of the rock-variations and “basic secretions,” whether by pure differentiation or differentiation combined with absorption, are a few of the problems presented for solution.
The last rock is an isolated beach-pebble picked up at Waikawa, and possesses interest as being a type not hitherto recorded in New Zealand. The other beach-pebbles consist mainly of microgranites derived from the Triassic conglomerates; but from its soft nature it is more probable that this rock has come from a neighbouring intrusion. It shows a rich mineralogical association, consisting of amphiboles, biotite, muscovite, clinozoisite, epidote, two varieties of chlorite, talc, magnetite, and pyrite, but hornblende is so abundant as to render the designation “lustre-mottled hornblende rock” applicable.
2. “On a Method of introducing the Decimal System in British Weights, Measures, and Volumes,” by Henry Skey.
Weights.—The pound is the unit, placed in the middle of a symmetrical system or scale, and the numerical method of counting is proposed up to 10,000, and the division of the pound into 10,000 new grains called minis. Thus:—
10,000 minis = 1 pound.
10,000 pounds = 1 myriapound.
Measures.—This deals with the advantages to be derived from employing a unit of 10 inches, making a new foot, or ped, for the centre of the system, counting its multiples up to 10,000, and the divisions of it into 10,000 parts called minipeds. Thus:—
10,000 minipeds = 1 ped.
10,000 peds = 1 myriaped.
Volumes.—A new measure, which may be called a vol, is made the centre, it being the tenth part of a gallon, counting it up to 10,000; the vol itself being divided into 10,000 parts called minims, thus showing the advantages to be derived from dividing the pound weight into 10,000 minis, for the weights and volumes for water can be made identical throughout, and can thus check each other. Thus:—
10,000 minims = 1 vol.
10,000 vols = 1 myriavol.
The weights, measures, and volumes are thus all shown to be connected and intercalculable.
These papers form a continuation of a former paper on the currency.
3. “Some Notes on the Glaciation of Wakatipu Region,” by Professor James Park, F.G.S.
This paper traversed Dr. Marshall's views as to the ancient glaciation of Otago. The author believed that the glacial epoch consists of two phases, the first being the period of maximum refrigeration, when the greater portion of the South Island was covered with an ice-sheet, and the second the period of valley-glaciation. He contended that the surface-features everywhere showed two generations of erosion—namely, the glacial, distinguished by smooth, flowing contours; and the fluviatile, impressed on the former, and often obliterating it. Domed hills, truncated spurs, and glacial shelves were to be seen in many places along the east coast of Otago; and added to these there was the Taieri moraine, over twenty miles long, three miles wide, with a thickness exceeding 1,000 ft. It was the greatest accumulation of morainic material in New Zealand, and, when considered in conjunction with the glacial surfaces, must be taken as conclusive proof that the Otago ice-sheet reached the present coast-line. The author contended that, judged by the criteria of glaciation formulated by Dr. Marshall, no ice-sheet ever crept over Scotland. No terminal moraine, for example, marked the southern limit of the ice-sheet in England. Chamberlain, Garwood, and others had shown that the differential movement of the layers of a glacier were due to thrust, disproving Dr. Marshall's contention that ice was incapable of producing thrust. The Hector mountains showed ice erosion up to 6,500 ft., and Ben More was terraced to nearly the summit, 6,000 ft. high. The author considered his estimate of 7,490 ft. thick a conservative one. Taking the mean gradient of the Greenland ice-sheet, the Wakatipu ice-sheet must have reached the east coast.