Art. LXII.—On the Sand-worn Stones of Evans' Bay.

Transactions and Proceedings of the Royal Society of New Zealand, Volume 2, 1869, Page 247

Art. LXII.—On the Sand-worn Stones of Evans' Bay. By W. T. L. Travers, F. L. S. (With Illustrations.) [Read before the Wellington Philosophical Society, February 9, 1869.] The first specimen of these curious stones brought under my notice was given to me by young Mr. Hackworth, the son of the Acting Collector of Customs here, who informed me that he had found it near an old Maori kitchen-mound, in Lyall's Bay. This specimen (Fig. 1), is an inch and a half in length, pointed at both ends, and presenting three equal triangular facets. Both extremities of the stone have a slight twist in opposite directions, such as would, if it were used as an arrow-head, insure its more direct flight, in the same manner as the twist given to a bullet by the rifling of a gun. The facets, moreover, are perfectly smooth and slightly concave, and the edges quite sharp. A cross section anywhere would give an equilateral triangle, the greatest length of side, through the middle of the stone, being rather over half an inch. Looking to the extreme regularity of the shape of this stone, it is difficult, even with our present knowledge of the manner in which it was formed, to realize the fact that it is not an artificial production. When I first obtained it, I showed it to Dr. Hector and Mr. Mantell, and although we all came to the conclusion, at that time, that it was an artificial production, we were unable to assign any particular use to it. The most plausible suggestion was that it had been used to cut and polish the grooves in the “Hei Tiki” or jade ornaments worn by natives of rank. However, on applying to several Maoris, they said that they had never seen any stone like it, and that the grooves in the “Hei Tiki” were not cut in the manner suggested. A short time after I received the stone I again saw young Mr. Hackworth, who described to me where he had found it, and promised to show me the exact spot, at the same time informing me that “there were plenty more there.” This was somewhat puzzling, and soon afterwards I went to the locality indicated, in company with Dr. Hector and Mr. Mantell, who were both anxious to solve the apparent mystery, and we then found that this stone had been reduced to its present form by an action, and under circumstances which I will now describe to you, and at the same time we collected the series of illustrative specimens now on the table. You all know the peninsula occupied by Mr. Crawford as a sheep run, which lies at the eastern side of Evans' and Lyall's Bays, and you also all know that the side of that peninsula adjoining those bays presents a pretty

regular hill face running north-west and south-east. The hills on the western side of both bays also present an equally regular slope running in the same direction. The distance between these two ridges is about half a mile, and the space intervening between the waters at the heads of Lyall's and Evans' Bays is occupied by a boulder bank and sand-dunes, about a mile or a mile and a quarter in width. The boulder bank lies in the middle of this space, and forms a ridge sloping from a summit towards both bays—the summit being slightly higher than the general level of the sand-dunes on either side of it. Between the boulder bank and the water line in each of the bays, lie these sand-dunes, composed of ordinary siliceous sea sand, here and there clothed with the vegetation usual to such habitats. The stones composing the boulder bank are chiefly sandstones, varying much in size and hardness, and in some instances intersected with little veins of quartz. Now you are aware that the prevalent winds here are north-west and south-east, and blowing as they frequently do with considerable force through the opening between Evans' and Lyall's Bays, they are constantly carrying the sand of the dunes from one side of the boulder bank to the other. The motion of drift-sand is by a succession of jumps along the surface of the ground, and, strange as it may seem, it is the cutting action of the sand in its passage over the boulder bank which produces these stones. This is evident from an examination of the series of specimens before you, and becomes the more so when they are seen in the locality indicated. The action of drift-sand in cutting rock has long been observed, and, indeed, in the Museum you have many specimens illustrative of this action, but in no instance that I am aware of, has it been noticed as producing results of so remarkable a character, as those which I have so imperfectly brought before you. The cutting action of drift sand has received much attention from geologists and engineers engaged in examining the line of the great Pacific railway, and it would be interesting to ascertain whether anything of the same kind had been observed by them.