Wide, Flat, and Thin Form, with Transverse Ridge

This is a lone specimen of black-veined aphanite, and an interesting one (see Fig. 89, Plate XIV). It is 11½ in. long, 4⅝ in. wide at the cutting-edge, whence it narrows to 2⅞ in. at the poll. The face is convex both longitudinally and transversely, but not markedly so. The back is straight, save for a natural hollow (apparently) of the original surface of the stone. The sides slope inwards to the back, and preserve almost the same thickness throughout, from 1⅝ in. to 1 in., the latter figure representing a thinning of the butt end. The transverse ridge is not so prominent as those of the other specimens described, and has a rounded top. It is the only specimen in which the ridge is not situated on the shoulder-line, where the maximum thickness of the tool breaks down into the blade-bevel. In this case the ridge is situated 1 in. back from the shoulderline, which, however, is not a sharply defined one. This specimen is not wholly ground. The angle of inclination of the blade is from 35° to 20°. Weight, 4 lb.

The use or purport of this peculiar transverse ridge is not understood by us. It can scarcely be left for the purpose of page 303strengthening the tool, for it is situated at the thickest and strongest part thereof. Whether the stone-worker of yore left it for use or ornament we wot not, but it assuredly gave him a considerable amount of extra labour to form such a ridge, and much lengthened the period of time occupied in the manufacture of the adze. In this wise: The tool could not be rubbed lengthwise on the grindingrock, or the ridge would be ground down and soon be no more. It had to be rubbed sideways on the grinding-stone, and the parts adjacent to the ridge would probably have to be rubbed down with a hand-stone, a slow process. Some of these forms, indeed, show plainly the transverse striæ that betoken rubbing sideways on the grinding-stone, or vice versa.

Were this ridge situated on the face of the adze it might be thought that it was designed as a sort of fulcrum to assist in forcing off a thick chip or sliver. But they are invariably on the back of the adze, and so situated that they would not come into contact with the timber being worked. The thickness of blade in the stone axe also precludes the idea that the ridge was left for the purposes of clearing the chip. No danger that so thick and blunt a blade would "bind" in timber.

The only idea that occurs to us in regard to the utility of this ridge is that the lower part of the handle may have been butted against it, so that when lashed tightly on it prevented the adze from being forced upward and displaced by the shock of the blow when used. But, apparently, no lashing would have been applied so low down, or it would come into contact with the timber being worked, and thus render a blow ineffective. The utility of the transverse shoulder-ridge is not proven. In those specimens that have the butt end worked down to accommodate the lashing the cord used has not extended more than about 3 in. from the poll.

The supplementary ridge is never seen, says Mr. H. D. Skinner, in any collection of stone adzes from the Taranaki district; and he is of the opinion that it was confined to South Island forms.