Page:Picturesque Dunedin.djvu/94

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84
PICTURESQUE DUNEDIN.

of the fact, that the rare phenomenon of sonorous or musical sand is stated to be occasionally heard.

The Moa deposits in the neighbourhood of Dunedin are not extensive; crop-stones are occasionally met with, and only recently a tolerably perfect skeleton of dinornis casuarinus was ploughed up at Green Island. Mr J. Buchanan, F.L.S., one of the early settlers, has informed the writer that very numerous bones existed on the surface of the ground on Maungatua, but that the first fires destroyed them.

II. Pleistocene, Newer Glacier Deposits.—Formerly it was believed that glacially striated stones, with boulder clay and grooved rocks, were to be observed in, or near Dunedin, but on closer examination it was found that the former were merely spheroidal masses of basalt, in which decomposition had revealed a previously hidden structure, resembling striation. The grooved rocks also were found to be caused by water running over calcareous sandstones, in which it had formed narrow gutters.

Older Pliocene (?)—The large glacier deposit described on p. 79, and extending from Brighton southward, is referred by Prof. Hutton to this period, but Sir Jas. Hector considers it to be either Miocene or Eocene, at any rate prior to the latest manifestation of volcanic agency within the Otago district.

III. Cretaceo-Tertiary.—This formation has been determined by Sir James Hector, on account of the impossibility of making a distinct division between the Tertiary and Secondary periods. It comprises a large series of strata, which are stratigraphically associated, and contain many fossils in common throughout; "while at the same time, though none are existing species, many present a strong Tertiary facies from both the highest and lowest parts of the formation, but even in the upper part, a few are decidedly Secondary forms." (Hector "Guide to Geol. Exhibits, Ind. and Col. Exhibition," p. 55.) In the vicinity of Dunedin, the formation is commercially important, as in it are the coal deposits. As its area and character are described elsewhere, it need not be further referred to. In the appendix will be found some details of the more distant portions at Shag Point, and in the Clutha District.

IV. Palæozoic. Silurian or Lower Carboniferous (?)—The schists, which approach Dunedin to the south and south-west, and