Page:Picturesque Dunedin.djvu/100

88, and some few parts where the trachytic roots have unfavourably influenced it, we have usually a rich decomposed basaltic soil, mingled in some places with the débris of limestone, and thus forming a most excellent material for dairy produce. The swampy flats, now drained, of the lower parts of Dunedin, and of the Taieri plains, are wonderfully fertile: the latter being formed in great part of decomposed schist rock, brought down from the interior of the Province, and enriched by the decay of many generations of plants.

The building stones surrounding Dunedin are principally in the volcanic rocks; certainly the Caversham sandstone has been used for this purpose, but without success, as it is incapable of resisting the action of the weather. The following analysis indicates its composition, which is mainly carbonates of lime and magnesia, with a small proportion of silica:—

On the Peninsula, near the camp, is averya very [sic] good siliceous sandstone, which has been utilised by the Hon. Mr Larnach in building portions of his residence. From the volcanic series can be obtained not only the hard bluestone or basalt, but also trachytic breccias of considerable beauty and great durability; both are largely used in the public buildings of the city. For purposes of cement manufacture, very good limestones exist in several parts of Otago; and there is a large deposit of valuable hydraulic limestone in a line extending from Seal Point on the southern side of the Peninsula to Dowling Bay on the northern shore of the lower harbour. This yields an excellent material, but, unfortunately, the cost of cartage is too great to allow of its being extensively utilised.

The necessary mud for the manufacture of Portland cement is obtained from the Dunedin harbourharbour. [sic]