Building Stones.

The older formations, owing to the numerous well defined joints generally passing through the rocks in different directions—the cause of the polyhedric debris, or shingle covering our mountain sides—have hitherto not yielded a single building stone, except for coarse rubble work. Latterly however the attempt has been made in the Malvern Hills and the Kakahu river to utilise some deposits of marble for ornamental purposes. Some blocks of fair dimensions have been brought to Christchurch and Timaru, but I am not aware if specimens of similar sizes may be obtained in any quantity.

Both the Waipara and Oamaru formations are capped by a calcareous sandstone (or perhaps more correctly named an argillaceous limestone), which may be considered one of the best building stones in the Colony. This stone, easily cut by the saw when quarried, has an even texture, hardens on exposure, and can be worked with great facility. It occurs in several tints from a greyish to a yellowish white. This building stone (Oamaru formation) has for years past been exported from Oamaru to Australia and other Colonies, and page 463similar stone from the White Rock quarries north of the Ashley and some other localities has gained much favour with the public. There have lately been opened quite a number of quarries in the Canterbury province in many localities, as for instance in the Weka Pass, the Waipara, Rampaddock, and Mount Brown, at the Ashley and in Castlehill basin. In the southern portion of the province the same free stone is of common occurrence, and will no doubt be extensively used, and exported in years to come.

Besides this calcareous stone, there are a few deposits of sandstone occurring in the Waipara and Oamaru formations, which might prove useful for building purposes, although they are generally of too incoherent a nature for outdoor work. Some of the gritty sandstones of the Grey coal measures, at the West Coast, will however make an exception, as they may be classed with the best building material of that kind. Of igneous rocks, some of the fine grained granites and syenites in Westland, and of the quartziferous porphyries of the Malvern Hills and Mount Somers might be utilised for monumental buildings, although their hardness, and consequently the difficulty of working them, has hitherto prevented their introduction. The Anamesites at Timaru have however been already extensively used for a great number of buildings in that town and its immediate neighbourhood, and I have no doubt that the same material from the Malvern Hills will be quarried in years to come for the same object. They also would form valuable millstones.

Amongst the volcanic rocks of Banks' Peninsula, a number of very fine building stones of various colours, qualities, and value exist. For rubble buildings two kinds of rock have principally been used of late years, of which one is a dolerite flagstone, from the so-called Guise Brittan quarries, and another a porphyritic dolerite lava obtained principally in Tait's and Greig's quarries. Besides these two characteristic rocks, taken from well defined lava-streams, there are a number of dykes offering excellent building and dressing stones. Many of them will rub to a fine face. They are all mostly of a trachytic nature.