Geological and other Reports
Wellington, December 13, 1863
I have the honor to inform you, that on the 8th November ultimo, I discovered a series of strata on the shores of Porirua Harbour, containing impressions of plants and carbonized substances. There are at least six of these strata, of various widths of from fourteen, to two or three feet; and with the associated shales and sandstones they make up a thickness of at least 800 feet,
I have strong reasons for supposing that these strata belong to the true carboniferous era, but, as I hope to be able soon to obtain the opinion of an eminent palæontologist, it may be as well to defer their further consideration for another report. The locality is between the Peninsula of Tutae Manu and Duck Creek, on Porirua Harbour.
In an endeavour to trace this series to the Belmont road and the Hutt, I have found a fossiliferous stratum on the above named road, which it is to be hoped will throw some light on the age of the rocks.
On my return from this latter expedition, I observed some very mineral looking pyritous quartz, at a point which the roadmen are cutting down, on section No. 14, Harbour District, on the south side of the big slip on the Petoni road, Pyritous quartz has long been known to exist here, but perhaps this is the first time that a section of the rock has been so well exposed.
Dr. Levy, (a French Geologist who has been residing here) very kindly undertook the analysis of a piece of this rock and his report is, no gold, but containing sulphide of antimony, cobalt, iron and mica. Another specimen he reports rich in chromate of iron.
Now the effect of this discovery is much greater than may appear at the first glance, for it proves the existence of mineral veins in the rocks of this district, a point hitherto undetermined. The minerals discovered may also be looked upon more as indications for the discovery of more valuable metals in the same or other lodes, than as being valuable in themselves, although chrome and perhaps cobalt if found in sufficient quantity on the shores of this harbour would doubtless prove valuable exports.
The quartz at the point indicated is laminated and corrugated, and a similar quartz is found at many different points. On the hills above, I think I made out several lodes, also on the Ohariu road, behind Dr. Taylor's the same veins appear to crop out. I have heard of similar quartz in the Ohariu valley and at Terawiti, and I think I also found it at Waikanae.
As the discovery has taken place on private land, and as most of the land in the district has been sold, perhaps the Government cannot do more than call the attention of the public to the fact.
At the point of discovery on the Pe- page 6 toni road there is at least one lode of some 14 feet thick, and I think the roadmen are likely soon to lay bare the face of another. These might be easily proved on the level, by simply driving into the hill, but proving in depth would of course be more expensive Possibly a careful examination might show a series of parallel lodes, all of which might be proved on the level by one drift at right angles to their direction.
I may state that Dr. Levy was strongly impressed with the idea that the quartz ought to be auriferous, and although he failed to find gold in the sample operated upon, yet he thought it likely to be found in others.
Should indications of metals and mineral veins continue to be discovered, the necessity of having the services of a good and trustworthy analytical chemist, will be very much felt.
The schistose rock adjoining these quartz lodes would appear to underlie the soft sandstones, which may again underlie, or else form part of, the series of the carboniferous rocks of Porirua Harbour.
I have the honor to be,
Your most obedient Servant,
James C. Crawford,