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The Pamphlet Collection of Sir Robert Stout: Volume 71

IV., V., and VI

IV., V., and VI.

These are subdivisions which have been distinguished on the map of the Cretaceo-tertiary formation, which includes in one sequence all the strata from the lowest Tertiary to the Middle Chalk.

The formation indicates a gradual but extensive subsidence of the land, from the earliest to the latest-formed members of the sequence.

The upper division (IV.) contains:—
1.Grey Marls.—These are strata of fine gravel sand, clay with beds of pure sand, and layers of indurated sandstone. This passes into
2.Ototara Stone.—This is also known locally as the Weka Pass sandstone, and consists of a calcareous sand sometimes estremely pure and even-grained, and having the particles cemented with infiltrated lime. This stratum affords the well-known Oamaru stone that is so extensively used both in New Zealand and Australia for ornamental building purposes.
3.At the base of the Ototara stone there is a concretionary [unclear: bed] containing inclusions of pure limestone, and nodules of lime [unclear: phosphate], varying from lin. to 5in. in diameter and of very [unclear: irregular] form. The matrix of this strata is a light-green calcareous sand. [unclear: It] has been observed occupying the same position at many [unclear: distance] localities, but can be nowhere better studied than at the foot of [unclear: the] Big Bluff in Gore Bay. This bluff is 270ft. high, nearly [unclear: vertical,] and from top to bottom composed of the grey-marls, 170ft.; [unclear: Ototan] stone, 90ft.; nodule layer, 10ft. This is not the total [unclear: thickness] however, as a measurement I made some years ago of the same [unclear: bed] in the Kaikoura Peninsula gave a thickness of 1,250ft.

In the grey-marls, towards the upper part of the section, [unclear: several] strata, from a few inches to 2ft. thick, of pure sand occur, one [unclear: in] particular being of very even grain and rich brown colour, that [unclear: would] probably answer well for moulding purposes.

The reported coal proved to be merely a few blocks of [unclear: drift] page 9 wood cemented into lignite and imbedded in one of the sand-layers, but not form Lug anything like a regular or workable seam, being in irregular masses like compressed timber, and having the woody structure preserved.

Two of the best samples were gathered for analysis, and gave the following results:—

Laboratory No. 6381 (A) and (B)—Lignite: Colour black and lustrous, but showing woody structure. Powder brown-black; ash red, being nearly pure iron sesquioxide.

Compositions.
(A.) (B.)
Fixed carbon 35.87 35.52
Gas and tar 28.48 28.63
Moisture 29.22 2.82
Ash 6.43 6.03
100.00 100.00

1lb. of (A) evaporates 4.651b. of boiling water; 1lb. of (B) evaporates4.6llb. of boiling water.

If a solid seam over 6ft. thick of this lignite could be found it would afford a fairly useful fuel, but under the circumstances such a discovery is not probable. The phosphatic nodules could not be profitably mined at the locality where they are exposed on account of the mass of the cliff; but the outcrop of the stratum could be traced into a more favourable position for working, as, for instance, along the south side of the Jed Valley from the Dingle to the homestead.

An average nodule was analysed, with the following results:—

Laboratory No. 6382.—A nodule of the mass afforded 24.70 per cent, of phosphate of lime, while the average sample gave the following results:—
* Tricalcic-phosphate 23.87
Carbonate of lime 49.56
Carbonate of magnesia 2.04
Siliceous matters 23.24
Water 1.29
100.00

These results show that the proportion of phosphoric acid is nearly uniform through the mass, and that the mineral would have a certain value for agricultural purposes when finely pulverised.

* Equal to 11.00 per cent. of phosphoric acid on the mineral.