Page:Picturesque Dunedin.djvu/103

From Wikisource
Jump to navigation Jump to search
This page has been validated.
GEOLOGY OF DUNEDIN.
91
Augite.
Hornblende.
Scolecite (?)
Gismondite.
Prehnite.
Natrolite.
Chabasite.
Gmelinite.
Nepheline
Clay.
Halloysite.
Muscovite.
Orthoclase Sanidine.
Labradorite.
Oligoclase.


IV.—Appendix.

No account of the geology of this portion of Otago would be complete without a reference to the adjacent coal-fields of Kaitangata and Shag Point.

The former is situated north of the Clutha River, about 40 miles to the south-west of Dunedin, and covers an area of about 40 square miles. The coal measures may be traced to 9 miles north of the Tokomairiro river, where the schist again appears.

The formation consists of conglomerates, sandstones, clays and shales, with coal seams, forming hills 700 feet high in the neighbourhood of Kaitangata, and of less altitude to the north, where they rise against the flanks of Mount Misery, which is upper schist rock. Very good sections would be exposed on the coast, were it not that faults have somewhat obscured the sequence. The seam worked in the Kaitangata Railway and Coal Company's mine, which is at present the only important undertaking on the field, varies in thickness up to over 30 feet. It is, however, somewhat dislocated, and the dip varies from a moderate inclination up to 45 degrees. The coal is a lustrous, black, compact fuel, with a conchoidal fracture. It ignites readily, and forms a first-class household and locomotive coal; but on account of the contained water, which causes it to ultimately break up on exposure, it is not fitted for long sea