H.—34.

pectens in the strata are black, whereas the fragile shells are white. Opoiti beds also outcrop for two miles along the upthrow side of the Waikopiro Fault. The series is about 1,200 ft. thick. Though the beds appear to be parallel with those of the underlying Tertiary groups, their base was observed to be directly on greywacke and also on Tutamoe beds, the Mapiri Series not being present. Evidently there was a period of uplift and erosion before the deposition of the Opoiti strata. Te Aute Series.—The lowest bed of the Te Aute Series is a massive sandy limestone containing many shell fragments and at the base numerous pebbles of greywacke, sandstone, and mudstone. Blue sandy mudstone, 400 ft. thick, overlies, followed by a 50 ft. band of strongly cemented limestone, above which are blue-grey sandy mudstones with concretionary bands. The whole series is about 2,000 ft. thick. In places the lower Te Aute limestone rests on a bored surface of Opoiti sandstone and this, with the sandstone pebbles it contains, suggests erosion of the underlying sandstones. The bedding in these massive layers is obscure, angular unconformity is not proved, and in two localities three miles apart the highest member of the Opoiti beds has the same thickness under the Te Aute limestone. Petane Series. —The Petane Series consists of rocks lithologically similar to those of the Te Aute Series. The lowest bed, a strong limestone consisting largely of shell fragments, contains numerous shells as well as calcareous algse. Fossiliferous blue sandstone and mudstone, 300 ft. thick, overlies, followed by limestone which weathers reddish-brown and has characteristic cemented layers. On this rests in upward sequence 200 ft. of less fossiliferous blue mudstone, 30 ft. of coarse current bedded sandstone with shell bands, 20 ft. of sandy shell limestone, and 300 ft. of blue mudstone and sandy mudstone that weathers to a dull-orange colour. Altogether about 1,100 ft. of strata are contained in the Petane Series of the district. The lower limestone may be in contact with a worm-bored surface of Te Aute or Opoiti strata, and at one point there is angular discordance of about 15°. Movement and erosion separate this series from the Te Aute beds. Mangatarata Series.—Current-bedded pumiceous sands and silts containing fragments of greywacke and mudstone, and interbedded with thick bands of well-consolidated greywacke gravels, predominate in the Mangatarata Series. A few lignite bands occur. Lithologically similar beds in the Clifton district east from Napier conformably overlie massive beds containing Castlecliff fossils. Near Norsewood finely banded lake silts and sands should perhaps be separated from the Mangatarata beds. Pleistocene and Recent.—The greywacke gravels of the high terraces form the Pleistocene deposits of the district. Those of the flood-plains and low terraces, together with the red volcanic ash and the intermediate terraces near Norsewood, are of Recent age. Economic Geology. Shell limestone is quarried and pulverized in the Maharakeke valley for agricultural purposes. There are vast deposits of this type of limestone which, however, is usually not of high grade. Samples from this district so far examined show a content of from 20 per cent, to 40 per cent, of insoluble material. The fine, well-graded silica sand forming lenses in the Mangatarata beds at a few points may have value in industry. The pumiceous silts of the same series could be used in sandsoaps or as a filler in bituminous surfacings. Some of these silts have pozzolanic properties. Roadmaking materials occurs in vast amount. Though there is definite evidence of the presence of petroleum farther east, the prospects of the Takapau district are distinctly unfavourable. The Tertiary beds of the district are 5,000 ft. or more thick, but likely source rocks such as shales and mudstones are relatively thin, and though several faults are active no oil-seepages or gas-emanations are known. REEFTON GOLDFIELD. By Maxwell Gaoe. A geological re-examination of the Reefton goldfield which has been carried out during the preceding two field seasons in connection with the geophysical survey has now been completed. The eastern portion of the auriferous belt was studied at Alexander River and Kirwan's Hill, and a small antimony-bearing reef in McConnochie Creek was examined. The area consists mainly of greywackes, quartzites, argillites, and phyllites of the Greenland Series. Considerable areas are occupied by granite, and, in addition, there are infaulted small blocks of mudstones, sandstones, breccia, and comglomerate of Tertiary age, denuded remnants of Tertiary cover, as well as basic igneous intrusions, morainic materials, and alluvium. No fresh localities of Devonian fossiliferous rocks have been discovered. Attention was, as before, directed almost entirely to the gold-bearing series. The difficulties that in the past have hampered detailed geological mapping of these rocks were again encountered, and to combat them methods were employed similar to those described in the introductory paragraph to the previous annual report on the work in this area. These, however, proved rather less successful owing to the prevalence of faulting in the eastern area and to the common occurrence of massive greywacke in which the bedding is obscure over considerable distances.

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