MINES DEPARTMENT. GEOLOGICAL SURVEY BRANCH [SEVENTEENTH ANNUAL REPORT (NEW SERIES) OF THE].

Appendix to the Journals of the House of Representatives, 1923 Session I-II, C-02c

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Session 11. 1923. NEW ZEALAND.

MINES DEPARTMENT. GEOLOGICAL SURVEY BRANCH [SEVENTEENTH ANNUAL REPORT (NEW SERIES) OF THE].

Laid on the Table of the Howe of Representatives by Leave.

CONTENTS.

PAOE rAaB Letter of Transmittal .. .. .. .. 1 6. Owera-Materangi District (P. G. Morgan) .. 8 7. Copper Deposits near Cape Runaway (JVI. Ongley Director's Retort, and E. (). Macpherson)' .. .. ..10 Summary of Field Operations .. .. .. 2 8. Taupo Earthquakes (P. G. Morgan) .. .. 10 Progress of Areal Survey .. .. .. 2 9. Paint-pigments near Pukeiti Hill, South-west of Dargaville Subdivision .. .. .. ..2 New Plymouth (L. I. Grange) .. ..11 Waiapu Subdivision .. .. .. 2 10. Wanganui-Hawera District (J. Marwick) .. 11 Tongaporutu-Ohura Subdivision .. .. .. 3 11. Paint-pigments, Onahau, Nelson (J. Henderson) 11 Waihi Goldfiold .. .. ..' ..3 12. Marble in the Takaka District, Nelson (J. IleuPalseontological Work .. .. .. . .* 3 derson) .. .. .. .. .. 12 Publications and Reports in the Press .. .. 3 13. Coal in the Takaka District and in the Otimataura Office-work, &c. .. .. .. 3 Valley (J. Henderson) .. .. .. 12 Library .. .. .. .. 3 14. Talc Schist in Springburn Valley, Kawarau Survey District, Otago (J. Henderson) .. 12 SrECiAL Reports. 15. Notes on the Geology of the Nevis Valley, Otago 1. Dargaville Subdivision (H. T. Ferrar).. .. 4 (J. Henderson) .. .. .. .. 12 2. Waiapu Subdivision (M. Ongley and E. 0. Mac- 16. Cinnabar in Greenvale Survey District, near pherson) .. .. .. .. 5 Waikaka, Southland (.T. Henderson) .. 12 3. Tongaporutu-Ohura Subdivision (L. I. Grange) 7 17. Notes on the Geology of the Naseby District 4. Supposed Petroleum Indications near Silverdale, (J. Henderson) .. .. .. 12 North Auckland (H. T. Ferrar) .. .. 8 18. Gold and Platinum in the Oropuki District B, llauraki Mine, Coromandel (P. G. Morgan) .. 8 (J.Henderson) .. .. .. ..13

LETTER OF TRANSMITTAL.

Sir, — Geological Survey Office, Wellington, 19th June, 1923. I have the honour to forward herewith the seventeenth annual report of the Geological Survey Branch of the Mines Department. This report covers the work of the Geological Survey for the twelve months ended 31st May, 1923. In addition to brief reports on the districts examined in detail by the field geologists, various special reports, or summaries thereof, are appended. I have, &c, P. G. Morgan, Director, Geological Survey. The Hon. G. J. Anderson, Minister of Mines, Wellington.

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DIRECTOR'S REPORT. Summary of Field Operations. During the field season of 1922-23 detailed topographical and geological surveys have been in progress in the following districts : — (1.) Dargaville Subdivision, North Auckland, under the charge of Mr. H. T. Ferrar, M.A., F.G.S., assisted by Mr. W. H. Cropp, A.0.5.M., in the early part of the-season, and later by Mr. E. 0. Macpherson, Assistant Geologist. (2.) Waiapu Subdivision, East Cape Peninsula, under the charge of Messrs. M. Ongley, M.A., B.Sc, and E. 0. Macpherson, Assistant Geologists. (3.) Tongaporutu-Ohura Subdivision, North Taranaki, under the charge of Mr. L. I. Grange, M.Sc, A.0.5.M., Assistant Geologist. Field-work in. all three subdivisions has been completed, and detailed reports are in course of preparation. During June-July, 1922, and again in November-December, I was engaged at Waihi in obtaining additional data for a report on the Waihi Goldfield. In addition. I made brief visits to the following places : Taupo, Te Puke, Coromandel, Opitonui, Owera, and Kuaotunu. Dr. Henderson, Mining Geologist, during September, 1922, visited Takaka and Onahau. Later in the year he inspected various localities in Otago and Southland, including Orepuki, Waikaka, Waikaia, Nevis, Springburn Valley, Naseby, and Kaitangata. During February and early March of this year he made an examination of the asbestos deposits of the upper Takaka Valley. Promising data were obtained, and it is proposed to continue the examination next field season. On the 12th and ,13th March Dr. Henderson visited the Mangahao hydro-electric works and examined the excavations at the Arapcti dam-site. During October, 1922, Mr. H. T. Ferrar made a visit to the Silverdale (Wade) district in order to inspect some reported indications of petroleum. Mr. J. Marwick, Assistant Geologist and Palaeontologist, during September, 1922, visited various localities in the WanganuiPatea district in order to make representative collections of fossils and obtain general geological information. Messrs. Ongley and Macpherson during November made a special examination of copper deposits in the Cape Runaway district. In December Mr. L. I. Grange inspected mineralpaint deposits near Carrington Road, at a spot somewhat over ten miles in a direct line south-west from New Plymouth. Particulars regarding most of these visits and the data obtained will be found on later pages. At the time this report was sent to the printer Dr. J. Henderson's full report on the upper Takaka or " Mount Arthur " asbestos deposits was not completed, but an interim report will very shortly appear in the New Zealand Journal of Science and, Technology (Vol. vi, No. 2, 1923). Progress of Areal Survey. During the twelve months ended 31st May, 1923, an area of 1,106 square miles was geologically surveyed in detail, and incidentally much topographical work was done. Of this area 382 square miles is in the Dargaville Subdivision as originally defined, 102 square miles in adjoining territory, 298 square miles in the Waiapu Subdivision, and 324 square miles in the Tongaporutu-Ohura Subdivision. The present state of the detailed geological survey is given in the following table, which contains also the corresponding data for last year: — , 1921 22. 1922 23. Sq. Miles. Sq. Miles. Surveys completed and work published on the scale of 1 in. to the mile .. .. .. .. .. .. 8,884 9,674 Surveys completed and work published on the scale of Jin. to the mile .. .. .. .. .. .. 325 325 Field surveys completed but work not yet published .. 5.509 7,276 Surveys in progress —area actually surveyed .. .. 1,553 102 Total area surveyed .. .. .. ..16,271 17,377 Area in which work is suspended (Hcaphy) .. . . 293 293 Areas resurveyed (Whatatutu and Waihi) . . .. 352 352 Dargaville Subdivision. Field-work during the 1922-23 season covered the southern part of the Dargaville Subdivision, which in the main is a strip of country extending across the North Auckland Peninsula from the coast south-west of Dargaville to Bream Tail. The adjoining peninsula north of the entrance to Kaipara Harbour was also surveyed. Attention was given to the soils, the limestones (which cover large areas and are of great value), sands, clays, and kauri-resin deposits. Coal occurs near Waipu, but there is little likelihood of any workable seam being present. Outcrops of volcanic and other rocks suitable for roadmaking were mapped wherever they occur, and the information obtained will be of value to road engineers and others. Waiapu Subdivision. The area of the Waiapu Subdivision has been extended by including Raukumara East, M'atakaoa, and East Cape survey districts, which were examined during the last field season. In these districts occur several gas-vents, some of which, emit large quantities of inflammable gas containing in addition to methane, a considerable proportion of heavier hydrocarbons. Deposits of limestone and greensand were examined, and vast bodies of hard igneous rock were mapped. Since other

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parts of the East Cape-Gisborne district are notoriously deficient in rock suitable for roadmaking, harbour works, and building purposes generally, the last-mentioned deposits arc of great economic value. Tongaporutu-Ohura Subdivision. The area which it has now been decided to call the Tongaporutu-Ohura Subdivision extends over the greater part of North Taranaki and contains a large part of a considerable coalfield, portions of which were described in last year's report and in Bulletin No. 24, lately issued. During 1922-23 Mr. Grange's work extended over Mimi, Upper Waitara, and the western half of Waro survey districts. In this area no indications of petroleum have been found, and Mr. Grange is of opinion that the prospect of shallow boring for oil being successful is slender. Coal may exist in depth. No high-class roadmaking material occurs in the area examined, but conglomerates suitable for roads carrying light traffic outcrop in various places. The geological results of the past season's work are summarized by Mr. Grange on later pages. Waihi Goldfield. The further examinations of the Waihi district made last year on the whole confirm the favourable opinions expressed in the preliminary report published in the New Zealand Journal of Science and Technology (Vol. 5, No. 2, pp. 109-22, 1922). A lengthy bulletin written during the past year has been submitted for publication. Work. During the past year Mr. J. Marwick, M.A., Assistant Geologist and Palaeontologist, has been engaged mainly in examining the Tertiary Mollusca of the Geological Survey collections. Special attention has been given to the collections made by officers of the Survey in the course of field-work and to material collected from horizons adjoining coal-measures, such as the lower part of the Oamaruian and the Wangaloa beds, near Kaitangata. The results now in sight are of importance. It is therefore to bo desired that the difficulties at present attending the publication of scientific work will soon disappear, and that before long those interested will be fully informed of the work already accomplished, thus clearing the way for further progress. Through, the instrumentality of Dr. F. A. Bather, Keeper of the Geological Department of the British Museum, Dr. H. L. Hawkins, Professor of Geology at University College, Reading, has kindly undertaken the description of the Tertiary Echinoderms sent to England in 1913, and since then stored at the British Museum. Some additional material has lately been sent to Dr. Hawkins. Dr. Otto Wilckcns, of Bonn, has examined a few fossils from Shag Point and elsewhere, and in a brief report which he has kindly furnished expresses the opinion that the beds from which the Shag Point fossils come are probably of Upper Senonian age. Publications and Reports in the Press. The following publications have been issued during the year : — Sixteenth, Annual Report (New Series) of the Geological Survey (Parliamentary Paper C.-2c, 1922). Palajontological Bulletin No. 9, " The Upper Cretaceous Gastropods of New Zealand," by Dr. Otto Wilckens. Bulletin No. 24, " The Geology of the Mokau Subdivision," &c, by Dr. J. Henderson and Mr. M. Ongley. Bulletin No. 25, " The Geology and Mineral Resources of the Collingwood Subdivision," by Messrs. M. Ongley and E. 0. Macpherson. Two reports by members of the staff have been published in the New Zealand Journal of Science and Technology (Vol. 5, No. 3). These are " The Genesis of the Puhipuhi Cinnabar Deposits : a Working Hypothesis," by Mr. W. H. Cropp (till lately Geological Assistant), and " Notes to accompany a Geological Sketch-map of the Marakopa District," by Dr. J. Henderson and Mr. L. I. Grange. An article by Mr. J. Marwick entitled " The Genus Glycymeris in the Tertiary of New Zealand " will appear in the overdue volume of the " Transactions of the New Zealand Institute " for the year 1921 (vol. 54). Separates have already been issued. Mr. T. H. Withors's report on " The Fossil Cirripedes of New Zealand," mentioned last year, is now in the press, and is expected shortly to be issued. As already stated, a bulletin dealing with the Waihi Goldfield has lately been submitted for publication. Various other reports are ready, or nearly so, for the printer. Office-work, etc. The office-work during the past year has been of the ordinary character. Reports and bulletins for the printer have been prepared, revised and edited. Various reports, not necessarily intended for publication, as well as other information, have been supplied to the Mines Department. Numerous mineral samples have been examined for members of the public, but in only a very few cases have the results been of more than passing interest. During the year Mr. G. E. Harris, Draughtsman, drew geological maps of nine survey districts, and various other maps to be reproduced by photo-lithography. He also prepared eleven field-sheets, and made a large number of tracings for various purposes. - Library. During the year publications were received from many Geological Surveys in other countries, universities, and learned societies, in exchange for the bulletins of this Survey. The care of the library entails a considerable amount of work, which is increased by the cramped shelving accommodation available for the ever-increasing number of volumes, but the library is invaluable for reference purposes, and the labour expended on it is amply repaid by results.

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SPECIAL REPORTS.

1. Dargaville Subdivision. (By 11. T. Ferrar.) Introduction. The systematic survey of North Auckland has been continued during the past season, which extended from the 12th October, 1922, until the 20th May, 1923. During this period an area of some 484 square miles was geologically mapped, and an excursion to Silverdale was made in order to report, upon an alleged occurrence of mineral oil in that locality (see Special Report No. 4). During various portions of the season assistance was rendered by Mr. W. H. Cropp, A.0.5.M., Field Assistant; Mr. E. 0. Macpherson, Assistant Geologist; Mr. P. T. Cox, 8.A., New Zealand University Senior Scholar ; and Mr. H. E. Fyfe, Otago University. A strip of country extending from Bream Tail on the east coast to Kaipara North Head on the west coast was mapped in detail on a scale of 20 chains to the inch. This area, which is immediately to the south of the strip surveyed last year, includes the survey districts of Mangawai, Waipu, Matakohe, Tokatoka, Kopuru, Te Kuri, North Head, part of Hukatere, and part of Okaka, a closely settled but hitherto geologically unexplored district. Physiography. The district mapped during the past season displays five types of country —namely: (I) tilted fault-blocks of greywacke which in part have been stripped of their covering of younger sedimentary rocks ; these fault-blocks rise to heights of 1000 ft. or so, and are confined to the neighbourhood of Waipu : (2) hills of dacite and andesite which cover a belt of country stretching from Mangawai to Maungaturoto and rise to heights of 800 ft. and 900 ft. above sea-level; the conspicuous rocky peaks of Tokatoka and Maungarahu also belong to this typo : (3) a dissected peneplain of Notocene limestones, claystones, and sandstones, with an average height of 500 ft. above sea-level, which occupies the greater part of Matakohe and Tokatoka survey districts : (4) a belt of consolidated sand-dunes, 400 ft. to 500 ft. high, which occupies the peninsula extending south-westward from Dargaville to Kaipara North Head ; on the sea-board of this peninsula a fringe of moving dunes, 20 ft. to 30 ft. high, expands to form the North Spit at the entrance to Kaipara Harbour : (5) the recent alluvial flats of the Wairoa, Waipu, and Mangawai estuaries and of the inland valleys. With the exception of the Waipu and Mangawai, all the larger streams of the area flow to Kaipara Harbour, by way of its numerous ramifications. Some of the streams, notably the Piroa, have maintained their courses across uplifted fault-blocks ; others, such as the Pukekaroro, have cut their way through ranges of volcanic rocks ; and others again, such as the Mangonui, a tributary of the Northern Wairoa, have entrenched themselves in the peneplain of Notocene sediments. General Geology. The most comprehensive report upon the district is that by S. H. Cox in " Reports of Geological Explorations during 1879-80," No. 13, 1881. In 1885 (R.G.E. No. 17) and again in 1887 (R.G.E. No. 18) Park examined portions of the area with a view to locate coal which was supposed to be present in the district. He rightly pointed out that if coal existed it would crop out on the surface owing to the high angles of dip of the strata, and recommended surface prospecting rather than boring. Since 1885 no geological map of the district has been published. The account of North Auckland, stratigraphy, as outlined in the Annual Report for 1920, still holds good for the area under review, although uncertainty exists as to the precise age of some of the strata. The oldest rocks found in the district are the greywackes belonging to the Waipapa Formation, which is- regarded as of Trias-Jura age. Such rocks form the hill country surrounding the Waipu basin, and they underlie the central portion of the area, but westward are exposed only at Whakahara, one mile move the wharf at Tokatoka, on the left or east bank of the Northern Wairoa. The argillaceous limestones and claystones of the Onerahi Formation have not yet yielded any internal evidence as to their age. These beds are correlated with the Waiparan of other parts of New Zealand, and are tentatively regarded as Cretaceous. The formation covers large areas in the Waipu, Matakohe, and Tokatoka survey districts, the claystones giving place to argillaceous limestones towards their southern boundaries. The Whangarei Formation is represented by brown sandstone and, locally, by crystalline limestone. The formation is correlated with the Oamaruian of the South Island, the sandstone being provisionally placed in the Waiarekan and the limestone in the Ototaran stage. In the eastern portions of the district the sandstone rests upon the denuded surfaces of the Waipapa greywackes, in the northern and western portions it overlies the argillaceous Onerahi Formation, and in the southern and south-western parts of the district it covers but small areas. Coaly partings are fairly frequent in the sandstone, and near Waipu a thin coal-seam of no commercial value occurs in a sandstone outlier resting on greywacke. Beds of crystalline limestone of small extent are found scattered over the whole area. The long tongue of land between the Wairoa River and the Tasman Sea, extending from Dargaville on the north' to Pouto Pilot-station on the south, consists of consolidated and unconsolidated windformed sandhills interrupted by swampy valleys. A similar though smaller belt of dune-sands occurs in Mangawai Survey District on the east coast. The sand-dunes are of Pleistocene and Recent age. The Horehore and Raupo flats are alluvial plains of recent origin.

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The igneous rocks of the district are mainly volcanic in the broad sense of the term. Dacites form Bream Tail and Mangawai North Head, and extend westwards along an east-west fault as a narrow ridge which ends near Maungaturoto, where the rocks become andesitic in character. The Tokatoka-Mangarahu Range near the Wairoa contains dykes of andesite, dolerite, and allied rocks, and is partly covered by volcanic agglomerates and breccias. There are numerous small isolated occurrences of such rocks in Tokatoka Survey District. Basalt-flows form the Tara plateau near Mangawai, known for its great fertility, and the Mapau ridge in the south-west corner of Matakohe Survey District. The dacites are correlated with the Parahaki Series of the Whangarei - Bay of Islands Subdivision, the andesites and agglomerates with the Wairakau Series, and the basalts with the Kerikeri Series. The following table gives a synopsis of the geological series present in the district, together with the local names of the rock-series and their probable equivalent in type localities : —

Economic Geology. Deposits of high-grade limestone of use to agriculturists have been delineated, and large areas which are covered by argillaceous limestone similar to the hydraulic limestone used at Wilson's (N.Z.) Portland Cement Works have been -surveyed. Outcrops of igneous rocks suitable for macadamizing roads have been carefully mapped. Such rocks occur in quantity in some localities, but are absent from others ; a study of the geological maps when published will show which outcrops are easiest of access to such localities as require road metal. Silica sands, suitable for glassmaking, abound in some localities, but ceramic clays are scarce. The kauri-resin deposits, as is shown by their distribution, accumulated under peculiar conditions, and their mapping will enable the State to utilize for settlement much resin-free land which is at present held in reserve. 2. Wajapu Subdivision. (By M. Onglky and E. 0. Macpherson.) The general geology and oil-indications of the southern parts of the Waiapu Subdivision were briefly described in the annual reports for 1921 and 1922, and only a few notes dealing chiefly with the past season's work need be added. During the season the survey districts of East Cape, Matakaoa, and Raukumara East were examined in detail ; and trips were made through Matakaoa West, Matakaoa North, Raukumara West, Whangaparaoa North, and Whangaparaoa. As a result of the work the northern part of the possible oilfield has been mapped ; several more emanations of " wet " gas and important beds of limestone and greensandstone have been examined and sampled with favourable results ; several dejjosits of cupriferous pyrites and one of coal were inspected and found wanting ; and a large area of igneous rock has been mapped. This last contains an immense amount of stone which will be immediately useful for road and harbour works and for concrete aggregate, and may later be used as a building-stone. The systematic report of the district, with the necessary maps and sections, is being prepared for publication ; the deposits of economic interest will in the meantime be briefly described under the headings of (1) Petroleum and Natural Gas, (2) Limestone and Greensandstone, (3) Copper, (4) Stone for Roadmaking and Harbour-works, (5) Building, Decorative, and Monumental Stone, (6) Coal. (I.) Petroleum and, Natural Gas. No seepage of petroleum is known in the area covered ; but emanations of inflammable gas were examined at four places in. Matakaoa Survey District. Only one sample, that from Tangakaka, has been analysed ; it has the following composition :— Carbon dioxide (C0„) .. .. .. .. 0-75 Methane (CH 4 ) .. .. .. .. .. '74-02 Ethane (C 2 H (i ) .. .. .. .. .. 21-69 Nitrogen (N) .. .. .. .. .. 3-54 The composition is significant, for in the many natural-gas fields that have no oil the gas contains little or no ethane and is called " dry," whereas the oilfield gas, called " wet " gas, is distinguished by its high ethane content. The Tangakaka gas, like the gas from the many other vents in the subdivision, is a " wet " gas, and indicates that oil occurs in the vicinity. The amount of gas escaping was not measured at any place, and can be indicated only roughly. At Omaika the gas escapes slowly in small bubbles ; at Tangakaka and Hart's it escapes freely enough to support a continuous flame ; and at Oweka, a swampy area 4 chains long and 1 wide, is spotted with hundreds of small

Local Name. Description of Strata. Scries or System. Approximate Age. Kerikeri Series Wairakau Series Whangarei Formation Swamps, alluvia, and drift-sand .. Consolidated dune-sands Basaltic dykes and flows Andesitic agglomerates and flows .. Brown sandstones and crystalline limestones Dacitic extrusions Claystones and argillaceous limestones Argillites and greywackes :: Recent. Pleistocene. Pleistocene-Pliocene. Pliocene-Miocene. Miocene and Oligocene. Oamaruian Parahaki Series Onerahi Formation.. Waiparan Hocene. Late Cretaceous. Waipapa Formation Hokanuian Trias-Jura.

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mounds emitting gas. Shattered sandstones in Raukumara East Survey District have their fractures filled with pitch, and the sandy mudstone along the Karakatuwhero Stream has a strong smell of benzine. (2.) Limestone and Greensandstone. On. the south side of Iron or To Koau Point, near Hicks Bay, a thick and extensive bed of limestone outcrops in the surf, and extends west across the road into the Punaruku, forming high cliffs encircling the stream. It could be readily quarried, and is easily accessible.. Several bands of the same limestone crop out in the Oweka, and form cliffs westward above the site of the new road. Near Cape Runaway, also, limestone forms easily accessible cliffs. The samples taken have not yet been analysed, but the stone appears suitable for burning or grinding. Besides this limestone, which occurs in thick regular continuous layers at the base of the Tertiary rocks, and can be distinguished by its coarse texture and fossils, there is an inconspicuous shattered fine-grained limestone that forms broken, irregular patches in the lower, sharply folded strata. No large deposit of it was seen ; but it appears in many places in the subdivision, close to the boundary of the Tertiary rocks, in small deposits which should be useful for local needs. Associated with the' fine-grained limestone are thick beds of greensandstone. In Arowhana and Hikurangi survey districts it forms several large hills difficult of access ; but in Waiapu Survey District some beds outcrop in places along the coast and in the Poroporo Valley. The greensandstone when ground would improve the soil-texture and supply potash. Incomplete analyses of three samples are as follow : — P 2 (> B . K 2 O. Na 2 0. Awanui greensandstone .. .. . . .. 0-36 4-56 0-86 Weraroa greensandstone .. . . .. . . 0-38 3-52 0-32 Puniatara greensandstone .. .. .. ~ 0-30 5-66 0-13 Under present conditions little limestone, lime or greensand could be profitably used in the subdivision ; but in the near future, as more of the flats are tilled and subdivided into small farms, the increasing demand will enable these materials to be economically worked. (3.) Copper. In November a trip was made to Te Kumi, in Raukumara West Survey District, whence for the past eight years or more prospectors have been sending small samples of copper-ore for analysis. The result of the inspection is given in a special report. Similar samples have also been received from other parts of the Waiapu Subdivision, and at Potikirua, on the north coast in the east of Matakaoa North Survey District, prospectors sank a shaft in search of copper. When visited it was full of salt water. It is in. a crush-zone in the basalt marked by twisted and broken red and green bands and by irregular veins of oalcite. Many similar crush-zones were seen, especially along the north coast. At several places they contain masses of pyrito 10 ft. long and 6 ft. wide in the middle, thinning away at the ends. So far as seen the pyrite is small in quantity and poor in quality. Samples have not yet been analysed, but probably, like the Te Kumi stone, contain less than 1 per cent, copper. East of Te Kumi, in the headwaters of the Mangahamea, a tributary of the Tapuwaeroa, 20 ft. boulders of siliceous haematite containing secondary copper sulphides littered on the hillside show that a solid outcrop must exist on the slope close above. The sample from these boulders lias not yet been analysed. (4.) Stone for Roadmaking, Harbour-works, &c. In the North Island east of the mountains from East Cape to Wairarapa no high-grade stone has been recorded as a possible source of material for roadmaking or harbour-works, and rock for the Gisborne roads has been brought from the Hauraki Peninsula and from Dunedin. Yet as early as 1874 Hector mapped the district and showed two large areas of igneous rock (" trachytic agglomerate ") extending inland from Matakaoa Point and Iron Point. Later geologists confirmed this, and extended the boundary of the rocks, till Marshall in 1914 mapped the northern igneous area and showed that the rock ranges from tachylite to gabbro. There is an immense amount of igneous rock : it covers more than 50 square miles and builds mountain-masses 3,000ft. high. It is not, of course, all of the best quality; but high-grade stone forms long high cliffs in many places along the coast and inland, so that there should be no difficulty in getting blocks of any transportable size. For works requiring small stone there is much rock already broken by natural agents ; the agglomerate and breccia will furnish a great amount of 3 in. angular pieces, and the conglomerate at the base of the Tertiary contains a great quantity of the harder stones rounded to smaller dimensions, and set in an easily worked matrix. (5.) Building, Decorative, and Monumental Stone. As timber gets scarcer more concrete will be needed. Beach-shingle from Napier and rivershingle from the streams of the district have already been used ; but the Napier shingle is expensive, and the river-shingle poor in comparison with the igneous rock so abundant in the district near Hicks Bay. Some of the larger blocks of the limestone found in the crush-zone would yield slabs of fine-grained pink " marble " beautifully veined with white ; but there is only a small quantity of such material. The large masses of coarse-grained crystalline rock would yield black-and-white stone, similar to the Coromandol " granite." In several places were seen boulders of a basalt-porphyry which has a fine dark groundmass enclosing large light crystals, and a coarsely crystalline augitefeldspar rock shows a pleasing contrast of large crystals of dark augite and white feldspar. Both would yield decorative and monumental stone.

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(6.) Coal. Specimens of lignitic coal showing woody structure were found in the Haungakakau Stream near the west of Matakaoa Survey District, and another outcrop was reported a few miles farther west. The coal is poor in quality and small in amount, and does not warrant any outlay on prospecting on the assumption that it will get better and thicker as the cover increases. The black selvages on the rock at Hicks Bay and elsewhere are not coal, but basic volcanic glass (tachylite). In conclusion, considering only the more apparent economic results of the work, we find, that the long-continued copper-prospecting has been ill-advised, that an immense amount of stone has been located that is urgently needed to-day, and that further favourable oil-indications have been discovered. The observations made in the three seasons indicate that the Cretaceous rocks east of the Raukumara Range are a potential oilfield. As the. same rocks extend southward east of the ranges through Hawke's Bay and east Wellington, and. the black shales and " wet " gas persist throughout, it is important that these possible oilfields should be mapped in detail. 3. Tongaporutu-Ohura Subdivision. (By L. I. Grange.) Introduction. In the past field season, which commenced in October, 1922, and ended early in April, 1923, the detailed mapping of the districts examined during the two previous seasons was extended westward to the coast between New Plymouth and Mokau subdivisions, described in New Zealand Geological Survey bulletins Nos. 14 and 24. The survey districts explored last season are Mimi, Upper Waitara, and the western half of Waro, containing in all 324 square miles. For the total area of 1,021 square miles the name Tongaporutu-Ohura Subdivision is proposed. The coastal section of the New Plymouth Subdivision as far westward as Tertiary rocks outcrop was also examined. Physiography and, Structure. The earth-movements that caused the emergence of the sea-floor at the close of the Tertiary gave to the rooks of this district gentle dips averaging about 3°. In the north the beds strike north-north-west, a direction which changes to north in the south. A gentle westerly dip is maintained along the coast to within five miles of the town of Waitara, where the beds are obscured by volcanic deposits. The area is singularly free from faults of any great consequence ; but since the beds vary little through great thicknesses, dislocations of small throw may easily have been overlooked. A notable feature of the physiography of North Taranaki is the nearly accordant heights of adjacent ridges. In the area under description the ridges on the sea-coast are about 600 ft. above sea-level and rise to the east to about 1,400 ft. The accordant summits are the remains of a land of low relief shaped largely by subaerial agencies during a depression of the land in the Pleistocene. A coastal terrace, at its broadest one mile and a half wide and about 100 ft. above sea-level, extends, except for a break at White Cliffs, along the coast of the subdivision. General Geology. The Mokau and Mohakatino series described in the last annual report extend into the north-east corner of the area examined during the 1922-23 field season. Of the former only the upper beds are exposed, and occupy a small area at the head of the Tongaporutu River. The Tongaporutu Scries, which lies with apparent conformity on the Mohakatino beds, consists of shallow-water deposits showing considerable lateral variation. On the north is sandstone 800 ft. thick, which, grades southward, in the upper part, to evenly bedded sandstone and argillaceous sandstone. Conglomerate composed of rolled concretions and pebbles of sandstone succeeds on the coast near Waikiekie and at several points in the Tongaporutu Valley. Sandstone overlies and grades laterally and vertically into an argillaceous rock with bands of sandstone, typically exposed in the lower half of White Cliffs. The total thickness of the series is approximately 1,400 ft. A bed of conglomerate similar to that mentioned above, or sandstone exhibiting cross-bedding, introduces the Onairo Series. The basal beds point only to a shallowing of the sea, but what palseontological evidence there is shows that a break occurs in the sedimentary record. The series is sandy at the base and grades upward into arenaceous mudstone. In the Okoke, Urenui, and Mimi valleys the upper beds contain fairly loose conglomerate, which is generally followed by sandstone about 50 ft. thick. The Onairo Series is more than 1,000 ft. thick in this district, and in its extension along the coast west of the boundary of the subdivision at least another 1,000 ft. is represented. The chief Post-Tertiary deposit is volcanic ash, which covers dip slopes and the coastal terrace in places to a thickness of 50 ft. ; undoubtedly its source was the Taranaki volcanoes. Economic Geology. Most of the land in Taranaki likely to contain oil or likely to provide evidence concerning the oil possibilities of the province has now been surveyed in detail. As a result of the most recent work more information on this subject has been obtained. The only beds capable of acting as oil-reservoirs are the sandstones of the Onairo and Tongaporutu series. If no faults of large throw have displaced the strata below the cover of fragmental igneous rocks west of Waitara, the base of the Onairo beds close to New Plymouth lies roughly 4,000 ft. below sea-level. Mr. Morgan* has stated that at New Plymouth the most important oil horizon is at 2,100 ft. to 2,300 ft. below sea-level, and that oil also occurs at 2,600 ft., 3,000 ft., and 3,700 ft. below sea-level. Probably the highest horizon reaches the

* I'. (i. MoHciAN : "The Taranaki Oilfield." N.Z. Geol. Surv. Bth Ann. Rep., C.-2, p. 136, 1915.

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surface where the loose conglomerate outcrops near the mouth of Waiau Stream some six miles east of Waitara Township. The sandstones at the base of the Onairo Series and in the Tongaporutu Series have been passed through in the Blenheim bore (5,720 ft.), near New Plymouth. In Mimi and Upper Waitara survey districts the lower oil-bearing horizons of New Plymouth can be revealed by shallow bores ; nowhere, however, is found any indication that oil occurs below, and it is believed that boring in this area would have little hope of success. From the fossils collected it is possible to state approximately what depth in the Tertiary sequence the Huiroa oil-bore (fifteen miles by road north-east of Stratford) has reached. One of three shells from between 4,550ft. and 4,760ft., forwarded by Mr. J. Henchman, the manager at the bore, to the Geological Survey in 1916, and identified by the late Mr. H. Suter* has now been classed by Mr. J. Marwick as a new species of Verconella that has not been found in beds older than the Onairo Series. The other two do not occur below the Tongaporutu Series. Thus the bottom of the well, at 4,921 ft. is perhaps still in the Onairo Series, and certainly not lower than the Tongaporutu Series. Roadmaking material is scarce. Most of it is obtained from the conglomerate at the base of the Onairo Series close to Uruti Township. Thick deposits of conglomerate loosely held together have been located in the Mimi Valley below Uruti and in the Okoke Valley. This material will not withstand the heavy traffic carried by main roads, but is quite suitable for branch roads. Pebbles of andesite and argillitc at the base of the volcanic ash on the coastal terrace are usually not in sufficient quantity to warrant the heavy stripping which is invariably necessary. 4. Supposed Petroleum-indications near Silverdale, North Auckland. (By H. T. Ferrar.) In the Silverdale; (Wade) district comparatively undisturbed sandstones belonging to the Waitemata Series unconformably overlie claystones and argillaceous limestones probably belonging to the Onerahi Formation of North Auckland. The latter are underlain by serpentine, which in places formed the sea-floor upon which the Onerahi beds were deposited. In Matthews' quarry (Section 29, Block 11, Waiwera Survey District) boulders of serpentine occurring 1 ft. above a smooth surface of the same rock show that it does not intrude the argillaceous limestone.f In one locality an epidiorite, probably an altered gabbro associated with the serpentine, underlies the Waitemata beds. McKay and Park, who examined the Silverdale or Wade district many years ago, made no mention of oil-indications, and the driller who put down the borehole in 1910 affirms that he saw no indications of oil. The borehole and two coal-prospecting shafts sunk on Oak Farm (Carter's) penetrate disturbed argillaceous limestone beds which apparently belong to the Onerahi Formation. In North Auckland no indications of oil and no beds capable of forming oil-reservoirs have yet been found associated with this formation. In the present case there were no indications of oil whatsoever. 5. Hauraki Mine, Coromandel. (Summary of Report by P. G. Morgan.) The Hauraki Mine, Coromandel, was visited on two occasions during the early part of December, 1922. No work had been done at the mine for about two months and a half, but the water, whiph while pumping was in progress flowed in at the rate of about 300 gallons per minute, had not reached sea-level. The recent and deepest workings were on the " New reef" from winzes about 30 ft. below the 400 ft. level. Rock-specimens, said to be obtained from the country at this depth, were examined under the microscope. They consisted of light-bluish-grey highly altered andesite and andesitic tuff containing a considerable amount of pyrite, and in general character were not essentially different from the rocks of higher levels. Numerous veins occur in the ground held by the Hauraki Mines (Limited), of which the most productive was known as " Legge's reef." This yielded much rich ore from its cap, which was hidden by a few feet of surface debris, to a depth of about 260 ft., whereas the " New reef " was poor above the 220 ft. level, but productive from that level to 400 ft. At no great distance to the southwest the old Green Harp and Telephone companies obtained much gold from workings near the surface. The value of the gold obtained from the ground beld by the Hauraki Mines (Limited) is not less than £470,000, and probably exceeds half a million, all obtained above the 400 ft. level. An area of 60 acres or so with such a history should be prospected at greater depth. The work done recently extended only 30 ft. below the 400 ft. level, and the results obtained have little bearing on the prospects of the Hauraki Mine in depth. 6. Owera-Materangi District. (By P. G. Morgan.) This district, which lies on the Bay of Plenty side of the Hauraki Peninsula, south and east of Whangapoua Harbour, was visited early in December, 1922, and several old mining claims were examined. This area and the mining operations prior to 1907 are described by C. Fraser and J. H. Adams in N.Z.G.S. Bull. No. 4, pp. 130-33, 1907. Owera Mine. The Owera Mine was worked during the years 1890-95. A ten-stamp battery was erected, and 1,786 tons of ore obtained from the Owera lode were treated for a return of 2,207 oz. of bullion, valued at £3,386. It is stated that gold-bearing stone was left underneath the main adit. About 19.04-5 the mine seems to have been renamed the Plunket Mine, and some work was done under the direction of a

*N.Z. Geol. Surv. Pa!. Bull. No. 8, p. U, 1921. t Professor W. N. Benson has stated ("Palaeozoic and Mesozoic Seas in Australia," Trans. N.Z. Inst., vol. 54, p. 53, 1923) that he has been informed by Mr. .1. A. Bartrum that the serpentine at Wade has been injected into the hydraulic limestone. This statement, if correct, would not only invalidate that made above, but would justify farreaching deductions, one of which is suggested by Professor Benson.

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Mr. Woodhouse. Recently Messrs. W. F. G. Scott and Collier, having obtained a lease or option of some kind from the landowner, Mr. J. Schiscka, of Auckland (also the owner of the mineral rights), began to reopen the main adit. I am informed that gold-bearing stone was found underfoot a short distance in from the mouth of the adit, but heavy rain caused the loose ground above the adit to slip, and thus the opening was again completely closed. Scott and Collier then attempted to form a company to work the mine, but so far their efforts have not been successful. According to Fraser and Adams the principal vein in the Owera Claim (the Owera lode) strikes 30° east of north, dips steeply to south, of east, and has an average width of 2 ft. As seen in a small spur south of the old workings, the width is from 1 ft. to 8 ft., the strike 36° east of north, and the dip, though not clearly distinguishable, seems to be 85° to the north of west. The enclosing rock is a light-coloured highly altered andesite (" propylite "). To some extent it is silicifiod. The quartz of the Owera Mine is in part of the laminated or platy variety. This shows that calcito has once been present, but has been removed by leaching. Some is brown and sintery looking, and some of a glassy character. Small druses or cavities lined with quartz crystals are common. Trenched outcrops of quartz on the spur north of the old workings on the Owera lode seem to indicate the presence of a parallel, vein of some size. North-eastward, in the valley of Siberia Creek, a branch of the Otanguru Stream, other outcrops have been found on the line of the Owera lode. The vein fissure, at any rate, probably persists in this direction to Murphy's Hill. Murphy's Hill. A good deal of prospecting by means of trenches and adits has been done at Murphy's Hill, and several veins or lodes have been found. The largest of these in one place is 14 ft. wide, and is reported to be even larger elsewhere. It is, however, very variable in size, and in places is probably only 2 ft. or 3 ft. wide. Its strike is about 30° east of north, and its dip, as seen in the trench close to where the track over the hill reaches its highest point, is 80° 85° to the south of east. The lode is here extremely shattered by fault-movement. It- consists of numerous fragments of nearly white quartz (in part stained by manganese oxides), soft white powdery material (" silica "), and a great deal of clayey material, much of which is coloured black with manganese oxides. Some of the quartz is cavernous, and some of flinty appearance. In an opening about a chain to the south-westward the lode is 10 ft. wide, and of the same character as at the 14 ft. outcrop. Several adits have been driven into the lode from various points on the hillside, and the tips show quartz of various kinds, much manganese-stained. Some of the quartz is pilaty. According to Fraser and Adams, 4 tons of ore from Murphy's Hill, treated during 1891-95, y-.elded 48 oz. 1 dwt. bullion, valued at £105 12s. More bullion than this, however, may have been obtained, either during the years mentioned or at some other time. The prospector, P. Murphy, after whom the hill is named, still lives in Coromandel. He is reported to have made a few hundred pounds at least out of ore mined by him from the southern part of Murphy's Hill. Many years ago a few tons of quartz from Murphy's Hill was carted to the point where Otanguru Creek crosses the road to Kuaotunu. It was intended to ship this to Coromandel or elsewhere for treatment, but some of it still remains on the roadside. Materangi Hill (or Ridge). A vein of quartz (mixed with country) up to 4 ft. wide outcrops near the top of Materangi Hill. It strikes east of north (16°) and dips westerly at 80°. It has been stoped to a small extent, and the quartz shipped to Coromandel or elsewhere for treatment. South of the mine-workings is a trench which exposes a large body of somewhat cavernous poor-looking quartz, in part nearly white, in part iron-stained. This body probably represents a continuation of the 4 ft. lode. Five or six chains west of the old workings on the 4 ft. lode a small ore-body, now entirely worked out, has been stoped from the surface for a good many feet downward. The opening is about 2 ft. wide, and of some length, but no vein of any kind can be seen. It is said that rich stone was obtained here. According to Fraser and Adams, during 1892-93 34 tons of ore from the Ocean View Claim, Materangi Hill, was crushed for a return valued at £200. A much greater tonnage than this has been mined, and apparently shipped away, for there are no quartz dumps. Prospects. The Owera lode and any adjoining veins seem to deserve further prospecting. More than this cannot be said. Murphy's Hill is decidedly a promising locality. In the first place the lodes should be properly sampled at all accessible points, and if the assays are at all satisfactory, one or more winzes could advisably be sunk on the principal lode. An adit might then be driven from the foot of the hill to intersect the various lodes. The faulting to which the main lode has been subjected is a factor which lessens the possibility of success. In other respects the conditions are generally favourable. 1 was not favourably impressed by Materangi Hill, though the quartz seen at the old workings on the 4 ft. lode was of a fairly favourable character. The rock of this hill does not seem to have been widely altered or " propylitized " by hydrothermal solutions during the period of vein-formation, and I would not recommend spending much money on further prospecting.

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7. Copper Deposits near Cape Runaway. (Summary of Report by M. Ongley and E. 0. Macpherson.) The deposits of copper-ore which occur in the basin of Mangahaupapa Stream, a branch of Raukokore River, are difficult of access, the country being unroadod, very broken, and covered with forest. The locality is in Te Kumi No. 2 Forest Reserve, Block 3, Raukumara West Survey District, some sixteen or seventeen miles south of Cape Runaway. Iron pyrites, probably concretionary, occurs in detached masses in a zone of crushed greywacke. The largest mass seen was 22 ft. long by 7 ft. wide, but others of larger size are reported to occur. Some years ago three short adits, now collapsed, were driven and other prospecting undertaken, but little can now be seen except the outcrops in the stream-bed. Three representative or average samples wore taken, but all showed on assay less than 1 per cent. - of copper, although several samples, presumably picked, from this locality, which were examined in the Dominion Laboratory in former years contained a much greater proportion. 8. Taupo Earthquakes. (By P. G. Morgan.) On the 9th June last, in company with Dr. C. E. Adams, Government Astronomer and Seismologist, and Professor E. Marsden, I left Wellington for the Taupo district, where somewhat severe earthquakes were being experienced. We arrived at Wairakei, near Taupo, on the afternoon of the following day. Three days were spent in investigating the earthquake shocks, which continued during our visit and for months afterward. During April, 1922, a few light shakes were felt at Waiotapu, about thirty miles north of Lake Taupo. On the 10th May, at 6.5* p.m., a, light shock was felt at Taupo. On Friday, the 12th May, at about 7.50 p.in., a 3evere shock occurred at Whakatane and Te Teko, Bay of Plenty district. This earthquake was also felt at Matata, Tauranga, Rotorua, &c, but was not reported, from Taupo. There were numerous after-shocks. During the latter half of May earthquakes in the district at the north end of: Lake Taupo became common, and during the nights of the 24th and 25th twenty or more were experienced, some rather severe (probably reaching an intensity of almost vii on the Rossi-Forel scale). Thenceforward shakes became still more numerous. About 8.16 a.m. on Saturday, the 10th June, a, strong earthquake (maximum intensity over vii on the Rossi-Forel scale) occurred. It was severe at Oruanui, Wairakei, and Taupo, and sharp at, Mokai. It was also felt at Tarawera, on the Napier-Taupo Road, at Rotorua, at Taumarunui, &c. Many tremors followed, and at 5.15 p.m. and 5.30 p.m., after our arrival, there were strong shakes at Wairakei. Sharp shakes and tremors occurred, at frequent intervals during the rest of our stay. As many as eighteen (including a boom or rumble) were counted in. one hour, and though there were hours without any perceptible tremor, the average number per day was probably nearly one hundred. All of any consequence were accompanied or slightly preceded by rumbles of various kinds. Alter our departure the shakes for a few days were milder and perhaps less frequent. Heavy shocks, however, occurred on the 18th and 25th June, those between 0.30 a.m. and 1.30 a.m. and at 9.10 and 9.13 a.m. on Sunday, the 25th June being especially severe. Very strong shakes occurred at 4.43 p.m. on Tuesday, the 4th July, at 3.30 p.m. on Wednesday, the 12th July, and at 3.48 p.m. on Monday, the 17th July. Oruanui had a heavy shake on the afternoon of Friday, the 14th July. There was a sharp shock at 3.50 p.m. on Wednesday, the 26th July. During August tremors continued to occur, but the month was comparatively tranquil. Early in September there was a renewal of activity. During the early morning hours of Sunday the 3rd, over one hundred shakes wore felt at Tokaanu, at the south end of Lake Taupo, and at 5.30 a.m. there was a very severe shook. During the day another forty shakes are reported to have occurred. Previously ouly one or two light tremors had been felt there. ,At 2 p.m. on Tuesday the sth, a series of shakes, one closely succeeding another over a period of 12| minutes, began at Taupo. Strong tremors were felt from Tokaanu to Mokai. After this date no alarmingly heavy shocks were reported, but from the 12th to the 15th October there was a renewal of seismic activity, and perceptible tremors occurred at varying intervals until December and even later. The material damage done by the Taupo earthquakes was confined to the shaking-down of several chimneys at Oruanui, and to the breaking of articles such as crockery and bottles, which were shaken off shelves. Somewhat numerous though as a rule small slips occurred along roads and elsewhere, especially along the north shore of Lake Taupo. The most remarkable effect, however, was the subsidence of a considerable block of land on the north side of Lake Taupo, between Whakaipo and Whangamata bays. The drop at the beginning of September was about 4|-ft. near the south end of the peninsula between these bays.* Northward it gradually diminished. Its eastern boundary was probably a largo crack, or series of cracks, seen early in June, to the north-east of Whakaipo Bay. On the western side of this a drop averaging 18 in. was observed. The number of shocks, great and small, comprising the Taupo " swarm " was very large, and probably has seldom been equalled in earthquake records. The loose unconsolidated nature of the surface rocks and perhaps the weakness of the deeper-seated rooks were probably contributing factors to this distribution of the seismic energy. The shocks wore undoubtedly of a tectonic nature, and had their origins along a north-north-east-striking fault-zone a few miles to the west of Taupo Township and Wairakei. They were not " volcanic," nor directly due; to movements of magma in subterranean reservoirs. Gentle movements along this fault seem, to have begun near Waiotapu in April : during May the centres of activity migrated to the neighbourhood of Oruanui, Wairakei, and Taupo Township. Early in September there were movements near Tokaanu also. Many earthquakes occurred in neighbouring districts during the time of activity in the Taupo district. That at Whakatane and Te Teko on the 12th May has already been mentioned. Others occurred in the region to the west

* During the following months the subsidence increasi d, and has lately been reported as 7Jft.

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traversed by the Main Trunk Railway, but of these there is far from a complete record. Shakes were felt in the Te Awamutu district (over sixty miles north-west of Taupo) during June and. other months, and one was recorded at Hamilton (about fifteen miles north of Te Awamutu) at 7.10 a.m. on Sunday, 15th October. Several, sharp shocks were felt at Ohakune on Sunday, 3rd September, between, 3 a.m. and 4 a.m. at a time when numerous tremors were being experienced at Tokaanu, thirty-seven miles to the north-east. About midnight on Thursday, 12th October, a " heavy shock " was felt at Taumarunui, thirty-five miles west-south-west from Taupo, and many " distinct " tremors followed during the next few hours. During the previous three weeks or more many light shocks had been felt. The Ohakune shakos no doubt had an origin in the Taupo fault-zone : those in the Te Awamutu - Hamilton and Taumarunui districts seem to have had independent origins. 9. Paint-pigments near Pukeiti Hill, South-west of New Plymouth, Taranaki. (By L. I. Grange.) On the 21st December, 1922, I examined the deposit of paint-pigments on Section 18, Block 7, Cape Survey District, the property of Pouakai Minerals (Limited). Mr. R. W. Davies, of New Plymouth, who has a wide knowledge, of the locality, showed mo the work that had already been done. I have to acknowledge his valuable help. The pigments are ochres which consist chiefly of iron oxide and small amounts of wad, a darkcoloured oxido of manganese. They outcrop in a small branch of a tributary of Timaru Stream, about 20 chains north of Pukeiti Trig., a hill lying between Pouakai Range and Kaitake Hills, about ten miles south-south-west from New Plymouth. The deposit is reached from Saxon's hut on the Carrington Road by way of a walking-track. The company has prospected the material by sinking eight shallow pits with a maximum depth of 10 ft. All arc situated on the banks of the creek and rills joining from the west, and are enclosed in an area 3| chains by 2 chains. Mr. Davies had bailed a pit which is the middle one of five on the west branch of the creek, and from the others, almost filled, with water, a number of samples were taken. In. the empty pit the succession is : Soil and subsoil, 2 ft. ; wad, 2 ft. ; golden-yellow ochre containing pockets of brown ochre and wad, 4 ft. A. borehole 4 ft. deep from the bottom of the pit was in ochre. Of the other pits, three expose ochre as much as 6 ft. thick, and four wad up to 10 ft. thick. Previous to my visit samples of the pigment were sent to the Dominion Analyst,* who reported favourably on them. The ochres is invariably free from gritty particles, and the colouring is constant. The two colours golden-yellow and brown could be kept separate in working. The greater part of the wad is exceedingly fine-grained. Judging from the data obtained, I consider that the deposit is certainly worth further prospecting. The quantity cannot be estimated, but if the bed in the more eastern creek has a width of oven a few yards several hundred tons of paint-making material are present. 1 recommend sinking on the bank a few yards west of the pit that was bailed in order to ascertain, the depth, and trenching to find the width of the deposit on either side of the creek. 10. Wanganui-Hawera District. (By J. Marwick.) During the first week of September, 1922, extensive collections of fossils wore made by Dr. G. H. Uttley and the writer from the marine strata exposed along the beach from Wanganui west to Manaia. These specimens will furnish valuable material for the study of our Tertiary Mollusca, and for exchange with other institutions. Only a part of the material has as yet been sorted and identified, so that complete results of the fauna! relations of the different localities cannot be given. The work already done supports Vaughan's contention that more attention should be paid to the study of faunas and their relation to disconformities. An erosion surface, additional to those described by Marshall and Murdoch, was observed on the beach about two miles west of Wanganui, between the Castlecliff and the Kai Iwi beds. The Mollusca of the lowest horizon studied, that at Waipipi, were found to have fewer affinities with those of the, Awamoan than had previously been supposed. This may mean either an important stratigraphical break with the arrival of a new fauna, or a long time interval between the two horizons, probably shown by a great thickness of sediments. The recent surveys in North Taranaki have demonstrated the presence of thousands of feet of strata at a higher horizon than the Awamoan, and the uppermost beds, the Onairo Series of Clarke (Bull. No. 12, 1911), according to the contained fauna, are well below the Waipipian. 11. Paint-pigments, Onahau, Nelson. (Summary of Report by J. Henderson.) Over thirty years ago a settler of the Takaka district named M.cKcoghanf manufactured paintpigment from a deposit on his property, which is situated on the eastern side of the Onahau Stream, four and. a half miles north-nOrth-west from Takaka Post-office. At this locality the gravels forming the coastal plain contain a red-coloured ochreous band from which the pigment was obtained. Iron oxides leached from 3 ft. of gravels immediately beneath the soil have been redeposited in the clay matrix of the next 3 ft. of gravel. A large quantity of paint-pigment no doubt occurs in this locality, but until further prospecting has been done no reliable estimate of the amount can be made. * Dom. Lab. 55th Ann. Rep., p. 23, 1922. f See Lab. Hop., Wo. 22, p. 49, 1887, and R.G.E., No. 20, p. 220, 1890. The name in both reports is printed Keoghan, which is believed to be an error.

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A sample of the pigment separated from the gravel was examined by the Dominion Analyst, who reported that it consists of " a fine-grained clay and possesses a pleasing red-brown colour. It is, however, deficient in tinting and covering powers, due no doubt to the low percentage of iron oxide present." The sample contained 10-56 per cent, of iron oxide, whereas an ochre of good quality should contain 20 per cent, or more. 12. Marble in THE Takaka District, Nelson. (Summary of Report by J. Henderson.) Fine-grained light- and dark-grey marble, estimated to be from 2,000 ft. to 3,000 ft. thick, occurs on the western side of the Takaka Valley, some five or six miles south of Takaka Post-office. The lower part.is interbedded with feldspathic micaceous schist, and rests on similar rock. The strike is from north-west to west-north-west, and the dip north-eastward, at angles of 25° to 60°. Quarrying for building and decorative stone has been started at several points on the low hills that rise from the valley-flats, here about 170 ft. above sea-level. Unfortunately most points of attack are close to a fault which, striking north-north-west, has, as indicated by the displacement of the Tertiary limestone resting on the marble, a throw to the east of about 180ft. The master joints strike nearly east and west and dip steeply southward, and there are other joints more or less parallel with the fault, which, of course, has shattered the marble close to it. The stone, which is of fine quality and pleasing appearance, is from eight to ten miles by level road from the port of Waitapu. 13. Coal in the Takaka District and in the Otimataura Valley. (Summary of Report by J. Henderson.) The coal-measures and coal-scams of the Takaka district have been described in N.Z.G.S. Bull. No. 3, and those of the Otimataura Valley in Bull. No - . 25. Some few details were observed in addition to the descriptions of the coal-bearing strata given in these reports, but nothing of special interest or at variance with their general conclusions. 14. Talcose Schist in Springburn Valley, Kawarau Survey District, Otago. (Summary of Report by J. Henderson.) Kawarau Survey District forms part of an area geologically examined by Profossor Park and described in N.Z.G.S. Bull. No. 5. The Springburn, a branch of Gentle Annie Creek, which joins Kawarau River from the north four miles east of Gibbston, drains part of the southern end of the Crown Range. A fault striking south-east along the headwaters of the Springburn extends towards the Nevis junction, where the Kawarau forms an abrupt southward bond. In this fault, near the source of the Springburn, occurs the large mass of serpentine described by Professor Park (pp. 28 and 29 of Bull. No. 5). In another part of the same fault, downstream from the serpentine, crushed chloritic schist containing talc outcrops in the bed of the Springburn. Talc-chlorite schist also outcrops at several points along the western side of the valley and some 5 or 6 chains from the stream. Other outcrops occur about 15 chains east of the Springburn. Wherever observed the talcose chloritic schist was crushed and contained a large proportion of light-greenish, fine, flaky material which could readily be separated from the rest of the rock. This flaky material has been analysed by the Dominion Analyst (see p. 26, 54th Annual Report of the Dominion Laboratory, 1921). 15. Notes on the Geology of the Nevis Valley, Otago. (By J. Henderson.) This report is being published as a Departmental Report in the New Zealand Journal of Science and Technology (see Vol. vi, No. 2, 1923). 16. Cinnabar in G.reenvale Survey District, near Wajkaka, Southland. (Summary of Report by J. Henderson.) Three veinlets of cinnabar in a zone 10 ft. to 12 ft. thick have been exposed in trenches on the top of a rounded hill 920 ft. above sea-level on Section 8, Block 11, Greenvale Survey District. This locality is a few miles north-east of Waikaka. Two vertical shafts respectively 25 ft. and 50 it. deep have been sunk, and some 150 ft. of driving done at a depth of 25 ft., mostly on the largest veinlet, which consists of about 1 ft. of somewhat crushed, rock occasionally showing slickensides and containing a nearly continuous but thin and irregular sheet of cinnabar up to \ in. thick. An adit has been started 100ft. below the outcrop, and when visited (November, 1922) had been driven 230 ft. on a northerly course. The veinlet prospected above should be cut at about 600 ft. Dabs of cinnabar were observed on joint-faces at 166 ft. ; from the rock broken from the face at 230 ft. a little cinnabar could be obtained on panning. The country containing the cinnabar is weathered greywacke, the veinlets in places are slightly silicified, and pale iron pyrites occurs. The rock removed from the drives on the veinlet on the top of the hill had boon kept separate and a general sample of this, taken by the Inspector of Mines, Dunedin, was found by the Dominion Analyst to contain 0-88 per cent, of mercury. 17. Notes on the Geology op the Naseby District. (Summary of Report by J. Henderson.) The oldest rocks of the Naseby district are the greywackes of Mount Ida and the schists of Quartz Reef Hill, a rounded prominence at the head of Hogburn, Stream, on which the township is situated. These schists contain numerous quartz veins. The beds next in age, consisting of redcoloured breccia-conglomerates known as the " Red Bottom," are probably the oldest Tertiary strata in the district, but their relation to a series of quartz-grits, which pass laterally into white quartz

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sands, clays with lignite and fossiliferous greensands, is not known. A brown gravel, by some called the " Maori "or " Old Man Bottom," overlies the quartz-grits. It consists chiefly of pebbles of decomposed greywacke in an abundant clayey matrix, but contains numerous quartz fragments, probably derived from the underlying quartz-grit*,, as well as smoothly rounded but irregularly shaped boulders known as " Chinamen," which are portions of the quartz-grits cemented together with secondary silica. The "Maori Bottom" is overlain unconformably by gravels resembling it in colour and most other respects, but rather coarser and with a smaller amount of matrix. These gravels, in. places, have a thickness of 20 ft. Detrital gold is present in all the beds overlying the schists and greywackes. The upper brown gravels have been extensively sluiced, and parts of the Maori Bottom have also been worked. But probably the bulk of the gold won in the Naseby district was obtained from the loose gravels of the flood-plains which were enriched by the degradation of the older gravels, quartz-grits, and conglomerates. Those in turn derived their gold from quartz reefs in the schists. 18. Gold and Platinum in the Orepuki District. (Summary of Report by J. Henderson.) A coastal plain, which rises gently from sea-level to about 120 ft. on its inland margin and varies from one to three miles in width, extends along the north shore of Foveaux Strait from Colac Bay northwestward to beyond the mouth of Waiau River. In parts the waves have encroached upon this plain till cliffs up to 80 ft. high have been formed, exposing the layers of buff-coloured gravel, sand, silt, and clay with lignite of which the plain is formed. These deposits were for the most part laid down as beach beds on an ancient shore, and contain auriferous leads. Gold seems to have been discovered at Round Hill in 1868, and at Orepuki a little earlier. The first workings were on. the beach and along the valleys of the streams crossing the coastal plain, the deposits then worked containing gold concentrated from the mass of old beach beds removed by sea and stream erosion. Old beach leads more or less parallel with tin; present coast and representing ancient shores were later discovered. The lead worked by the Groveburn Company is an example ; this lead, which is truncated by the present cliffs at a point about two miles and a half west of the Waiau River, as it was worked westward was found to strike obliquely inland. The bottom on whicli this lead was worked was the surface separating the sands forming the lower part of the cliffs from the brown gravels forming the upper part. Similar leads have been extensively worked in the Orepuki district. Near Orepuki the claims near the inland edge of the coastal bench bottomed in part on Tertiary strata and. in part on a decomposed surface of basic igneous rock (locally known as " granite "). The main bottom at Round Hill is also of basic rock (norite) decomposed to a depth of from 12 ft. to 20 ft. Several layers of gold-bearing sand occur in this locality, an especially rich one resting on a bed of lignite. Platinum, in small amount is associated with all the gold obtained in the Orepuki district. For many years, owing to the low price offered by the banks for impure platinum, concentrates, the Round Hill Company was the only producer. The platinum saved is from Ito 1| per cent, of the alluvial gold. It is obtained as a residue after amalgamation of the gold, and is further concentrated by careful washing, the final concentrate being about two-thirds platinum. It is said that the platinum obtained when the Groveburn claim was working amounted to about one-eighth of the gold saved, and that on the beach near the mouth of the Waiau River the proportion was as high as one in four. The amount obtained by the Round Hill Company, by far the largest producer, is but 10 oz. or 12 oz. a year, the total annual production for the district being perhaps 20 oz. Platinum is found along the coast of Southland from west of the Waiau to the Waikawa district, a distance of about ninety miles. Throughout it occurs in very fine scales, especially in the Waikawa district. According to Farquharson (Trans. N.Z. Inst., vol. 43, p. 480, 1911) nuggets weighing as much as 2 oz. or 3 oz. were found, at the mouth of the Waiau, but the present writer could get no confirmation of this statement. The metallic grains known to commerce as platinum contain other metals in appreciable amount. According to Farquharson (op. cit., p. 171) a sample from Orepuki had the following percentage composition : Platinum, 74-61 ; iridium, 1-30 ; palladium, 1-36 ; rhodium, 3-52 ; gold, 0-39 ; iron, 5-08; copper, 0-15 ; iridosmine, 14-32 : total, 100-73.

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