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Sess. 11.—1897. NEW ZEALAND.
REPORT ON THE GEOLOGY OF THE CAPE COLVILLE PENINSULA, AUCKLAND. BY ALEXANDER McKAY, F.G.S., HON. M., N.Z. INST., GOVERNMENT GEOLOGIST.
Presented to both Houses of the General Assembly by Command of Hts Excellency.
OCOSTTEiTTS.
Page. Upper Miocene Formation— continued. Page. Introduction .. .. .. .. .. 1 Beeson's Island Group— continued. Physical Geography .. .. .. .. 1 In the Waiwawa and Kauaeranga Valleys ~ 62 Previous Geological Explorations .. .. .. 6 In the Puriri, Omaha, and Hikutaia Valleys .. 63 By Yon Hochstetter .. .. .. .. 6 Near Mackaytown, and thence to Te Aroha .. 63 By Sir James Hector, 1864-70 .. .. ..8 Relations of the Beeson's Island Group.. 63-64 By Captain Hutton .. .. .. .. 12 Older Pliocene .. .. .. .. .. 64 By Sir James Hector, 1870 .. .. .. 17 Acidic Group .. .. .. .. .. 64 By S. H. Cox, 1880-82 .. .. .. .. 19 At Mercury Bay .. .. .. .. 64 By A. McKay, 1883 .. .. .. ..26 On East Side of Cook Bay .. .. ..65 By James Park, 1893 .. .. .. 26 Round Sources of Purangi Creek, thence to Stony By Professor Hutton, 1887 .. .. ..28 Creek .. .. ; .. ..65 By James Park, 1890 .. .. .. 34 Stony Creek to Lower Tairua River .. 65 Description of the Different Formations present .. 40 i Bull's Run to Upper Kauaeranga .. .. 65 Table of Formations .. .. .. .. 40 West of Table Mountain .. .. .. 66 Maitai Series .. .. .. .. 41 In Fourth Branch, Tairua Valley .. .. 66 Slate in the Northern Part of Peninsula .. 41-42 On Marsh's Farm, Upper Landing, Tairua River 66 Slate at Cabbage Bay .. .. .. 42 On the Main Divide south of Puriri Stream .. 66 Slate at Kennedy Bay .. .. .. ..43 In the Middle Tairua and Wharekawa Valleys .. 67 Slate in the Tokatea Ranges .. .. 43 Round Sources of Tairua and Hikutaia Rivers .. 67 Slate in the Success Ranges .. .. ..44 In Upper Ohinemuri Valley .. .. ..67 Slate at. the Tiki .. .. .. .. 44 Between Waitekauri and Owharoa .. .. 67 Slate in the Manaia Valley .. .. ..44 Near Mackaytown .. .. .. ..68 Slate, Kirita Bay to Tapu Creek .. ..45 Forming Hikurangi Mountain .. ..68 Slate in Kuaotunu Peninsula .. .. ..45 Age and Relation of Acidic Group .. ..68 Metalliferous Deposits of the Slate Formation .. 46 Where Gold-bearing, yielding Opals, &c. .. 69 Remarks on the Relations of the Older Rocks of Cape Its Building-stones, Spherulite, Perlite, Ac. .. 69 Colville Peninsula .. .. .. ..47 Newer Pliocene or Pleistocene .. .. ..70 Cretaceo-tertiary or Goal-bearing Formation .. 47 Kauaeranga Beds .. .. .. ..70 Description of the Bods at Cabbage Bay .. .. 48 Recent .. .. .. .. .. 70 Their Relation to the Volcanic Series .. ..49 Dyke-intrusions.. .. .. .. ..70 Volcanic Formations .. .. .. .. 49 Thermal Springs, Sinter Deposits .. .. .. 71 Thames-Tokatea Group .. .. .. ..49 Faults .. .. .. .. .. ..73 Thames-Coromandel Area .. .. .. 50 Gold .. .. .. .. .. 73 Puriri Area .. .. .. .. 54 Concluding Remarks .. .. .. 75 Karangabake Area .. .. .. ..54 Silver-bearing Lodes, Great Barrier Island .. .. 75 Te Aroha Area .. .. .. 55 General Geological Sketch of Great Barrier Island .. 75 Kapanga Group .. .. .. .. ..55 Extract from Professor Huttou's Report.. .. 75 Coromandel Area .. .. .. ..56 Rocks compared with those of Cape Colville PeninNeavesville Area. .. .. .. 58 sula .. .. .. .. 76 Southern Area .. .. .. .. £9 Area specially examined .. * .. ..76 The Kapanga Group compared with the Thames- The Reefs .. .. .. .. 78 Tokatea Group .. .. .. 59 Proprietary and Premier Claims .. 78 Upper Miocene Formation .. .. .. 60 Aotea No. 2 .. .. .. .. .. 78 Beeson's Island Group .. .. .. 60 lona Claim .. .. .. .. 78 Beeson's Island to Kirita Bay.. .. ..60 Kaitokai Claim .. .. .. ..79 At Cabbage Bay .. .. .. 60 Great Barrier Claim .. .. .. 79 Stony Bay to Port Charles .. .. .. 61 Ryan's Freehold .. .. .. .. 79 Kennedy Bay to Whangapoua .. 62 Egerton's Claim .. .. .. 80 Whangapoua to Kuaotunu .. .. 62 Mount Argentine, &c. .. .. .. 80 In the Mahakirau Valley .. .. .. 62 Great Barrier Excelsior and Other Claims .. 80
ERRATA.—Page 37, fourth paragraph, third-last line, for " scalanohendrons," read " scalenhedrons." Page 41, third paragraph from bottom, first line, for "Thames, Port Charles," read "Thames for Port Charles."
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Sess. 11.—1897. NEW ZEALAND.
Presented to both Houses of the General Assembly by Command of His Excellency.
Introduction. The revival in mining, which within the past two years has taken place at the older established centres of gold-mining on the Cape Colville Peninsula, and the impetus thus given to prospecting, has led to the discovery of gold at many places at which formerly its presence had been but suspected. Further prospecting has also proved the presence of gold at many places not before known to be gold-bearing, or where hitherto the prospects were considered too poor to pay, further and more exhaustive search is being made. The phenomenal proceeds from a number of mines in the north and south parts of the Peninsula has aided the introduction of foreign capital, which, whether applied to the development of known mines, or to the discovery of new, has led to a general search being made from Cape Colville in the north to Te Aroha in the south, and in many cases has brought the prospector and miner face to face with a variety of conditions with which they were comparatively unacquainted, the nature of the country and the character of the auriferous material not always according with their former experiences. There has thus been aroused a considerable interest as to the exact nature, position, and extent of the different rock-formations of the Peninsula in which gold-bearing lodes have been or may be found, and at the same time a desire that these should be so studied as to enable the production of a map showing the extent and limits of the different formations, and thus aid the prospector in his work, and be also of value to those engaged in other branches of mining. Aware of these facts, and alive to the importance of such a work, the Hon. the Minister of Mines directed the commencement of a geological survey of the Peninsula, which was accordingly begun in September of the present year (1896-97). Up till the present time (May), the work has been carried on continuously, either on the Great Barrier Island, or on the mainland within the area lying between Cape Colville, the northern extremity of the Peninsula, and the county road between Te Aroha and Katikati, on the shore of Tauranga Harbour, was so far examined that the general sequence of the rock-formations has been determined, and their extent and boundaries ascertained with a fair degree of accuracy. Yet, while this much can be claimed, it has to be admitted that further and most careful work will have to be carried on to determine many things respecting which there is still a doubt. Hitherto, but small areas of the Peninsula have been geologically explored. At Cabbage Bay, Coromandel, on the Hauraki and Ohinemuri goldfields, and at Te Aroha, partial surveys have been* made; but the north and south parts of the east coast, except at Kuaotunu, and the central region south of Coromandel, up to the present time have remained practically unexplored. The sequence of the different rock-formations has till now been unknown, most of the published reports dealing only with restricted areas in the vicinity of where gold was being mined. Within the past two years, the prospector has penetrated to almost every part of the Peninsula, finding gold more or less at all places. My first duty, therefore, was a hasty survey of the whole Of the Peninsula, to determine the sequence of the rock-formations, and, as far as might be, their boundaries. Survey in detail was in no instance undertaken. Physical Geography. Peninsular Auckland, or that part of the provincial district which lies to the northward of a line drawn from Kawhia, on the western coast, to Tauranga on the Bay of Plenty, has extension in I—C. 9.
REPORT ON THE GEOLOGY OF THE CAPE COLVILLE PENINSULA, AUCKLAND. BY ALEXANDER McKAY, F.G.S., HON. M. N.Z. INST., M.E., GOVEENMENT GEOLOGIST.
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a north-west and south-east direction, and gives evidence —contrary to what now is—of a former linear extension of New Zealand along such line far beyond the limits of the present land. This obtained during early Cretaceous times, and long prior to the appearance of the Southern Alps, or of the mountains of the main chain extending from Cook Strait to the Bay of Plenty in the North Island. From the east side of the south part of peninsular Auckland springs the Cape Colville Peninsula. This is bounded on the east side by the ocean, and on the west side by the Hauraki Gulf and the Frith of Thames. Strictly speaking, the Peninsula may be considered as terminated along a line drawn between the mouths of the Thames and Tairua Eivers. Doubtless this is true, but it must be apparent to every one having knowledge of the district that the tract of broad low swampy plain across which the Thames and Piako Rivers find their way to the sea is of extremely modern date. This extensive plain is for many miles to the south but a few feet above the level of the sea, and is unquestionably due to the action of the Waikato River filling-in and reclaiming the southern portion of the Hauraki Gulf. There is thus reason to believe that once, and (geologically speaking) at no distant date, the southern continuation of the mountains of the Cape Colville Range were peninsular to and beyond Mount Te Aroha, or, in other words, to where the range ceases and the high sloping plateau to the south and south-east begins. Hence the whole region may properly be treated of as included in and forming the Cape Colville Peninsula. The surface of the Peninsula is generally broken, in some parts extremely rugged, and along the main axis the mountains rise to an elevation of 2,000 ft. to 3,000 ft. The culminating points are in the extreme north and south parts, Moehau and Te Aroha being mountains of about equal height. Te Aroha does not stand on the main axis or water-divide, but somewhat to the westward, and is built up of rocks belonging to the first and second periods of volcanic activity, as displayed on Cape Colville Peninsula. Moehau, on the other hand, of nearly equal height, terminates towards the north the main range, and is itself a mountain formed of Palaeozoic or older Mesozoic strata, hence for it may be claimed the chief place among the mountains of the Peninsula. South of Moehau the mountains lessen in height, till on the road between Cabbage Bay and Port Charles the heights do not exceed 800 ft. to 1,000 ft., and the road crosses the range at an elevation of 500 ft. Further south the water-divide attains to 1,500 ft. above the sea, till the range is again broken a little south of the track from Cabbage Bay to Kennedy Bay. This may be called the Cabbage Bay Range. South of the Cabbage Bay Range and the saddle mentioned the water-divide shifts a little to the westward, and suddenly attaining a height of 1,700 ft. is continued in a straight line along the Austral and Tokatea Ranges to the Tokatea Saddle (1,200 ft.). Along the Success Range the same line of elevation is continued to the saddle by which the Coromandel-Kuaotunu Road crosses the ranges, and further to the south in the same line the main line of height is continued along the Tiki and Castle Rock Ranges to the saddle at the source of the Waiau by which the Tiki-Mercury Bay Road crosses the range here, also at a height of 1,200 ft. above the sea. Yet farther south the range is continued in a direct line to the source of the Waiwawa, flowing north-east into Mercury Bay, and of Tapu and Puru Creeks, draining into Hauraki Gulf. Opposite the source of the Puru Creek the water-divide turns sharply to the eastward, and runs in this direction a distance of six miles across Table Mountain to the source of the Kauaeranga River. South of the source of the Puru the main range of the northern part of the Peninsula is continued as a spur range between the middle and lower parts of the Kauaeranga Valley and the east shore of the Hauraki Gulf to the Kauaeranga River. In Table Mountain a new line of water-divide is established, which at first trends a little to the west of south, and divides the waters flowing eastward into the Tairua River from those flowing west along the Kauaeranga, Kerikeri, and Puriri Streams to the sea or the Thames River. This is a range distinct from that extending from Moehau to the Thames, and appears to be of younger date, denudation having barely sufficed to reduce and break into peaks and saddles what in the first instance was a high table-land, on which are yet represented, in its northern parts, the youngest of the volcanic rocks of the Peninsula. Beyond the source of the Puriri the water-parting trends slightly to the south-east, to the divide between the Hikutaia Stream and the source of the Tairua River, and thence in the same direction between the waters falling to the eastward and the Waitekauri, a tributary of the Ohinemuri River, on the west. The range of mountains beginning with Table Mountain terminates on the north side of the Hikutaia Valley, from which point the waterparting again departs to the east, and again takes up the south-east line, terminating at Waihi as already described. Between the Hikutaia and Ohinemuri Rivers and west of the Marototo and the Waitekauri Streams, the southern continuation of the second main range commencing in Table Mountain is broken up into a series of high hills having no definite arrangement. The Komata Stream cuts deeply into the heart of these, while other lesser streams falling into the Hikutaia and Ohinemuri Rivers also break into and interrupt the continuity of these hills, so that they do not form a range, but a cluster of separate and distinct mountains. The Ohinemuri River, in its middle course, breaks through between these hills and Karangahake Mountain, and its upper valley opens out into the wide basin of the Waihi Plain, the actual water-parting receding nearly to the East Coast. From the south side of the Waihi Plain the water-parting goes south-west to Mount Te Aroha, and includes between this and the crest of the Karangahake Range the watershed of the Whaitawheta, the principal southern tributary of the Ohinemuri River. The Karangahake-Te Aroha Range thus lies on the western verge of the mountainous district, and is separated altogether from the water-parting between the East Coast and the valley of the Thames or Waihou River. At the source of the Whaitawheta and the Waiorongomai a high saddle connects Te Aroha with the mountain range to the east, which, as the main range, once more constitutes the true water-
MAP OF THE CAPE COLVILLE PENINSULA
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divide between the Bast Coast and the valley of the Waihou River. This range continues in a direct line to the south boundary of the district examined. Prom Cabbage Bay to Coromandel the principal range is flanked by different groups of hills divided from each other by the valleys of the different creeks draining towards the Hauraki Gulf. Between Kevin's Point and the foot of the Tokatea Hill, the last of the series, a group of four or five, constitutes an irregular spur range running north-east and south-west. To the south of Coromandel Harbour, like clusters of hills, often rising into mountains, flank the main range, and form a bold coast-line as far south as Tapu Creek, beyond which, to the Thames, the descending spurs of the main range reach the shore-line. Cut through by the Kerikeri, between the Kauaeranga and the Puriri, a block of mountains flanks the main range, and between Omaha and Hikutaia a spur range runs west to the main road from the Thames to the southern goldfields. Also between Paeroa and Te Aroha a range of hills strikes westward into the plain, and is divided from the principal range, by the saddle by which the coach-road crosses from Paeroa to the southern side. On the east side of the Peninsula a spur range runs from Castle Bock Eange to Kuaotunu, and south of Mercury Bay there commences a coastward series of mountains and ranges, that more or less divided from the different parts of the main range or water-divide, and broken through by various rivers and tidal inlets, reaches to and terminates at the upper or Katikati portion of Tauranga Harbour. The sketch on the opposite page shows the position and trend of the principal water-divides and different sections of the main range. North of Cabbage Bay the bulk of the country is formed of slate and sandstone of Carboniferous age, but on the east slopes of Moehau, and between the foot of the main peak and the sea, there is a considerable development of volcanic rock. Slate rocks, however, appear in the valleys on this side of the mountain down to 140 ft. above sea-level. Abreast of Cabbage Bay the slates are confined to the western slope of the range, but more to the south they appear on both the east and west flanks of the range, the volcanic rocks merely capping them and forming the higher parb of the range. Slates appear as a small outcrop at the head of Cabbage Bay, on its south side, and on the coast-line from Torihine to Paparoa, but are not again seen on the shore-line till reaching the south side of Coromandel Harbour. The presence of slate under the volcanic rocks of the Tokatea Eange has been proved in various mine-workings, which show that the slates rise to a height of 1,020 ft. above sea-level. On the western middle slope of the Success Range the slates are exposed at the surface, and on this side of the main water-divide they continue to the southward to abreast of the middle part of the Castle Rock Range, where in connection with the main range for a time they terminate. A little to the north of this termination slates appear further to the west, on the shore of Coromandel Harbour, and this area of slate for a time, flanked to the west by volcanic rocks, in its south extension, reaches the shore of the gulf at Kirita Inlet, south of Manaia Harbour. There is between the shore of the gulf at this point and the eastern limit of the slate a breadth of four miles, which, next to the Moehau area, is the greatest width of slates on the Peninsula. Gradually the width of the slate belt lessens in a south direction to its termination in the gorge of Tapu Creek. Further south, at Waiohanga or Rocky Point, near the Thames, there is a small exposure of slate beyond which no slate is known in the southern part of the Peninsula. Slates appear isolated and away from the main range in the Kuaotunu Peninsula. These rocks are thus mainly confined to the western slope of the main range north of the Thames, and to both slopes of Moehau in the northern part of the Peninsula. Near Cabbage Bay there is a development of the coal-bearing series of Cretaceous or old Tertiary date, but this, though once a widespread formation, has for the most part been denuded away, and is now of but little consequence as affecting the physical features of the district, being to a large extent covered up by younger volcanic rocks. Volcanic rocks of different ages overlie the slates, and each division, with the exception of the youngest, the acidic rocks or rhyolite formation, are at one or other place found resting on the slate formation. The general arrangement, however, is as a succession of strata and groups of volcanic rocks that strike in a north-east direction, and dip to the south-east, and this is true of the whole of the Peninsula, though local deviations from the rule are not infrequent. After all the important formations of the Peninsula had been deposited, movements still were continued, the commencement of which was of the date of the Kapanga group, whereby the rocks to the west and north were elevated and those to the south and east were depressed. And thus as time went on and denudation proceeded, the slates —the oldest rocks—appeared along the west coast, and in the northern part, and in accordance with and as a result of the same causes the rhyolite formation has its greatest development in the south and east, and is altogether absent from the northern part of the Peninsula. The slates and the older volcanic rock thus form the main range in the north part of the Peninsula, and it is along the western slope of this range that the principal reefing localities at and north of the Hauraki Goldfield are situated. At the Thames and at Coromandel, as a rule, the gold-bearing reefs occur in the volcanic rocks, but also at no great distance from an outcrop of slate, or from where the presence of slate has been ascertained in mine-workings. This western range terminates at the Kauaeranga, near its mouth; but eleven miles to the north the waterdivide between the east and west coasts, at the source of the Puru Creek, turns sharply to the west, and runs between the Kauaeranga and the upper part of the Waiwawa to Table Mountain, and west of Table Mountain to the divide between the Upper Kauaeranga and the waters flowing into Mercury Bay on the one hand, and into the Tairua River on the other. In Table Mountain and the range immediately to the north begins the second group of mountains, that, standing more to the east, forms the main water-divide south to where the range terminates on the north side of the Hikutaia Valley. This is composed of a variety of rocks
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variously affected by mineralising agents, so as to produce physical features that resemble or differ from each other, but which for the most part are not represented in the western range. In Table Mountain and the range to the north the whole upper part is formed of prismatic columns of grey andesite that in the mountain itself forms vertical walls 300 ft. to 600 ft. in height, while the top of the range for a breadth of some two miles is perfectly flat. Hence the name. To the north these intrusive rocks die out before reaching the Waiwawa. To the south the line of intrusive rocks trends with a diminished width of exposure across various tributaries of the Kauaeranga, and, acquiring a more easterly direction, forms Mount Kaitarakihi, on the main range, at the source of the fourth branch of the Tairua River. This mountain is not table-topped; the thickness of the dyke of columnar rock being less than farther to the north ; a rounded outline is the result. The Ehyolite formation forms the higher part of the range east and south-east of Table Mountain, and on this and on part of the adjoining and underlying andesic rocks of the Kapanga group, intense and long-continued thermal action has so saturated the rocks with silica, and built up mounds and terraces of siliceous sinter, that, supplemented by denudation carrying away the less resisting, less coherent rocks, extremely gorgey and rugged country, full of precipices and crowned by conical and fantastic peaks, is the result. In the Neavesville part of the district, between the sources of the Puriri and the streams flowing into the fourth branch of the Tairua, the rocks are mostly volcanic ash and moderately fine-grained breccias belonging to the Kapanga group, and where not saturated with silica from thermal springs they weather and are denuded much after the fashion of the same rocks in the typical locality. On Pakirarahi, the mountain on the main water-divide west of the Neavesville mines, former thermal action is strongly manifested. The higher part of the mountain—2,ooo ft. to 2,400 ft.—is formed of sinter, and the eastern slope is strewn with sinter fragments down nearly to the first crossing of the fourth branch of the Tairua. The London Eock, on the western fall of the range, forms one of a series that extend along the whole length of this range, and form small areas of indurated or more mineralised country, which denudation has been unable to remove as rapidly as the other parts, and thus, singly or in pairs, as in the case of the Marototo, four in a line, they rise as gigantic crags to heights from 400 ft. to 1,000 ft. above the general surface upon which they stand. On the south side of the left branch of the Puriri Stream rhyolite again forms the higher part of the main range. Now, however, it takes on the outlines of tent-shaped mountains, with here and there a peak or dome-shaped projection above the general level. The western slope of the southern part of the range is very abrupt. On the eastern side the descent to the Tairua Valley is not so steep. In the Puriri Valley there is a small area of Thames-Tokatea rocks, the oldest group of the volcanic series; but the great bulk of this range is formed of rocks belonging to the Kapanga group and the Ehyolite formation. The range ends abruptly on the north side of the Hikutaia Valley. On the south side of that valley, between the Marototo Creek and the west border of the mountain region, there is in the line of the range of mountains just described an irregular cluster of hills and mountains that may be said to continue this range south to the Ohinemuri Gorge, yet, as their arrangement is not as members of a mountain range, and the rocks composing them are different, and the main water-parting lies considerably to the east of these, they have to be regarded as distinct, and as forming a group of mountains not directly connected with the range terminating on the north side of the Hikutaia Valley. It has been said that the main water-divide leaves the first, or western, range eleven miles before that terminates on the north side of the Lower Kauaeranga. In like manner the water-divide leaves the second range before that is terminated on the north side of the Hikutaia Valley. The displacement to the eastward in the first case amounts to about six miles; in the second instance it is scarcely more than half that amount, and also the set-off is nearer the termination of the second range by more than half the distance between the Lower Kauaeranga and the source of the Puru. Yet, for all that, there is great similarity in the two cases as to the manner in which the western range terminates, and the recession of the water-parting to the east and the commencement of a distinct range forming the water-parting more to the east or south-east. The third, or Hikutaia Eange, commences at the source of the right-hand branch of that stream, and trends more to the south-east than either the first or second range to its termination on the north side of the Upper Ohinemuri Plain, near Waihi. This range, in its northern part, is composed of rhyolitic tuff, and in some parts, of sedimentary beds composed of rhyolitic material. At the source of the left or main branch of the Hikutaia, intrusive rhyolites or quartz porphyries form the mountain mass of Ngapuketurua, between 2,000 ft. and 3,000 ft. in height. This mass of rhyolitic rock, forming a very bold and rocky mountain, extends westward across the valley of the left branch of the Hikutaia, and forms the most easterly of the Marototo peaks. The belt of acidic rocks is of no great width, and the section laid bare along the banks of the Hikutaia shows clearly the intrusive character of the rock. The southern end of the range is wholly composed of andesite, as solid floes, or as ash and breccia beds, and constitutes the mining country of Waitekauri and the neighbourhood of Waihi. The features presented by the mountains of this part are a main ridge from which outrunning spurs proceed in various directions, all of them evidently due to the action of denudation on material of varying grain and hardness, deposited irregularly as ejectamenta from volcanic vents. The northern source of the Ohinemuri lies on the east side of this range and some distance to the north of its southern end ; so that here we have again repeated the same feature that marked the recession of the water-divide to the eastward before the second and third ranges began. In this case the water-parting lies between the Wharekeraupunga and the sources of the Ohinemuri, and goes east till the coast range is reached. The coast range, composed wholly of rhyolite to within a short distance of the mouth of the Waihi Eiver, has had its eastern slopes carried away by the action of the sea, and a consequence of this is that the drainage flows east from within half a mile of the sea-cliffs of this part,
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The Upper Ohinemuri or Waihi Plain, on the east, is bounded by low hills, and on the south side by a cluster of hills, the eastern part of which is cut through and drained by the Waiau Stream, falling into the upper part of the Tauranga Harbour. Among these bills the water-parting winds irregularly, but trends generally in a south-west direction to the commencement of another definite range, which, from the source of the Whaitawheta Eiver, east of Mount Te Aroha, trends south to the limits of the district examined. This southern range, which is for the most part composed of moderately fine-grained volcanic breccia, is deeply cut into by gullies, and very abrupt on its western side. Its crest at frequent intervals is crowned by sharp or castellated crags, and stands in wonderful contrast to the smooth outlines of the last mountain to the south and the high sloping plateau plain that lies beyond in the direction of Tauranga and Eotorua. A lesser range, mainly composed of rhyolitic rocks, follows the coast-line from Mercury Bay Heads to Waihi Beach. A portion of this, east of Waihi Township, is for a short distance the main water-divide. Between Cabbage Bay and Coromandel, hilly country, at places rising into mountains, stretches along the shore of the Hauraki Gulf, and generally is separate from the main range in that part. The same applies to the coast-line between Coromandel Harbour and Tapu Creek, and, with the exception of the foot-hills along the borders of the plain west of the mountains south of the Thames, the only feature of consequence is the range that from the KarangahakeTe Aroha Bange runs out to the north-west some four miles on to the plain, and near its junction with the Karangahake-Te Aroha Eange is crossed by the coach-road from Paeroa to Te Aroha. The main water-divide of Cape Colville Peninsula, from the foregoing, it will be seen, is not one continuous range, but in reality consists of five sub-parallel ranges, the first four of which have depressions between them that lie nearly in a north-north-east and west-south-west line, and, assuming the ranges to have the same general direction (which is barely true of the third and fourth, but is of the first and second), they can be imagined as at a former period having extended beyond their present limits to the south-west. Some such extension of high land is necessary to account for peculiarities of the geological structure of these mountains, it being evident that extensive lakes at one time existed, of which the retaining barriers have long since been removed. The lacustrine strata referred to are found usually at considerable elevations, and forming in part the crests of the higher ranges. This and other peculiarities that come to light in a study of the physical features of the district can only be explained by having regard to the geological history of the Peninsula from prior to the deposition of the coal-bearing series, or the commencement of the Cretaceous period, to the present time. Those who have made the geology of New Zealand a special study do in most part agree that, towards the close of the Jurassic and during the early part of the Cretaceous periods, the land over and outside what is now the New Zealand area was not only much more extensive than it now is, but was also in particular regions elevated and mountainous in character. Generally, however, it is thought that the direction of its principal mountain chains were as now — i.e., in a northeast and south-west direction —and this in spite of the fact that it has been pointed out that the main lines of elevation in the Pacific Ocean are in the contrary direction, or as near as may be in a north-west and south-east direction. Hochstetter says, " The three islands of New Zealand constitute only parts of one and the same system of mountains, which, running from south-west to north-east, forms a distinctly marked line of elevation in the Pacific Ocean. This longitudinal line is crossed by a second, almost at right angles, which is indicated by the direction of Foveaux and Cook Straits, but still more so by the direction of the long-stretched north-west peninsula of the North Island. This north-west peninsula corresponds to the line striking N. 52° W., and designated by Dana as the axis of greatest depression in the Pacific Ocean."* Geologically, the oldest rocks of the Auckland Provincial District are found along the eastern side of the long peninsula extending from south of Auckland City to North Cape, and which Hochstetter shows lies parallel to the line of greatest depression in the Pacific Ocean.| Dana, in " Corals and Coral Islands," shows that the submerged lands of the Pacific Ocean over the coralbearing region have a general trend in a north-west and south-east direction, which is likewise the direction of the greatest depression in that ocean. On the south-west side of the great depression in the Pacific there is evidence also of a north-west trend of lines of elevation, and of depressions parallel to these—to wit, the Auckland peninsula, and its extension to the south-east, and the depression of Cook and Foveaux Straits. It is not difficult to imagine that the land of which the Auckland peninsula is a remnant was at one time prolonged to the north-west as far as Norfolk Island, and to the south-east as far as Bounty Island, the Chatham Islands lying in the line of this south-east extension. The broad expanse of deepest Pacific having always been ocean (Dana), and the lines of structural elevation to the north-east and south-west of this having the same direction, these, whether appearing above the waters as lines of low coral islands to the northeast, or as higher yet depressed lands to the south-west, must be regarded as the oldest and most permanent features of the physical geography of this division of the earth's surface. On the other hand, we have in the mountain structure of New Zealand and the islands themselves an axial direction from north-east to south-west, or at right-angles to that of the Pacific depression and its bordering lands. Which of these two are the oldest need scarcely be made the subject of discussion. Geological investigation within New, Zealand has made it clear to me that the Alps of the South Island and the mountains of the main chain in the North Island appeared at a comparatively modern date, and that the north-west and south-east axis, as illustrated by the North Auckland Peninsula, is of far older date. As part of this, the Cape Colville Peninsula trends nearly north and south, and is raised towards the north and north-west, and gives clear evidence of depression along its eastern side and southern end, w 7 here it abuts upon the mainland. The
* "New Zealand," by Hochstetter (English edition), p. 36, f " New Zealand," by Hochstetter, p. 37.
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younger rocks present lie along the east side of the principal water-parting, but attain their greatest elevations towards the western or south-western border of the different areas. The different mountain ranges of the Peninsula trend sub-parallel to each other and to the south-west, and it must have indeed been that they were continued in that direction considerably beyond their present limits, as otherwise it would be impossible to account for the presence of lake deposits on the tops of some of the higher mountains between the Kauaeranga and Ohinemuri watersheds. The mere erosion of the western end of these different ranges, though sufficient to remove the lake barriers in that direction, does not account for the tilted and disturbed state of the strata of lacustrine origin. Elevation of the western side of the Peninsula has to afford reasons for this. The movements whereby the western side of the Peninsula has been raised and the eastern lowered have been in operation for a considerable time, and are still going on. The evidences of elevation within quite modern times are seen at the Thames, and on the coast-line north of Tapu Creek as far as the Orunui Stream, sea-beach gravels in this part being found at levels 200 ft. above the sea. North of this, direct evidence, as exemplified by the presence of old sea-beaches on the coast-line, is not abundant, nor very apparent; but at Torihine, three miles south of Cabbage Bay, old beach shingle reach to a height of 80 ft. above the present tide-mark. All the streams on the west side are tidal but for a short distance from where they enter the gulf, or the different harbours along its eastern shore, and none of them are tidal at low water. The deeper-seated rocks of the Peninsula appear also on this to a greater extent than on the eastern side of the Peninsula. On Moehau they rise to 2,500 ft. ; at Cabbage Bay, on the Tokatea and Success Ranges, and thence to the Tiki, the height to which the slates attain on the west side of the range is from 800 ft. to 1,000 ft. Further south they reach to lesser heights, till they disappear beneath the volcanic rocks of Tapu Creek, at a moderate height above sea-level. In Rocky Point, near the Thames, they are last seen on the west side of the principal water-divide, and as an isolated outcrop reach to from 200 ft. to 300 ft. above the level of the sea. On the east side of the Peninsula the slates appear at various places between Cape Colville and Mercury Bay. On this side they are last seen in Kuaotunu Peninsula, in which they reach a height of from 500 ft. to 600 ft. Here, however, they are in an axis of elevation different from that of the main range from Moehau to the Thames. Nevertheless, if a line be drawn from Kuaotunu to the Thames, this will be at right-angles to the greatest dip or plunge of the slates and the younger succeeding formations to the south-east. The Tokatea rocks, though not confined to the west side of the main range, have likewise this general plunge to the south-east; and the Kapanga group, though having its typical locality on the west side of the range, and largely developed between Coromandel and Cabbage Bay, has still the larger area of its development on the east side of the main water-parting. The rocks of the Beeson's Island group are developed largely on both sides of the main range, and form the whole of the mountain range beyond Te Aroha, in the southern part of the district. The acidic rocks, generally spoken of as rhyolites, are mainly confined to the eastern slopes of the main water-parting, but reach into the western fall in the Kauaeranga, Puriri, Omaha, and Hikutaia Valleys, and in the Omaha and Ohinemuri Valleys reach nearly to the level of the plain. In the Omaha the rhyolites are intrusive, as they are in the upper valley of the Hikutaia. In the Rahu, a small tributary of the Ohinemuri, and in the valley of the Ohinemuri itself, below Mackaytown, the rhyolitic material is of a more tufaceous character, and it is possibly of younger date than the great bulk of the acidic rocks. From the disposition of the different groups of volcanic rocks, and their unconformable relation to each other, it is evident that the elevatory movement to the north and north-west began before the close of volcanic energy concerned in the outpouring and building-up of the younger rhyolitic rocks, and, as would appear, even before the deposit of the rocks of the Kapanga group. Previous Geological Explorations. Professor Yon Hochstetter was the first geologist of note who made an examination of any part of Cape Colville Peninsula. He arrived in New Zealand in December, 1858,* and in June, 1859, made an examination of the district surrounding Coromandel Harbour, firstly and more particularly with reference to the occurrence of gold in that part of the Auckland District, and more generally with reference to the peculiar character of the rocks, as gold-producing, and the geological structure of Cape Colville Peninsula. The early history of the Coromandel Goldfield may fittingly here be given in Hochstetter's own words. He says : — " People began to prospect for gold here, and already in October, 1852, a Reward Committee was formed which promised a reward of £500 to the discoverer of a valuable goldfield in the northern district of New Zealand. Within less than a week the reward was claimed by Mr. Charles Ring, a settler recently returned from California, who asserted that he had discovered gold upon Cape Colville Peninsula, forty miles east of Auckland, iv the vicinity of Coromandel Harbour. The specimens produced by Mr. Ring were pieces of auriferous quartz, and some minute particles of gold-dust, which he had found on the Kapanga, a creek flowing into the harbour. The Commissioners sent out to investigate the matter also confirmed the existence of gold, leaving it, however, doubtful whether there was a goldfield extensive and rich enough to pay for the working. "This was the first discovery of gold upon New Zealand. There was a general rejoicing in Auckland over the lucky event; the people indulged in the most sanguine hopes, and at once arrangements were made for working the goldfield. As the land upon which the gold was found
* "In 1854 and 1855, Mr: Heaphy, of Auckland, published geological notes on the Coromandel district, near Auckland, and in the gold-diggings in Coromandel Harbour. The trachytie rocks found there were mistaken for granite."--" New Zealand," by Hochstetter (English edition), p. 49.
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belonged to the Natives, an agreement with the latter on the part of the Government had first to be brought about. The Maoris agreed for a certain payment to cede the acquisition of gold upon their own lands to Europeans; and already, in November, 1852, a treaty was made with the Coromandel chiefs for the term of three years, in which the Government pledged itself to pay the Natives for each square mile of land upon which gold was being dug £1 sterling annually, and for each gold-digger 2s. per month. In consequence of this the Government was, of course, obliged to lay a tax upon the gold-diggers. Granting an exemption for the first two months, it afterwards exacted from each digger £1 10s. per month for a digging license. " About three thousand diggers set to work. On the Kapanga River towards north the Coolahan Diggings promised favourable results, and likewise the Waiau Diggings, a short distance from the former, on the Matawai Greek, a tributary of the "Waiau Eiver, which flows southwards into the Coromandel Harbour. The ore produced was sold in Auckland by public auction. But when the taxes were to be paid there were only about fifty diggers who took licenses. These also, however, were not able to subsist under the heavy taxes demanded ; and as, moreover, nothing at all was heard of any encouraging results on a grand scale, and more and more difficulties arose on the part of the Natives, the whole enterprise died out after about six months. The simple verdict was that the gold-mines were too poor, and the promised reward was withheld from the discoverer. The whole produce upon the first New Zealand goldfield up to the time when the enterprise was given up was computed at £1,200 in gold-value, and the largest nugget found was a spheroidal piece of quartz of the size of an egg, which contained gold equivalent to about £10. " Despite various trials and movements in later years, and although the Natives brought from time to time small quantities of gold to Auckland for sale, no serious trial was ever afterwards made upon the Coromandel Goldfield ; and the Natives at last denied the Europeans even the right to make experiments. " Such was the state of affairs when in June, 1859, I visited the goldfield in company of Mr. Charles Heaphy, the late Gold Commissioner. What the traveller observes on entering Coromandel Harbour and examining its shores does in no way correspond with what a geologist expects of a gold region. The Coromandel Peninsula consists mainly of a mountain ridge, running nearly north and south, the mountains having a bold serrated outline, and varying in height from 1,000 ft. to 1,600 ft. The most noteworthy point is Castle Hill (1,610 ft. high), a rocky peak resembling the ruin of a castle. The valleys between the spurs given off laterally by this main or dividing range are of the character of ravines or gorges, occupied by mere mountain streams; the flats or alluvial tracts at their mouths and on the coast are inconsiderable. The coast consists of nothing but trachytic breccia and tuff, in the most varying colours, and in the most different state of decomposition, from the hardest rock to a soft clayish mass, and in various places broken through by doleritic and basaltic dykes. Siliceous secretions in the shape of chalcedony, carnelion, agate, jasper, and the like, are a very frequent occurrence in these tuff's and conglomerates, likewise large blocks of wood silicified and changed to wood-opal. By local geologists those trachytic rocks were erroneously taken for granite and porphyry, and, by a gross mistake, the most sanguine hopes were based upon the notion that these siliceous secretions might be auriferous quartz veins. "The Coromandel gold originates from quartz reefs of crystalline structure, belonging to a Palaeozoic clay-slate formation, :;: of which under the cover of trachytic tuff and conglomerate the mountain range of Cape Colville Peninsula consists. I The mountains are so densely wooded that it is only here and there in the gorges of the streams that sections of these slates may be examined. In these sections the clay-slates are frequently found to resemble Lydian stone ; they are arranged more or less vertically, their irregular upturned edges affording the most convenient and abundant pocket 3 for the detention and storage of the alluvial gold washed from the higher grounds. The most gold was found in the narrow valleys, where, after digging to a depth of 4 ft. to 5 ft. through boulders and shingle, the bed-rock is struck. Where the valleys extended into broader alluvial plains, there was always but little and very light gold found. "At a small branch of the Kapanga in the vicinity of Coolahan's Diggings, not far from Mr. Ring's mill, at a place pointed out to me by Mr. Heaphy as especially rich, I went to work myself to make an experiment in washing. We dug, partly from, the bed of the small creek, partly from the banks, several shovelfulls of quartz-gravel intermixed with earth and clay, which, after removing the larger pieces, we washed in round tin dishes. The result of the very first trial was a considerable number of extremely fine scales of a light yellowish-green gold, which glistened among the black magnetic ironsand that had remained after the washing process, and some small pieces of ochrey quartz, in which fine scales were seen imbedded. Each successive trial yielded the same result, nor was there a single dishful of ' dirt' that did not show the ' colour,' so that I had to acknowledge to myself that if those deposits of detritus should extend over a larger area, and could be worked on a large scale with the necessary machinery, the result must doubtless be a very remunerative one. But in regard to the former point I had no opportunity to convince myself; and, as to the latter, the Natives would not have consented at that time. The pieces of quartz, among which there were many violet-coloured or amethystine, all being angular fragments, could
* It is now a well-known fact that while gold is not absent from the slate-formation, the great bulk of gold production of the Cape Colville Peninsula lias been obtained from the two older groups of the volcanic series, the Thames and Kapanga groups ; and it is also the general opinion, reasonably held, that the gold is mainly a product of the volcanic rocks, and merely by a process of segregation, as it were, descends into the slate-formation a certain and variable distance. However, at Kuaotunu, on the east side of the Peninsula, the auriferous reefs in the slate country appear to have been formed in the presence of thermal waters, and the gold may have been brought from far beneath any volcanic rock resting on the slate formation. —A. McK. t " The same clay slate formation constitutes the Hunua Range, in the brown-coal district, south of Auckland, near Drury and Papakura, and continues towards south and north to a great distance. It is but very recently (May, 1862) that traces of gold are also said to have been discovered in the Hunua district."
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not have been brought from any considerable distance,, although in the creek itself we found nowhere a quartz vein in situ. On the slope of the hills I saw large blocks of quartz lying, which from all appearances originated from ' reefs ' or veins, that—according to the statement of Mr. Heaphy —protrude on the top of the dividing-ridge in various places like walls, 8 ft. to 10 ft. high and 10 ft. to 20 ft. thick. I much regretted the inclemency of the weather at the time, which frustrated our intention to examine these quartz reefs more closely. It is worth mentioning that gold was also found on the creeks flowing from the east side of the Cape Colville Range on Mercury Bay into the sea; on the Arataonga, Waitekauri, Cook's River, and others. The traces of gold, therefore, seem to extend over a larger district, and the Coromandel goldfields —such was my opinion in 1859 —bid fair to grow into importance in future years, when the country, as yet covered with dense woods, shall have become more accessible, when the auriferous-quartz reefs themselves shall have been discovered, and the difficulties which the Natives have hitherto opposed to every undertaking on a more extensive scale have ceased."* The volcanic rocks of the Cape Colville Peninsula were regarded by Hochstetter as forming part of the older series of volcanic formations, as given at page 66 of his work on " New Zealand " above referred to. The rocks of Beeson's Island and the shores of Coromandel Harbour he mentions as being formed of trachytic rocks : " The coast consists of nothing but trachytic breccia and tuff, in the most varying colours, and in the most different state of decomposition " ; and, referring to the more interior parts of the Coromandel district, he says, " The Coromandel gold originates from quartz reefs of crystalline structure, belonging to a Palaezoic clay-slate formation, of which, under the cover of trachytic, tuff, and conglomerate, the mountain-range of Cape Colville consists." When Hochstetter visited Coromandel, gold-mining was at a standstill, and the state of the weather at the time prevented the making of any examination of the interior parts of the country. Mining in the Coromandel district languished for some years, but in October, 1861, Coromandel again became the scene of mining operations, and a fresh impetus was thus given to prospecting and mining, which speedily made itself felt in the northern part of the Peninsula, and the district was proclaimed a goldfield in June, 1862. In the meantime the district had been visited by Sir James Hector, who in his report " On the Geology of the Cape Colville District," 1870, says : — " My first visit to Coromandel was in June, 1864, at which date the mining operations were being conducted with considerable activity, but confined to a very limited area. The following notes, made at the time, indicate the state of our knowledge of this mining district at that date, and before additional experience of the manner in which the mineral lodes in other parts of the Colville Peninsula had been obtained. " On entering the harbour, the rocks on each side are seen to be stratified, and dipping to the westward from the land, but rising again to the north and south, and, on landing at Beeson's, on Wanganui Island, were found to consist of trachyte, tufa, and conglomerate. The included fragments of trachyte, often of large size, are porphyritic with crystals of hornblende. In some places beds of compact trachyte occur, but this is probably only a variety of the tufa which has been more consolidated, or composed originally of finer-grained material. These tufas decompose freely to a ferruginous earth, which is sometimes bleached white, and frequently traversed by veins of quartz. " Where excavations had been made in this formation in search of auriferous reefs, the rock appeared to be a mottled purple trachyte porphyry, traversed by bands of felspathic clay—probably decomposed dykes, which contain masses and veins of crystallized quartz—also, a soft vein in the same description of rock, Bin. to 10in. in width, containing masses of horny quartz. These veins underlay to the east, and strike north-north-east. No gold has been found in any of these veins. "At Keevin's Point, a spur of the hills terminates in a bold ridge composed of light-grey tufaceous porphyry, containing iron-pyrites. The hill has been prospected in all directions by the miners, and the existence of two distinct reefs established. These consist of a banded quartz of a blue colour, with cavities lined with crystals. The rock appears to be originally a clay-stone porphyry, in which veins of segregation have been formed. The rock contiguous to these veins has been converted into a mottled pipeclay, stained with oxides and carbonate of iron. No gold has been found in these veins, which strike north 35° east, and dip eastward at 40°. [ "The chief diggings are up Driving Creek, two miles from Keevin's Point, in a north-east direction towards the highest point of the range. [Kapanga Mine?] Only one mine was in active operation (in 1864), having a five-stamp battery at work crushing a blue sub-crystalline quartz. The main reef is 6 in. to 8 in. thick, strikes north-by-west, and dips to the west at 45°. Since the new batteries began work they had crushed 40 tons, with a yield of 1,120 oz. Three shafts were sunk the depth of 150 ft., and one main level put in on the reef for 200 ft. Two other 'leaders' occur parallel with the main reef, with 30 ft. and 40ft. of white rotten rock between. The lower or east side of the main reef is a very hard fine-grained breccia, charged with pyrites. Each leader consists of a band of bluish mullock, containing strings and nodules of quartz, generally quite detached, and frequently very auriferous. From practical trials by Mr. Ninnis, the pyrites obtained as tailings from the mill contains gold in the proportion of 7 dwt. to the pound. It is not established, however, that the pyrites from the rock contains this large proportion, or only that which is derived from the vein-stuff put through the mill. As much of the quartz is evidenty rich to the eye, these portions are selected and crushed separately as specimens. A crushing of 1,7061b. of such specimens gave 2,198 oz. of gold. The rest of the ore from which the above specimens were picked weighed 100 tons, and yielded in the proportion of 4 oz. per ton.
* "New Zealand," by Hochstetter (English edition), pp. 94-98. f Keevin's Point and the adjacent hills, now the scene of active mining operations, are in this report regarded as formed of volcanic ash and fine-grained breccias of an andesic type, and as belonging to the Kapanga group of volcanic rocks, extending north along the coast-line to Paparoa, south to Preece's Point, and inland to the lower slopes of the Tokatea and Success Ranges.—A. McK.
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The total] produce, therefore, taking the gold at £2 15s. per ounce, was £7,143, representing the return of work executed from July, 1863, to May, 1864. " The yield for the vein-stuff is, therefore, about 26 oz. per ton. No calls had up to this time been required to be made on the shareholders in this claim, as the first ground worked was the richest. " From the shaft nearest Driving Creek the main reef had been worked out to ' day ' in the bed of the stream, the vein being very rich as the surface was approached. It was from the outcrop of this reef that the rich specimens found in the creek must have been derived, which first attracted attention to this goldfield. The stream winds about among the outcrops of the various reefs that have been discovered, but, owing to the nature of the rock, has not formed any proper water-worn gravel or ' wash.' The rock is decomposed very freely to a red soil, which is washed down as a coating of clay on the surface. The reefs can be traced as blue bands through the red rotten rock. They are rarely more than 10 in. in width, and, as a rule, lie parallel to a mass of breccia which forms barren ground cutting off the gold to the east, for, although superficial quartz veins have been found in this breccia, they have never proved worth working. " In the main or lowest reef are waterworn quartz pebbles, mixed with the same mullock or dark clay, in which are embedded the masses of crystallized auriferous quartz. The breccia consists of angular fragments of trachyte porphyry, and other rocks, but no quartz. Embedded in the surface soil, and lying in the bed of the creek, are masses of dolerite, and a dyke of the same rock appears north of Keevin's Point, but no proper volcanic rocks have ever been met with in the underground workings when they have proved auriferous. " On the occasion of a second visit, in February, 1866, I found many more claims occupied, but still only in the vicinity of Driving Creek, and from their being chiefly among the old workings which had been abandoned for many years, no additional information was obtained. "In April, 1868, after the discovery of the richer field at Shortland, the mining operations were again restricted to the Kapanga Mine. This mine had then reached a depth of 300 ft., or nearly to the sea-level. I found that the lode at this depth had the appearance of a fissure, with a well-defined hanging or west wall, but no regular vein-stone. The quartz occurred in larger concretions than in the higher parts of the mine, and these concretions contained, in addition to the gold and iron pyrites, native arsenic and crystals of calcite. Some of the specimens from this depth were exceedingly beautiful, but the main lead ceased to be practically remunerative, owing to the scarcity of auriferous ore at this depth. " On the spurs extending from the high range [the Tokatea Range] at the head of Driving Creek, there were, in 1864, several drives and shafts on small leaders of quartz in the decomposed porphyry, which passes into what the miners term sandstone, a few fathoms below the surface. The quartz then changes from the friable crystalline texture into a compact blue variety containing a large admixture of iron-pyrites. On the surface of the spur leading to Tokatea Peak large blocks of crystalline quartz are strewn in a zigzag line, having a general north-east direction. The principal claims were Murphy's,* in which there is a drive and shaft; the Coromandel, where there is a shaft 120 ft. deep sunk in the bottom of the gully; and the Royal, in which claim a drive has been put into the spur for 150 ft., to meet a shaft sunk in the crest of the ridge. All these are excavated in the porphyritic tufa, in the hope that small leaders which cropped out on the surface would change to reefs as they increased in depth, but they did not prove successful ventures in any case. '' As all these works have been abandoned for many years, and are now inaccessible, I have stated the above facts as observed at the time, and will now proceed to the general consideration of the structure of the district from the result of a recent examination, in the course of which I crossed the range to Kennedy Bay, and returned by a different route, from Whangapoua. I also re-examined the valley of the Matawai Creek, following it up to the Tiki Diggings, which had been discovered since my previous visit to the district. " In crossing to Kennedy Bay from the old diggings at Driving Creek, I found the difficult path by which I scrambled to the top of the Tokatea Range, in 1864, now superseded by a well-cut bridle-track, the cuttings along which afforded the additional advantage of clean sections of the rocks. The general direction in which the claims have been taken up towards the top of the range is in a north-north-east line, continued from Keevin's Point through Driving Creek and on to the Tokatea Reef. This great ' blow 'of quartz, as the miners term it, strikes to the north-west, and therefore crosses the auriferous belt nearly at right-angles.t " The shafts and drives on the Tokatea Hill, and also a few of the road-cuttings which penetrate the hard rock, show it to be the same grey tufaceous sandstone, full of mundic, as at Keevin's Point and Kapanga, thus proving this rock to extend in a narrow belt from the sea-level to 1,600 ft. altitude. On the surface it is everywhere so decomposed as to be scarcely recognisable from the patches of alluvial slope deposit. The auriferous reefs are generally in the decomposed rock, and, as at Shortland, have a general direction parallel with the boundaries of the formation, or north 40° east. " The eastern descent of the range, to Kennedy Bay, is at first very steep, and, so far as could be judged from the superficial appearance of the rock, the first slope is composed of green decomposing sandstones and breccia, like the barren rocks on the east side of Driving Creek. These are
*Murphy's Hill is on the left bank of Driving Creek, at the foot of the northern part of the Success Range. The rocks belong to the Kapanga group, but in the bed of the creek to the south slates appear.—A. McK. f From Keevin's Point to Scotty's Hill and the foot of the Tokatea Range a belt of auriferous country strikes north-east, which if prolonged would be continued to the lower grounds at the head of Kennedy Bay ; but during the progress of the work of the present year I came to the conclusion that this line does not cross the main range, and that the reefs on the Tokatea and Success Ranges, and the main range as far south as the Tiki, are in a belt of country running parallel to the main range, and consequently nearly at right-angles to that ending at Keevin's Point or at Preece's Point.—A. McK.
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succeeded by what might be taken for crystalline dykes, but which are probably only highly metamorphosed beds of sandstone [sandstone of the miners], containing mundic in cubic crystals. " The low spurs along the eastern base of the range are formed of blue and yellow felspathic slate ; while the hills along the coast, both north and south of Kennedy Bay, are formed of the volcanic agglomerates, presenting the same broken, but distinctly stratified, character as on the west side of the range. * " The country occupied by the volcanic rocks has a very distinct appearance from the central portion of this part of the range, which is composed of the tufaceous and porphyritic sandstones, and felspathic slates. The eastern limit of these rocks is marked by a bold scarp, which is seen . . . from Kennedy Bay, looking south-west. . . ." The boundary here indicated in the bold scarp seen looking south-west from Kennedy Bay is identical with the boundary between the Tokatea group and the Beeson's Island rocks to the east. In the opposite direction, for some distance from the shore of Kennedy's Bay, the Beeson's Island rocks rest upon coarse sandstones with abundance of minute fragments of slate, finer-grained sandstones, and slaty shales or mudstones. " In passing round the coast, from Kennedy Bay to Whangapoua, fine sections were exhibited in the cliffs of this volcanic formation . . . and from the frequent alternation of agglomerates and tufas, intersected by dykes in various directions, the formation has all the character of a superficial or submarine volcanic accumulation. At Whangapoua Harbour this formation is confined to the hills near the coast, as it was not met with in ascending the Waitikooti Stream in recrossing the range towards Coromandel. The first rock met with in this section was the green indurated sandstone, interstratified with siliceous slates containing mundic.t " The final ascent to the summit of the range is very steep, and passes over several alternations of rock, the changes being generally indicated by knobs on the spurs. The rocks are chiefly siliceous and clay-slates, weathering to various shades of white, pink, and red. The crest of the ridge is of vertical beds of sandstone, and descending the western slope a succession of slaty beds and. indurated clay-stones is met with. To the north of the part of the range crossed by the track is a low dip, near which the abandoned Whangapoua Diggings are situated. The rock is the usually grey porphyry tufa, but the reef was remarkable from its consisting chiefly of a black ferruginous substance, entangling the gold in finely-divided leaves and filaments.} . . . "The above may be considered as the northern district of Coromandel, and in the south district may be included the abandoned diggings on the Patawau, the alluvial diggings on the Matawai, and the recently-discovered reefing district on the top of the range behind the Tiki. The first-mentioned of these is about three miles south of the Wynyard Township, where in 1862 about two hundred pounds' worth of gold was obtained, of better quality than is usually obtained on this goldfield. It appears to have been confined to one small tributary of the creek from the north-east, which flows through decomposed argillaceous slates traversed by irregular quartz veins. A spur consisting of these slates had been cut through by a drive 300 ft. long, communicating with the surface by a shaft, but no auriferous leader was discovered. " The Matawai is the next stream to the south from the Patawau, and the spur which divides leads back to that part of the main range where the Tiki reefs have been discovered.§ The section afforded by the valley of the Matawai is very interesting. The junction of the volcanic agglomerate, which forms the peninsula separating Coromandel from Manaia Harbour, with the older rocks is well exhibited below the old mill, where the Matawai and Waiau Streams meet. Following up the Matawai Valley, the stream is seen to flow over vertical ledges of green and blue slates, sandstones, and porphyritic breccias, containing small quantities of pyrites, and having a general north-west strike. On the steep spurs above the creek the same rocks are very much decomposed and altered in appearance. The creek is skirted by patches of coarse red gravel containing coarse gold. These deposits were supposed, when I examined the creek in 1864, to have been worked out; but I lately found several parties of diggers systematically turning the river, and obtaining a fair return of gold, generally in the form of nuggets, one or two having been obtained which weighed over an ounce. The quality of the gold obtained is the same as at Driving Creek and at the Tiki Diggings in the back range, and not like that on the Patawau side of the spur. The gold has been traced in these gravels for about two miles, to where a branch creek joins the stream from the north. No trace of gold has been found in the other or south branch, which rises near Castle Hill, which is a mass of trachytic agglomerate. |] " Ascending the hill, at 800 ft. above the creek, on the north side is the Golden Crown Claim, which is the furthest south of forty claims that have been taken up along the ridge constituting the Tiki Diggings. Several drives and shafts enabled me to examine the formation, which is the same decomposed blue slaty sandstone as at Patawau Creek. Two distinct leaders of quartz had been found, the one running due north with a westerly underlay, and the other north 28° east, with an easterly underlay, the thickest being 16 in. The only gold which has been obtained is not from these veins, however, but from thin irregular leaders in the rotten rock near the surface.
*On Beeson's Island and on the coast-line to and south of Manaia Harbour. These are the trachytes of Hochstetter, Beeson's Island group, of this report, and different from the Thames-Tokatea and Kapanga groups.—A. McK. f No slates were observed by me on the east side of the range on the road from Whangapoua to Coromandel.— A. McK. J The route followed was not what is now the road from Whangapoua to Coromandel, but from the saddle north to opposite the Success Mine, and thence by the spurs descending west to the low grounds.—A. McK. § Gold has, however, since then been discovered in the slates at the Tiki, and during the past summer prospecting in the slates near the saddle between Tiki spur and the main range was being carried on.—A. McK. | Castle Rock is a massive dyke of grey rock, containing more or less abundantly crystals of hornblende.— A. McK.
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" The absence of trachytic rocks up the Matawai Creek is rendered very obvious by comparing it with the Waiau, which flows direct from the trachytic district, of which Castle Rock forms part. The gravel in the Waiau is chiefly composed of a porphyry, consisting of grey felspathic base, with large crystals of hornblende. Half a mile up the river from its junction with the Matawai, it flows over solid ledges of this trachyte porphyry, and, although the valley has been well prospected, no gold has ever been obtained. From this circumstance, I think it probable that the trachyte will be found to cut off the auriferous rocks to the south, just as the volcanic agglomerates bound them on the east and west. The reefing district will therefore be limited at Coromandel to the range of hills that extends from the Matawai on the south to some little distance beyond the Tokatea Peak. Two bands of the auriferous formation appear to cross this range obliquely, as shown in the accompanying map [illustrating Dr. Hector's report]. The first of these extends from Preece's Point (which consists of the decomposed greenstone tufa), through Keevin's Point, Driving Creek, Tokatea, and on to Waikawau Bay, where traces of gold are reported to have been discovered. The second extends from the Tiki Diggings, by the old Whangapoua Diggings, to the Haratuhunga Creek, which flows to Kennedy Bay from the south. "At a low estimate, this district must be held to include an area of not less than five square miles, but in which gold has only been obtained in notable quantity at the Kapanga."* In the first part of this report Sir James Hector makes an extract from Hochstetter's " New Zealand," pointing out what were the determinations made by that geologist, and the opinions he had arrived at, and then goes on to say :— " Professor Hochstetter thus clearly expresses his opinion that the more recent volcanic rocks of the district, to which he alone refers in the above passage, would not prove to be auriferous, a view which I think is fully borne out by our extended knowledge of the field. The gold is not, however, as he supposed, derived only from quartz veins in clay slates, for, as Captain Hutton very justly points out in his report on this district, the area of these exposed at the surface is very limited. On the other hand, Captain Hutton, in the same report, does not distinguish between the comparative modern breccias and agglomerates, which he describes as containing blocks of variously-coloured scoriae and lavas, and the more ancient formation of green tufaceous sandstone and porphyry in which most of the auriferous lodes occur."! Sir James Hector visited Coromandel in 1864, and the report from which the above extracts have been made was written in 1870, and, as in the meantime great discoveries were made in the district farther south (at the Thames, Tapu Creek, &c), the opinion formed in 1864 may be considered expressed in his writings prior to 1870, and subsequent to the discovery of gold at the Thames. Introductory to Captain Hutton's first report on the Thames Goldfield, at page 2 of the report as printed, is an extract from Dr. Hector's instructions to Captain Hutton, in which, evidently referring to the visit made to Coromandel in 1864, or to a subsequent examination of other parts of the Peninsula, he says : — " The range which separates the Thames Valley from the Bay of Plenty I found to consist of a nucleus of aphanite slates, interbedded with green brecciated and greywacke slates, being part of the Upper Palaeozoic series. Flanking and capping this nucleus is a great development of the following members of the Tertiary series : (a.) Brown-coal formation, very local. (5.) Quartzose gravels cemented, so that they break away in large blocks, (c.) Waitemata series (Pliocene), (d.) Trachytic tuff, (c.) Trachytic breccia. " The Palaeozoic rocks are cut by dykes of trachyte (granite of the miners), which is charged with auriferous and cupreous iron-pyrites. They, moreover, contain quartz veins, which are also pyritiferous and auriferous. The older rocks decompose very freely to laterite, and the fissures then contain secondary deposits of silica, manganese, &c, especially when near the supposed trachyte dykes, alongside of which in some cases there would seem to have been fissures that were only gradually filled up by deposits from thermal waters, giving rise to the banded, irregular, and crystalline structure of the lodes, which is so characteristic of Coromandel. " The composition of the several reefs in the vicinity of tne lodes at Coromandel shows this singular character, arising, I suspect, from all the soluble matter of what was once a basic rock having been removed and replaced by silica, and partly by iron-pyrites containing gold. That this mineral is the main source of the gold is shown by a section of the lode ground I made in 1864, when I found that the so-called quartz reefs were contained between two varieties of pyritous rock, the sulphurets having been removed from the overlying rock, but still remaining in the lower, the reef itself being a band of mullock containing kernels and geodes of quartz and carbonate of lime, and evidently formed by infiltration. A third manner in which quartz occurs in the district is in the trachytic tufas, but it is then more chalcedonic and crystalline, and associated with jasper and chert, and is non-auriferous, as proved by the numerous trials at Keeven's Point, Coromandel. " The older rocks present too limited an area in the Coromandel district to form the source of much gold by direct denudation, as in the south of New Zealand; still, where they have been decomposed to form the red clay or laterite and secondary minerals thereby formed, gold may be among these. The gold in the case of Patawai Creek, Coromandel, must have had a different source from the gold got in Driving Creek, as its value was £3 17s. 6d. per ounce ; but such deposits seem to be very small and patchy, as only two hundred pounds' worth "was got, I believe, by Mr. Turner in 1862. I would not, therefore, recommend as a guide in forming an opinion as to the prospect of cold the mere presence or absence of Palaeozoic rocks, without at the same time taking into consideration their peculiar association with the pyritous rocks above referred to. The same Palaeozoic rocks occupy a large area in Otago, without a trace of gold; but on the west coast of Nelson, where they are associated with pyritous felstones and porphyries, they are then auriferous."
* Geological Reports, 1870-71, pp. 88-95. f Geological Reports, 1870-71, p. 89.
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In a covering letter, dated the 23rd September, 1867, with which was forwarded to the Under Colonial Secretary Captain Hutton's Report on the Thames Goldfield, are the following remarks : — "The associations of gold with volcanic rocks belonging to the Tertiary period; near the point where they have been erupted through the older Palaeozoic slates, has a very important bearing on the question of the occurrence of gold in the interior of the North Island, as there is a probability that many other localities besides the Cape Colville Peninsula will prove auriferous to a similar extent. 1 see no reason, however, to expect any extensive alluvial diggings in the Karaka district, or that it will afford a field for the employment of a large mining population." From Captain Hutton's Report (his first on the Thames Goldfield), above referred to, is taken the following : — " The whole country [the district east of the Thames] is much broken, rising, except at the mouths of four of the streams, into hills of from 600 ft. to 800 ft. close to the sea, and increasing in height towards the eastern boundary of the block to more than 1,000 ft. The country is for the most part covered with dense bush (except where close to the sea), and the streams are all mountain torrents, with large boulders occupying their beds. " Geological Structure. —The geological structure of the country is very simple, being almost entirely composed of a huge mass of trachytic tufa, resting on Palaeozoic rocks, which are cut by numerous dykes mostly of diorite, but occasionally of trachyte. This tufa appears generally as a softish grey coarse-grained rock, weathering white, and sometimes much stained with peroxide of iron. Where cut by dykes it is hardened for considerable distances, and much altered in appearance. As might be expected, however, from its origin, it varies a good deal in character, often containing rounded blocks of diorite 1 ft. or 2 ft. in diameter ; indeed, in three or four places it passes into a true conglomerate, while occasionally small angular stones are seen in it, forming a breccia. These latter, however, are very local. " Near Hongikori the rounded blocks of diorite are encased with a coating of red jasper. The rock is also traversed by numerous veins of quartz, carbonate of lime, or both these minerals mixed together, in which case it is seen that the carbonate of lime is a subsequent introduction, as it is found incrusting well-formed crystals of quartz. The whole of the rock, including some of the dykes, is much impregnated with iron-pyrites, generally in the form of minute cubes, but decomposed to a grey powder near the auriferous veins. The " tufa is probably of Tertiary age, and not older than the Waitemata beds. In structure " there are no marks of bedding nor stratification to be seen, but from the extent of country that it covers, and the general vertical direction of the dykes, I think that it is not far from horizontal, dipping, probably, slightly to the west or north-west. The absence of slate boulders in the streams and on the coast seems to show that this tufa extends over much more ground than that visited by me, and I can see no reason why auriferous veins should not be found in any part of it. These veins, being thin and variable, must always render gold-mining in this district highly speculative, and if, as I believe, the stratification is nearly horizontal, deep sinking will be useless, and, in order to enable a company to make a profit, it will require more' ground than is usually allotted to a gold claim. " In one locality only, between Tararu and the Waiohanga Creeks, are Palaeozoic rocks seen in the district. They here consist of blue aranaceous slates, covered by a fine-grained felsite tufa, the whole dipping 35° south-west. " Lying on the tops of the old tufaceous hills, between Shortland and Tararu, a deposit of fine red-and-white trachytic tufa is seen, of a much later date than the old one on which it rests. This does not cover much extent of country, and is probably of Pleistocene age, and formed by the former eruptions of Aroha Mountain."* Thus, according to the above report, the mass of the country is composed of trachytic tufa, cut by numerous dykes of diorite and trachyte. The tufa varies a good deal, and contains frequent boulders of diorite; is sometimes a conglomerate, shading off into a finer-grained breccia. Quartz veins are numerous, but not large, and carbonate of lime is often associated with the quartz. The trachytic tufa is of Tertiary age, and not older than the Waitemata beds. Palaeozoic rocks are seen only on the coast-line between Tararu and Waiohanga Creeks, and a yet younger trachytic tufa of Tertiary date rests on the older, which is probably a product of Te Aroha, this mountain evidently being regarded as centre of eruption. The following extract is from the " Second Report on the Thames Goldfields," by Captain Hutton, Wellington, 1869. The extract begins with a description of the country dealt with in the report, which is as follows :— " Description of the Country. —The district included in this report is a narrow strip of land on the right or east bank of the River Thames, and on the eastern side of that part of the Hauraki Gulf known as the Firth of Thames. It is some twenty-five miles long, by two to four broad, the direction of the longer axis being about north 18° west. Shortland, the principal town, is distant from Auckland about forty-three miles by sea. At Puriri, the southern end of the district, the alluvial plain on this bank of the Thames is about three miles broad, and it gradually narrows until it comes to an apex at the Kuranui Creek, north of Grahamstown. The remainder of the country is hilly, the hills having generally very steep slopes, and rising to about 2,300 ft. near the head of the Karaka. The sides of the hills are generally covered with slipped ground and vegetable soil; very few precipitous places occur, and with the exception of the beds of the streams or creeks, and occasional landslips, are the only natural sections to be found. The most important of the creeks beginning from the south are the Puriri, the Kauaeranga, the Tararu, the Puru, the Waionau, the Pohue, the Tapu, and the Mata. The first two run for the last few miles of their course through alluvial flats; but all the others are mountain torrents almost to their mouths, their beds consisting
* " Geological Reports on Thames Goldfields," 1867 : first report, by Captain Hutton.
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of the solid rock of the country, generally filled up with more or less rounded boulders. Near the sea the hills are covered with fern, but in the valleys, and further inland, by dense forest, which, however, is rapidly disappearing in many localities before the axe of the miner. " Historical Account. —Gold had been known to exist at Coromandel, a little north of this district, in 1852, and it had been regularly worked there since 1862. Rumours had also long existed that gold was plentiful in the Thames Valley, and several Maoris and Europeans had brought specimens to Auckland at various times from 1865. In July, 1867, a Native chief named Taipari, stimulated by the offer of the Provincial Government of a reward of £5,000 for any one who should discover a payable goldfield, employed several men, both Europeans and Natives, to prospect his land ; and gold was obtained by sluicing in the Karaka and Hape Creeks. This was taken to Auckland and shown to the Deputy-Superintendent and the Native Commissioner, and at the same time Taipari offered to throw open his lands as a goldfield. Satisfactory arrangements having been made with him, the result was that a block of land from the Hape to the Pukehinau Creeks, known as the Karaka Block, was proclaimed a goldfield on the Ist August, 1867, and a town was laid out at the mouth of the Kauaeranga, and named Shortland. Parties at once set to work sluicing on the Karaka, Waiotahi, and Moanataiari, but with indifferent results; when, on the 17th August, four men discovered the gold in situ in the Kuranui, on the face of a waterfall, on the spot now so well known as ' Hunt's Reef.' This led to further exploration for quartz veins, and in a month's time gold had been found in about a dozen places. Further discoveries quickly followed. Sluicing was abandoned, and quartz-mining recognised as the true industry of the field. So satisfactorily did this turn out that at the end of December, 1868, or seventeen months after the first proclamation of the field, not only had two other distinct districts —Tapu and Puriri —been started, but about twelve hundred claims had been taken up near Shortland, between eight hundred and eight hundred and fifty of which were then actually working, and probably six hundred of the number had seen gold in greater or less quantities. Twenty-seven crushing-machines were on the ground, and thirteen others were going up. The yield of gold had exceeded 83,000 oz., valued at more than £200,000; and the population numbered about 18,000 souls. Gold is now being worked at Puriri, in the district between Shortland and the Tararu, and at Tapu. It has also been found in one or two places between Tararu and Tapu ; and, as the same geological structure extends over the whole district, there is every probability of it existing much more extensively than has yet been discovered. " Geological Structure — Slates. —The oldest rocks found in the district are a series of darkblue, more or less arenaceous, sub-metamorphosed slaty rocks of a fine grain, rather closely jointed, but not cleaved. At Tapu they strike east 10° south, and are nearly vertical, their dip oscillating to about 80°, in some places to the north, and in others to the south. They here consist of blue, rather friable slates, interbedded with soft brown arenaceous slates, that weather white, and hard green slates traversed by innumerable minute veins of compact white quartz. Near Shortland a small patch of blue and reddish-yellow ribboned slates is seen on the beach, a little north of Tararu, and again up the Waiohanga Creek. On the beach the dip of the beds is 35° south-west. These two are the only localities in the district in which this formation is found. No fossils have as yet been found in these slates, and their age is therefore uncertain. Judging, however, from the lithological characters, they appear to belong to the Maitai series of the South Island (as described by Hochstetter). A few miles north of Hastings, on the coast between the Mata and Waikowhau Rivers, these rocks are cut by several dykes, running within a few points east or west of north, or about at right-angles to the strike of the beds. These dykes are composed of a coarsely-crystallized diorite, generally of a dark-green colour, but occasionally red, with white crystals of felspar (orthoclase?), sometimes more than long. They also contain as accessories small quantities of magnetic iron and iron-pyrites. These dykes would be called syenites by many geologists, although they contain no free quartz. The patch of slates on the beach north of Tararu dips towards a mass of fine-grained yellowish-white felstone, containing pyrites, which forms the first point north of the Tararu Creek. This felstone is not seen up the Waiohanga Creek, and probably, therefore, it is an intrusive mass. "In the Tapu district gold is found in lodes traversing these slates. Pyrites also is abundant in some places, but it is not generally distributed through these rocks. Quartz veins also are by no means so common as in the formation to be next described. " Trachytic Tufas. —Lying unconformably on the denuded and waterworn surface of the slates, and covering by far the greater part of the district, is a mass of trachytic breccia, agglomerate, and tufa, in places at least 3,000 ft. thick. This rock, in its normal condition, is a hard, grey, granular rock, with more or less rounded grains of white potash felspar (orthoclase). It passes in places into gravelly tufa, breccia, and agglomerate, the included fragments being pieces of the tufa itself, of dolerite, trachy-dolerite, trachyte, and occasional small pieces of obsidian. Near the older rocks it also contains pieces of slate, and the igneous rocks penetrating them. The junctions of the two formations that are seen on the coast between the Mata and the Waikowhau is very interesting. The tufa here passes into a coarse conglomerate, by far the largest portion of the enclosed fragments being more or less rounded pieces of the slates, while the surface of the slates rises from a very waterworn base into a nearly perpendicular cliff. It appears to have been an old sea-beach when the tufa was accumulating, and, if this be the case, the tufa must have been deposited during subsidence, as the upper portions of the formation are evidently sub-aqueous. " North of Tararu, where the tufa lays upon the slates, the lower part of the formation is a breccia, containing fragments of tufa, slate, and felstone. This passes upwards, through gravelly tufa, into the ordinary granular blue tufa, at a height of about 30 ft. above the sea. The upper portion of the tufa is decomposed by the action of the atmosphere into a white, or yellowishwhite, soft rock, stained red in places by peroxide of iron, which is derived from the decomposition of the iron-pyrites, with which the blue tufa is highly charged. The action of water further
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decomposes it into a stiff clay. The lower part of the formation has generally been metamorphosed to a variable height above the sea into a hard, green, pink, or purple felspar porphyry, or more rarely into hornblende porphyry; and this action is also distinctly traceable in the neighbourhood of the various igneous dykes which traverse it. The tufa, whether in its normal or metamorphosed condition, never contains mica in this district. " I can see no reason for supposing that the lower part, or porphyry, is distinct in age from the upper part, or decidedly trachytic tufa. When decomposed they are both alike. There is no appearance of any line of separation between the two rocks, but the one passes gradually into the other ; and there are no signs of any suspension of the volcanic energy for so long a time as to divide it into two geological periods. No doubt the fact of the tufa often containing angular blocks of the hardened tufa itself (not necessarily metamorphosed into porphyry), as well as the great thickness of the formation, prove that the volcanic action lasted so long that the lower part of the tufa was consolidated, broken through, and ejected by volcanoes while the upper part was forming. Although evidently of sub-aqueous origin, no fossils have as yet been discovered in it, and its age can only be inferred from other considerations. No scoriae or other signs of the proximity of volcanic centres of eruption are seen at the Thames ; but on the Great Barrier Island a trachytic tufa, similar in most respects to that at Shortland, is largely charged with scoriae, and is seen to be connected with subaerial volcanic cones, whose craters can still be distinctly traced. The same trachytic formation extends across the Hauraki Gulf to Manaia, at Whangarei, where it rests upon Tertiary sandstones and limestones ; and at the North Head of the Manakau a formation, essentially the same, but differing in the composition of the dykes which cut through it, forms the upper part of the Waitemata series, which is known to be of late Tertiary, probably of Upper Miocene date. On the whole, then, it is probable that this trachytic tufa, breccia, and felspar-porphyry is of Upper Miocene age, but more information must be obtained before the question can be considered as settled. " Gold is found both in the porphyry and in the softer blue tufa, but more abundantly in the latter. This may, perhaps, be owing to the greater hardness of the porphyry, and to the more perfect crystallization of the pyrites contained in it, which prevent the water percolating freely through the rock and decomposing the pyrites, and so liberating the gold contained in it. "The tufa formation is traversed by many dykes of igneous rocks, generally more or less magnetic, some of which seem not to have reached the surface. These dykes may be divided into two classes —viz., 1., Dolerites; and 11., Greenstones. The first class are composed of dark-gray dolerites, showing crystals of augite in a compact dark felspathic base. One is seen in the Star of Karaka Claim, on the left bank of the Karaka Creek, a little above the Hokianga machine. Another runs along the top of the ridge between the Karaka and the Waiotahi, and traverses the Galway, Fair Maid of Perth, and the upper part of the Monster (Karaka Gold-mining Company) claims. In the Waiotahi Creek, on the Lovers' Walk Road, in the upper part of the Freeman's Bay Claim, another dolerite dyke appears, probably the same as the one in Star of the Karaka. This throws off a branch which runs through the Duchess of Kent Claim. Another dolerite dyke occurs in the Cosmopolitan Claim, at the junction of Madman's Gully with the Moanataiari; and this is again seen lower down, on the right hand side of the creek, in the Pheasant Claim, about 200 yards below the Launceston (Carter's) battery. " The second class of dykes is much more numerous, and can be again divided into two groups, which are, however, connected by many intermediate varieties. These groups are : (a.) Metaphires : Dark bluish-green, weathering red, generally fine-grained, with only occasional distinct crystals of hornblende or augite. Examples : Fiery Cross Claim, on Ponga Flat; Tararu Creek ; Waiohanga Creek; Tinker's Gully ; Moanataiari Creek, below the Point Russell Claim ; and also near the junctions of the Lucky Hit and Alabama Creeks with the Karaka. (b.) Timazites ; Paler green, weathering red, with well-developed crystals of hornblende. These rocks appear to be the same as G. Rose's dioritic-trachyte, or the greenstone trachyte of Van Richthofen; but Breithaupt's name of Timazite is the more euphonious. Examples : Pukihinau Creek ; Heart and Hand Claim, in Wiseman's Gully; and in the Ballymore Claim, Waiotahi. " Besides these dykes, there are several masses of what appear to be highly metamorphosed tufa traversing the field. One of these extends from the Waiotahi, a little above the Waiotahi Gold-mining Company's machine, to the Otago Claim, in the Moanataiari, and strikes the Shellback above Bleazard's machine. These masses are just similar to the tufa when in proximity to a dyke, and I therefore suppose that they are the tops, or caps, of dykes that have not penetrated as far as the present surface of the land. As there is no evidence of the tufa ever having been covered up by younger formations, it is evident that we might expect that few if any of the dykes had reached the surface, for if they had done so they would probably have formed volcanoes, and traces of them would have been left by pieces of vesicular scoriae becoming embedded in the tufa. It is highly probable that these dykes influence considerably the direction of the quartz veins; but it would be premature at present to form an opinion as to what effect, if any, they may have on the distribution of the gold, as neither the position of all the dykes, nor the richest parts of the field, are as yet perfectly known. "Besides the gold, which is always combined with more or less silver, the following metals have been found in the tufa, but not in sufficient quantity to be worked. [Mercury, zinc, lead, antimony, copper, arsenic, and iron.] " Alluvial Deposits. —These are of four kinds. The oldest is a loose, red, and more or less sandy clay, containing rounded boulders of dolerite. It occurs in many places on the top of the spurs that divide the creeks from one another. On the ridge between Karaka and Waiotohi, above the Hauraki Gold-mining Company's Claim, it reaches an elevation of 1,550 ft. above the sea-level. It also, at Tapu, fills up some of the gullies on the flanks of the spurs, as seen in the Hit-or-Miss and Marquis of Hastings claims. It here contains many rolled agates and carnelians from the
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tufa, and gold, which latter curiously enough, is very little worn. The boulder formation on the top of the hills must have been formed when the land -was still under water ; but the alluvium in the gullies may have another and more recent origin. Next in age come the deposits of pumice sand that underlie the Town of Shortland. A shaft sunk just behind the town, after passing through a marine formation of sand with broken shells, about 10 ft. thick, traversed about 68 ft. of gravel composed of stones of tufa, dolerite, trachyte, quartz, and occasionally rhyolite and obsidian. It then got into pumice sand, after penetrating which for 10ft.it was abandoned. These two last beds are evidently an old river-deposit, and must have been brought down the valley of the Thames when the land was at least 100 ft. higher than at present. " The bed of sand with broken shells belongs to the third kind of alluvial deposits. Up the bed of the Kauaeranga it is seen to pass into two beds, the lower of which is a stiff blue clay full of shells of Turbo (recent species), Venus intermedias , Tellina alba, and a species of Mactra, which, although very abundant in this deposit, is now either extinct or very rare in the neighbouring seas. Upon this rests a bed, 3 ft. thick, of brown clay, only the lower part of which contains shells. " The fourth kind of alluvium is formed by landslips from the adjacent hills, but between the Hape and Waiotahi it assumes much more important dimensions than landslips usually do. It consists of tufa more or less decomposed into yellow, white, or pale-blue clays, containing boulders of tufa, dolerite, and quartz, which latter are sometimes auriferous. Below the Royal Standard Claim, on the Karaka Hill, at a depth of 30 ft., kauri-gum, pieces of wood, and rotten raupo (Typha) have been found; and near Shortland, at about the same depth, an old Maori padddle was dug out in sinking a shaft. It would thus appear that when the alluvium full of boulders found on the tops of the hills was forming, the land was 1,600 ft. lower than at present; that it then gradually rose until it was at least 100 ft. higher than now; and at that time the Thames ran further north than Shortland. The land then sunk to about 10ft. or 12ft. lower than now, and subsequently has again risen to its present level."—(Second Report on Thames Goldfield, by Captain Hutton, pp. 3-11.) In this second report by Captain Hutton, the slates at Tapu Creek and on the coast-line to the north (over and above those at Tararu or Rocky Point) are described, and the dykes of diorite cutting through the slates on the coast-line between the Mata and Waikowhau Rivers, and the presence of gold in lodes, traversing the slates at Tapu Creek, is noted. The trachytic tufa formation is more fully described than in the first report by the author, and as giving evidence of having been deposited in the sea and in places altered to a felspar porphyry more rarely to a hornblende porphyry, the lower altered parts of the tufa formation are not necessarily older or of a different age than the upper unaltered part that still shows as a trachytic tufa. Though the tufa formation is believed to be of sub-aqueous origin, the absence of fossils is noted, and its age can only be inferred from other considerations, the conclusion being that the tufa is of Upper Miocene age. The absence of scoriae and other signs of the proximity of volcanic centres is noted. The many dykes in the tufa formations are divided into two groups : 1., Dolerites; 11., Greenstones; the latter being divided into (a) Melaphyres and (b) Timazites. Other hard rocks in the field are considered probably metamorphosed tufa, as in the immediate neighbourhood of the Thames. " Veins and Lodes. —The tufa formation is traversed by a large number of quartz veins of all sizes, and running in all directions—one in the Portuguese Claim, on the Karaka Hill, being quite horizontal. Although there is no point of the compass to which veins may not be found running, still there is a most decided tendency to a more or less north-east and south-west direction. Out of nearly two hundred veins observed in different parts of the field, the bearings of 90 per cent, were in the quadrant between north and east, while only 10 per cent, were in the quadrant from east to south ; north-east, north-north-east, and north being the most favoured directions, and south-east by south, south-east, and east by south the least favoured. The fact that the three least-favoured directions are almost at right-angles to the three most favoured ones is sufficiently remarkable. The direction of the veins does not appear to have any influence on the abundance or scarcity of the gold. They vary in thickness from a Jin. to 14ft., and, as a general rule, the smaller they are the more irregular is their bearing and clip. The thicker veins are not so rich as the thinner ones. The larger veins are often laminated or divided into different layers of quartz by thin bands of clay, or ' flucans.' The quartz is generally crystallized, the points of the crystals meeting in the centre, but it is also often compact, cavernous, or geodic. The veins often contain chert, red and green jasper, and (more particularly at Tapu) carnelian, chalcedony, and agate. Opal has not yet been found, but may be expected to occur. The jasper is sometimes highly charged with pyrites. Carbonate of lime, both as calcite and aragonite, and carbonate of iron are also found in some of the veins. In the Lady Bowen Claim at Tapu, a reef of pure white calcite, about 2 ft. thick, occurs. Gold is found in the clayey casing of this reef, but not in the reef itself. These carbonates have generally been introduced after the quartz. " Gold is found in every description of quartz, from the most tough and flinty varieties to quite crystalline ; and I have been informed that it has been found in red jasper, but I have not seen the specimen. It has not, I believe, been seen actually enclosed in a quartz crystal, as many other metals have been found. "Besides the veins, lodes or reefs of three different characters are found in the district. The first occur only in the slates at Tapu, and consist of a mass of soft stiff blue clay generally from 1 ft. to 2 ft. thick, charged with small nodules of quartz. A good example may be seen in the Little Jessie Claim, at Tapu. The second kind is found in the tufa. These lodes consist of a tufaceous gangue, thoroughly infiltrated with silica, which also forms nodules and small veins and strings of quartz through it. The walls of these lodes are not easy to recognise, and the amount of quartz contained in them varies very much. Examples are found in the Golden Crown, Hunt's, and Middle Star reefs. The third kind also occurs in the tufa. These are fissures filled up with fragments of rock fallen into them, and cemented together by a silicous matrix. Such are Dixon's No. 1, and the Dawn of Hope reefs.
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" With the exception of iron pyrites, which is abundant, the auriferous veins and lodes are, as a rule, remarkably free from the ores of other metals, small quantities of stibnite, blende, arsenical pyrites, and copper pyrites being the only ores found ; and even of these the copper pyrites and blende are comparatively rare, and, as well as the stibnite, appear to have been introduced subsequently to the gold. The gold is nearly always found in or associated with quartz, although probably it also occurs in places in the bed-rock, but encased in iron pyrites. A series of analyses are necessary to determine this point. The gold in the quartz may be conveniently arranged under two typical forms, which may be regarded as the extremes of a series connected together by many intermediate varieties. Often, however, the two forms may be combined in one specimen. " The first form is when the gold is finely peppered, generally in small grains, but sometimes in flakes, through amorphous quartz. In this case it is so intimately mixed up with the quartz that it is impossible to doubt that the two were deposited simultaneously, and from the same menstrum. In well crystallized veins this kind of gold is often seen to be plentiful in the amorphous, or semicrystalline quartz at the base of the crystals ; as soon as the crystals of quartz begins to be regularly formed the gold ceases. This is the commonest form in which gold is seen at Shortland, and it is found in all the best claims, both in the quartz veins, and in the irregular nodules that occur so plentifully in the mullock reefs or lodes. The nodules in these mullock lodes often show no trace of gold on the outside, but when broken are seen to be thoroughly impregnated with it. The second form is where the gold lies in fine threads or scales on the surface of the quartz without penetrating it. This is seen only in the smaller veins, generally where the points of the two sets of quartz crystals, starting from either side of the vein,approach so near as almost to touch each other. Here, entangled, as it were, between the points of the crystals, most beautiful specimens of leaf and filiform gold are found, while the quartz on either side is often quite barren. In these cases it is evident that the gold must have been introduced after the deposition of quartz had ceased; and, as the veins in which it is found are almost always not far from the surface, and the quartz is generally stained red by the oxide of iron, there can be little doubt but that the gold is a secondary deposit and derived from the decomposition of auriferous iron pyrites. Many claims in which most magnificent specimens of this form of gold have been found have not paid for working, all the gold contained in the vein being apparently visible to the naked eye; while, when the gold is of the form first mentioned, exceedingly good results are often obtained from stone in which little or nothing can be seen. " It may be taken as a general rule applicable to the whole field, that all the veins and lodes show more gold, and crush better, when taken from the red iron-stained upper portions, and that as they descend into the blue undecomposed parts the yield is less satisfactory, not that they contain a less quantity of gold, but because that the undecomposed pyrites contains a large percentage of it that cannot be got out by the ordinary processes at present in use; and also on account of the injurious effect of the pyrites itself on the mercury, preventing it amalgamating with some of the gold that is in a free state, and that would readily be attracted by clean mercury. The pyrites also cause the mercury, when used in the battery-boxes, to break up into very fine globules, which float over the tables and cannot be caught, but which probably carry away with them more or less gold. "The quality of the gold differs considerably in different parts of the field, and even from the same claim it often varies a good deal. Out of twenty-eight assays from various parts of the Shortland district, kindly furnished to me by the assayer of the Union Bank of Australia, the highest gave 195 and the lowest 9625 carats fine, both being from the Waiotahi Creek; while from the Lord Derby Claim, also on the Waiotahi, some stone yielded nearly pure silver, being only 2-75 carats fine, and worth only 9s. Bd. an ounce. The average of the twenty-eight assays is 15 carats fine. . . "The gold is very widely distributed through the district, although certain parts appear at present to contain it in more considerable quantities than others; but the mines have not yet been long enough worked to pronounce with much certainty on this point. The fact before mentioned, that probably six hundred out of twelve hundred claims had seen gold, shows well how widely it is distributed through the country, for it must be borne in mind that, unlike most quartzmining districts, the reefs here are not continuous for far, and that the greater part are but thin irregular veins, so that the country was not taken up along lines of leads only, but, en masse, nearly the whole of the country between Hape and Tararu being pegged off. " Tapu District — Description. —The Tapu Creek is situated about twelve miles north of Shortland, and in size about equals the Tararu. At its mouth it forms a small harbour, available for coasters and small steamers. On this harbour the Township of Hastings is situated. Rather more than one hundred claims have been taken up in the district, and it has at present a population of about five hundred. The north side of the stream is for the most part covered with bush, and rises to a height of 950 ft. above the sea. The south side is almost entirely fern, and does not attain to quite so great an elevation as the other, the highest point in the Golden Horn claim being 880 ft. The north side is chiefly composed of the blue slates, nearly vertical, and with a strike of east 10° south. They attain an elevation at the Southern Cross and Diggers' Rest Claims of about 810 ft., and are capped by a horizontal layer of white decomposed tufa, stained red in places. These slates cross to the south side of the creek, but are quickly cut off by two faults, one of which runs northeast and south-west, and the other north-west and south-east. The rest of the district is composed of trachytic tufa and breccia. I have only seen one dyke in the district, which is situated on the beach on the north side of the harbour, just where the alluvial sands joins the rock. It runs northwest and south-east, and is about 10 ft. thick, and is composed of pale-green, nearly compact, greenstone, with occasional small crystals of hornblende. Until recently only one machine (Buckland and Gibbon's) was at work in this district, and consequently but few claims as yet have had any Considerable crushings. . . .
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"One of the most remarkable features of this district is the occurrence of considerable quantities of gold in the decomposed soil on the slopes of the hills. This gold is usually flaky and free from quartz, but sometimes attached to small portions of matrix. It is not at all waterworn. It probably is due to the action of rain, which has slowly washed away the rock and reefs contained in it, as they decomposed, leaving the gold behind, almost on the spot where it originally occurred. " The gold varies much in quality, both from the slates and from the tufa, and the best samples from the latter are purer than the worst from the former, but on the whole the gold from the slates appears to be the most valuable. . . . " Puriri District. —The Puriri Stream falls into the Thames about eight miles above Shortland. It is navigable at high water for cutters for nearly a mile, the tide rising about 6 ft. Above this, large boulders in the stream form rapids, and prevent boats and canoes from going any higher. The stream flows for its last three miles through an alluvial plain composed of reddish-yellow and green clays, containing many trunks of trees, but with little or no pumice. At about two miles from the Thames the valley of the Puriri is about a mile wide, bounded by low, fern-covered hills composed of trachytic tufa. These hills are about 500 ft. high, and continue at about the same altitude for a mile, when they become covered with bush, and rise abruptly to a height of 2,000 ft. It is in these steeper hills that the gold has been found. They, too, are composed of trachytic tufa, containing large rounded boulders of dolerite and greenstone. Behind, again, the ranges are still higher, and probably composed of blue and pink slates, for boulders of these rocks are seen in the streams." * In the report, dated April, 1870 (Geological Reports, 1870-71), at page 98, where describing the Tapu Creek district, Sir James Hector remarks : — " This is the next locality south of Coromandel where gold has been found in quantity. Very little progress has been made in this mining district since the date of Captain Hutton's report in 1869. Mr. Davis, who has recently examined it, is of opinion that it has been to some extent sacrificed to the superior attractions of the Shortland field. The number of diggers had fallen from five hundred to fifty, but those that remained were well satisfied with their returns. " The structure of the district bears a strong resemblance to that of the Matawai Valley, Tapu Creek flowing over green and blue slates, sandstones, and breccias, which rise on the north side of the river to form an isolated mass of hill, about 1,000 ft. high, in the decomposed surface-rock of which most of the remunerative reefs are situated. No well-defined lodes have been established, the reefs being in the decomposed slates and bands of greenstone porphyry which intersect them with a prevalent north-east strike. In the slope-deposits on this hill rich patches of alluvial gold were obtained when the field was first discovered, some of the nuggets weighing over an ounce. " On the south side of the creek are hills of trachytic agglomerate, which have been thoroughly tested, but, except in a few claims near the junction of the two formations, they were not remunerative. In the same manner the eastern extension of the gold is cut off by trachytic rocks. In this district, therefore, we have the auriferous reefs confined to the surface of the older slate and greenstone rocks, which have been laid bare by the denudation of the trachytic breccias. " On this subject Mr. Davis furnishes me with the following notes : ' Tapu Creek district furnishes very conclusive evidence of the existence of two distinct and two widely separated volcanic formations. Section I. shows this clearly. It is from the south head of the bay in which Hastings is situated to the top of the hill above the Tapu Gold-mining Company's claims. The dotted line shows a supposed plane of marine denudation, subsequent to the deposition of the older trachyte breccia which lies against the slates, and prior to that of the recent tufas which rest nearly horizontally on the top of all. It would appear as if the stream originally ran more to the north than at present, and that it has gradually cut away the tufas, leaving the slate until it reached the dyke, which has for a time arrested its progress in a southerly direction, and compelled it to cut a channel in the slate itself; the blank space in the section cannot be filled in, as Ido not know what formation exists there ; at the same time I see no reason for supposing that the slate is cut off by the dyke. The slate and volcanic formations are quite unconformable, the one running north and south, the other east and west. The more recent tufas are nearly horizontal.' " Sir James, as will be seen from the above, considers that in the Tapu district there is an older (greenstone) and a younger (trachyte breccia) formation, and that the gold is confined to the first or older of these, and in confirmation of this he quotes from notes made by Mr. Davis, who had recently made a more detailed examination of the district. Mr. Davis's remarks are given immediately above. Sir James Hector then goes on to say of the— " Ohinemuri [District]. —Deferring for the present the discussion of the Shortland district (including the Puriri), which has recently been reported on by Captain Hutton and Mr. Davis, I pass [to] the most southern locality in the Colville Peninsula, which has been prospected for gold. The Ohinemuri River is the largest tributary which the Waihou or Thames receives from the eastward, the two rivers joining about eighteen miles in a straight line south of Shortland, but about thirty miles by the windings of the stream, which is navigable as far as the Junction. The mountain-range, which forms the backbone of the Colville Peninsula, is at this point reduced to a single narrow ridge, broken through by the gorge of the Ohinemuri River. This river drains the eastern watershed of the Peninsula by three principal feeders : one, the Whatakura, rising in the ranges to the north, apparently near the sources of the Kahurangi; a middle branch, which rises close to the sea-coast, taking the drainage of a large extent of open level country extending eastward to the edge of a steep cliff that rises abruptly from the
* Probably rhyolite, of which the higher part of the main range is composed, and of which boulders somewhat answering the description of them as above given are found in the bed of the Puriri Stream. In Omaha Peak the rhyolite forms nearly the whole mass down to 500 ft. above the sea, or even lower. —A. McK.
3—C. 9.
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sea-shore on that side of the Peninsula. The third and largest branch, the Oraki, is fed from the eastern slope of Te Aroha, and the ranges which flank it on that side. These branches join to form the main stream of the Ohinemuri at the gorge, after passing which the stream has a short course of five miles through the alluvial deposits of the Thames Valley, receiving only a few insignificent streamlets from the western side of the range. I may remark that this exceptional physical conformation affords a practically level route through the range at this point, the gorge being short and not precipitous, and the greatest elevation in this line, at the source of the middle branch, within three miles of Waihi, on the east coast, being only 370 ft. above the sea, with very favourable ground for grading down to Tauranga Harbour. " I recently explored the district (19th to 26th April, 1870) crossing the range north of the gorge to the head-waters of the northern branches. In crossing the alluvial flat between the Thames River and the base of the hills several outlines of dolerite were observed, being the remains of what were once continuous sheets that occupied this part of the valley at a low level. The outer range proved to be formed of dark-coloured trachyte tufa, beyond which is a basaltic range, the summit of which is 1,100 ft. above the river. This range has broad, massive ridges, which continue for six miles, when the formation changes, at a marked dip in the ground, beyond which the ridges become narrow and the gullies steep. The formation is here a yellowish-white, smoothgrained, or gritty felspathic rock, intersected by quartz veins, which frequently mark the summits of the ridges. Several of these reefs have been opened at the surface, and consist of sub-crystalline quartz, not unlike that which occurs at the top of the Tokatea Hill, at Coromandel. From the highest point of these hills (1,210 ft.), at what is called the Bare Patch, a magnificent view is obtained, especially to the south and east, in which direction the country is quite free from timber, except in the valleys leading from Te Aroha. An abrupt descent of 500 ft. leads to the valley of the Whatakura, with several principal branches, in some of which a good deal of prospecting had been done along the base of the terraces. The most extensive of these workings, which were all abandoned at the time of my visit, consisted of two tunnels, driven for about 130 ft. in a north direction. They both passed through a soft porphyritic rock, decomposed to a white mottled clay, with obscure crystals interspersed. A few small leaders of compact sub-crystalline ferruginous quartz had been cut, but no decided reef found. I was led to understand by one of my party, who had been digging there, that no gold had been obtained from these drives, but that some small specimens found in the adjacent creeks had led to the underground exploration. Small quantities of gold are reported to have been found in several places on the west or right-hand side of the Whatakura, but never in any of the creeks on the opposite side. The main stream, which is 30 ft. wide, flows in a bed cut in this soft porphyritic rock, but is filled by rolled holders of trachyte and dolerite derived from the surrounding hill-tops. On following down the river for five miles, to its junction with the Ohinemuri in the low-level land seen from the top of the mountains, the trachytic lavas are met with, forming widespread floes, over which the river runs in a broken, rocky bed—falls, 30 ft. to 40 ft. in height, being frequent. The plains are about four miles in width, and expand towards the eastward, the soil being everywhere extremely poor, owing to the trachyte being near the surface. The vegetation is chiefly short wiry manuka, rushes, and straggling ferns. In one part of the plain, a little below the junction of the Whatakura, and almost directly south of the Bare Patch Hill, there is a good deal of quartz, in fragments, strewn on the surface, which I failed to trace to its source, but which appears as if derived from veins in the neighbourhood. Along with these are fragments of quartz, porphyry and nodules, with large well-developed crystals of quartz. It is, no doubt, the occurrence of these fragments on the surface, and the wide expanse of terraced plain, recalling, as it does, the surface features of the southern goldfields, that has led to the general belief that alluvial gold will be found in this district. Following up the valley of the middle branch of the Ohinemuri to the eastward, the only rock exposed at the surface is a compact trachyte, sometimes porphryritic, until a low range of hills, 360 ft. above the general level of the country, but presenting broken rocky cliffs 500 ft. in height to the sea, is reached. The coast is, on the whole, very bold, and in the cliffs between Matuara and Waihi, of true trachyte agglomerate, intersected by dykes of trachyte, that give rise to remarkable promontories enclosing a few sheltered bays, in some of which are small Maori settlements. The upper part of these hills is formed of true rhyolite, or quartzose trachyte, apparently similar to those at Rotorua, in the Lake District, and which, by their disintegration, give rise to extensive beds of felspathic and quartz sands. The only exception observed to the above formation is on the south headland of the first sandy bay north of Waihi, the Maori settlement at the commencement of the long sandy beach that extends to Tauranga. The north headland of this bay is composed of the ordinary agglomerate, containing masses of scoria and basalt in a tufacious matrix; but the rock at the south headland contains large angular blocks of primary slate and sandstone, and masses of green breccia, so that probably the junction of the agglomerate with the older rocks of the district is not far distant. On the face of the spur above this point a small quartz reef crops out at the surface, and in the gully beyond a soft blue rock is exposed, covered by a wash of rolled fragments of green sandstones and diorite, thus indicating a nearer approach to the character of the formations in the auriferous parts of the Peninsula than I had observed in other parts of the district. The deficiency of pyrites, however, [it is] which argues against the probability of gold being found in any quantity in any of the places where the ground has been tried. Returning down the river to the westward, through the gorge, heavy deposits of alluvium are found at a considerable elevation above the stream, indicating the higher levels of the former river channels as it cut its way gradually through the barrier of trachyte rock. These drifts contain well-rounded boulders of large size, chiefly fragments of trachyte and chert, intermixed with ferruginous sand, and it has been ascertained that a little gold is irregularly interspersed. . . There is a similarity in the character of the formation [on the] . . . summit ranges . to that of the ' country-rock ' at Shortland."*
♦ Geological Reports, 1870-71, pp. 98-102.
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C-09 REPORT ON THE GEOLOGY OF THE CAPE COLVILLE PENINSULA, AUCKLAND. BY ALEXANDER McKAY, F.G.S., HON. M., N.Z. INST., GOVERNMENT GEOLOGIST., Appendix to the Journals of the House of Representatives, 1 January 1897
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21,026C-09 REPORT ON THE GEOLOGY OF THE CAPE COLVILLE PENINSULA, AUCKLAND. BY ALEXANDER McKAY, F.G.S., HON. M., N.Z. INST., GOVERNMENT GEOLOGIST. Appendix to the Journals of the House of Representatives, 1 January 1897
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