THE NEW ZEALAND OFFICIAL YEAR-BOOK, 1924

The largest sheet of fresh water in New Zealand is Lake Taupo, which is situated in the very heart of the North Island, at an elevation of 1,211 ft. above the sea. Its greatest length in a S.W.-N.E. direction is 25 miles, and its greatest breadth is about 17 miles, but its shape is somewhat irregular owing to a large indentation on its western side. Its area is 238 square miles, its greatest depth 534 ft., and it has a catchment area of about 995 square miles. About 60 per cent. of its water-supply comes from the Upper Waikato River, which drains the northern and eastern flanks of the central volcanoes as well as the western slopes of the Kaimanawa Range and its northern extensions. The lake discharges at its northeastern corner and forms the main Waikato River, which falls within a short distance over the Huka Falls, where the volume of water which passes over is estimated to reach an average of 5,000 cubic feet per second. The surroundings of the lake are picturesque, on the western side especially. Here it is bounded by cliffs of volcanic rock, generally between 100 ft. and 800 ft. in height, but at the Karangahape Bluffs they rise to over 1,000 ft. sheer. The northern shore is bold with promontories terminated with bluffs and intervening bays with gentler slope. The south side is generally fringed with alluvial flats, while the cast is bordered in places with pumice cliffs, and is somewhat uninteresting, but relieved from absolute monotony by the graceful extinct cone of Tauhara. About 20 miles to the south rise the great volcanic peaks of Tongariro, Ngauruhoe, and Ruapehu, with their bush-clad foothills, forming a splendid panorama when seen from the northern shore of the lake.

To the south-east of the middle of the lake lies the island of Motutaiko, in all probability the summit of a volcanic cone on the line of igneous activity which stretches north-east from the central volcanoes towards Tarawera, White Island, Tonga, and Samoa. The formation of the lake itself is attributable either to a great subsidence after volcanic activity waned, or to a great explosion which tore a vast cavity in the earth's crust and scattered the fragments far and wide over the middle of the Island; and evidence of declining igneous action is furnished by hot springs in the lake itself and near its shore, especially at the north-east corner near Wairakei and on the southern shore near Tokaanu. Earth-movements have in all probability continued down to recent times, for an old shore platform or wave-cut terrace surrounds the lake, indicating that its waters were formerly at a higher level.

The lake forms an enormous reservoir of power conveniently placed for exploitation; it is estimated that the Huka Falls would develop up to 38,000 horse-power, and its central position renders it peculiarly suitable for supplying a wide district. Although the immediate vicinity does not hold out much hope for its utilization, the rich agricultural districts which lie at some distance will no doubt rely on it in the near future as a convenient source of mechanical energy.

To the south of Taupo, nestling in the hills between the great lake and the northern slopes of Tongariro, lies Roto-Aira, a beautiful sheet of water, 3 miles in length and with an area of 5 square miles. It discharges by the Poutu River into the Upper Waikato. The other lakes of this region are small in size and usually occupy small explosion craters on the line of igneous activity mentioned above.

A most interesting group of lakes lies in the midst of the thermal region to the north-east of Taupo. These comprise the following: Rotorua, Roto-iti, Roto-ehu, and Rotoma, which belong to a system lying to the north-west of the area, and Tarawera, Rotokakahi, Tikitapu, Okareka, Rotomahana, Okataina, Rotomakariri, and Herewhakaitu, which lie to the south-east. The former group is connected either directly or indirectly with the Kaituna River basin, and the latter with the Tarawera River basin, both of which discharge their waters into the Bay of Plenty. All these lakes occupy either explosion craters or depressions due to subsidences of the crust or hollows formed by irregular volcanic accumulations. They lie at an elevation of about 1,000 ft. above the sea. The largest is Rotorua, which is nearly circular in shape, except for a marked indentation on the southern shore. It is 32 square miles in area, 84 ft. deep, with flat shores; but in the middle, rather towards the eastern side, rises to a height of 400 ft. the picturesque and historical Island of Mokoia. The lake discharges at its north-eastern corner by the Ohau Creek into Lake Roto-iti, a shallow and irregular depression, which runs in turn into the Okere River. To the north-east lies the small lake of Roto-ehu, separated from it by low ground, and farther on lies the picturesque Rotoma, of still smaller size.

The largest lake of the south-eastern group is Tarawera, lying to the north and west of the mountain of the same name; discharging directly into it are Rotokakahi, Okareka, and Okataina, the last two by subterranean channels, while Tikitapu and Rotomahana are separated from it by comparatively narrow ridges.

All these lakes owe their interest to the thermal manifestations which occur in their vicinity, and to the remnants of beautiful bush which have survived the eruption of Tarawera in 1886. They are also noted for their fishing, being well stocked with trout. Their water is available for power purposes to a limited extent; and a small installation is placed near the low fall where the Okere River discharges from Lake Roto-iti.

Two small lakes of volcanic origin are situated on the peninsula north of Auckland: these are Takapuna and Omapere. The former lies close to the City of Auckland, and occupies a small explosion crater near the sea; while Omapere is between the Bay of Islands and Hokianga, in a shallow depression, which owes its origin to the obstruction of the Waitangi River by a lava-flow. It is three miles long by two wide, and is placed at a height of 790 ft. above the sea.

About forty miles from the east coast, in the Hawke's Bay District, lies the most important lake of Waikare-moana, twelve miles in length by about six miles and a quarter in breadth at its widest part, but with an extremely irregular outline; it has an area of twenty-one square miles. Its surface is 2,015 ft. above the sea, and it has a maximum depth of 846 ft. It discharges by the Wairoa River to the northern shore of Hawke Bay. This lake is most favourably situated for the development of water-power, and it is estimated that it would generate, owing to its admirable position, as much as 134,000 horse-power. A few miles to the northeast lies the small lake called Waikare-iti, which discharges into the large lake.

The only other inland lakes of any importance in this Island are those situated in the lower course of the Waikato River, the most noteworthy being Waikare and Whangape. The former has an area of nearly eleven square miles and has a depth of 12 ft.; the latter is smaller, with an area of only four square miles and a depth of 9 ft. These owe their origin to flooding of low-lying land alongside the river—in all probability attributable to a slight lowering of the land in this part of the country, with the consequent inability of the river to discharge its surplus water without a proper channel being maintained.

Along the coast-line, especially behind the fringe of dunes, numerous small lakes are found, such as Rotokawa, near Kaipara, and Horowhenua, near Levin; and a large sheet of water occurs near the mouth of the Wairarapa Valley, called the Wairarapa Lake. The lake is very shallow, and liable to remarkable variations in size owing to heavy floods from the neighbouring ranges. Between it and the sea is a considerable area of swampy ground in which are several small lakes, the largest of which, Lake Onoke, is separated from Palliser Bay by a narrow shingle-spit.

By far the great majority of the lakes of the South Island are dependent for their formation either directly or indirectly on the action of glaciers. They may be either small tarns high on the mountains or large lakes occupying considerable lengths of old stream-valleys which have been overdeepened by the excavating-power of ice during the Pleistocene glaciation, or lakes formed by the filling of hollows in the irregular heaps of debris laid down on a plain at the base of the mountains or in a wide open valley. Accumulations of debris may also assist the first two causes in the formation of lakes.

Included in the first class are numerous sheets of water from the size of small ponds upwards, found in all parts of the mountain region, but especially in the high plateau regions of western Otago, and to a limited extent in north-west Nelson. To the second group belong the large lakes of the eastern watershed of the Alps and a small number which drain west, such as Rotoroa and Rotoiti in the Buller Basin, while to the last must be assigned the majority of the lakes of Westland; but Brunner and Kanieri should perhaps be assigned to the second class.

Seeing that glaciation was not so intense in the northern portion of the Island, it is not surprising that the lakes of that region are small and few in number. Attention has, however, been drawn to Boulder Lake, in the valley of the Aorere River, since it might be used for power purposes in connection with the great deposit of iron-ore at Parapara. It is only 151 acres in extent, but it lies at an elevation of 3,224 ft., and is conveniently placed for the establishment of an electric-power plant. Farther south, near the head of the Buller, are two larger lakes—Rotoroa and Rotoiti—occupying ice-eroded valleys dammed at their lower ends by moraine. The former has an area of eight square miles, and the latter two and three-quarter square miles; their heights above the sea being respectively 1,470 ft. and 1,997 ft., and the latter being 228 ft. deep.

In the valley of the Grey River are two lakes of considerable size—viz., Brunner and Poerua. These are shrunken and separated parts of a former extensive sheet of water which was ponded back behind a great glacier moraine. Lake Brunner is five miles long by four broad, has an area of 15.9 square miles, is 280 ft. above sea-level, and 357 ft. deep. It is surrounded on two sides by high wooded granite peaks, and on the other two by low ground. It discharges by the Arnold River to the Grey, but a very slight change of level would turn it into the Taramakau.

Lake Kanieri, which lies in the basin of the Hokitika River at the base of Mount Tuhua, is a beautiful sheet of water. It is five miles long by one and three-quarters wide, has an area of eight square miles, is 422 ft. above sea-level, and 646 ft. deep. It owes its origin partly to the hollow formed behind an immense morainic dam, and partly to the erosive action of the valley glacier. Farther south on the coastal plain of Westland are numerous small and picturesque lakes, wooded to the water's edge, lying behind heaps of glacial debris or in ice-eroded basins. The most notable of these are Ianthe and Mapourika, both of small size, the former with an area of only two square miles, at a height of 80 ft. above sea-level, and with a depth of 105 ft., and the latter remarkable for the fine panorama of mountain scenery, with Mount Cook in the background, which can be obtained from the shore of the lake. Along this strip of coast-line there are numerous lagoon-like expanses of the water, cut off from the sea by areas of dune or of moraine, the chief of which is Mahinapua, which lies close to the Town of Hokitika. This is but 6 ft. above tide water, and has an area of one and a half square miles. The creek discharging from it is noted for the perfect reflections to be seen in the dark, peat-stained water.

On the eastern side of the main divide lie the great valley lakes which belong to the following river-basins: Hurunui—Lake Sumner; Rakaia—Lakes Coleridge and Heron; Waitaki—Lakes Tekapo, Pukaki, and Ohau; Clutha—Lakes Wanaka, Hawea, and Wakatipu; Waiau—Lakes Te Anau, Manapouri, and Monowai; Wairaurahiri—Lake Hauroko; Waitutu—Lake Poteriteri. These are all formed on the same plan; great glaciers have excavated the floor of a river-valley and have piled the debris across its lower portion, leaving a great hollow which was filled with water when the ice retreated. Even in those river-basins where no lakes now exist the traces of their former presence are evident; especially is this the case with the Waimakariri, Rakaia, and Rangitata Valleys. Besides these large lakes each valley has its quota of small ones, usually hidden away among the piles of moraine or ponded back behind shingle-fans. Among these small lakes should be noted the following: Tennyson, in the valley of the Clarence; Taylor, Sheppard, Katrine, and Mason, in the Hurunui; Pearson, Grassmere, and Letitia, in the valley of the Waimakariri; Evelyn, Selfe, Catherine, Ida, and Lyndon, in that of the Rakaia; Clearwater (or Tripp), Howard, and Acland, in the Ashburton; Alexandria, in the Waitaki; Lochnagar, Hayes, and Moke, in the Clutha. In the valley of the Waiau there are numerous lakes of small size hidden away in bush-clad valleys, the chief of which is Mavora, which discharges into the main Waiau by way of its large tributary, the Mararoa. On the west coast of this region are also many insignificant lakes as far as size is concerned, such as Lake Ada, a well-known beauty-spot on the Milford Sound track, while farther north the McKerrow, a lake of larger size, discharges into Martin's Bay.

The only other lakes in this Island that are worthy of mention are Waihola, which occupies the lower portion of the Taieri Plain, and drains to the sea by a deep winding gorge cut through a ridge of moraine-covered hills, the gorge being tidal for the greater part of its length; while on the coast immediately south of Banks Peninsula lie Lakes Forsyth and Ellesmere, both ponded back behind a great shingle-spit formed by the drift of material brought down the rivers and carried north under the influence of a strong shore current. Both are very shallow and liable at times to be invaded by the sea. Ellesmere is sixteen miles long by about ten broad, and Forsyth is about six miles long by one in breadth.

Among all these lakes three stand pre-eminent for their scenic interest—Wakatipu, Te Anau, and Manapouri. The first-named is walled in on both sides by steep mountains which rise at the head of the lake to over 8,000 ft. in the Humboldt Range, and to over 9,000 ft. in Mount Earnslaw. Te Anau has an uninteresting eastern shore, but its western shore is broken into three great arms, whose impressive scenery is strongly reminiscent of that of Milford Sound and George Sound; while Manapouri, with its many bush-clad islets and indented shore-line with innumerable sheltered coves and pebbly beaches, belongs to the same type as Dusky Sound, the most beautiful of all in the fiord region.

The lakes of Canterbury lie in a treeless area and owe their scenic interest principally to the background of snowy peaks, while Wanaka and Hawea are intermediate in character between them and the more southern lakes of Otago.

These lakes are enormous reserves of energy awaiting development. Estimates of the amount available are somewhat uncertain in their upward limits, seeing that modifications of proposed schemes may increase the possible power to a marked extent. The only one, however, which has been utilized in an adequate manner up to the present is Lake Coleridge. This is estimated to yield 10,000 horse-power, and if the scheme be developed to its full capacity the amount will probably reach 90,000. Lake Tekapo would furnish at least 400,000 horse-power; Pukaki, 70,000; Ohau, 100,000; Hawea, 90,000; Wakatipu, 100,000; Te Anau, 90,000; Manapouri, 420,000; and Hauroko, 80,000; and there are many lakes which could very easily be adapted for smaller installations. Especially is this the case in the fiord-region country, where the heavy and well-distributed rainfall produces an unfailing supply of water, where lakes are placed in ideal situations as reservoirs, and deep water and secure harbours provide ample facilities for the transport of manufactured products. When these are properly utilized the now wild and deserted region will become the home of industry in the Dominion, and one of the main centres of manufacture in the Southern Hemisphere.

The oldest rocks in New Zealand appear to be those of western Otago, where over a large area is exposed a complex of gneisses and schists, intruded by granite and other igneous rocks. The gneisses in the main are altered granites and diorites, but some of the schists, at any rate, are of sedimentary origin. A pre-Cambrian age was assigned to these rocks by Professor F. W. Hutton, but Professor James Park considers them to be probably of Cambrian age, and includes them in his Maniototo Series.

Perhaps next in age to the western Otago gneisses and schists are the mica, chlorite, and quartz schists of Central Otago. In the absence of fossils, however, the age of these rocks is uncertain. Professor Hutton regarded them as pre-Cambrian, Professor Park assigns a Cambrian age, whilst Dr. P. Marshall considers them to be little, if at all, older, than the Triassic. Some schistose rocks in north, central, and western Nelson may be as old as, or even older than, the Otago mica-schists. The gneisses and schists on the western side of the Southern Alps may for the present be classed with the Nelson schists.

The oldest known fossiliferous rocks in New Zealand are the Ordovician argillites (“slates”), greywackes, and quartzites occurring near Collingwood (Nelson), and Preservation Inlet in south-west Otago. Ultimately these rocks may be found to have a considerable development in various parts of Nelson and Westland.

Rocks containing Silurian fossils occur in the Mount Arthur district, Nelson. They are principally altered limestone (practically marble), calcareous shale or argillite, sandstone, and quartzite.

At Reefton a small area exhibits quartzite, limestone, and slaty shale containing fossils believed to be of Devonian age. Elsewhere considerable areas have been assigned to the same period by Mr. Alexander McKay, but owing to the non-discovery of recognizable fossils definite proof of age is wanting. For a similar reason the age of most of the rocks placed in the Carboniferous period (“Maitai Series”) by McKay is uncertain. At Reefton the supposed Carboniferous rocks, which here contain many auriferous quartz-veins, are probably of Ordovician age. In the typical locality near Nelson the fossils found in the Maitai rocks indicate a Trias-Jura age, though possibly older rocks may be present also.

So far Permian rocks have not been satisfactorily identified in New Zealand. Park, however, considers his Aorangi and Kaihiku Series to be of Permian age.

During some of the Palæozoic periods it is conjectured that New Zealand formed part of or was the foreland of a large land-mass that extended far to the west. This land-mass possibly persisted to late Palæozoic times, and may have been the now-dismembered and all-but-lost continent known to geologists as Gondwana-land.

As yet the early and middle Mesozoic rocks of New Zealand have not been clearly separated by means of unconformities or fossil evidence. What may be called a Trias-Jura system is extensively developed in both the North and South Islands. The most fossiliferous localities are Hokonui Hills (Southland), near Nugget Point (Otago), Wairoa Valley, near the City of Nelson, Kawhia Harbour, and Waikato Heads, the two latter localities both on the west coast of Auckland. A broad belt of Trias-Jura or, according to Park, of Permo-Jurassic rocks extends through western Canterbury and Marlborough, and is continued as a somewhat narrower belt on the north side of Cook Strait from Wellington to the Cape Runaway district. Rocks of much the same age occur in the Mokau River watershed, in the Lower Waikato Valley, in the Coromandel Peninsula, and in North Auckland.

The supposed Jurassic rocks of Kawhia Harbour and Waikato Heads, mentioned above, may possibly be of Lower Cretaceous age. Admittedly Cretaceous rocks extend in a not-quite-continuous belt from Cape Campbell in Marlborough to the neighbourhood of Waipara in North Canterbury. At Amuri Bluff they are richly fossiliferous. Here and in several other localities the fossils include saurian remains. To the Cretaceous may also be assigned a somewhat extensive belt of rocks near the east coast of Wellington and southern Hawke's Bay. A continuation of this belt extends from a point north-west of Gisborne to the East Cape district.

The oldest known workable coal-seams in New Zealand probably occur in Cretaceous rocks. Much controversy, however, concerning the age of our coalfields has arisen. The late Sir James Hector, and with him Mr. Alexander McKay, considered that the coal-measures belonged to a Cretaceo-Tertiary system that extended from the Upper Cretaceous to the Middle Tertiary. For many years Mr. McKay was practically the sole exponent of this theory, but quite recently Dr. Marshall has advocated a very similar if not identical view. The truth, however, seems to be that the coal-measures concerning which there is a dispute are of two different ages. The Shag Point, Malvern Hills, and North Auckland coalfields are probably of Upper Cretaceous age. To these Park would add the Milton-Kaitangata coalfield and a small portion of the Green Island coalfield. The other coalfields, as mentioned below, are Tertiary.

Although there is certainly a palæontological break between the Upper Cretaceous (Waipara Series) and the Early Tertiary, the existence of an unconformity, as may be inferred from the previous paragraph, is a matter of doubt. The subdivision of the Tertiary strata, which are well represented in New Zealand, is still more or less tentative. To the Eocene may be assigned the bituminous coal-measures of the Grey, Buller, and Collingwood districts, and probably also some of the coal-bearing patches of central Nelson. Elsewhere Eocene rocks are not certainly known.

During the Early Eocene it is believed that New Zealand was again part of a continental area that extended far to the north, and was joined, or all but joined, to New Guinea and northern Australia. This continent may have included much of the area in the Pacific now studded with coral islands. Its former existence is inferred mainly from various features in our plant and animal life. According to Mr. T. F. Cheeseman, no less than 366 New Zealand plants are found also in Australia. More significant, perhaps, is the occurrence of many closely related species and genera in the two regions, for comparatively few of the 366 species are likely to have persisted since the Eocene. Many of our birds show marked affinities to Australian and Malayan species. In this connection an interesting line of support for a Tertiary extension of New Zealand to the north is afforded by the annual migrations of the New Zealand cuckoos and of the godwit.

During the Miocene period New Zealand subsided until little of the present land-surface was above water. Consequently, notwithstanding extensive denudation in later periods, Miocene strata are well represented in almost all parts of the country. They are typically developed in the Oamaru district (north-east Otago), and hence Hutton's name of “Oamaru Series” is generally applied to the Miocene strata of New Zealand. Miocene rocks are well represented in north Westland, an area in which a decided unconformity separates them from the Eocene coal-measures. They form much of the surface of the North Island, where the name “papa" is commonly applied to the calcareous claystones and argillaceous sandstones which there form a great proportion of the Miocene rocks. In many places the Oamaru Series is characterized by the development of a fairly thick, soft, fossiliferous limestone about the middle horizon. This marks the time of greatest subsidence, or rather the time when the Miocene sea was deepest. Owing to their calcareous nature, the Miocene rocks give rise to some of the richest agricultural districts in New Zealand. In places they contain, in their lowest horizon, seams of good brown coal. There are also brown coals of late Miocene age.

In many localities the Miocene rocks pass without unconformity into strata considered to be of Pliocene age. In the Hawke's Bay and Wanganui districts these are marine and highly fossiliferous. They give rise to much good agricultural and more especially pastoral land adapted to sheep-farming or dairying. In Nelson and north Westland the Pliocene strata are largely composed of river-transported material, and are known as the Moutere Gravels. These in places are of a poorly auriferous character. In Nelson the Moutere Gravels form a poor pastoral soil, but one well adapted for apple-culture.

Towards the close of the Miocene and during the whole of the Pliocene period many parts of New Zealand, more particularly in the South Island, were undergoing elevation. As a result the North and South Islands (then quite different in outline from their present configuration), together with most of the outlying islands now in existence, such as the Chathams, Auckland Islands, &c., must have formed one large land-mass, which probably was united to an Antarctic continent. Since many New Zealand plants^* are identical with, or closely allied to, South American forms, and there are also some striking resemblances in bird and other forms of animal life, it is thought that this Antaretic continent formed a bridge, probably at no time quite complete, between New Zealand and South America. By this route, in all likelihood, came the now extinct moas or their ancestral forms. At the time of this continental extension the Southern Alps rose far above their present heights, and were covered with one vast snowfield that fed immense glaciers spreading far and wide over the lowlands to the east and the west. According to Park, during the Pleistocene there was one great sheet of ice over the whole of the present South Island, and over part of the North Island. Moreover, this ice-sheet was joined to the Antaretic ice. The extreme views of Professor Park are not shared by other New Zealand geologists, who, however, unanimously agree that a large area in the South Island was glaciated. The great ice-streams of Picistocene times gave rise to rivers that carried enormous quantities of gravel and finer material derived from the mountains beyond the ice-front, and in great measure built up the lowlands of Canterbury and Westland. In the latter district the gravels sorted by these streams are in many places richly auriferous, but a greater and more permanent source of wealth is furnished by the fertile soil of the Canterbury Plains.

In many parts of Otago, Canterbury, Westland, and Nelson evidences of past glacial action are afforded by huge moraines, perched blocks, ice-worn surfaces (roches moutonnees), rock-benches, rock-basins, and other tokens of glaciation. To ice-action, it may here be mentioned, we owe some of the most magnificent features of the western Otago sounds.

At or before the end of the Pleistocene period the mountains lessened in height, through both denudation and a well-marked subsidence of the land. The climate grew milder, and the lowland ice melted away. The mighty glaciers rapidly retreated, geologically speaking, and are to-day represented only by the comparatively modest valley and mountain glaciers of north-west Otago, Canterbury, and Westland, with which may be included the small but permanent snowfield and glacier on Mount Ruapehu. While the glaciers were retreating the rivers of Canterbury and Westland, swollen by the melting ice, were unusually active in transporting debris to the lowlands and the sea-coast. At this time, too, as well as at somewhat earlier periods, the volcanoes of the North Island furnished an abundant supply of fragmentary material, much of which was transported by the streams, and used in building plains and river-flats. Many of these are fertile, but in those districts where pumice abounded a more or less barren soil, difficult of utilization, has resulted. Thus the land gradually became much as we see it now. In recent times geological changes, such as the lowering of heights by denudation, the filling of lakes by sediment, the outward growth of coastal plains in some places, and the wearing-away of the shores in other places, have slowly proceeded, and are to-day, of course, still going on. Slow movements of the land are probably in progress, but these have not been certainly detected. In 1855, however, as the result of a violent earthquake, the northern shore of Cook Strait, near Wellington Harbour, was raised on the average at least 5 ft., whilst the southern shore near Tory Channel and towards the mouth of the Wairau River was almost correspondingly depressed.

In the preceding paragraphs little notice has been given to igneous rocks or to volcanic action. The oldest igneous rocks of New Zealand are probably represented by the gneisses of western Otago, which, as previously stated, are mainly metamorphosed granites and diorites. Plutonic rocks intrude many of the Palæozoic and Mesozoic strata, and some of the formations also show evidence of contemporaneous volcanic action. Of the more ancient Plutonic rocks granite is the most prominent. It occurs in many localities in Stewart Island, western Otago, Westland, and Nelson. It has, however, not been found in situ in the North Island, though in at least four localities boulders of granite, probably derived in all cases from ancient conglomerates, have been discovered. Ultra-basic igneous rocks, now largely altered to serpentine, occur in north-west Otago, Westland, and Nelson.

*According to T. F. Cheeseman's “Manual of the New Zealand Flora” (preface, page ix), 108 New Zealand plants extend to South America.

Throughout the greater part of the Tertiary periods volcanic action in New Zealand was probably more intense than in any former age. During the Late Eocene or Early Miocene period eruptions, at first principally of andesitic rocks and later of rhyolite, began in the Coromandel Peninsula, and with little intermission continued throughout Miocene and Pliocene times. These volcanic rocks contain the gold-silver veins which have yielded rich bonanzas at Thames and Coromandel, and are now being worked at the Waihi, Talisman, and other mines.

There are many areas of Miocene volcanic rocks in North Auckland, and near the City of Auckland numerous small volcanoes were in action during the Pleistocene. Some of these—for example, Mount Rangitoto—have probably been active within the last two or three thousand years. In Taranaki the beautiful cone of Mount Egmont was built up during Pliocene and Pleistocene times. It is in the central part of the North Island, however, that the most intense volcanic activity has been displayed. Volcanic rocks, and more especially the pumice ejected during the Pliocene and Early Pleistocene, cover large areas. Vulcanism has not yet ceased, for minor eruptions of fragmentary material still take place from Ngauruhoe, a typical volcanic cone near Ruapehu. The most striking evidence of volcanic action, however, is afforded by the numerous steam-vents, hot springs, and geysers found in a belt extending from Ruapehu to White Island (in the Bay of Plenty), itself a volcano in the solfataric stage. It is more than a coincidence that this belt is in line with the Southern Alps. Solfataric action is generally regarded as a sign of dying vulcanism, but that the subterranean forces are still capable of mischief was shown by the eruption of Tarawera, an apparently extinct volcano, on the 10th June, 1886. On this occasion over a hundred lives were lost.

In the South Island vulcanism is apparently quite dead, for the hot springs of Hanmer Plains and the western side of the Alps are due to many causes. During the Miocene, however, volcanic outbursts took place in many localities, in some on a grand scale. Banks Peninsula is formed mainly of basaltic and andesitic rocks, Lyttelton and Akaroa harbours are believed to represent ancient craters or centres of eruption. In the neighbourhood of Dunedin occurs a very interesting series of alkaline volcanic rocks. These were first described by the late Professor G. H. F. Ulrich, and in later years Dr. Marshall has given them exhaustive study.

In the course of a short article it is impossible to give any adequate idea of what has been accomplished by geological workers in New Zealand, or what remains yet to be done before even the foundation for future work shall be securely laid. The important branches of geology in its application to agriculture and mining have hardly been mentioned, but elsewhere in this volume will be found references to the agricultural and mineral resources. For detailed information the reader is referred to the bulletins of the New Zealand Geological Survey; to Professor Park's “Geology of New Zealand,” which contains an excellent bibliography; and to the treatise on “New Zealand Geology,” by Dr. Marshall, as well as to many other publications too numerous to be here named. Finally, it may be mentioned that in each of the University Colleges excellent instruction in geology is being given by capable and enthusiastic teachers, so that in the near future we may expect increased progress in solving the many knotty problems of New Zealand geology.

Since 1888 there has been established in New Zealand a system of observing local earthquakes at selected telegraph-stations—about eighty in number—distributed throughout the extent of the Dominion.

Whenever a shock occurs and is felt by an officer in charge of one of these stations he fills up a form giving the New Zealand mean time of the beginning of the shock, its apparent duration and direction, and the principal effects observed by him. Some of the officers exhibit considerable care and skill in making up these returns, and the data have been used to determine principal origins of earthquakes within the New Zealand region.

All observers of earthquakes are cordially invited to forward their reports to the Government Seismologist, Hector Observatory, Wellington, giving all or any of the following particulars:—

The Rossi-Forel scale of earthquake intensities is as follows:—

The New Zealand returns are valuable not only in themselves, but as part of a world system of seismological observations; and the attention of observers is called to the fact that the reliable character of the record depends upon the individual accuracy of each observer. No shock, however slight, should be omitted. It is especially important that the first two questions should be answered accurately.

Three seismographs, all with photographic registration, are installed in New Zealand: two are Milne horizontal pendulums, and one is the new Milne-Shaw horizontal pendulum. One Milne and the new Milne-Shaw seismographs are installed at the Hector Observatory, Wellington, with their booms placed at right angles; and the other Milne seismograph is installed at the Magnetic Observatory, Christchurch.

The records of the New Zealand stations are sent to the General Secretary of the Seismological Committee of the British Association, to the Station Centrale Sismologique, Strasbourg, France, and to the principal observatories of the world, and thus form part of the general system of earthquake-observation being conducted throughout the world since 1890.

* A convenient means of verifying the time is provided by the wireless time-signals sent out every day, except Sundays and Government holidays, at 10.30 a.m. N.Z. time, by the Hector Observatory on a wave-length of 600 metres.

The accompanying diagram illustrates graphically the number and intensities of the earthquakes reported to the Seismologist in the years 1921 and 1922. These reports were supplied by officers of the Post and Telegraph Department, by private observers, and by the newspapers. Each vertical line represents the maximum effect of an earthquake, with the intensities according to the Rossi-Forel scale shown at the sides of the figure. It will be seen that two earthquakes in 1921, and four in 1922, reached intensity VIII on this scale. The figure also shows the distribution in time of the earthquakes.

Deaths due to earthquakes in New Zealand are fortunately very few. In the last seventy-five years seven have been recorded.

The shock of October, 1848, threw down a wall in Wellington, and three people were killed.

On the 24th January, 1855, a death occurred at Wellington recorded as “accidental death from the falling of a chimney.” The large earthquake took place during the night of the 23rd January, 1855.

On the 16th November, 1901, a child was killed by the Cheviot earthquake.

On the 12th April, 1913, a Maori was killed at Masterton by material falling from the post-office, due to an earthquake.

On the 7th October, 1914, a shepherd was killed by the Gisborne earthquake.

The climate of the Auckland Province, speaking generally, combines degrees of warmth and humidity agreeable by day and comfortable by night, North of Auckland City conditions are almost subtropical, and in summer balmy easterly breezes prevail, and are responsible for delightful conditions. In winter the winds are more north and west, while changes to the south-west or south-east mostly account for the rainfall. Cumulus clouds are frequently formed in the afternoons, and, while tempering the heat of the day, also cut down sunshine records somewhat, but add considerably to the beauty of the land- and sea-scape. Southward of Auckland the climate is more varied, the west coast experiencing more rain, while the central parts are warmer in the day and considerably colder at night. In the winter months frosts, which are unknown farther north, now and then occur in the hours of darkness. Eastward from Rotorua (the great health resort and centre of the thermal region) is to be found one of the most genial climates in the world, and Tauranga and Opotiki have charms all their own, especially for their weather and the fruits which ripen to perfection in these regions.

The monthly and annual means of the temperature, rainfall, and sunshine of Auckland and Rotorua are shown in the following tables:—

The Hawke's Bay Province is one of the richest in New Zealand, and is favoured with a pleasant climate, being sheltered from westerly winds, though occasionally they are of the warm and dry (Foehn) type. It is rather dry, but ex-tropical disturbances are occasionally responsible for heavy downpours. Though the number of days with rain is less than, and sunshine above, that of other parts, the rainfall is still a good one, and fairly regular throughout the year, though some seasons have been notably dry. The meteorological records of Napier show reliable normals for the coastal districts. Inland the country is rather mountainous and less mild.

Wellington, the capital city, as disclosed by its meteorological records, has a mean climate for the whole Dominion. Wellington occupies a central position, and is situated near Cook Strait, which divides the two main Islands. It has a somewhat changeable but temperate climate, and, though occasionally subject to disturbances from warmer regions, is usually controlled by the terrestrial wind-currents which have a westerly direction round the world in the latitude of the “forties.” It is popularly regarded as a rather windy spot, for high winds are frequently experienced, although they hardly ever reach hurricane force. Its windiness is largely owing to local configuration, for places quite near Wellington experience very little wind; and to compensate for this rather disagreeable element is a bountiful sunshine, averaging 2,027 hours per annum. There is a plentiful rainfall, amounting to nearly 50 in.

Between Wellington and Taranaki, following the Taranaki Bight, is probably one of the most fertile and agreeable regions in Australasia; but inland, though very productive, conditions are not so favourable.

Taranaki has a rather heavy rainfall, and in most parts of this region the grass is always green. Its climate is mild, and cattle winter in the open. Wanganui and Manawatu districts (which lie between Wellington and Taranaki) have less rainfall than either Wellington or Taranaki.

It may be useful to make a comparison between the records of Wellington and those of Camden Square. London.

Nelson and Marlborough are highly favoured regions with regard to sunshine and shelter from marine winds. Long ago Bishop Selwyn said, “No one knows what the climate is till he has basked in the almost perpetual sunshine of Tasman's Gulf, with a frame braced and invigorated to the full enjoyment of heat by the wholesome frost or cool snowy breeze of the night before.”

Pastoral and agricultural industries are thriving, and the Province of Nelson is also famous for its fruit cultures—apples especially being celebrated for their variety, colour, and flavour. The rainfall about Nelson is very reliable, and averages from 35 in. to 45 in. per annum. Marlborough is also a sunny province, and its rainfall averages from 25 in. to 30 in.

The climate of Westland is influenced by its position with regard to the prevailing westerly winds, its proximity to the sea from which these winds blow, and the mountainous character of its eastern half. The rainfall, as might be expected, is heavy, and ranges from about 70 in. per annum in the north on the coast to as much as 200 in. in the mountainous country. The weather-changes are chiefly due to atmospheric depressions, with lowest pressures passing south of the Dominion. Cyclones centred in the north, while bringing heavy rains to the North Island and the east-coast portions of the South, do not, as a rule, affect Westland, as easterly winds, which then prevail, are not conducive to cloud-formation in this province. Sunshine at Hokitika averages 1,871 hours a year, and, though not so abundant as in east-coast districts, this is a good average amount considering the rainfall. Westland is noted for a clear, beautiful atmosphere during fair-weather periods.

The chief health resort of the South Island, Hanmer Spa, is situated on a small plateau in the northern portion of the Canterbury Land District. On account of its altitude, 1,120 ft., it enjoys an invigorating climate, with a mean annual temperature of only about one degree below that of Christchurch. Owing to its elevated position and nearness to the mountains Hanmer is in some winter seasons subject to rather severe snowstorms, such as are never experienced on the Canterbury Plains. The mean annual rainfall is 38.15 in., and the mean total sunshine 1,992 hours.

The district of Canterbury comprises a variety of topographical features. A plain stretches over a hundred miles from north-east to south-west, with a maximum width of about forty miles from the east coast to the foothills to the westward. The latter merge into the mountainous country culminating in the main range of the Southern Alps, which divide the provinces of Canterbury and Westland, and afford a protection from the heavily moisture-laden north-westerly winds. The rainfall of the Canterbury Plains is in consequence much restricted, the average being about 26 in. There is, however, a remarkable progressive increase from east to west, as is shown by the records. At Christchurch the mean is 25.13 in.; at Mount Torlesse Station (near Springfield), 39.86in. The climate of Canterbury might almost be described as Continental in type, with large extremes of temperature between summer and winter and day and night. Except in the three summer months frosts are numerous, and even in the early spring and late autumn they are at times severe enough to damage vegetation of a tender nature. In summer, day temperatures of over 90° in the shade are sometimes experienced. With regard to both climate and soil, the Plains have proved most suitable for agricultural farming, and much of the district is capable of growing splendid cereal and root crops. The prevailing winds in Canterbury are north-east and south-west, while north-westerlies are not, as often supposed, of frequent occurrence. They are most common in the springtime, and, being dry and warm, they have a somewhat enervating effect, though in winter-time they come as a welcome change from the keen temperatures then generally ruling. The bright sunshine, as recorded at Lincoln, shows a daily average for the year of 5.8 hours.

Otago, the southernmost part of New Zealand, is very diversified as regards both its physical features and its climate. Inland, in Central and North Otago, the climate is dry and clear—hot in summer and cold in winter. The rainfall for this district averages from 13 in. to 20 in. Near the coast, in the Dunedin district, the rainfall is more plentiful, averaging from 30 in. to 40 in. per annum, a good deal of which falls in light drizzling rains.

There are continuous rainfall records from various parts of Dunedin for sixty-nine years, of which the median rainfall is 33.5 in., and the mean in the table following may be regarded as too high.

Queenstown, on Lake Wakatipu, amongst the mountains, at an elevation of over 1,000ft., furnishes the following averages:—

At Invercargill, the chief town of Southland, the averages are as follow:—

The average rainfall of Southland is between 40 in. and 50 in., but towards Queenstown the rainfall is between 30 in. and 40 in. The rainfall is well distributed throughout the year, but there is less wind in winter than in summer.

Stewart Island has a wonderfully mild and moist climate, especially on its eastern side, with an average rainfall of 65.18 in.

The total year's rainfall was below the average over most of the Dominion, but slightly in excess north of Auckland and also at scattered places in Westland and Central Otago in the South Island. Following is a short summary for each month of the weather and the chief atmospheric systems which were in evidence:—

January.—Anticyclones dominated from the beginning until the 20th January, and the weather was fair though somewhat changeable, owing to several small disturbances passing south of the Dominion.

After the 20th a cyclone developed northward of New Zealand. It proved a very intense and extensive one, the effects of which practically lasted until the end of the month. Easterly to south-easterly gales were prevalent during this period, and very heavy rains were experienced in the northern and east-coast districts of the North Island. Waihi recorded 20.43 in. for the month, of which amount 16.78 in. fell between the 25th and 28th (inclusive), the greatest fall being 6 70 in. on the latter day. At Keretoki Station, Waimatenui, on the 29th, a fall of 0.87 in. took place in twelve minutes.

The total rain for the month was below average in the country surrounding Cook Strait and in the south-west portion of the South Island. All other parts of the Dominion had an excess, the greatest being on the east coast of the North Island, where some stations recorded as much as five times the average.

February.—During the greater part of February the weather was chiefly fair, under the influence of high atmospheric pressure.

After the 22nd an extensive depression northward of New Zealand- accounted for unsettled conditions, with strong easterly winds and heavy rain, in the northern and east-coast portions of the North Island. These districts had a total rainfall considerably above the average for the month, while generally elsewhere a deficiency was recorded.

March.—Westerly disturbances were frequent during the month of March, and all parts of the Dominion with a westerly aspect had rainfalls considerably above the average. Gisborne and Napier districts on the east must, however, reported little more than half the normal for the month. There were floods in Westland in the beginning of the month. Some exceptionally heavy winds were recorded on the 16th and 17th in various parts, when lowest barometric pressure was recorded in the South. Stormy weather continued generally until the close of the month. These heavy winds were mostly regarded as “Equinoctial gales,” although it does not appear that they hare really any connection with the Equinox.

Thunderstorms were prevalent at this period.

On the 26th an unusual visitant to New Zealand, in the shape of a tornado, made its appearance at Wellsford, seventy-three miles north-east of Auckland, and its track was marked by considerable damage in destruction of trees, houses, and sheds, though fortunately without loss of life. Mr. Osborn, whose dwelling was destroyed, described the oncoming of the storm as follows:—

“It looked rather misty outside, and we were sitting on the couch by the window talking about the weather, one passing the remark that it looked like rain. It commenced to blow then, but not very hard at the start. The door was open, and I and my wife walked over to close it. The cyclone looked about ten chains off. It just seemed to look like one big cloud in the middle of a lot of mist. Just when I closed the door it hit us hard. A blinding flash of lightning seemed to be the prelude to the ‘big noise.’ Everything was then one big roar. The whole sky seemed to swirl round about our house, and the force of the wind was terrific.”

The small house then rose bodily with its three inmates and was swirled around in the air, and after being carried some distance was smashed to matchwood, and papers were found twenty miles away.

On the same evening a water-spout was seen at the distance of about twenty miles, and it was believed to have connection with the tornado. It was described as a great pillar of water rising from the sea to black low-lying clouds, sweeping hundreds of feet of water at its base and travelling rapidly with irresistible force.

April.—Fair weather prevailed during the first week of April, but the remainder of the month, owing to several extensive westerly depressions, was characterized by changeable conditions. These disturbances accounted for strong northerly and westerly winds generally and occasional heavy rain in the west-coast districts. On this account places in the west-coast and southernmost districts received a rainfall above the average, but over most of the Dominion the total was below, the east-coast provinces experiencing very dry and mild weather.

May.—The month was a dry one generally, and the total rainfall was below normal over most of the Dominion, only a few scattered places in the northern and east-coast districts of the North Island and in the northern portion of the South Island recording falls over the average.

From the 1st to the 10th a westerly disturbance brought squally westerly winds and rain, mostly to districts with a westerly aspect.

Dull and misty conditions prevailed from the 13th to the 18th, while a shallow depression moved from the north-west over the country.

Between the 24th and 27th an intense cyclone, passing in the North, accounted for some heavy downpours in the northern and east-coast districts of the North Island, and very cold weather generally.

On the last day of the month strong easterly winds, with threatening conditions, prevailed in the far North, owing to the presence of a depression to the north-west of the Dominion.

Fine, mild days and cold nights were frequent during the month, particularly in the South Island, and, except in the far North, the average wind-force was lower than usual.

June.—June proved a cold month, the mean shade temperature being below the average of previous years. Frosts were more frequent and more severe than usual in places generally subject to them. Rotorua reported 17 degrees of frost on the morning of the 28th, while Hanmer, in the South. Island, registered 21 degrees of frost on the 11th and 12th, and experienced twenty-seven mornings with temperatures below freezing-point.

The month opened with unsettled weather generally and stormy conditions in the northern districts, where some heavy rain fell between the 1st and 4th owing to a cyclonic disturbance passing over the Dominion from the north-west to the south-east. Its centre was apparently located in the neighbourhood of the Chatham Islands on the 4th. From the latter date until the 20th, although anticyclonie pressure enveloped the country, continuous tropical depressions northwards resulted in a prevalence of cold east and south-east winds generally and frequent drizzling rains in the east-coast districts, especially of the North Island.

The West Coast, at this time, experienced fine, clear weather.

After the 25th a storm-centre to the eastward of the South Island developed considerable intensity, and accounted for strong southerly winds and showers on the east coast, which prevailed until the 30th.

The month, on the whole, was a dry one, and, except for a few stations along the east coast, all parts of the Dominion recorded a total rainfall much below the average.

July.—The July rainfall was nearly everywhere below the average, some places showing the lowest fall ever recorded for this month. Precipitation came mostly as light showers, but some heavy downpours occurred in various parts, with boisterous north-west winds on the 10th, while an intense westerly disturbance was pasting in the South, and in the northernmost districts about the 28th and 29th, when a tropical depression was located northwards of New Zealand on the edge of an anticyclone centred in the South.

The month was remarkable for a frequency of dry southerly winds, clear days, and cold nights, and frosts were again above the average in number and degree.

August.—The weather during August was of a changeable character, being dominated chiefly by disturbances of a westerly type with lowest pressure moving from west to east southward of the Dominion. Of these depressions the most notable was one which persisted between the 14th and 25th, and, although not of remarkable intensity, it accounted for unsettled and, at times, boisterous conditions. Most of the rainfall occurred during this period, and in the west-coast districts of both Islands some heavy downpours brought the total for the month in excess of the average. In all other parts of the Dominion the aggregate rainfall was below the mean of previous years, and in the east-coast provinces the weather might be described as dry and calm generally, with mild days but cold nights. Frosts were numerous and severe in many parts.

September.—Rainfall was below the average except at isolated places, particularly in the north-east portion of the South Island and the extreme north of the North Island.

Unsettled weather was generally confined to two periods—viz., between the 9th and 14th and the 22nd and 28th. In the former period an extensive though rather shallow cyclonic depression ruled, bringing welcome rain in most parts on the 10th and 11th. Some snow was reported on the 11th on the high country in the South, and also on the 13th on the higher levels in the North Island as far north as the Gisborne district.

The heavy rains that occurred in parts towards the end of the month were accounted for by a succession of disturbances on the edge of an anticyclone which at that time overspread the Dominion.

Except during the periods mentioned, fair weather predominated, with several sharp frosts in various parts. The month was a good one for agricultural work, and, although growth was not abundant, it was sufficient for grazing purposes.

October.—October was remarkable for the large number of westerly disturbances, which accounted for a prevalence of strong north-west winds generally and heavy rainfall in the west-coast and northern districts of the South Island. The total rainfall was also above the average in the extreme north of the North Island, while other parts of the Dominion experienced a deficiency, the east-coast districts suffering most in this respect.

The month opened dry and fine generally, but warm and humid conditions were shortly followed by heavy west-coast rains, and more general rains at the end of the first week. Barometric pressure was very low in the South on the 14th at 9 a.m., but increased rapidly in the next thirty-six hours, and some snow fell on the higher levels about this time, with stormy conditions in the South. Fair weather ruled between the 15th and 19th, after which boisterous westerlies continued until the end of the month.

November.—Westerly or antarctic disturbances accounted for the stormy weather conditions which were rather prevalent during the first half of the month and again at the close. Between the 18th and 28th an anticyclone brought fair weather generally. The total rainfall was considerably below the average on the east coast of the North Island, but, with few exceptions, all other parts of the Dominion experienced an excess, which was greatest on the west coast of the North Island and the east coast of the South.

December.—The weather during December was dominated by disturbances of both tropical and antarctic origin. Of the former type there were at least three, and of the latter four, while anticyclones, though conspicuous during the first half of the month, were mostly centred northward of the Dominion.

Warm, dull, unsettled conditions predominated, with rainfall well distributed in time and place. The total precipitation was nearly everywhere above the average and on the east coast of the North Island it was in marked contrast to the low falls of the past few months.

Below-average falls were, however, recorded in the central and southernmost districts of the North Island and in the northernmost and extreme south-west portions of the South Island.

The following tables show the difference, above or below the mean, for each month in the year:—