THE NOVARA EXPEDITION.

New Zealander, Volume XVIII, Issue 1715, 16 August 1862, Page 5

THE NOVARA EXPEDITION.

[From the "Australian and New Zealand Gazette," May 17.] Amongst the most useful, if not the most important results of the Novara Scientific Expedition, fitted out by the Austrian Government, are the geological researches of the eminent men who accompanied it. It is also a singular and somewhat humiliating fact that to .Dr. Ferdinaud von liochstetter we are indebted for the first practical geologic surveys of New Zealand, although a British colony and affording a field of great

mineral weath and still greater scientific interest, to which we should hare thought British geologists would have promptly and even eagerly betaken themselves. Dr. Hochstetter's surreys were necessarily very restricted. Those which he has already published have appeared in our columns, and Dr. Haast, whose valuable explorations iu the provinces of Nelson and Canterbury wo have also reported, is still following them up in the colony with great success. We have been favoured with the following translation from the German report of Dr. Hochstetter on the Isthmus of Auckland, New Zealand:—The great southern mass of the North Island of New Zealand is connected with the narrow peninsula stretching away to the north-west by a small isthmus in about the 37th parallel of south latitude. On the eastern side the sea penetrates deeply into the land by the Gulf of Hauraki, with its numerous islands, washing in its south-western branch—the so-called Waitemata River —the northern side of the Isthmus. On the west coast, the exposed weather-side of New Zealand, the forced a narrow entrance through the hard volcanic conglomerate rock, expanding inland and forming the southern shore of the isthmus, under the name of the Bay of Man akau. The general width of the isthmus is here not more than fire or six miles, and is further reduced in two places, where narrow creeks of the Waitemata River penetrate deeply in a southern direction towards the Gulf of Manukau, to about an English mile. These spots have been used from time immemorial by the natives to carry their canoes across from one side to the other, and have naturally often turned the attention of the colonists to the feasibility of cutting a canal to join the two bays. That this important plan -will be eventually carried out there is no reason to doubt, as it is only a question of time and expense. The western isthmus, which is called the " Whau portage," is a mile wide and only 111 feet high at its greatest elevation, whilst that to the east, near Otahuhu, south of Mount Richmond, i-nd known by the name of the f Taraaki portage," is only 3,900 feet long and 66 leet above the level of the sea.

Whilst the Waitemata River forms the most central harbour on the cast coast of the island, so rich and safe and accessible ports', the Bay of Manukau on the west coast is by far the best on that side, and, indeed, the only one that can be frequented by large vessels without danger. Great credit is due to the penetration of Captain Hobson for selecting this beautifully situate narrow isthmus for thi site of the iuture capital of New Zealand and the seat of Government, for which it is most admirably adapted, being so easily approached on both sides. No other spot on the Northern Island combines with a central situation the same advantages of a safe and easy water communication in every direction; for to the numerous arms of the sea that indent the laud on all sides must be added the natural waterroads of the Northern Island - the large and navigable rivers—the Kaipara, the Wairoa, the Waikato, the Piako, and the Waiho, which arc all quickly and easily accessible from the isthmus.

Auckland, the present capital of New Zealand, as well as of the province of Auckland, the seat of the Colonial and Provincial Governments, was founded in the year 1840, on the northern side of the isthmus, on the shores of the deeply indented VVaitemata. Annually increasing in extent and prosperity, it contained in 1860 more than ten thousand flourishing inhabitants —whilst an equal number are found residing ill the immediate vicinity of the capital and its suburbs. A good macadamised road leads from Auckland to Onehunga, on the shores of the Bay of Manukau. This rising place was originally a settlement of civil and military pensioned officers, to each of whom the Government gave a cottage and an acre of land, but it has now assumed the importance of a town, and on account of its charming situation and the romantic beauty of the surrounding neighbourhood, becomes every year more and more the favourite residence of the more wealthy of the colonists, who have their business at Auckland and their dwelling at or in the vicinity of Onehuuga. Between these two isthmus towns lie a number of country houses and farms scattered about, and at the points of intersection with other roads whole villages have sprung up, among which are Newmarket, Mount St. John village, and Epsom. All over the isthmus nearly every trace of the original wilderness has disappeared, and the native vegetation is succeeded by European trees and plants; stone walls and green hedges separate the possessions of the new owners of the land, and wherever the nature of the soil admits of it are to be found beautiful meadows, gardens, fields, and plantations. Cattle are seen grazing peaceably on the farms, omnibusses and other conveyances enliven the roads, and the total effect to the'eye is that of a well ordered and flourishing colony of enterprising, peaceful, and wealthy settlers.

In a geological point of view, the Isthmus of Auckland is one of the most interesting and peculiar volcanic districts in the world. It owes its own unique physiognomy to a great number of extinct volcanoes with their craters more or less in a state of preservation, streams of lava forming extensive fields of this volcanic matter at the foot of the parent cone from which they emanated, as well as the tufFa craters which surround, like an artificially constructed circular wall, the cone of eniption formed by the gradual deposit of dross and other erruptive productions strewed without any regularity all over the isthmus and the adjacent coast* of the" Waitemata and Manukau. The volcanic eruptions appear to have broken out each time at a ;ditfercnt spot, and thus have covered the country with an innumerable quantity of small eruptive cones, all now extinct craters; in the immediate neighbourhood of Auckland in a square of twenty miles in extent by twelve in breadth, there are no less than sixty-one all plainly defined and recognisable. They arc of all sizes and elevations, mostly from 100 to 300 feet above the level of the sea, and the highest is that called Rangitoto, which forms a separate little island of itself near the entrance to Auckland Harbour and rises to the height of 920 feet. But they are perfect models for giving a complete insight into the formation of craters by volcanic action, opening a rich field for the prosecution of geognostic researches, and completely refuting Leopold von Buch's theory of elevation craters, so implicitly believed in by the scientific world in Germany.* They rise from a substratum of tertiary sandstone and marly clay, whose horizontal deposits (only here and there locally disturbed) are fully visible in innumerable places along the steep cliffs of the Waitemata and Manukau Bays, whilst an examination of the localities proves that eruptions have taken place at repeated periods and with different sorts of volcanic action at one and the same place. The most primitive eruptions—probably submarine and at the bottom of a shallow bay not much exposed to the agitations-of the wind —consisted of loose masses, fragments of the rocks themselves, slacks, and volcanic ashes. The eruption took place in several successive shocks, and the volcanic matter was, therefore, deposited in layers, one over the other, around the centre point, forming gently rising cones with a more or less circular and basin-shaped crater in the middle—tuffa cones and tuffa craters. The Pupaki Lake, on the north shore; the Orakei Bay, to the east of Auckland ; Geddc's Basin, near Onchunga; the Basin of Waimagoia, near Panmure; and the Kohuroa Hill, south of Otahuhu, are all beautiful specimens of these tuffa craters. Like the so-called Maaren in the volcanic region of tne Eiffel, in Germany, these basins are very deep and full of water—that of the SweetI water Lake of Pupaki has a depth of 28 fathoms, or 168 feet,—though occasionally flat and dry or covered with marsh and bog. Where they are situated near the sea, the side has been broken in by the continued action of the waves, and the sea flows in and out with the tides. On account of the extremely fruitful nature of the volcanic soil, these tuffa cones play a conspicuous part in the domestic economy of the settlers round Auckland, as the summit of most of them is crowned by farm buildings or dwellings. The practical good sense of these farmers has taught them, without any knowledge of geology and without in the least suspecting that they were buihng their houses on the verge of a crater, to select these tuffa craters for the residence and the seat of their farming operations, and the grazing lands and clover fields formed on them are clothed with most beautiful and luxuriant verdure, favourably contrasting with the sterile clayey soil of the original rocks, which are covered only with bushes of fern and manukau (Leptospermum). Shortly after the first primitive eruption, the whole of the isthmus district appears to have been subject to a slow and gradual upheaval, by which the subsequent instances of the volcanic action were accomplished above the level of the sea, and, consequently, dry land. During this secondary period, large masses of red hot slacks weio emitted and streams of liquid lava ejected

* This absolute and categorical assertion ought to be received by your readers with due caution, as L. von Buch's beautiful theory of the origin of craters, which has gained admiring partisans and fervent supporters among the scientific aud reflecting part of the community, not merely in Germany —where Alexander von HuraboU unhesitatingly accepted the theory and endorsed it with his own great name,—but in all parts of the civilised world, stands too firmly rooted to be overturned by a mere statement as that made with such selfcomplacency in the text. But to do justice to Dr. von Hochstetter and not to prejudge the case, it is but fair to state here that in a note he refers for further information on this interestlng subjpet to a descriptive work, written by himself, on the <teo!ogy of New Zealand, which will shortly be publishtd, with maps and sketches, as a separate volume of the scientific partof theNovara cxpeditijii; and your readers will, therefore, do well at least to suspend their judgment till they havo perused Ihe learned doctor's theory and examined the argument he brings forward to prove iss plausibility. [Thk Tkansl.vkto.

in considerable quantities. In those days the volcano** of Auckland were really- " fire-spitting mountains?' * (Fever Spiende Bergc) in the most literal sense, heaping up around their funnel shaped crater the slacks, lapilli, and other produce of volcanic action, with a slope of from SO to 35 degrees, at Mount Eden, Three Kings, Mount Smart, Mount Wellington, and others;, and in those places where repeated ernptions of lava took place, cones of lava were formed, as at Eangitoto. Where these fresh outbreaks occurred, the cone of . slacks rises conspicuously in the centre of the crater ring of tuna; and in proportion to the mass of the eruptions, as well as the measure of the subsequent subsiding of the surface—probably after the extinction of the volcanic action,—they form larger or lesser islands, resting on the bottom of the tuffa craters or filling them with water. Fetrographically speaking, the substance of all tho t Auckland volcanoes is identical and homogeneous, consisting of a porous basaltic lava with a large admixture of olivin and making admirable materials for building, whilst the slacks are profitably used fot metalling the roads. Were the name of Eangitoto to be read in the sense of its literal meaning—the " bloody Heaven"—as conveying the idea of reflecting in a dark night the red light produced by the eruption of liquid lava, and which may have induced the natives to give it that fanciful appellation, it might be used as an argument to prove that the volcanoes of tbe Auckland district have only been extinguished at a very recent period and were seen in action by the natives a few generations back; but this is, for many scientific reasons, very unlikely to be the case. On the other hand, it is not to be denied that there are strong grounds for believing that the Volcanoes were in full activity not long ago, speaking geologically, and that in fact they belong to the present geological period of the earth—in proof of which it may be here mentioned that the volcanic ashes cover the ground everywhere, and that the : streams of lava, which are unquestionably of different dates, all took the direction of the valleys nearest to the crater out of which they originated. These valleys must consequently have been extant when the streams . of lava flowed into them, and therefore the surface of the country has not since that period undergone any , material alteration.

Whilst the Auckland volcanoes are now the ornaments of a district transformed from its native wildness to a beautiful and well cultivated garden by the industry and enterprise of European immigrants, they involuntarily awaken recollections of a wonderful period of ethnological history. Only a few generations ago the Isthmus of Auckland was inhabited by a powerful tribe of Maories—the Ngatiwatuas,—numbering from twenty to thirty thousand of both sexes. The extinct craters, with their commanding situation and extensive view all round, played a conspicuous part in the habits and domestic economy of the savages —like the robber castles on the Rhine and other parts of Germany in the middle ages. Their summits were the strongly fortified defences or pahs of the chieftains of this warlike race, whilst at their feet lay scattered the cottages of their dependents amidst tho extensive fields of the kumara which they cultivated for their food. The slopes were formed into regular terraces and defended by rows of strong palisades. In tho present day these houses and cottages no longer exist, the formidable palisades have disappeared, and the Maori castles are in ruins. The terraces alone remain as the sole memorial of the brave and warlike race that was exterminated during the bloody wars of the cannibal chieftain Hongi, called "tho New Zealand Napoleon," about tho year 1820, whose deeds of arms are now only recorded in tradition and song.