REPORT.

Colonist, Volume II, Issue 131, 21 January 1859, Page 2

REPORT.

Of a Geological .Exploration;of. the Coed-Field in the Drury and Ilunua District, in the Province of Auck' land [N. Z.), by Db. Ferdinand Hoohstetteb, Member^ of the I. R f ■ Geological Institution of the Austrian Empire,—and Geologist on board the Austrian frigate Novara. • ..;■..'-. . • Having been requested hy the GoYennrientof New Zealand to examine and report upon'the coal-field recently discovered in theneighborhood of Auckland, —and having received the sanction of Commodore Baron de WuUcrstorf-Urbair, of the Austrian frigate Novara, for this purpose; I have the honor to report, as follows:— t . . ■„ ■•■.; After having spent the 24th and 25th of December last in making' an investigation of the geological structure of the country in the "immediate neighborhood of. Auckland, between the Isthmus of Whau on the west. and theisthmus of Otahuhu on the east,—l started on the. 28th- of December, in company with the Rev. A. G. Purchas,. Mr. C. Heaphy, Provincial Surveyor, Mr. Drummond Hay, • and several"other gentlemen, together with some of my colleagues; for the Drury and Huhua Districtj' to examine, as-closely as my time permitted," the coal, which had recently been discovered there by the Rev. G. A., Purchas, and has since , been 'opened in sevferaljplaces,by various settlers'. -.- .'■ *! •■ '•"<■,''*■'.' "" • Our head quarters we're at Mr.'. Young's""hotel, at Drury, from the top of which the Austrian flag floated as a pleasant token of welcome.' Our reception was most gratifying; nearly all the settlers in,the neighborhood were assembled, shewing the great.interest felt in our mission. I would here state; that it was mainly owing to the excellent arrangemehts'.madeby the Government, to the energy and perseverance of the accompanying gentlemen, and to .the useful infoiv mation afforded by of some of the settlers,, that I have been enabled, in the very short time at'my disposal,, to visit and examine the most important points of fhe portion of the coal-field brought under my notice,— and likewise to .pay a hasty visit to the Waikato River, between Mangatawhiri and Tuakau. I have, thus obtained a general view, of the .geological formation of that part of the country.;, and'lihavtfarrived at results, which I trust; will in. some -measure answer the expectations of the Government,- and prove of value to the people-of Auckland-by leading to the development of so important a source of natural wealth.' I shall confine myself at present tomatt'ers having ■ bearing, reserving -my report"on the strictly scientific portion of the subject • until my: return to Vienna^ in : order to afford time and: opportunity for a careful examination of the'fossils, and an analysis of the Various minerals and rocks, Of which Thaveeollected specimens.. .■;■•' :•■-.. ; •;■.: ■■■■■-/:■■■.; '<■' : 1-'-i-; <'^;;^i '•' The plains of Papakura and Drury on the-eastern shore of the Manukau Harbor are of an undulating character, and but. slightly elevated above the; sea. They are bounded on the south-east and south by a thickly wooded range of hills'of moderate elevation, perhaps from 1000 to 1500 feet in height; ~' ';■? The general direction of this range is from southwest to north-east, from the ".Waikato to tile Wairoa; except a portion near Drury vvliich1 raris neiarly north and south, and rises almost immediately from the plain. On the slope of that portion, in more or less deep gullies, seams of coal are exposed, in some places by the natural action of the water, and in others by the exertions of the settlers.... . , .. .:'. ~, . > Vr -..- ■: 1. The first, arid the mostsoutherrimostplaco.we visited was on Mr. Farmer's land near Drury, on the right bank of a small stream in a gully just inside the forest, where: a shaft about 20 feet deepis opened by Mr. Tuvnbull, exposing three seams of coal, separated by thin layers of shale* amounting altogether to about 15 feet in thickness. A considerable quantity'has been raised from this shaft: but, on account of the water it contained at the time= of my,visit, I could not examine as accurately .as I should have wished the Bection and character of the'seam. The dip here is 10 degrees towards south-west. The roof is a soft argillaceous sandstone; which passes above into bituminous shale, containing ivegetable- impressions. The bottom was not exposed,' but large basaltic boulders, filling up the bed of the-creek and lying on the brow of the hill at the edge of the forest, seem to belong to a basaltic conglomerate below the c0a1.,.

■2.' Some openings at Mr. Hall's and Mr. Pollock's farms. - ■ •■..- ';• '■'■■.r "■•'.'■■- ,'' .',■": '",} \ , ,\V .

(a.) A small hole near Mr.'Hall's hotise jiist at the foot of the range exhibits a'decomposed basaltic conglomerate; large boulders of which are lying for soirie distance along the face of the'-hill, extending as far as Mr. Pollock's house ; where an abrupt hill seems to consist of a compact mass of eruptive basalt. (b ) At a somewhat'lower elevation and a,little further on to the north, a shaft has been sunk to the depth of thirty-eight feet;1 with the following section :— ■•' ■' " ■'; "... .':■. .. :.: . ; . feet ■■ , Yellowish clay .._........ .-.'.......... 10 Fire clay, of a bluish grey .c010r......,.,'.. 8 . Shales, alternating with'a hard argillaceous sandstone, both containing fossil plants,

and very thin layers of'coal

............. 20

(c ) Still further to the north,, and at a level of about 200 feet below, the last mentioned stratum, a tunnel has been excavated by Mr. Pollock through basaltic conglomerate interspersed. with large . boulders. It was reported to me that a few marine fossil shells were found in this coiiglomerate,~rbut I did not see any specimen of thetn. . If a coal seam exists in this portion I think it will not be'found beldw'tho last mentioned basaltic conglomerate; but in the. strata hpt.yet exposed, lying between the conglomerate and. the shales found in thelower part of the'.sliaft (6.) '.'.. ".:..., ~.

3... Symonds' Creek :—

" (a.) On Mr. Symonds' farm, just at the point where the creek which bears his name emerges,lrom^the gorge on the ,'right bank of the. stream ; I saw some rocks, of a soft tufacious sandstone, containing.numerous small marine shells, .and gravelly .particles ,of various .basaltic and aphanitie rocks.; j This ;is the lowest exposed stratum in -this valley. . Higher up.iii* the forest we find on the surface of a stiff clay:soil the same large boulders'as at Mr.' Pollock's. ( . ~; : •■■■■;''

(b.) Further up the stream, near Mr. Campbell's house, seams are. exposed at three , 'different, points almost close together, just at the level of the stream on its right bank. ; At: the first point in-going up, the coal is about two feet thick, a, few feet above the water; at the second point the coal is in the bed: of the s ream, and therefore its thickness could not be ascertained; at the third point, ..at a bend of. the stream, the coal is seen again, of a thickness of about: seven feet, part of which is. below the level of the. water. As in this place the layers are nearly in a horizontal position, I am of opinion that the coal on these three points belongs either to one.and the same seam, varying in thickness, or' to ■ a'set of scams similar to that described in Section 1.

The ropf; of the .coal was on iall places a soft yellowish white sandstone. ; ;yr\Z:&s/.*p~-?'■'&>■•'?•'■'''■ "''r'.~

(c.) Another pointvisited;by us, also on Mr/Campbell's farm, is a short distance.before one_comes toMr.;. Glare's house, and afa considerable-height above the last mentioned/places, where in a sihall gully, this ,coal was first discovered a few months-ago by theBey. A. G. 'Purchas, and opened, at his direction,* fey Mr. Campbell., The coal has.-here a somewhat dif- } ferent appearance; from-that of the. other places;' its' 1 structure being more.laminated, r The first ppecimena brought to Auckland'were:obtainedfrom this seam.

4. Mr.-Fallwell's fannr-rr

(a.) A shaft, 25 feet, .deep, .southward from the house, in the forest, .on the other side of a^ small gully, contains in the'uppenpart,fire-clay, and'-in the lower dark; grey bituminous shale, with fossil'plants and; thin- layers of coal., ' :liv ;the Valley between 5 this and the house occurs, in the bed of the stream y& dark aphanite in rocky masses.of a considerable size. .-■''■

(b.) On the northern slope of the hill on which Mr. Fallwell's house stands, this gentleman has made a cutting, affording the best view of the strata that can be obtained in any of the places we visited. The section is from the surface downwards, as follows:— feet.

On the surface, stiff clay soil, with nodules of

argillaceous iron ore, about 3 Soft .shales; with vegetable impressions, more or less sandy, about .. ... ~ . ". 30 Coal, about .:'..;' ..:.'•.. ..• '.'B..' This seam consists of three portions} the upper \ part, a laminated ,coal of inferior quality,.one foot; then a band of shales, two inches; the. middle part,' coal of a good quality, one-and a half feet;.then a, band ofbituminous shale, six inches; the lowest part, coal of the best quality I have seen, two and a half ' feet. Thu& the whole thickness of the coal itself may -< be considered to amount to about five feet. The floor of the coal consists of bituminous shale, with fossil plants, paßsing into yellowish clay, ( Tkmmrget.)

Thestrike of the strata is from W. 20 dea:- N., to W/20 deg.:S.;—the dip 20-80 deg, to S. 20 deg. (e.Y A shaft north fcom; Mr. Fallwell's house, at a lower level on^ the-left-bank of; Symonds' Creek, twenty-six feet deep, shews in its upper part nearly liorizontaKstratft, consisting of three band sof bituminous shale, alternately with sandy layers;—in the lower part greenish earthy tufas of a diontic character, which I taketo be the bottom of the coal for- , id) The same dioritic tufas, unstratified, occur in pother pit; which is sunk at a lower level on the left bank of Symonds' Creek, near Mr. Clare's house. I do not believe that coal will be found even if this pit Should be 'suhVtoalowerdepth ;~but am inclined to : think that the carboniferous strata wjll be found to run out in.the higher; parts of the hills behind Mr. •Ckre's house,'where, I. was told, indications of their -out-cropping have been found; _ ; ; In.the upper part of: Symonds' Creek, hiijherup than Mr. Clare's house, occur rocky masses of aphanite, •<iver which the stream falls in a cascade of considerable height. . x a a Farther observations on other points were rendered impracticable on account of the thickness of the forest, and the consequent inaccessibility of the country. Moreover, the shortness of time did not permit ■His to extend our examinations over other districts; as, • for instance, Wairoa, Karaka, &c, where coal probably 'likewise occurs. The following general conclusions, therefore, may hot be considered as established facts: but as probabilities ,■ resulting from a very limited mumbcr-of observations:—.. I. Quality of the Coal. • The coal is a tertiary coal. .With respect to its - equality, it belongs to the best sort of brown coal—to sflie so-called' Glajiz-kohle, with conchoidal fracture. 'It'has quite.thejappearance of : a cannel coal, but does liotiii factijelopg'tb the old carboniferous formation, • ibut to that of tertiary, probably, Miocene age. A .future palseontological examination of the fossil plants ■which are found in the bituminous shale connected ■: -with the seam, as well as that of fossil marine shells i ?found in different strata above and below the coal, mW. lead-to a more exact determination of the geolo- ' gicaTage of the coal,—and furnish an opportunity for '■ making a comparison with similar tertiary coal-forma-f ttioha in Europe. ■: - The practical quality of the coal, for steam pur- ' poses and for producing gas, can only be proved by A chemical analysis of the coal will be i made at the labnratorj' of the Imperial Geological Institution of Vienna, from the specimens collected at the different localities, and its result duly reported to ■ the Government of New Zealand. The iron pyrite does not occur in the coal in such a quantity as to lessen materially .its value. The fossil gum found in the coal ia a kind of " -"Ketinite," derived .from a' coniferous tree, probably •closely related to the Kauri, but by no means the ■ ,same species. . ■ ' There is no great difference in the quality of the 7;coal found at the places i, 3b. and 4b. ; 11. Thickness of the Seam.

;I was not able to convince myself of the existence •of different series of seams, one above the other, in •'different levels. I am much rather of opinion that •the same series occurs at the localities 1, 3, and 4, a ■difference of thickness in the same series of seams at

-different spots is quite a common occurrence. The fact that thp same seam is found at varying heights above the level of the sea, arid'with different dips, is accounted >for by the occurrence of disturbances and dislocations having taken place after the formation of 'the coal-measures—such as must have-accompanied •the eruption of the later volcanic hills in the vicinity of Auckland. : ■_.. ; •

3?he-average.thickness of the seam, which at the locality No. I'is greater than at 3 and 4, may be e3ti- * mated to amount to above six feet. The sections

.through: the coal seam shew, both at 3 and 4, distinctly that the seam consists of three parts—an upper, •middle, and lower part. The section which has been described as 4b, can be taken as.a. fair average. 'j I ■ .;';. '111. Extent oe the Coal-field. The existing openings seem to justify the conclusion .that the coal-field extends from the southernmost ■opening. No. lj in a N.N.E.''direction, as far as the r>6ut-croppihg in Mr. Campbell's farm, for a breadth, ,from the base of -the hill inwards, of about two miles. "In a southern direction..it probably extends still far<ther ; while in a move northern direction the coal-field ..seems to be interrupted ■■ in the higher ridges near Mr. Clare's house (see 4 d.), and near Hay's Creek, where, 4n the vicinity of a native settlement, eruptive basaltic and dioritic masses, and conglomerates occur. ■

,37. TfIE.DBURr. AND.,IJiJNUA.COAL-FIEI-D IS IN REality but a part of a large basin of tertiary ' Formation, extending over a considerable tor-

TION OF THE PROVINCE OF AUCKLAND,

;■> Erom information* (for which I am indebted to the Hon. Mr. Whitaker, Mr. Heaphy, Rev. Mr. Purclias, iand others), on the general geological features of the 'neighbourhood x>f Auckland, the probable boundai'ies of this basin may be described as follows :— .On the south and east.its boundaries are formed by 'tlie range of hills running from Waikato Heads, along ♦the course of the river to Maugatawhiri, thence

•through the Hunua to the Wairoa, and along the course of that river to the sea. This range consists of eruptive basalt, breaking through, older formations, Send interspersed' with a thick stratum of conglomerate (Boulder formation). These basaltic eruptions belong ..to geological psriod of an older date than the volcanic hills near Auckland.

' On the eastward the line runs,across the island of Motiitapu, to the east of Tiritirimatangi,'between Motukeki and Kawau, across Takatau Peninsula towards Cape Itodney. Thence it turns to the westward, along a range of hills of.older geological formation,— running -to the west coast, and following that coast to Waikato Heads.' ,

The middle of this tertiary basin is occupied by a inarine formation, consisting of beds of a soft sandstone, alternating with bands of a yellow clay (Thoumergel). Some of these strata contain numerous «iarine shells, —-(as for instance at Hob3on's Bay), and small pieces <5f driftwood changed into lignite*. To this formation, X believe, belong likewise the interesting and valuable beds of limestone, "discovered by Messrs. Smith and Cooper in the Wairsa district, abounding in marine shells^ I do not think that workable coal will be found;, ,-either in or below this formation :—which is 'exposed in steep.cliffs at the entrance, and along a ■considerable portion of the coasts of the Waitemata harbour.

Coeval with, .and subsequent to the deposit of this marine formation, there existed on the flat margins of iihe sea-basin marshy forests of a considerable extent, from which, in the course of time, the brown coal now found on .the margin and along the above-des-cribed; inner edge of .the basin, was formed. Coal deposits similar to those oF Hunua and Drury.niay ''therefore exist at different places within these boundaries; —as for instance in the creeks running into the western portion of the Waitemata, and north-western portion of the' Manukau harbours'; &ko in the high land of tb.3 Karaka and Wairoa Districts.

' The volcanic eruptions in the middla of the basin, in" the neighbourhood of Auckland, must have taken place at a comparatively recent period, subsequent to the formation of-the coal. To the same period belong the strata found on the Eastern and Southern boundaries of the Manukau harbour, extending over the flat ; poi4ions of Papakura and Drury. ':> '."'<■■'■■'■■ • . In the: tidal creeks, .and other places where wells Jhave been sunk, a soft lignitic-deposit, nearly allied to peat,l is found at different depths, and in beds varying in thickness from a few inches to twenty feet. This ■deposit is covered in many places by a greater or less ■thickness of a remarkable white siliceous matter in a Btate»f very fine division; The latter seems tobede■riyedfrom] a hot lake of large extent, in connection "with, the 'recent volcanic eruptions in the neighbourhobd: of Auckland-; —but its true' nature can only be by future microscopic and chemical exiamination. , .

I have thus given a slight sketch of the geological :hietory ef Auckland and its neighbourhood ; and ex3>6ct to be able, on my return to Vienna, to furnish a ■more minute and ample description, illustrated by a ■map of the geological features of the country, compiled from the.materials which I "have now collected, &nd from those which* I .hope,' hereafter, to receive tfrom my friends in New Zealand. ' . .

The Working of the Coal,

There exists no doubt that the Province of Auckland is, as we have seen,'rich.in.the.possession.of abundance of good workable coal, —which will prove <bf the greatest importance, both for steam navigation •and manufacturing purposes. . With regard to'the questions,. wliere and. in what ■manne^tiie working ef the Drury and Hunua coal-field •should he carried on, I venture to Offer the following ■suggestions.:— .... 1. I consider the locality of Mr. Farmer's place as ■one of the most suitable for- commencing, a systematic mining., For .this purpose it would be deairable-to con•struct a tunnel, commencing from the most convenient paint at the foot of the range of the hills,—to be carTied in an eastern direction, inclining upwards just 'onoiigh to allow the water, to . drain off. This tunnel ■will run below the cos, or, perhaps 6trike it. A shaft should then be sunk from above to meet the tunnel, avoiding the present working (is'o. 1). This shaft will

pass through the coal-scams, and the working will then be carried on in the usual mariner,—the produce of the mine being removed through the tunnel, and the shaft supplying air to the workings. A railway from the mouth of the tunnel to Slippery Creek can be constructed without any difficulty.

2. In a: similar way working could to carried on at Mr. Campbell's "and Mr. FallwelTs; and a railway through the valley of Symonds' Creole may convey the produce of both mines to the Manulcau Harbour. If it would be desirable to work the lower seams in the stream itself, the water can be used as a motive power to drive the pumping machinery, which would be required in this locality. 3, It is of great importance to ascertain whether the coal is confined to the ranges, or extends underneath the plains stretching from.Papakura to Karaka and Mauku, at a lower level than the above mentioned recent lignitic, deposit. As I was unable to see any natural, section of the lower strata in these plains, I would recommend that borings be made in the following places:— ■ ■■ ■- ; ; One on the low land between Young's Inn at Drury and the range;, Another at Chisholm's bush;

A third on one of the higher undulations of the Karaka District:

And perhaps a fourth on the flat between Papakura and Wairoa. ~

I would also recommend that a similar exploration by boring should be made on the widest part of the Mauku flats. ,

Should these suggestions be carried out, I should be highly gratified to have the results communicated to me at Vienna without delay; in order that my promised report may be made as complete as possible. And now I conclude with the German miner's hearty " Glmh 4m/.'" ';•_. I?ERDINAKD ETOOHSTETTER, Dr. P. H. ' Auckland, Jariuary 4,1839.

Two Men Lost itf the Bush. —We have received information that two men of one of the Great North Boad parties, m the Mahuraugi district, have been missing for nearly a fortnight, and that every effort thus far made to discover them has proved fruitless. It seems that they went out from the camp last Saturday week to hunt for pigs—a task in which they had often engaged. Not returning that night or next day, it was supposed they had lost themselves; another day or two passing over, their comrades went in search of them, uuavailingly. Rewards were then offered to the natives to go in search, but though very handsome sums were offered, the natives declined— saying that the pakehas must have been very foolish to lose themselves. The first day that search was made, some slight trace was found in the bush in the direction they went—but after a short distance, no mark of the tomahawk could be discovered. No other surmise can be formed at present as to the cause of their non-return or arrival at some part of the coast, than that they must have got bewildered in the bush, or fallen into some deep guliy, for the bush is not more than six miles through, and there are many streams intersecting it. — New Zealander, Jan. 8.