« EelmineJätka »
NEW SOUTH WALES.
Borah, and the latter at Stony-batta Creek; the ores of copper are red and grey. Viewing
V. CARBONIFEROUS FORMATION.-In my Report of 6 November 1852, I stated my
Mr. Stutchburyt has also described very carefully the order and direction of the coal beds of Dubbo and Talbragar, with which I was slightly acquainted some years since, and coal beds occur, under similar conditions, on the Castlereagh. From the heads of that river to the base of the Nundawar Range the flat country bears many evidences of the continuation of the same formation, in patches of sandstone, conglomerate, and in fragments of fossil wood, which occur either on low ridges, or in the drift that is spread over the surface, or forms the banks of creeks.
I have also mentioned that sandstone caps some of the ranges on the Gwydir.
We have, therefore, evidence of the continuation of the carboniferous formation so far; and, from what has been adduced, it is plain that the order of succession common on the eastern waters is also the consistent character of the formation on the western.
As Mr. Stutchbury's operations have commenced in the Namoi country, he will probably work out successfully the details of succession in that district, and be able to verify the proofs which I am about to bring forward as to the extension of the carboniferous formation in nearly an unbroken line, and with only such interruptions as older or younger rocks may produce, and in continuation of the same formation from the extreme south, as far as Darling Downs, from which the researches of the Surveyor General, Mr. Kennedy, and Dr. Leichhardt, have extended it to the far north. I may, hereafter, be able to shew that there is a similar continuation of the same formation on the eastern waters, that extensive coal fields occupy the basins of the Karua, Gloucester, Clarence, Richmond, and other coast rivers, as the basins of the Wollondilly and Hunter are occupied.
I have already stated, in former Reports, that there is some evidence of the existence of patches of this formation on the Highlands of Maneroo and New England, whence it has been denuded. During my late explorations I came upon a patch of sandstone in the midst of trap, which, at the junction of the two rocks, exhibited the identical character of those rocks of "doubtful age" which I saw in Maneroo amidst the trap, and which, therefore, I can now refer to the carboniferous formation, as the relics of abraded, hardened and denuded strata. I expected, therefore, in addition to the existence of fossil wood, which I have since discovered on the high ranges of the Cordillera, north of Ben Lomond, to be able to detect some of the beds associated with coal on the lines of westerly section which I adopted in the parallels of 30° and 29° from and to the Table Land and the Interior. The only instance which I found, however, eastward of the 151st meridian on that parallel, was of so singular a character, that it deserves to be distinctly recorded. I have before mentioned the singular condition of the trap over granite on the banks of the Macintyre, between Ouerra Creek and Paradise Creek. On examining the former rock on the right bank of the river I found beds of grit and sandstone of unmistakeable character entangled in the trap, and these had become exposed by the decay of the latter. The space occupied by these beds was very confined; but there was sufficient exposure to exhibit the phenomenon clearly. I afterwards became acquainted with the existence of a small tract of a coarse free-stone on the edge of a range a little below the spot in question. The occurrence of sandstone unaltered in connection with igneous rocks of this class is not the only one in New South Wales, for there is an instance of trap resting on unaltered sandstone not far from Kircobil, in the Liverpool Plains. In that case, as in this, it is probable the sandstone was protected by the interposition of some heat-resisting clay. With so many instances at hand of the great changes effected in sandstones, conglomerate, and other rocks, by the agency of heat, this example, affording almost the sole evidence of the former existence of now extensively destroyed strata, is curious and interesting.
In the Gwydir district the carboniferous formation begins to develop itself in some force about the 151st meridian. Westward of this meridian, it crests the summits of the Mywon Ranges, the Bingera, Cobbadah, and Horton River Ranges,-mantles round the flanks of Nundawar, and passing by Warialda and the Mosquito Mountains to Ottley's Creek, the Macintyre, and Dumaresq Rivers, and at the back of the slate country of Macintyre Brook stretches to the Condamine.
It was the presence of the crumbling sandstones of this formation, and the arid scrubs of brigalo and myall about the Blue Nobby Range that induced me to dissent from the SOUTH WALES. opinion that gold will be found there in any abundance. In all the line of country just indicated the formation is interrupted by outbursts of basalt, amygdaloid, or other trap, the detritus of which forming black plains of mud is in striking contrast with the sandy wastes arising from the disintegration of sandstone, and which alternate with the former. These are on the same level with the Liverpool Plains from 800 to 1,100 feet above the sea. The vegetation partakes of the character of the soil, bare surfaces of muddy soil being in alternation with ridges clad with pine, myall, brigalo, dogwood, grasstrees, white gum, spotted gum, and ironbark.
The neighbourhood of Warialda furnishes the best position for examining the geological phenomenon connected with the succession of the carboniferous and the underlying formations.
From the head of Reedy Creek which rises near Corajin to its junction with the Gwydir, there are many instructive superpositions of strata.
At that place the porphyry already described is covered by beds of conglomerate and sandstone, which contain seams of cannel coal, that have occasionally been used in the furnace. The conglomerates are coarse, and pass into sandstone, as on the Hunter. These are surmounted by beds of grit and sandstone, and ferruginous conglomerate, which alternate together, the whole presenting a series of beds, which in color, consistency, and all physical conditions of structure, are in no degree different from beds of the same formation which I have explored in various parts of the sea-board. It would be easy to imagine that we had not left the coast in some of the broken ranges in this tract of country. To detail the succession of constantly varying beds is unnecessary on this occasion. But there are two sections which are deserving of especial notice. The first occurs on Kelly's Gully, a branch of Reedy Creek.
In the bed and on the banks of the creek serpentine, extremely distorted, containing veins of picrolite and nodular masses of diallage rock, and having the appearance of schistose structure, the laminæ being much distorted around the diallage rock, abuts upon and surrounds a dome-like mass of grey marble, of which the fossils are nearly obliterated. Next to the marble is a bed of thin green jaspery substance, which, in broken fragments, also studs the surface of the limestone adhering to it. The strike of the limestone is apparently from south to north. Resting upon this conjunction are beds of that peculiar conglomerate which occurs on Mount Murulla, and in other parts of the Hunter River coal-field, and which have sometimes occasioned to observers doubts as to the supposed origin of some of the green and red pebbles contained in them. The conglomerates at Kelly's Gully settle the question, for, in addition to hard and quartzbearing pebbles of flinty slate, quartz, and other siliceous pebbles, there is a considerable proportion of pebbles of the very green rock which is now found in contact with the underlying marble, and of those jasperoid masses which occur in the Gold Field.
I have before proved that porphyry has assisted largely in the composition of the conglomerate of the Hunter, and other parts of the eastern coal fields.
We see here that the metamorphic rocks of the Gold Field have also assisted, and therefore, though the rocks may, in part, have been impregnated since the coal-bearing strata were formed, the rocks which contain gold must have been partially destroyed before the coal-bearing strata were deposited: and therefore, there may be, in the case of the older gold, if there were different periods of production, drift gold below the carboniferous deposits in some very ancient conglomerates. The question respecting those conglomerates which are known to retain gold becomes, therefore, interesting; and the suggestion that some of the carboniferous beds, derived from gold-bearing rocks, might hold traces of gold equally so, though, in a commercial point of view, a search for gold in such strata would be likely to disappoint.
Over the conglomerates of Reedy Creek, sandstones quite undistinguishable from those of the great sandstone territory of New South Wales, rise in succession, till the formation attains a height of from 1,300 to 1,800 feet above the sea, except where it caps the range, opposite Bingera, that point being about 400 feet higher.
I do not doubt, that coal in some abundance will be found in the range of these beds, the strike of which seems to be north-east, as on the coast.
The occurrence of these crumbling rocks of sandstone on the edge of the western interior, is of more importance to the superficial character of the country, than nearer the sea.
We know from the explorations of Sir T. L. Mitchell, that the furthest rocks he met in his journeys along the Darling, were of this very formation, the insulated masses forming the separate ranges in that direction being merely preserved by the transmuting action which they had undergone, and their summits exhibiting rock-basins and hollows excavated by water, when they were portions of a tract of country along whose surface torrents and water-falls might have existed. These now stand as solitary monuments on the wilderness to mark the fact, that there has been a past as affects Australia, but without an indication to mark its epoch. Various patches of these rocks occur between the Gwydir and Karaula; and near Yagobie there is a slab, called "the polishing stone," marked by the mogos of the aborigines of long past times.
From the statements made by explorers, it is clear that the alluvia of the desert owe much of their origin to the decay and destruction of the formation of which these solitary
NEW SOUTH WALES.
masses are the relies. And so long as sandstones and shales and conglomerates like those on the western border of the Cordillera remain, so long will the softer portions continue to waste away and be borne downwards by rains and floods, obscuring the water-courses in which they travel, and filling up the hollows which were once natural reservoirs. This is not conjecture; for the summits of the sandstone ranges in the Gwydir district are traversed by joints, and are crumbling away year by year, the phenomena exhibited by the nodular blocks of a granite region being imitated by the rude and picturesque columns and tottering masses of rock, with their fillets of harder material between the fluted bands of the softer, which at a distance represent the outlines of old castles and towers, wherever the looser strata are exposed to the elements. The harder beds of conglomerate and grit have suffered only a rounding and smoothing process.
In Reedy Creek near Warialda, and in many others further north, where in the memory of man (and that country has been inhabited by white men not twenty years) there were abundant waterholes, there are now vast heaps of white or yellow sand, and, in the former, Mr. Bligh pointed out to me a great accumulation of dry sand which was brought down in the flood of 1848, and which nearly blocks the creek.
But whilst this decay goes on in some parts, it is prevented in others by the presence of a preserving covering of pyrogenous rock. Thus, at Colagool (Lagoon) below Tulumbah, there is the following section in ascending order :
1. Grey grit
2. Soft sandstone
3. Hard sandstone
5. Soft ferruginous sandstone
This trap forms an extensive series of arms on what is called the Highland Plain Range above the Gwydir, and at one point is called Koungundarrah or the Springs, because at the junction water wells out, offering a contrast to the ordinary geological fact of water generally breaking out when the harder material is below; in this case, however, the trap is broken by semi-crystalline arrangement, and the rain filters down to the sandstones below that have been slightly hardened by the overflow of the trap.
This brings me to the last point I have to touch on, after noticing the proof that the foregoing section affords of the truth of the inference I made above, respecting the age of the trappean rocks. In this case, and in hundreds of others, they are younger than the youngest sedimentary deposits not alluvial, for they pass through granite, porphyry, slate, coal measures alike (the summits of the Gold Field exhibiting points of trap in abundance), and overflow them, and amidst the conglomerates I could not detect a single fragment derived from any of them.
The question of water supply in a dry country is a matter of geological as well as social importance. In the district of the Gwydir, and other similar countries, where the rains are not periodical, but paroxysmal, drought often succeeds to a time of plenty. The interior country is made up of alluvia surrounding, as it appears, low, flat, and limited tracts of rock (at least it is so to the Karaula and Barwin, whence I have received fragments of sandstone from low bars of that rock across the stream), the disintegration of which, where the masses are larger, yet swells the alluvia, and through the looser portions of these alluvial deposits, the water which falls, even in scanty seasons, filters downwards to great depths, for wells have been sunk without attaining it, and the rivers alone contain a supply. But, in the progress of advancement, the herds and flocks trample down the surface and lay it bare from those retentive plants, the roots of which once collected and held the moisture. The rains, therefore, run off more readily where they are not absorbed, and thus, gradually, though the elements be equally abundant in rain, the surface of the earth must become drier, from the two causes assigned. If, then, the interior is to be tenanted, or traversed by rail-roads, something must be done to obtain a permanent water supply. On the other hand, having seen drift high up in the branches of trees, as it is plain, great floods occasionally visit the western waters, it becomes a painful thing to contemplate the condition of the flocks and herds, and those who have charge of them, in the far west, should one of these paroxysmal phenomena, which in the historic period of this Colony covered a wide tract with what was taken for an inland sea, again take place; for, if the subterranean channels should become charged, a few wet seasons would re-convert the wilderness and the now fertile borders of it into a lake, and the inhabitants would perish.
At a time when the population of the country is rapidly increasing, it cannot be beyond a thoughtful man's duty to weigh such contingencies as Nature presents to his reflections.
In conclusion, I have to state that, before I left the Gwydir, I was anxious to find a locality whence I could review the extensive field in which I have been occupied, in order to satisfy myself as to some of the conclusions at which I had arrived respecting the order of the formations described in this Report. Such a point of view offered itself from the summit of Koungundarra, and I regret that I am unable to convey with sufficient clearness, by a panoramic sketch, the scene which presented itself.
To the eastward were in the furthest distance the peaks and ranges stretching higher and higher towards the head of the Macintyre and the mountain bordering the table land,
the country receding on the one hand into the more level region of the Dumaresq River, and on the other merging into the ranges bordering on the Granite Gold Field, the dim SOUTH WALES. summits of the rolling country about the Rocky River closing in the view. Below this towards the south, the Bingera Gold Field,, with its broken lumps of ranges along Boro Creek, and the ranges opposite, with the courses of the Gwydir and Horton well defined by the depression of their valleys, carried the eye to the south-west, where the summits of Nundawar and the other volcanic ranges rose superior to all others. And between these and the eastern horizon, the ranges of Myall Creek, and below them the broken low cliffs of the carboniferous formation, filled in the middle ground; whilst to the westward, were the peaks and headlands of the Gwydir or Drummond's Range, with the river below flowing through an extensive well-wooded valley, the summits of the trap hills of Tulunbah and Bareena forming the opposite projections, and beyond these was a clear level horizon stretching for 85° of the arc; the northern landscape consisting of the peaks of Corajin and Balfour, below the massy forms of the Mosquito Ranges.
I thus saw the whole of the geological features at a glance, and was enabled also to see that my conclusions were correct; and these I now have the honour of submitting to his Excellency in an extended Report, which contains sufficient details to connect this Survey with those that have been carried on to the southward, and to form a connection with the geological notices contained in the works of Dr. Leichhardt and the Surveyor General.
I am far from presuming to think that this Report embodies everything which might be expected, or which I have observed; but it is difficult to introduce all the details of such an extensive region in a brief abstract prepared in the field. I hope, however, the above statements will be sufficient to convey a general idea of the structure of the country, and I am confident, that, however the outlines I have drawn may be filled in hereafter by those whose leisure will be less limited than mine, they will not, in any material point, be overruled. It now remains for me to append the result of my observations on the elevation of the Ben Lomond Range.
The basis I took for the observations were at Moredun, Lalambula, Stonehenge, and Beardy Plains.
The former place, by comparison with twenty-two sets of contemporaneous observations of the Legislative Council Barometer, Sydney, is 3,631 feet above the sea.
Lalambula, by forty-eight sets of like observations, is 3,550 feet above the sea. By barometric observations between Moredun and Ben Lomond, and by angles taken from a hill two hundred and twenty-feet above Lalambula, the mean, which differs but little from either extreme, gives 5,000 feet as the height of Rowendahl, the true Ben Lomond. The heights above the sea of the other points on that range are as follow:
1. West end of Rumbec, on the westerly spur above Graham's Valley 4947 feet.
These were obtained by carrying the barometer up and down from peak to peak, and
3. Aro-indal (North Brother)
4. Boulgering Peak
5. Flat under Rowendahl
I have, &c.,
Dr. Leichhardt makes Ben Lomond* 5,063 feet by the boiling water apparatus which I lent him; that apparatus required distilled water, which he could not obtain, and a contrivance, which the vessel he employed did not supply, to prevent the effect of steam upon the thermometer. These two difficulties caused him, I think, to place many of his points too high, the very opposite case with observations by the Aneroid, which, on former occasions, caused me to place some of my southern elevations too low. The difference between Dr. Leichhardt's calculation and mine for Ben Lomond is far less than those which he has recorded in other localities in New England and my results for the same.
When my leisure allows, I will calculate the height of many other localities in New England and on the lines of section across the "Cordillera ;" but, at present, I am unable to add more to the list which I have already furnished.
The Hon. the Colonial Secretary.
W. B. CLARKE.
The spot I selected as the highest was marked by a small heap of stones, which I thought had been collected by my long absent friend; but I am told, the point he selected was on the road at least 100 feet below. This makes the difference more proportionate to those I find between his and my own results for Dundee and Stonehenge.
NEW SOUTH WALES.
COPY of a DESPATCH from Governor-General Sir C. A. FITZROY to the Duke of NEWCASTLE.
Government House, Sydney,
MY LORD Duke,
In referring to your predecessor's despatch of the *24th December last, on the subject of a contemplated arrangement for engaging Lascar seamen in India to proceed to Australia and navigate to the United Kingdom such ships as have been deserted by their crews, subject to the condition that such Lascars shall be maintained and sent back to India at the expense of the respective shipowners; it is only necessary for me to say, that it will be my duty to comply strictly with the instructions conveyed to me in that despatch.
2. I beg, however, to mention that, from a report made to me by the Portmaster, there are not any vessels detained at present in Port Jackson on account of the desertion of their crews.
I have, &c. (Signed)
His Grace the Duke of Newcastle,
Copy of a DESPATCH from Governor-General Sir C. A. FITZROY to the Duke of NEWCASTLE.
MY LORD DUKE,
Government House, Sydney,
I HAVE the honour to enclose the following Returns for the Quarter ended on 30th ultimo :--
CHARLES A. FITZROY.
1st. Return showing the quantity and value of gold exported, gold brought to Sydney, and the number of licenses granted to dig, search for, and remove gold, to erect temporary buildings, tents, &c., and to carry on business in any way at the Gold Fields, and the amount received for the same.
2nd. Return of the quantity and value of gold exported from the colony of New South Wales during the Quarter.
2. The total amount brought to Sydney by the Government Escort and by the Post-office Mails during the Quarter was 33,352 oz. 17 dwts. 2 grains.
The licenses to dig, &c. amounted to No. 11,088; amount, 15,064l. 2s. 6d., not including the leases to work auriferous quartz veins, the royalty or matrix gold, and the conveyance of gold per escort.
3. The gold exported from Sydney in the last Quarter was 79,946 ounces 4 dwts. 15 grains, but this includes a large amount brought by sea from Victoria.
His Grace the Duke of Newcastle,
I have, &c.
CHARLES A. FITZROY.
*Page 150 of Papers on "Recent Gold Discoveries in Australia," presented by Her Majesty's Command, 28th February 1853.