NEW SOUTH WALES. Benlomond, are all composed of basalt much charged with olivine; but the basalt sometimes assumes a very compact texture, and occasionally a prismatic structure, and also passes into a greenstone and amygadaloid. Although the distinction between granite and greenstone is generally well defined, yet it is not surprising that the passage of the different species or varieties from one to another should be well marked in the course of a line of 40 or 50 miles, along which they occur in connection with granite. In many instances, there is the clearest possible proof, that these basalts as well as the greenstones have risen through the granite, which they overflow, producing in their disintegration by water the black soil of the plains, which covers up very frequently the basset edges of schistose and quartzose rocks. That these basaltic and other trappean rocks have also overflowed in wide spread masses is shewn by the hills along the Uralla (Rocky River), as near McCrossens, and along the right bank below that locality; and between Boorolong and Ollera, where the basalt breaks out amidst the granite and occupies the hollows and valleys which preexisted along the fissured portions of that formation. In some of these instances, the structure is tabular, putting on the form of horizontal or nearly horizontal beds from the parallelism and direction of the joint planes. The forms of the trappean hills vary with the composition of the material. Flat summits with gable ends, or high narrow ridges with much inclined slopes and sudden peak at the termination, characterize the basalt. The trap of the Dividing Range, at Williwa, which is in such intimate association with granite, assumes the granitic form, presenting a series of bosses which slope away in less and less prominent forms, and leave upon the horizon the outline of those similarly undulating ranges which characterize the existence of auriferous granite tracts. Such is the case with the Araluen Range, and with the auriferous granite hills between Omeo and Mount Buffalo, and indeed everywhere in which I found to the southward Gold in the neighbourhood of granite, It is the nodular structure which produces these rolling outlines, as it is the prismatic which forms the peaks of porphyritic granite and basaltic rocks. None of these must be neglected, in forming an opinion as to the probable auriferous character of a distant range from its superficial appearance. 4. So far as I have been able to come to a conclusion in this respect, the prismatic outlines belong to the more recent portions of an igneous overflow, and the nodular form is most frequently associated with such granitic tracts as are found to be auriferous. The experience I obtained in this respect in the southern counties has been confirmed by my observations in the counties of Inglis, Hardinge, and Sandon; and as in the former, so in the latter, hornblendic and quartzose granites which are porphyritic appear to be more associated with Gold than the other varieties of that rock. There can be no doubt, at least, that Gold in this part of New England is most abundantly found where granite has been disturbed and overflowed by hornblendic trap. This deduction has been confirmed by the testimony of the most intelligent of the observers amongst the Gold washers along the Uralla, with whom I have conversed. The hills Yattamburrambee (Great Duval), and Toombunyee (Little Duval), exhibit the intimate association of the granitic and trappean rocks, the peculiar outline above alluded to, and a position at the head of drainages (running into the M'Leay and forming that river) which I have found to be auriferous. A similar association of granite and trap is also the distinguishing character of the country between the Bundara River and the line joining Boorolong and Ollera, for some distance west of the Dividing Range; and there again we find Gold. In these and many other cases to the northward of the present area, as well as to the westward, there is the same relationship with trap and granite in association with Gold, to the general exclusion of auriferous quartz in association with schists, although it is certain from an infinity of circumstances, that the trap is younger than the schistose rocks, for they are transmuted by it. 5. That quartz veins bearing gold do exist, there is, nevertheless, reason to believe, even as respects the granite itself; but, as about Major's Creek in the Araluen Field, so along the Rocky River (Uralla) field, these veins are generally small and are connected with porphyritic patches, in which there is ferruginous matter, and the quartz appears to have been segregated. More to the westward there are auriferous quartz veins in schistose beds, in the neighbourhood of the present Bingera Gold Field, as well as in the Macquarie basin; but the quartz beds which are so common in the schistose regions are scarcely ever auriferous; and I am led, by a multiplicity of facts all bearing one way, to conclude, that in New South Wales, if any of the auriferous rocks can be considered anomalous, the anomaly is not in the association of Gold and Granite, which, under certain conditions, is always found to be somewhat auriferous and generally more so than the schists. I need do little more to illustrate this fact, than mention the Araluen country; that along the Mitta Mitta, and between it and Mount Alexander, including the Ovens Gold Field, Moamba, and other tracts in the Maneero district, and along the Alps; all of which exhibit the same superficial features and similar relations between granite and gold, whilst wide and lengthened tracts where quartz beds interpolate schists, and even quartz ve ins (of eertain normal directions) reticulating these, are barren. Should it be argued that the gold which is so universally distributed over tracts of granite, circumstanced as I have described, was originally derived from quartz-bearing schists, which have been denuded altogether, with the exception of the fragments yet remaining, in which case the higher tracts of these fragmentary schists ought to be auriferous, if any are so, it must be left to the asserters of that doctrine to show by indubitable proof that such must have been the case. For myself I can only say, that, having sought for such instances of auriferous schists I have never found any immediately over auriferous granite, at high elevations; and I have, over and over again, found granite at nearly all elevations parallel with those of existing unauriferous schists, to be auriferous. In the character of the gold itself, there is also a clear proof, that it has not always had the same origin in time or the same matrix. Whilst gold derived from veins of quartz in schist puts on divers distinct and remarkable forms, gold found over granite bears a kind of universal character; being granular, fine, and of similar purity, such as well could be supposed to have been once entangled amidst the granular elements of granitic rock. There is little difference in these respects between the Gold of the Uralla, of the Araluen, or of the Ovens Gold Field. It is immediately recognized by its features. 6. Before I proceed further in this part of my subject, it will be necessary to mention, that the quartziferous schists are not the highest formations (geologically) in this district. As in Maneero, not only over granite but over schists, and, as there, always in association with trap, and occasionally with some form of argillaceous or bog iron (called by some "ironstone") there occur very hardened beds of sandstone and conglomerate and breccia of quartz, which can only be referred to the upper part of the formation (in which some geologists may include the schists), or to a more recent formation characterised by me as of doubtful age." Associated with these beds are others composed of granular crystals of quartz minutely and closely aggregated, and striped, in the mass, by ferruginous lines, which have resulted, as well as the red soil in which they are found, from the iron set free in the decomposition of basalt. I believe that no geologist would expect gold to have been derived from such a rock as this, though it may be occasionally entangled in it. The origin of the gold, therefore, if derived from the same formations as those of which portions are still in existence, must be sought not in the compact baked siliceous grits and conglomerates, but in the granite itself; and I will now advance a reason, why I think in that portion of the granite which was once, or is now, in contact with trap of some kind, that is to say, on the surfaces of the granite or at the outer portions of the formation, in contact with some other formation. 7. It has been shewn already, that gold occurs at the Hanging Rock, and on the Peel (Report No. 1. p. 59), in quartz veins, in association with trap, passing through altered rocks, and the source of the gold is in such a case (whether the veins traverse schists or shales, or sandstones, or any other rock), not in the rock bearing the veins, but far below; in the neighbourhood of the granite, the existence of which was demonstrated at a lower level in the bottom and ranges of Duncan's Creek. But in the case of the granite itself, the conditions may be widely different. It is a well-known fact, that metals frequently occur at the junction of granite with other formations, and that in some countries (Brazil and Russia), even stratified rocks become completely charged by gold, under the influence of the igneous agents that have transmuted them. What reason can there be to doubt, that certain granites which are intimately allied to such ordinary igneous agents may not originally have been charged with gold whilst soft, under the ocean, by intrusive agents which may have also produced, by the assistance of steam, veins of auriferous quartz of various inclinations to the horizon passing through schists not visibly overlying granite, or themselves have elaborated the gold by agency of forces yet imperfectly known, at the upper surfaces of their masses, where they were in contact with overlying masses. In Kentucky Creek there are various instances of tables of leptynite and other binary forms of granite (as before mentioned), passing through the granite, where it has undergone some radical change; and similar examples may be found in the Rocky River. A metamorphic action in all probability would be traced, (perhaps an interchange and commingling of elements or of the dispositions of these,) could we strip the granite of its thick covering of basalt or greenstone or other igneous matter, and it is not improbable, that such action would be found to have extended in such a manner into the surface of the granite, as to allow for a certain thickness of auriferous deposit. I conceive this to have been the case. His Excellency the Governor-General, as well as the Honourable the Colonial Secretary, will remember the example of granite covered by gold, which I had the pleasure of exhibiting to them in August, 1852, from Major's Creek, in which the gold was in union with segregated quartz and iron; and this specimen was in conjunction with a porphyritic vein. Now, what has occurred in the Araluen Gold Field and on the Mitta Mitta (in both of which localities I separated gold from granite by the blow of a hammer) has occurred on the Rocky River. In one of the workings, I pointed out to the gold-washers a decomposing flaky covering from a large drifted mass of granite with particles of gold visibly apparent to the naked NEW SOUTH WALES. NEW SOUTH WALES. eye; and this could not have been washed into it. It was there, because the granite in which it was found contained it before the boulder had been rolled down from above. It belonged to a mass which in all probability had been at the outside of the granite formation. 8. What is there strange in the belief, that on the outside of masses, that is, at the planes of junction of overlying and underlying masses, thermo-electricity and other allied agents may have elaborated the work of metallic production, as it has done in the case of the quartz veins of the Peel River? (Report, No. 2. p. 4.) That the granite and the overlying trap were, one or both, formed under the ocean, or that the granite descended below the ocean level, and so became heated, since its original formation, and thus assisted in the changes of structure which have been mentioned, is not very improbable; nor is it improbable, that the basaltic and other trappean rocks which now pierce and overflow the granite, were (by the descent to the heated regions) then produced from the lower portions of the granitic nucleus. It may be conceived how, under such a condition, the gold may have been produced under the ocean level, just as when the auriferous mass in reascending became exposed to the denuding power of the waves, and to the effect of pressure, its surface and slopes would be rent and fissured, and the softer parts being removed, the heavier gold would be left, as it is now found, scattered over the surface or collected in hollows then first formed, afterwards to be attacked by elemental forces of the upper air, the floods and streams of the modern epoch. 9. If such an origin for the gold over granite be admitted, we ought to find some corroborating circumstance to correspond. It is determined that boracic acid rises with steam in the "lagunes" of Tuscany in connection with igneous agency.* It is also found in association with deposits of rock salt, and may be therefore, in some way present in sea-water or others during a plutonic eruption. "The transmission of mineral matter from the igneous and heating body into "the prior-formed rocks, whether these were or were not consolidated, seems well shewn "when boracic acid is present among the former." If thus, the celebrated geologist † from whom these words are quoted explains the wellknown fact, that tourmaline occurs on the outer portion of granite. He adds further: "The boracic acid might, indeed, have solely escaped out of the granitic mass, and meeting "with the other essential parts of schorl have produced the latter mineral amid the grains "of mechanically formed rocks thus acted upon. وو Again he says, "The presence of a mineral in any abundance which contains boracic "acid as an essential ingredient is one of importance, more particularly when we refer to "the researches of M. Ebelmen, he having shown that by employing that acid as a solvent "at an elevated temperature, minerals may be produced by the evaporation of this sol"vent, some of them gems, such as rubies." And in a note § he quotes the result of M. Ebelmen's experiments to have been the "production of rubies, sapphires, chrysoberyl, "chrysolite, chromate of iron, and others." 10. Now, it is most remarkable, that all over the tracts in which gold occurs amongst granite, such as the Ovens, the Alps, and New England, the gold is accompanied by a marvellous abundance of rubies, sapphires, and other gems, to the almost total exclusion of magnetic iron, (vulgarly called emery), though true emery does occur, whilst in other localities of gold, magnetic iron is a principal indication of the metal. In the New England Gold districts, as in the southern districts of granite, the indications are rubies and sapphires. 11. To show the proportion in which they exist, I mention here the chief produce which I obtained from two pans of earth collected from amidst the granite boulders in Tilbuster Creek, at a depth of about 2 feet below the surface. Gold Rubies 1 grain. 315 grains. 49 grains. There was also much emery, which is a black sapphire, and three or four particles of the peculiar iron known to all gold diggers. Another sample, consisting of four pans of earth from the Rocky River, produced, at two feet helow the surface, Gold with other matters. 15 grains. 118 grains. In the Tilbuster Creek detritus occurred one oriental emerald and one asteriated sapphire. The rocky River is a western water; Tilbuster Creek an eastern vater. So abandant are these gems, that they may be procured any where in the surface drift of New England, and in the granitic tracts, in any quantity, and of all sizes. Most of them are water-worn, in about the same degree as the gold, but I have found some perfect unabraded crystals of the usual octachedron form, which leave no doubt as to their identity. My opinion is, for reasons stated above, that these gems have been elaborated in the way mentioned, at the outside of the granite, or at its junction with overlying rocks; and, as constant concomitants of gold in the granitic region, and regarded by the gold washers as the truest indication of that metal, they must be considered as having a derivation from the same geological surfaces. I know but of one instance in all Australia of the occurrence of these rubies in any sedimentary rock; that is at Kayon, on the Richmond River, where spinel rubies of minute proportions occur abundantly in a fine sandstone of that carboniferous tract; these were, perhaps, derived from the igneous rocks, of which most of the beds in the Richmond district are the re-composed materials. 12. Probably, the point may be conceded, that the gold, as well as the gems in the granite country had its matrix on the outer portions of the granite, and the granite at the junction of other rocks. Some of these having been denuded, as we have seen already, much disintegrated and decayed, the heavy gems and the heavier gold have been left in the granitic sand, and in the scaly soft surfaces of still decomposing drifted blocks of granite, now filling the creeks and river beds, and which once belonged to the upper and outer portion of the granite masses. 13. Being under this impression, and seeing how completely a wide region in New England, both on the Western and Eastern Falls, is occupied by granite either partly destroyed, or still attaining a considerable elevation, and knowing that much of this granite is still covered up by partial relics of younger formations, or by universal gem-and-goldbearing local drift; seeing also how thoroughly this region has been pierced and overflowed by igneous rocks of various kinds, I cannot but conclude, that there is a vast amount of gold scattered over this portion of New South Wales, and along both falls from the table land; and so far as experience goes, this geological inference is borne out by facts. For, whether in small quantity or in abundance, every creek and river, and the deposits of drifts upon the surface of the country are found to contain gold and gems. And yet, in consequence of its depth, and from want of water, much of this gold can never be obtained. 14. The difference between an auriferous country of granite and one in which the gold is found in veins, is as much marked by this universal distribution of gold as by its occurrence in nearly equal sized particles; and a little reflection will show, why this equality in size and distribution is to be anticipated. Igneous rocks of intrusion rise either in a series of separate local foci of eruption or along lines of fissure. It is probable, that in neither case is the orifice large; but as all such eruptions must be preceded or attended by numerous fissures, either parallel to the axes of the disturbed and dislocated masses, or radiating through them from the centre of eruption, the formation of veins accompanied and followed by all the phenomena witnessed in the production of metallic ores or native metal, is the result. Such veins passing through overlying deposits are locally richer than any occurrence of metal produced, as supposed in the case of granite gold. Inasmuch, too, as the metal so produced is in massive lumps or bands, or crystallized on the large scale, and the veins are continuous through the whole mass of overlying rock, when such a rock and its veins are broken up, the auriferous detritus is proportionably on a scale of magnificence. Hence, gold derived from considerable quartz veins will be in general, locally, far more abundant than the gold derived from an equal space, where it is diffused in the surface of a mass of granite. The circumstances, too, of the case, agree with the expectation that such sources will be permanent. But, in the case supposed for gold derived from granite, inasmuch as the auriferous portion of the rock is, at the best, but thin; in order for a locality of auriferous granite to rival and excel in the richness of its produce that of a locality of vein gold, there must be a wider surface at the contact of the adjoining rocks; and if this be denuded, of course, that surface may supply as much as, or more than, the very richest Gold vein in schist or in any other rock. Still in time it will be found, that a supply from good veins is likely to last longer, because the veins are probably for, at least, some distance downwards, as rich as they are near the surface where they are exposed, whilst the auriferous granite, furnishing only a supply which is commensurate with an inferior depth, must much more easily be cleared of its contents. 15. It will be seen also, that such veins in their destruction supply to the local reservoirs much massive gold, and that these veins become triturated, and afterwards dispersed nearly only along channels in which continuous streams can carry on the process. But when granite, which is auriferous, has been stripped of its covering, and has begun over wide areas to decay, or when the violent debacles which have anciently laid waste It is held that gold veins are not so rich below a certain level as above. The phenomenon has not been accounted for. But on the hypothesis of the produetion of quartz veins by steam, this is explicable. As the steam would naturally condense at the upper portions of the fissures it is there, more likely than below, that one would expect to find crystalline products, such as gold and other minerals, so produced. NEW SOUTH WALES.. NEW not only the schists and their veins of gold, but have swept away the covering of the SOUTH WALES. granite, began to disperse the detritus of the respective regions, the fine granite gold was more evenly and generally distributed than the heavier masses from the schists, or capriciously collected in the hollows of the surface soil, or washed further away from its source by running streams*. The actual history of the Gold Fields of the Macquarie basin and that of such fields as those in the granite regions of Victoria and of New South Wales, testify to the soundness of the view here taken. A priori, therefore, it might have been anticipated, that a Gold Field in a region of quartz-bearing schists will last longer than one in a granite region; but that in the former a smaller number of workers will only find permanent employ or be able to find room; whilst a large number of adventurers in the granite field may for a time accumulate enormous profits, and yet, at length, discover that the supply is not permanent, or capable of maintaining to advantage a covetous multitude. 16. Such is the fate, it is to be supposed, of many of those tracts of country, the richness of which has, perhaps, appeared inexhaustible to some; and the comparative facility with which gold is procured from detritus of granite, without the labour attendant on gold digging, amidst boulders and heavy gravel, will, of course, precipitate the consummation. Yet it must not be forgotten, that a far wider space may be expected to be auriferous in a granite region, than in one of schist; though in the former there may not always be so many prizes as in the latter. When, however, as in the case of the New England districts, there are both vein gold and granite gold, and all the rocks over a vast area to the westward appear to have been more or less affected by gold-producing phenomena, we may safely anticipate that there is much gold yet to be discovered in the alluvia around the detached ranges between the table land and the flat interior, and that, hereafter, as the seasons may suit and diligence be called into requisition, not only the Hanging Rock and the Peel, and Bingera, and the Uralla, but divers other localities, will supply if not to a multitude greedy of great gain, but to men contented with moderate gains, gold through many years to come.† 17. In order to see what grounds there may be for anticipating this, it will be first of all advisable to consider the superficial phenomena of the table land, in the area now under discussion. The table of elevations which I have purposely calculated to assist this inquiry, will show, with sufficient exactness (though only approximations), what are now the culminating points, and what, without admitting further denudation than that limited by those heights, was probably, at the time when the country began to be denuded from that limit of elevation, the general horizon of the table land. On the eastern side of it, a series of convulsions and a long process of drainage have sufficed to break down any large accumulation of water in the hollows of the present surface, so that all the waters rising between the culminating point of the dividing range and a distance of 90 miles to the southward, and between that range and the 152d meredian (an area of probably 1750 square miles), after wandering through the plains, and among the ridges that diversify them, are suddenly precipitated into the lower country over successions of falls. The highest points of this broken down basin, for such it is, are about Ben Lomond to the north, and at a point about 30 miles eastward of the hanging rock, to the south; whilst the boundaries are the dividing range, and those separating the waters of the Clarence River from those of the Macleay on the one hand, and those of the latter from the falls to the Hastings on the other. This basin is broken down to the eastward, and to the westward the dividing range is in places very low, so that with the present disposition of the features there never could be any great depth of water permanently accumulated on the table land. Yet, there is undoubted proof that water of some depth spread out the detritus and has sojourned in limited spots, now called plains, such as those at Walcha, at Salisbury, at Armidale, and Falconer, and in their vicinities. On the dividing range itself, at a spot called "Dangar's Lagoon," about 160 feet above the Rocky River at the crossing, and in other localities, wherever the ground is similarly disposed in a crateriform hollow, rain water has accumulated; and at the former place, the water is studded by isolated blocks of granite, perfectly rounded, which rise as so many islands, and on the shores, the granite exhibits marks of erosion as if beaten by waves. A similar condition can be witnessed in the granite blocks which occur on the side of the creek near Gostwyk; and again on the granite near Gara, and in the Salisbury Plain. 19. The plains are also strewn with the detritus of the schistose and quartzose beds which are yet traceable in places; and on some of these ridges, where the harder rock has been a kind of reef, (as in Salisbury Plains, at and near Windmill Hill,) which are not 100 *Much of the gold so distributed is so thin and light, in cousequence of its originally minute bulk, that it easily floats or may be blown away by the breath. Hence, as much is washed out from the pan or cradle, as is retained; and this I found to be the actual case, on the Rocky River, on re-washing the rubbish or tailings" of various "claims." 66 + Experience proves that gold-diggers, who are familiar only with such locality as Ballarat and rich places in California, will not condescend to work gold fields of less importance. But the time s coming when the minor fields will obtain attention. |