GEOLOGY OF AUSTRALASIA.
While the science of geology has been making rapid progress towards maturity in determining the laws which affect the general structure of the earth's crust, in its local appli-
cation to three out of the five great divisions of the world, but little has yet been accom- plished. Of these divisions Australasia (including Tasmania, New Zealand, New Caledonia, and New Guinea) is the worst represented. We might well expect this from its recent discovery, the vast extent of its surface, and the comparatively few spots where European colonisation has com- menced, Thanks, however, to the infa-
fatigable zeal of some half-dozen talented geologists who dwell at different points in our Australian Colonies, the darkness which has hitberto attended the application of the science is being rapidly dispelled. The conclusions of Sir Roderick Murchison and Sir Charles Lyell, founded upon the information and specimens communicated by those gentlemen, have largely aided in clearing away misconceptions. We are indebted to the Rev. W. B. Clarke, the eminent geologist of Sydney, for a compendium of the results hitherto obtained in the investi- gation of this subject. It is contained in a paper read on the 20th of November before the Philosophical Society of New South Wales, "On some recent geological discoveries in Australasia, and in the correlation of Australian formations with those of Europe." The paper itself, though written with clearness and sim- plicity, was not intended for a popular audience. In setting forth the conclusions reached by the author we shall, as far as possible, avoid the technical language indispensable to strictly scientific reasoning. Those who have inspected the admirable geological charts in the Public Library of Melbourne must have been pain- fully struck with the absence of the chief mineral formations by means of which England has become so great. There is, or there was until lately, a blank, with one or two doubtful exceptions, extending from the upper silurian ro the lower tertiary. Consequently, the carboni- ferous group, from which nearly all the coal of England comes, and other formations rich in mineral deposits, are represented as entirely wanting. The peculiar fauna and flora of Australia had already prepared our philo- sophers to endorse views which made this part of the world as singular in its geology as its natural history. Blumenbach, an authority of no small eminence, propounded the alarming view that New Holland must have originally been part of the sun, knocked off by the tail of a comet, and deposited in the Pacific Ocean. Darwin, the author of the "Origin of Species," who has explored a great part of the Pacific, asserts that " not one oceanic island is as yet known to afford even a remnant of any
palæozric or secondary formation." Among the oceanic islands he includes New Zealand, though there is distinct evidence of the existence of these formations there. But re- cent investigations are proving that the vege- gation of Australia is not so peculiar to it as has been supposed. European species of plants living on the summits of our Australian Alps have been detected by Dr. Mueller, and any one who has travelled in the bush must have seen flowers familiar to him in England, which could not have been introduced since the colonization of Australia. More than this, beds of tertiary age have lately been found in Europe containing fossil plants of species and genera which are now peculiar to this part of the world, but which once flourished at the antipodes. The isolation of Australasia thus destroyed respecting its flora is denied by Mr Clarke respecting its geological formations he insists that they correspond with those which are found in the other hemisphere, that similar phenomena distinguish its solid struc- ture and superficiul deposits, that the same order is observed, and that few of the chief strata are wanting. It is extremely pleasant to obtain such an assurance from a geologist of such reputation and ability. We confess to having at times entertained fears for the genus homo of the future. If nature had been in so strange a mood when our home was formed, it was natural to expect that the conditions of existence shared in the bizarre development. Among these outlandish mar- supials and eucalypti, if they were so utterly foreign to all that the earth in all time had produced, why should not our descendants pre- sent a variety of the race such as Mr. Darwin himself has never dreamed of? It is consola- tory to one's feelings to have the definite assu-
rance that Australia is not, after all, so remark- able a production as we thought. In following Mr. Clarke to the conclusions he has arrived at on this point, we can, of course, deal with the question of evidence only in a cursory and general manner. Those of our readers who would wish to prosecute the subject we must refer to the paper itself, which will, no doubt, be published either in a sepa- rate form or among the proceedings of the Philosophical Society of New South Wales. We must premise that the classification of rocks adopted by Mr. Clarke is that which was made by Sir Charles Lyell in 1855, and which, with slight modifications, is now being gene- rally adopted in England, if not throughout Europe. This classification divides the fossili- ferous rocks, with which alone Mr. Clarke deals, omitting all reference to the azoic and meta- morphic rocks, into palæozoic or primary, those containing fossiIs of ancient life ; mesozoic or secondary, those containing fossils of middle life; and neozoic or tertiary, those containing fossils of recent life— the usually accepted terms being palæozoic, secondary, tertiary. Each of these great divisions is subdivided into several groups, which are arranged naturally in a given and invariable order. The great question to be determined is, have we in Australia strata similar to those in Europe, from which we may expect eventually to obtain the various mineral productions which are found there in such abundance? Much depends on the answer. The history of the world has proved, and especially the history of our own nation, that the metals and minerals indispensable to manufactures are far more productive of wealth and general prosperity than any quantity, however great of the precious metals. To give the most common example, Victoria would be far richer in the elements which conduce to the physical prosperity of a nation if great store of iron and coal should be found in immediate proximity to each other, than she is in pos- session of the auriferous treasures which are so widely scattered over her surface. The answer given by Mr. Clarke is far more favourable than we had ever hoped, and it is substantiated by evidence that we cannot but regard as satisfactory. The uppermost stratum, occurring in the tertiary formation of Europe, and lying immediately beneath the alluvial deposits of the surface, is that of the post pliocene. In Australia it is as extensive as in Europe, its existence being proved by the shelly sands of Botany Bay and Port Phillip, bones of extinct marsupials, reptiles, and fish on the Darling Downs, and, in addition to much previous information, by a collection of rocks sent last month to the Australian Museum from a district about fifty miles from Adelaide. The remaining divisions of the tertiary — viz., the pliocene, miocene, eocene — are proved, by evidence that Mr. Clarke deems sufficient, to exist in Victoria. Mr. Selwyn
demonstrates, by characteristic fossils found in the gold drifts, and at various points around the coast, that a larger proportion of the tertiary strata is to be found here than in England. The miocene, which is wanting in England, though well developed in Germany, has been discovered at Corio Bay, Cape Otway, &c. The evidence of Mr. Selwyn, corroborated with regard to most of these formations by rocks and fossils found in New South Wales, South Australia, Western Australia, Tasmania, and New Zealand. Within the last few months wells opened on the Murray Flats in our own colony at a depth of 120 feet revealed fish teeth, which are referable to the eocene or pliocene. It would be interesting to some of our readers if we were to mention the fossils which have been regarded as indicating the existence of the various formations, but our object has been to present conclusions rather than evidence. Lists of fossils with scientific names would not be very inviting, and perhaps not very profitable to the general reader. The secondary formation is well represented in Britain and the adjoining shores of the Continent, and is familiar to many of our readers in the chalk and oolite found so widely distributed in the south and west of England. It was suspected long since that some of the strata of this formation had an existence in Australasia, but no satisfactory evidence was afforded until about ten or eleven years ago. It was then demonstrated that the upper secondary or cretaceous system obtained in more than one district. Mr. Selwyn has found indications of its existence in Victoria. From statements made respecting the cliffs of the Australian Bight, it is presumed that it is developed there. In Western Australia am- monites and other fossils supposed to be cretaceous have been found. In New Zealand
an undoubted secondary formation extends along the east coast from Morokura to Kakanui, containing fossils which are charac- teristic of the chalk beds. Within the last two years an interesting discovery was made in New Zealand of the bones of a gigantic reptile, which were forwarded to Professor Owen, and were pronounced by him to be the remains of a plesiosaurus. This furnishes approximating proof of the existence of the green sand formation which underlies the chalk, or of one of the series between the. chalk and the jurassic rocks. A recent publication by a Dutch explorer announces that in the south-west corner of New Guinea a mountain was seen, from the detritus of which he obtained fossil shells and fossil vertebra, pronounced by an eminent German authority to belong to the Jurassic pe- riod. Professor McCoy, of Victoria, has as- serted his belief that the coal-fields of Port Phillip and New South Wales belong to the oolite, but on this question he is ably opposed by Mr. Clarke, who refers them to a much
older formation. Descending still lower in the acknowledged secondary deposits, we come to the lias and the trias, and evidence is adduced that these beds are represented in Australia. A considerable collection of fossils was recently obtained from the Fitzroy Downs, in Queens- land, which were forwarded by Mr. Clarke to Professor McCoy, and pronounced by him to be " not younger than the base of the great oolite, nor older than the trias." In addition to this, Dr. Hochsteller found in the province of Nelson, in New Zealand, about two years ago, a sandstone which he refers on reasonable ground to the middle triassic rocks. It seems sufficiently clear, therefore, that instead of the secondary formation being entirely wanting, each of the leading divisions, and probably most of the subdivisions, have their representa- tives iu the rocks of Australasia. From the se- condary we descend to the primary, or palæo zoic epoch. The uppermost formation is the permian; and there are indications of its exist- ence in the neighbourhood of the Mantuan Downs, about 200 miles north of the Fitzroy Downs, and in other localities. The next is the carboniferous series, to which Mr. Clarke refers most of the coal-fields of Victoria, in opposition to Professor McCoy, and, we think, several of the Australian geologists. It is admitted by most, however, that there are carboniferous fossils, and that these are associated with the epoch of the old red sandstone lying imme- diately beneath. We have thus arrived, with- out a single gap of any magnitude in the table, as far as the upper silurian. This, and the lower siluriian, are developed to a great extent in Australia, New Caledonia, and New Zealand. In Tasmania also it is not wanting. The lower silurian is the chief source of the auriferous quartz veins in the gold regions. This exhausts our catalogue. The cambrian rocks lying at the base of the lower silurian form the most ancient fossiliferous strata yet defined. The parallelism instituted by Mr. Clarke does not extend to the metamorphic and azoic formations on which all the other
rocks are superimposed. Sufficient has been said, we think, even if the evidence be judged by the straitest calculation of probabilities, to prove that the geological structure of Aus- tralasia is not widely different from that of Europe. The future will reveal far more coincidences than have yet been discovered, and it is not presumptuous to hope that few of the mineral deposits which are turned to so good an account in the older countries will eventually be wanting to our descendants. The question of the coal formations, which enters somewhat largely into the paper of Mr. Clarko recently read before the Philosophical Society of New South Wales, must here be discussed with fewer words than are necessary to do it justice. The possibility of our obtain- ing coal does not depend upon the existence of the carboniferous formation, since it is known to have occurred in all the geological ages. It has been found in the permian, triassic, jurassic, and even in the cretaceous rocks. It is produced abundantly in the tertiary. The greater part, if not all of the New Zealand coal belongs to this formation. But if we accept Mr. Clarke's theory that the chief coal seams of New South Wales are to be referred to the carboniferous era, we shall have greater confidence in the future of Aus- tralia. The great coal-fields of England, Germany, and America, and nearly all of any large productive power now worked throughout the globe are representatives of the great carboniferous series. It is cheering to be told that the Newcastle coal of New South Wales belongs to the same epoch. This statement, however, is contradicted; and evi- dence is forthcoming to strengthen the con- tradiction. Professor McCoy considers that the coal of Newcastle is not older than the
oolite, and that it must be regarded as belong- ing to this formation. In the controversy we cannot but think that Mr. Clarke has the best of the argument. The reasoning is strictly scientific, but it will be possible to lay its general fea- tures before those who are not deeply read in the arcana of geology. The facts on which Mr. Clarke relies are these- Fossil fish, which are undoubtedly palæozoic, occur in the Newcastle coal seams. The beds on which the coal seams immediately rest are equivalent in character to the Irish lower carboniferous beds. In some places the strata containing plants which have been considered oolitic — on which plants the adverse testimony chiefly rests — are so asso- ciated with the aforesaid palæozoic beds that the inference is they interpolate each other. Professor McCoy, on the other hand, lays great stress on the presence of the glossopteris, and other plants which are found in the great oolite of Yorkshire, and alleges that there is an absence in Australia of the distinguishing and characteristic genera of the old carboniferous flora. This adverse evidence is shaken by the testimony of some eminent geologists, who con- sider it an open question whether the said plants are confined to the secondary deposits, and by the fact that at least several genera of plants of the carboniferous type have been found in widely different parts of Australasia. We are content to leave the matter in the doubtful state it is in at present, but cannot help ex- pressing our hope that Mr. Clarke's theory may prove the true one.