VI C TOR I A. GEOLOGICAL SURVEY. REPORT OF THE GEOLOGICAL SURVEYOR ON THIil GEOLOGIOAL STRUOTURE OF THE ~,or,onJ! ,of Vittoria, THE BASIN OF THE RIVER YARRA, AND PART OF THE NORTHERN, NORTH EASTERN, AND EASTERN DRAINAGE OF WESTERN PORT BAY; WITH PLANS AND SECTIONS. LA! D upon the COmWIL TABLE by THE SURVEYOR GENERAL, by command of HIS EXCELLENOY THE OFFIOER ADMINISTERING THE GOVERN~fENT, and ale REPORT ol,del'ed to be printed, and the PLANS AND SEOTIONS to be lithographed, 5th j}[al'ch, 1856. 16n ~utbOtit)1: JOHN FERRES, GOVERNMENT PRINTER, MELBOURNE. A.-No. 108.11. 1 1 1 1 1 1 1 1 1 . 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Surveyor General's Office, 20th February, 1856. SUI., I have the honor to submit to your Excellency the valuable yearly report of Mr. Selwyn, the Geological Surveyor. The withdrawal, on grounds of economy, of Mr. Selwyn's Field Party during 1855, has narrowed very considerably the field of his observations, but I hope that with the progress of the more detailed Topographical Survey, and the provision made by the Legislature for the Geological Survey for the current year, which will enable two survey parties to be engaged, a very considerable progress in our geological knowledge of the province will be effected. The advantage of a minute description of the highly interesting organic remains of the palreozoic' and o~her formations, and without which the researches of the geologist are ,incomplete, leads me to submit to your Excellency th~ importance of obtaining for this object the services of Professor McCoy, now resident here. I am aware that this eminent palreontologist is to a certain extent engaged in these observations; but I would suggest, that they should be made rather the subject of public than private investigation, and thus become national property. Professor McOoy has expressed his readiness to undertake this task. The means at the disposal of the Government, sanctioned by the Legislature, will cover the cost of this undertaking, without impeding the progress of the survey in the field. I have the honor to be, Sir, Your most obedient Servant, (Signed) AND. CLARKE. _His Excellency , Major General Macarthur, &c., &c., &c. " REPORT ON THE GEOLOGICAL STRUCTURE OF THE COLONY OF VICTORIA, THE BASIN OF THE RIVER YARRA, AND PART OF THE NOR~HERN~ NORTH­ EASTERN, AND" EASTERN DRAINAGE OF WESTERN PORT BAY. THE geological IIJap accompanying the present report embraces the whole of the area previously surveyed and reported on, as well as the districts lying south of the great east and west dividing range between the waters of the Murray and those emptying into Port Phillip and Bass's Straits, which have been examined up to the present date; the former with numerous additions, and corrections made from subsequent observations. By the' insertion of copious geological notes, with local descriptions of strata whenever the rock is exposed in situ, and the careful delineation of the boundaries of the several formations, I have end!?avored to render the map in itself, together with the illustrative horizontal section, as complete a geological report of the country surveyed as it is at present possible to make. The section has been levelled and measured ,Vith theodolite and chain the entire length, and is protracted on a true scale, horizontal and vertical, six inches to, one mile; thus the actual outline and elevation above the sea level of the country passed over is correctly represented, and the approximate thicl~ness of the exposed strata ascertained. The, comparative smallness of the area as yet surveyed, the small scale, combined with, the topographical incompleteness and errors* of even the best existing map of the Colony, and especially the want of a minute examination and Classification of the organic remains which have been collected from various localities, preclude the possibility of at present making any more minute sub "divisions of the several stratified formations than has been ad O::i::O~'~~: Te";,ry { ~plVIl~~~~:ne , elOeene Pleistocene. Mesozoic-Secondary? Carboniferous of Australia. Devonian Palreozoic--:-Primary Silurian { Cambrian. A more extended knowledge of these formations and of their organic contents will, I have no doubt, eventually shew them to be susceptible of many of the recognised sub-divisions of their equivalents in Britain and other countries. The districts now under consideration are, both in geographical position and geological features, directly connected with those described in my last report, and are, in fact, exclusiv~ly occupi<;cl by the extension north and east of several formations .there noticed. ' Such being the case, only a brief recapitulation of their general. .. This obstacle is however now being rapidly diminished by the very beautiful topographical maps of' various districts of the Oolony in course of construction by the officers. of the SurveY9T General's Dep!lrtment. GEOLOGICAL REFORT-b. 6 geological eharacter, as there given, will be necessary, at the same time noticing such changes or new features as have been observed either in the general relations to each othe1'.of the several formations, their local lithological characters, or in their mineral and organic contents. A glance at the aecompanying lllap will afford fuller, more accurate, and more detailed information than could be conveyed by many pages of letter-press, as well regarding the relative area occupied by the several formations ns the localities in which they are chiefly developed. This, however, does n.ot apply to the superficial pleistocene deposits, except where . they ex~st in Sl10h thickness and extent as to render the character of the subjacent rock uncertain, as is the case in. the Carrum Swamp, on the east side of Port Phillip Bay, and Koo-wee-rup, or the Great Swalllp north of vVestern Port Bay. ' ~ I ...:-,sTRATIFIED, AQUE;OUS, AND SEDIMENTARY.. 1. CAINOZOIC 011 TERTIARY. a. Pleistocene {Alluvial and Di!u~ial drifts, and recent upheaved beach and estuary deposlts. Thickness, Range, and E:1:tent.-These strata may be seen in natnral sections from a few inches to twelve. or fifteen feet, and 'have been proved by boring and sinking to reach in some localities a thickness'of thirty feet. There is, lwwever, no reason to suppose this to be the maximum thickness which they anywhere attaiu.. In the.worked portions of' the Yarra gold fields (Caledonia) the average thickness of the diluvhtm never exceeds, and rarely re.aches twenty feet. In other gold fields it has been proved tD attain a thickness of 190 feet; at 170 fect fossil trees have heen discovered only very slightly mineralised. The specimens I have seen present the appearance and fracture of charcoal. In range and extent the pleistocene deposits iriRy be· said to be universal, as scarcely a' single square mile of country exists over some portion of which OIle or more .of. them could not be detected. For this reason it becomes impossible, without a map on a very, large scale, to define their limits; I have, therefore, as before stated, attempted to do so only where they attain considerable thickness and extend without interruption . over a large area. The most extensive tract of this description occupied by alLuvial and estuary deposits extends east fi'om Port Phillip Bay to the base of Strzlesld's Range, embracing the Carrum and Roo-wee-rup, or Great Swamp, the two being connected by a narrow band of low lying swampy country, in which the waters of the Dandenong, Eumemmcrring, and Gard,iner's Creeks are lost, .only finding their way to the sea in seasons of flood, either through the numerous tidal inlets at the head' of \;Yestern Port, or through the sandy bars at either end of the Nine-mile Beach. Many parts of this' area' are, I believe, still beneath the sea level, the water having been excluded from them by the successive terraces or. beaches of sand, which have beell, piled up by the cDmbined action of wind and waves, and now form the narrow' sandy belt diviqing the Carrum Swamp from the sea known as the Nine-mile Beach. A depressiDn of fifteen Dr twenty feet would be sufficient again to submerge the whDle of the above area, and to connect the waters of Port Phillip and "\Vestern Port, as was undoubtedly the case during some portion .of the pleistocene pel·jod..'. Along the entire coast· line from "\Villiamstown to Cape Patterson, including the shores. and islands .of Western PDrt, remains of a raised beacl~ 7 of the pleistocene period occur at intervals, the' greatest elevation above the sea level at which it is now found being nearly 300 feet, and in some ., instances as much as four or five miles inland. Two instances have occun'ed in which a single fragment of shells (ostrea and haliotns) apparently belonging to this period, have been discovered at a much greater elevation: the first on Monnt Blackwood, by Bryce Ross, Esq.; and the second on the flanks of River Hill, in 'Vestern Port, by my assistant, Mr. Daintree, in neither case at an elevation less than 700 feet. From the position in which these fragments were found, at or very near the smface, it is not impossible that *ey may have been conveyed there by aborigines. MINERAL AND LITHOLOGICAL CHARACTER. 1. Estuary and Littoral Deposits.-Accumulations ill stratified beds and layers passing into each other of fine and course siliceous, white, and black sand with shells; stiff blue, yellow, brown or mottled clays, and black mud with a few shells and carbouised vegetable matter.