GEOlOGICAL SU.RVEY PF . VICTORIA

BULLETIN Noo 59

GEOLOGY OF THE MELBOURNE DISTRICT, VICTORIA·

.WiJh conm1JUtlons frtJm .~ G. Bell, ~ G~ Bowen, J. G. Douglas, J. S. Hancock, J. J. Jenkin~ PeR. Kenley, J. L. Knight, J9 I. Neilson, D~ SpencermJonest J~ A. Talent, Dq Eor Thoma'S and~ G. Whiting

~ES · DEPARTMENt

MELBOURNE, :VICTO~ AUSTRALIA 1961: . I UJv UJa: V) i= Z , 0 <:<: LL. GEOLOGICAL SURVEY OF VICTORIA

D. E. THOMAS, D.Sc., Director

BULLETIN No. 59

GEOLOGY· OF THE MELBOURNE DISTRICT, VICTORIA

Explanatory notes on the stratigraphy, structure and economic geology to accompany the geological map of Melbourne and Suburbs (1959, Scale 1: 31,680)

lVitb contributions from : G. Bell, K. G. Bowen, J. G. Douglas, J. S. Hancock, J. J. Jenkin, P. R. Kenley, J. L. Knight, J. L. Neilson, D. Spencer-Jones, J. A. Talent, D. E. Thomas and R. G. Whiting

Issued by E. Condon, LL.B., M.Inst.T., Secretary for Mines

under tbe autbority of

The Hon. T. A. Darcy, M.L.A., Minister of Mines

1967 2288/66. PREFACE

In recent years the Mines Department has handled a large and steadily increasing number of enquiries relating to various aspects of the geology, underground water and mineral resources of the Melbourne area. This bulletin on the geology of Melbourne and its environs has been prepared to fill the need for general information of this type.

The volume is intended to accompany and provide an explanatory text to the geological map of Melbourne and Suburbs (scale 1 : 31,680) which was published in 1959. It also fulfils the function of a general reference book and introduces the reader to the work that has been done to date and the problems that remain to be solved.

The bulletin takes the form of a symposium of articles by various geologists of the Mines Department. Several of the articles are written so as to be readily understood by the interested layman, but others, from the nature of their subject, have required a more technical treatment. Geological information in many fields is accumulating very rapidly and it is hoped that the subject matter may be brought up to date from time to time by the publication of new editions.

I trust that this bulletin will prove a valuable addition to the publications of the Department.

D. E. THOMAS, D.Sc. Director of Geological Survey. CONTENTS

PAGE

PREFACE D. E. THOMAS 3

CHAPTER I-INTRODUCTION D. E. THOMAS 11 References 11

CHAPTER 2-THE PHYSIOGRAPHY OF THE MELBOURNE AREA J. L. NEILSON 12 Introduction 12 'J'he Nillumbik Terrain 12 Drainage System of the Nillumbik Terrain 13 The Brighton Coastal Plain 14 The Lava Plains .. 15 The Yarra Delta .. 16 Coastline 16 References 17

CHAPTER 3-GENERAL GEOLOGY OF THE MELBOURNE AREA 19 3-1 SILURIAN .. 19

STRUCTURE AND STRATIGRAPHY R. G. WHITING 19 Geological Structure 19 Folding 19 Faulting 20 Pitch Effects 20 Stratigraphy 21 References Cited 21 Other References 21

SEDE\illNTARY PETROLOGY AND pALAEONTOLOGY .. JOHN A. TALENT 24 Sedimentary Petrology 24 Palaeontology 25 Faunal and Floral Lists 26 Keilorian 26 ? Keilorian 26 Melbournian 26 References 27 Seclim.entary Petrology 27 Palaeontology of the Silurian 28 3-2 TERTIARY P.R. KENLEY 31 Introduction and Geological Setting 31 Major Structural Features 31 General Features of the Tertiary Sediments and their Relationships with the Older Rocks 31 Variation of Sedimentary Facies 31 Marine Transgression and Regression 32 Comparison with Bacchus Marsh 32 Stratigraphy . . 32 W erribee Formation 32 Sub-Older Volcanic Alluvials 33 Older Volcanics (" Older Basalts") .. 33 Altona Coal Seam .. 34 Werribee Formation-Newport Formation Contact 35 Newport Formation 35 Newport Formation-Brighton Group Contact 37 Brighton Group ( = Sanclringham Sands) 37 Black Rock Sandstone .. 38 Reel Bluff Sands .. 39 Brighton Group-Newer Volcanics Contact 39 Sub-Newer Volcanic Alluvials 39 CHAPTER 3-continued. PAGE Newer Volcanics (Exford Volcanics) .. 39 Basalts of the Greensborough Phase 40 Basalts of the \Verribee Pla,ins Phase 40 Detailed Geological Structure of the Tertiary Deposits 40 :Monoclines and Flexures 40 Folding .. 42 Jointing .• 43 Structure Contours-Base of Tertiary 43 Acknowledgmnent 43 Appendix 43 Sub-divisions of the Brighton Group 43 References Cited 45 Maps 46 Bathytnetric Charts-Port Phillip Bay 46

3-3 QUATERNARY J. L. NEILSON AND J. J. JENKIN 47 Altona "'"-rea .. 47 :M:aribyrnong Valley 47 Lower Yarra Area 48 Port Melbourne Sand 48 Coolle Island Silt 49 Newer Volcanics .. 49 Fishermen's Bend Silt 49 JYioray Street Gravels 50 Heidelberg Alluvial Terraces 50 Aeolian Deposits 50 References 50

3-4 IGNEOUS ROCKS 53 GRANITIC ROCKS P.R. KENLEY 53 Heferences Cited 53 DYKE RocKs .. K. G. BOWEN 53 Acid and Intermediate Dykes 53 Basaltic Dykes 53 Alkaline Dykes 54 Larnprophyre Dykes 54 Age of the Dykes 54 References 54 BASALTS G. BELL, P. R. KENLEY, AND D. SPENCER-JONES 54 General Re1narks 54 Older Volcanics P. R. KENLEY AND G. BELL 55 Physical Features of the Hocks 55 Petrology 55 Chernical Cmnposition 56 Centres of Eruption 56 References Cited 56 Newer Volcanics . . 61 Greensborough Phase P. R. KENLEY AND G. BELL 61 Petrology 61 Chem.ical Composition 61 Werribee Plains Phase D. SPENCER-JONES 61 Physical Features of the Basalt Rocks 61 Composition of the Basalts 62 Iddingsite Labradorite Basalt (Footscray Type) 62 Olivine Labradorite Basalt 62 Zeolite Minerals 63 References 63 PAGE CHAPTER 4-ECONOMIO GEOLOGY 64 4-1 AGGREGATES K. G. BOWEN 64 Basalt 64 Scoria 64 Acid Igneous Rocks 64 Sedimentary Rocks 65 Production 65 1\fethod of vV orking 65 Physical Properties 65

4-2 SAND DEPOSITS K. G. BowEN 66 Classification 66 Pleistocene to Recent Sands 66 Tertiary Sands 66 Concrete Sand 66 Glass Sand 66 Hot Mix Filler 67 Brick Sand .. 67 Moulding Sands 67 1\fiscellaneous Sands 67 Methods of 'iVorking 67 4-3 CLAY AND SHALE DEPOSITS G. BELL 68 Introduction and History 68 Production of Shale and Siltstone 68 Production of Plastic Clay 69 Silurian Clay Shales 69 Cainozoic Semi-Refractory Clays 70 Cainozoic Pipe and Tile Clays 70 Scoresby and Ferntree Gully 70 Tally Ho 70 Oak leigh 70 Cheltenham 71 Residual Granitic Clays 71 Hallam .. 71 Bulla 71 Acknowledgements 71 References 71 4-4 THE BRICK AND TILE INDUSTRY D. SPENCER-JONES 74 Historical Comment 74 Raw Material 74 Production 75 References 75

4-5 EXPAND ED SHALE AGGREGATE , . R. G. WHITING 75 Materials Used as Light Weight Aggregates 75 Expanded Shale 75 References 76 4-6 GOLD R. G. WHITING 76 Historical 76 References 77 4-7 BROWN COAL J. L. KNIGHT 78 CHAPTER 4-continued. PAGE 4-8 THE UNDERGROUND WATER RESOURCES P. R. KENLEY AND J. S. HANCOCK 79 Introduction .. 79 Occurrence of Ground \Yater in the Various Stratigraphic Units 79 Silurian .. 79 Tertiary .. 79 \Verribee Formation 79 Older Y olcanics 79 Newport Fonnation 80 Bl'ighton Group 80 Tertiary-Quaterna,ry 81 Newer Volcanics 81 Quaternary 81 Yarra River Alluvials (excluding the Yarra Delta Sediments) 81 Yarra Delta Sediments 81 Dune Sands between Mordialloc and Frankston .. 81 Aquifer Characteristics 82 Intake Areas 82 Natural Recharge 82 Water QuaUty Distribution 82 Bore Distribution and Construction 82 Utilization of ·water 82 Present .. 82 Fnture 82 Sources of Information 82 Acknowledgements 82

CHAPTER 5-FOSSIL PLANTS IN THE lYIELBOURNE AREA J. G. DouGLAs 84 Silurian 84 Tertiary 84 Tertiary-Quaternary .. 84 Quaternary 84 References 85 GENERAL ACKNOWLEDGEMENT 87

TABLES 1. Mineralogical composition of Silurian " sandstones " of the Melbourne District . . 24 2. Chemical analyses of Silurian sedimentary rocks from. New Northcote Brick Pit, Croxton, compared with analyses of two " well-washed " sandstones from. the Ordovician of Victoria . . . . 25 3. Stratigraphic table of Tertiary rocks in the Melbourne area 30 4. Approximate frequency of occurrence of lithological types in the vVerribee Formation, South-western and vVestern Suburbs (based on data from bore logs) ...... 32 5. Stratigraphic table, Yarra Delta area 48 6. Chemical analyses of basalts from. Royal Park, Tullamarine and Keilor 56 7. Chemical analyses of basalts from Coburg, Footscray and Maribyrnong 62 8. Percentage of the different rock types making up the total production of aggregates in the Melbourne area 65 9. Values of Los Angeles Abrasion Test Loss for different rock types used as aggregates in the Melbourne area 65 10. Production of various clay types in the metropolitan area for the period 1960-1963 69 11. lYiineralogica,J composition and physical properties of clays from the Melbourne area 72 12. Chenlical composition of some typical clay shales from the Melbourne area 74 13. Range of composition in thirteen Werribee Formation waters, south-western suburbs 79 PAGE TEXT FIGURES 1. Idealized plan showing structure of the Silurian bedrock and the approximate relationship between the Melbournian and Keilorian stages 22 2. Cross-sections of the Silurian rocks- Section A-Through Doncaster Junction and Merlynston Station . . 23 Section B-Through Camberwell Station parallel to Section A 23 3. Diagrammatic cross-section illustrating the stratig1•aphic relationships of the principal Tertiary formations in the Melbourne area 31 4. Generalized section showing the relationship of the alluvial forrnations on the JYiaribyrnong River near Dry Creek, Arundel 51 5. Plan of Yarra Delta area, showing positions of bores and cross-sections A, B and C (see Plate 3) 52 6. Examples of grading limits for concrete sand aml the grading for a typical washecl concrete sand from Springvale 66 7. Change in grading of sand produced by washing 68 8. Clay and shale deposits, Greater Melbourne area 73 9. Sketch map showing positions of geological cross-sections of the Tertiary rocks (see Plate 7) 83

PLATES 1. Fossils from the Silurian rocks of the Melbourne area 29 2. Base of Tertiary structure contours and geologica,! structure of the Tertiary rocks, Melbourne area facing p. 46 3. Cross-sections A, B and C, Yarra Delta area (see Te:s:t Fig. 5 for positions of sections) facing p. 52 4. 0 lder and Newer Volcanic rocks 58 Fig. I.-Newer basalt overlying Tertiary sands at Green (Taylor's) Gully, Keilor. Fig. 2.-Relationships of the Older and Newer basalts to the Tertiary sands and lhnestones at Green Gully. Fig. 3.-0lder and Newer basalt flows separated by a thin sand layer, Standard Quanies, Footscray. 5. Thin section of Older basalt from Keilor 59 Fig. I.-Ordinary light. Fig. 2.-Crossed nicols. 6. Older and Newer Volcanic rocks 60 Fig. I.-Flat-lying basalt of the Newer Volcanics overlying Silurian mudstones, Butler's Brick Pit, East Brunswick. Fig. 2.-Columnar jointing in basalt of the Older Volcanics, Bayview Quarries, Tullamarine. 7. Geological cross-sections of the Tertiary rocks, JYielbourne area (see Te:s:t Fig. 11 for positions of facing sections) p. 82 Section 1. Laverton to Spotswood. Section 2. Altona to Brunswick. Section 3. East JHalvern to Keysborough. Section 4. Box Hill to JYiordialloc. Section 5. Keilor to Heidelberg. 8. Plant fossils, Melbourne area 86 9. Silurian sandstones, claystones and siltstones 89 Fig. I.-East dipping strata at Dight's Falls, Studley Park. Fig. 2.-Minor tlu·ust faulting and jointing in a road cutting on the Boulevard, Studley Park. 10. Silurian sandstones, claystones and siltstones. 90 Fig. 1.-An anticline in Barker's Road, Kew. Fig. 2.-An anticlme in the Oakleigh Brick Co. Pit, Oakleigh. 11. Silurian sediments, Tm·tiary sediments and Newer Volcanics 91 Fig. I.-Deeply weathered Silurian 1nudstones, Franklin's Clay Pit, Carnpbellfield. Fig. 2.-Deeply weathered Silurian mudstones unconformably overlain by Tertiary clays and basalt. Campbellfield Clay Co. Pit, Campbellfield. 12. Silurian sediments, Tertiary seclhnents and basalts 92 Fig. I.-Flat-lying Tertiary samls unconformably overlying Silurian siltstones, claystones and sandstones. Railway cutting near Royal Pa1•k station. Fig. 2.-Relationships of the Older basalt, Tertiary sands and Newer basalt, at the western quarry Bayview Quarries, Tullamarine. ' PLATES-C011 tinu ed. PAGE

13. Brighton Group Sediments 93 Fig. 1.-Strata of the Black Rock Sandstone dipping at 20-30° in a cliff adjacent to the Beaumaris m.onocline, Bea-t.m1.aris. Fig. 2.-The Red Bluff Sands and the Black Rock Sandstone at Red Bluff, Black Rock. 14. Brighton Group sediments at Reel Bluff, Black Rock 94 Fig. 1.-Detail of the clisconformable contact between the Reel Bluff Sands and the Black Rock Sandstone. Fig. 2.-Axial view of the Reel Bluff anticline at Reel Bluff. 15. Reel Bluff Sands and Quaternary shell beds 95 Fig. 1.-Poorly bedded fiat-lying sands of the Reel Bluff Sands at Rowland's Sand Pit, Clayton. Fig. 2.-As above, but with the sand:" showing gentle clips. Fig. 3.-Quaternary shell beds and shelly sanely limestone near Seaholme.

JYIAP Geological map of JVIelbourne and Suburbs, scale, 1 : 31, 680 (in pocket at back).

PHONTISPIECE Aerial view of Melbourne looking south-west. The city is built on low hills consisting principally of Silurian sandstones and mudstones (foreground). Tertiary sediments and Older Volcanic rocks flank the Silurian in the western part of the city (rniclclle distance). Beyond lie the fiats of the Yarra delta and the confluence of the Yarra (left) and JYiaribyrnong Rivers. The extensive lava plains of the Newer Volcanics form the e-.;:treme background. [Colour photo: Air Photographs Pty. Ltd.] 11

CHAPTER 1. INTRODUCTION

D. E. Thomas, D.Sc., Director of Geological Survey.

Only a few attempts have been made to document Griffiths in 1890 were replaced in the 1900 handbook the geology of Melbourne, either by means of by an excellent brief account prepared by T. S. Hall. written descriptions or geological maps. The first Hall later amplified some aspects of Melbourne systematic treatment of the subject was provided geology in his book " Victorian Hill and Dale " by the Quarter Sheets of the Geological Survey of published in 1909. The next account to appear was Victoria prepared under the direction of A. R. C. "The Geology of Melbourne", by G. B. Pritchard Selwyn and published in 1863. These maps (1910), who modestly sub-titled his work "as told presented the distribution of the various rock forma­ by a few rambles in and around the city ". Pritchard tions and showed something of their major relation­ later wrote a small, but informative booklet entitled ships. The original data was republished with minor "Old Yarra History" (1944), in which he concen­ revisions in the form of a single geological map of trated on the country along the Yarra valley. All "Melbourne and Suburbs" in 1937. three books are now collectors' items but will still be found of value to the serious student. Apart from specialized studies of restricted areas, The ensuing bulletin is the first general descrip­ no further maps appeared until the current map tion of the geology of Melbourne published since was prepared in 1959. The extensive building and the early works of Hall and Pritchard. It is by no development which had taken place since the days means exhaustive and is intended primarily as a of the early mapping restricted the access of geolo­ handbook of explanatory notes to accompany the gists engaged in preparation of the new map and geological map. For further detail on particular verification or refinement of the old boundaries was areas the reader should refer to the original papers impossible in some places. In other areas informa­ cited in the lists of references. In general, the tion obtained from excavations, sewerage works and explanatory notes deal specifically with the area drilling added a wealth of detail locally. However, covered by the map, which excludes the more as excavations are commonly available for inspection southerly suburbs, but reference has also been made for only short periods of time there were limitations to certain key areas outside the limits of the map to the amount of information that could be gathered where it was considered necessary. from this source. The manuscripts were prepared by a group of The map is best regarded as a comprehensive geologists working independently and the subjects revision of the geological information available up have been treated in varying degrees of detail and to the time of publication. It shows the structural from differing points of view. This has led to geology of the Silurian rocks, fossil localities, igneous inconsistencies in presentation but the demand for dykes, quartz reefs, quarries, sand, gravel and clay the information gathered has been so great that it pits and other features not previously shown or was decided to proceed with publication of the absent from the 1937 edition. Officers of the volume in its present form. Department concerned in the preparation of the Although the bulletin incorporates much of the map are aware that further modifications are work of earlier geologists, it contains many new desirable and would welcome information which observations and puts forward a number of might lead to improvements in future editions. important new ideas. Some sections of the work Written descriptions of the geology of Melbourne will undoubtedly be superseded as additional infor­ have hitherto appeared independently of the maps. mation becomes available and revision of the text The first accounts dealing specifically with the will be carried out as the need arises. Melbourne area were published in the handbooks It is hoped that these notes will prove useful to prepared for Melbourne meetings of the Austra­ geologists, engineers, architects, students and all lasian Association for the Advancement of Science. others interested in the structure and history of the Somewhat digressive notes prepared by G. S. land on which our city is built.

REFERENCES. GRIFFITHS, G. S., 1890.-The Geology of Melbourne. HALL, T. S., 1909.-Victorian Hill and Dale. 8 vo, Australasian Association for the Advancement of Lothian, Melbourne. Science, Handbook. Melbourne Meeting, 1890, pp. 26-44. PRITCHARD, G. B., 1910.-The Geology of Melbourne. 8 HALL, T. S., 1900.-The Geology of the Neighbourhood vo, Taft, Melbourne. of Melbourne. Australasian Association for the Advancement of Science, Handbook. Melbourne PRITCHARD, G. B., 1944.-0ld Yarra History. 8 vo, Meeting, 1900, pp. 25-43. Cheshire, Melbourne. 12

CHAPTER 2.

THE PHYSIOGRAPHY OF THE MELBOURNE AREA

1 J. L. Neilson •

Within the Melbourne area, four main topographic Gregory (1903) named the Yarra Plateau. He units can be recognized each of which has its own regarded the Yarra Plateau as a shelf on the eastern distinctive morphology and mode of origin. The border of the Melbourne Basin, and believed it to four divisions are listed below. be a peneplain which once stretched from the Strathbogie Ranges across the present main divide 1. The Nillumbik Terrain. between Mount Disappointment and Mount Arnold. This is a sub-aerial erosion surface of low Gregory described the Yarra Plateau as " the old relief which has been uplifted and maturely platform around the Dandenongs ". dissected. Remnants of it are to be seen in the eastern and north-eastern suburbs. Jutson ( 1911) gave the Yarra Plateau a more precise definition, and demonstrated that it was 2. The Brighton Coastal Plain. much smaller than Gregory had supposed. He gave Found in the Elwood, Brighton, Cheltenham its northern boundary as the Great Divide or some and Beaumaris area, this uplifted and only of its southern spurs, with Mount Disappointment moderately dissected Tertiary sea floor is often at its north-western extremity. Jutson showed that veneered with Quaternary dune sands. the boundary of the plateau followed below the escarpment forming the south side of the Kinglake 3. The Lava Plains. Plateau, spreading from there through Croydon to The fiat and gently sloping youthfully Port Phillip Bay. To the west, he showed that the dissected surface of the basalt flows belonging Yarra Plateau was bounded by a line drawn from to the Newer Volcanics makes a characteristic Mount Disappointment to Port Phillip Bay. landform in the northern and western suburbs. East of the Yarra Plateau, covering the fiats at 4. The Yarra Delta. Yarra Glen and Bayswater and extending both eastwards to the foot of the Dandenong Ranges The Yarra Delta is an area of Quaternary and southwards through Dandenong, is a low-lying estuarine deposits, whose surface is only a few area which Jutson (1911) named the Croydon feet above the present sea-level. Beginning at Sunk land. The Yarra Plateau together with the Princes Bridge and extending to Hobson's Bay, Croydon Sunkland, form a single landform, which the delta has grown to engraft the former Jutson went on to name the Nillumbik Peneplain. estuaries of the Maribyrnong River and The Croydon Sunkland, he demonstrated, was Moonee Ponds Creek. merely a down-faulted portion of the Nillumbik The coastal features are discussed separately. Peneplain. The Nillumbik Peneplain is an erosional landform 1. THE NILLUMBIK TERRAIN. which has been cut in folded Silurian strata. To Melbourne is set in a basin, a feature clearly the north and east of Melbourne, it is overlain in seen from the north and first noted by Gregory some places by almost fiat-lying Tertiary sands, ( 1903), who introduced the term Melbourne Basin which cap the hills in places such as Doncaster, to cover the area which includes Port Phillip Bay, Camberwell, Kew, Preston and Heidelberg. The together with the country between the Rowsley Nillumbik Peneplain continues through to Port Scarp (Fenner, 1918) near Bacchus Marsh and the Phillip Bay, but from South Yarra and Oakleigh Christmas Hills near Yarra Glen. He drew the through Brighton to the sea, it is buried beneath eastern boundary of the Melbourne Basin along the a broad sheet of Tertiary beds which are mainly ridge through Queenstown, the Christmas Hills and ferruginous sands where exposed. Mooroolbark. This basin, then, is similar to the The continuity of the isolated patches of Tertiary down-faulted area defined by Fenner (1918) as the sands, found on hill-tops and higher areas of the Port Phillip Sunk/and. eastern suburbs, with the more or less continuous Immediately to the east of the Melbourne Basin, sheet of similar material south-east of Melbourne, the generally similar level of hill-tops is indicative seen typically at Brighton, was recognized by Selwyn of a maturely dissected erosion surface, which and Aplin (1863) in the early quarter-sheets of the

1 Manuscript completed 1960, revised 1964. 13

Geological Survey, and later clearly stated by Jutson The uplift has been dated as probably late Kalimnan (1913). These beds, labelled " Red-beds " by (Hills, 1934). The cycle of erosion inaugurated Hall ( 1909) on account of their prevalent colour, by the uplift of the Nillumbik Terrain has now are named the Brighton Group in the Tertiary reached a mature stage, with the non-marine section of this bulletin. Tertiary sands only surviving on hill-tops in the eastern suburbs. The widespread Tertiary sands of the Brighton Group and its equivalents were deposited on a land A seaward tilt probably accompanied the uplift surface of low relief, when that surface was close of the Nillumbik Terrain, with which should be to its base-level of erosion, that is, close to sea level. connected the faulting which produced the Croydon The seaward margin of this old land surface, in the Sunkland. That uplift was slow and gradual is coastal area where it is buried beneath beds of the shown by the antecedent course of the Yarra River Brighton Group, may have been produced partly by through the Yering George (Gregory, 1903). marine erosion. Away from this coastal area, Warping accompanying the uplift, Jutson (1911) however, in the absence of overlying marine considered, is indicated by the steady increase in deposits, the old land surface must wholly owe its elevation found proceeding eastwards along the origin to sub-aerial erosion. Peneplanation, though, Mitcham Axis, a broad divide running from the did not proceed to completion, and the topography north of Camberwell to Burt's Hill near Croydon. in existence before the deposition of the beds of the Brighton Group was a landscape of old age (Davis, 1909) with low hills ; it was not a true peneplain. Drainage System of the Nillnmbik Terrain. Jutson ( 1911) noted residual hills such as Sugar The Yarra River, Gardiner's Creek, Plenty River, Loaf Hill at Mont Park as clear evidence that Diamond Creek and their tributaries have cut deep peneplanation was incomplete. At Kangaroo mature valleys through the capping of Tertiary Ground recent mapping has shown that the land­ sands down into bedrocks, leaving only remnants of scape on which both Tertiary sands and basalts the sands on some of the hills, but entirely stripping were laid is an irregular one of low to moderate the sands from many areas. relief. To the west of Merri Creek, the Tertiary sands The term Nillumbik Peneplain is therefore are more widespread and less denuded than they inaccurate, and this erosion surface of rather low are further to the east, for they have been mostly relief should be named preferably the Nillwnbik protected by overlying basalt flows of the Newer Terrain, as Hills ( 1934) has suggested. In the Volcanics. In the time interval between the uplift Mitcham area, as the sands have been completely of the Nillumbik Terrain and the out-pouring of the removed, the re-exposed Nillumbik Terrain is Newer Volcanics, mature valleys were worn in these termed a stripped fossil plain by Hills (1946). sands, though dissection was still moderately The age of the Nillumbik Terrain is difficult to youthful when they were buried beneath the basalt determine precisely. As it is overlain by sands of flows. Cheltenhamian and perhaps Kalimnan age The Yarra River emerges from the W arrandyte (Singleton, 1941) of the Brighton Group, it must Gorge into a mature broad alluviated valley at be pre-Cheltenhamian, i.e., pre-Upper Miocene in Templestowe and Heidelberg, showing wide flats age. which are still subject to flooding. At Fairfield, After the extrusion of the Older Volcanics, the valley narrows and becomes youthful, due to sinking occurred in the Port Phillip area so that the partial infilling of the original valley by basalt the marine Tertiary rocks of the Port Phillip basin which flowed to the Yarra down the ancestral were being deposited concomitantly with the erosion valleys of Darebin Creek and Merri Creek. which was continuously reducing the elevation of Ponding of the river at Fairfield by the basalt the hinterland. By Cheltenhamian times, landscape caused the deposition of the broad flats at relief had become low. It is pictured as a low-lying Heidelberg and Templestowe. Flowing on down a coastal zone crossed by mature and old-age streams. mature valley the lava spread out beyond the valley The landscape at this stage was, in fact, the to form small lava plains, typically seen at Colling­ Nillumbik Terrain. During Cheltenhamian time, wood and Burnley. Below Fairfield the Yarra the sands and gravels of the Brighton Group were became a lateral stream to the basalt and flowed deposited on this landscape, both off -shore and on along the eastern boundary of the basalt to cut a the land. youthful winding valley in the Silurian rocks. The steep eastern slope of this valley, which rises high The Nillumbik Terrain was uplifted between late above the river at Studley Park, is but the sharpened Kalimnan time and the beginning of the Quaternary side of the pre-basaltic valley. The youthful valley Epoch, i.e., in late Tertiary time, as the Quaternary bordering the basalt continued through Heyington deposits of Melbourne have not suffered this uplift. to South Yarra. 14 Pritchard (1944) mentions sub-basaltic silts at Koonung Koonung Creek and Gardiner's Creek Richmond and Burnley which contain marine both have broad alluviated valley floors, which in Quaternary fossils, thereby indicating a Quaternary the latter is due to the ponding of Gardiner's Creek age for this basalt flow, which is regarded as the by the lava flow which came down the Yarra valley youngest flow in the Melbourne area (Hills, 193 9). (Pritchard, 1944). The pre-basaltic valley revealed at Burnley is bel?w the present sea-level, carved to that depth durmg 2. THE BRIGHTON COASTAL PLAIN. a time of low sea-level in the Quaternary ; at The Brighton, Elsternwick, Cheltenham and Cremorne Bridge, South Yarra, it is 50 feet below Springvale areas have a surface of sandy sedi­ present sea-level. From Richmond the basalt flow mentary rocks of the Brighton Group, though this continues along the river to Spencer Street Bridge is sometimes concealed beneath thin Quaternary and at Queens Bridge it once formed a small aeolian sands. An uplifted sea floor and coastal waterfall, now removed to enable boats to traverse zone, this surface overlies the Nillumbik Terrain, the river. which is buried here beneath Tertiary deposits, and In late Quaternary time, during an epoch of merges with it to the north-east. The surface is slightly higher sea-level, the sea invaded the Yarra thus a coastal plain, as Hall (1909) shows; it is valley as far upstream as South Yarra. This here named the Brighton Coastal Plain. North-west is shown by the presence of Quaternary marine of St. Kilda, it is succeeded by the Yarra Delta, foraminifera and diatoms in silts overlying the basalt and to the south-east it is terminated by the Carrum (Kitson, 1902 ; Gill, 1953). Shell-bearing silts Swamp. overlying the basalt at Olympic Park were also The surface of the coastal plain is of low relief, deposited at this time. and undulating in only a very gentle manner. Between South Yarra and Princes Bridge, the Valleys are very shallow indeed and quite broad, Yarra valley widens, with a narrow flood plain while interfluves are very flat-topped. The valleys developing, but even here the river is mature rather are remarkably parallel, with a pronounced north­ than old, as river bends still commonly have rock westerly trend. At first sight, it is anomalous that walls. Small lakes and swamps occupying aban­ the drainage should be sub-parallel with the coast doned river channels, and subject to periodic rather than at right angles to it. The unusual flooding, once occurred along this section of the drainage pattern of the Brighton district was river. With the exception of the lake in the attributed to control by Quaternary longitudinal Botanical Gardens these were removed by river sand dunes ( Whincup, 1944). However, evidence improvement works carried out at the turn of the given in the Tertiary section of this bulletin suggests century. The river reaches a stage of old age that it is due to a series of north-westerly trending below Princes Bridge where it winds across its delta, minor folds in the Tertiary sediments of the the level surface of which is now only a few feet Brighton Group, which have localized the valleys above sea-level. It enters Hobson's Bay near along the shallow synclines. Williamstown. Streams are poorly developed, as much surface The Yarra River has an interrupted history, with water finds its way underground through porous a disordered sequence of youth, maturity and old sub-surface rocks. Even so, it is difficult to know age. The cause of this disorder may be recapitulated the natural extent of surface drainage, as under­ as, firstly, the uplift, warping and faulting of the ground drains now take off most of the precipatation. Nillumbik Terrain, secondly, the outpouring of The main stream crossing the Brighton Coastal Plain basalt down the old Yarra valley, and thirdly, is Elster Creek, which flows to Elwood Swamp Quaternary changes in sea-level. through a broad low-lying depression. Elwood The tributaries of the Yarra River are of some Swamp, now a few feet above sea-level, contains interest. As Jutson (1911) has shown, those Holocene marine shells (Jutson, 1931) associated entering the Yarra from the north generally have with terrestrial spores and pollen grains (Cookson, deep, narrow valleys, while in contrast, those 1954) in estuarine silts. The swamp probably entering from the south are usually shorter, with originated during the slightly higher Holocene sea­ broad open valleys. Of the northern tributaries, level recorded by the Yarra Delta and the Altona the Plenty River has had its course lengthened by &hell beds (Plate 15, Fig. 3). the deviation into it of the former head of Darebin The uplift which formed the Brighton Coastal Creek by a basalt flow which came down that creek Plain probably belongs to the same movements (Jutson, 1910). From the south, the main which elevated the Nillumbik Terrain, i.e., late tributaries of the Yarra are Mullum Mullum Creek, Tertiary movements. The uplift was probably Koonung Koonung Creek and Gardiner's Creek. accompanied by minor warping, which is described Mullum Mullum Creek has a deep narrow valley in the Tertiary section of this bulletin. The area of where it meets the Yarra, and it may be a former uplift was bounded on the south by the Beaumaris tributary of Dandenong Creek now captured by the Monocline (Hart, 1913), south of which a depres­ Yarra River (Thiele, 1906). sion was made in which the Carrum Swamp formed. 15

3. THE LAVA PLAINS. name the Footscray Warp, appears inadequate, as The Newer Volcanics have had considerable irregularities in the lower surface of the basalt ~an influence in shaping Melbourne's topography. The be explained by the uneven topography over wh1ch lava plains, seen typically at Collingwood, Burnley, the lava flowed. Coburg and Footscray, are broad and rather flat. The streams crossing the eastern part of the They are only youthfully dissected, and crossed by Werribee Plains Lava Field vary in size, but all youthful valleys which are sometimes quite deep. flow through youthful valleys. Interfluves are brKororoit Creek pre-basaltic drainage system which had developed is the largest of these three, and like Skeleton Water on the uplifted Nillumbik Terrain ; the paths of the Holes Creek, it enters Altona Bay through a low­ streams have been displaced, but remain basically lying plain covered with stranded Quaternary the same. To the west of this line, though, the deposits. Stony Creek is similar in character, but present drainage system bears little relationship to enters the Yarra at Spotswood. that of pre-Newer Volcanic time. The pre-basaltic The laro-est of the streams crossing the lava plains streams to the west of Moonee Ponds Creek were is the Ma~ibyrnong River, which, like its tributaries southerly flowing consequent streams crossing a Jackson's Creek and Deep Creek, has cut a deep coastal plain, until the extensive early sheet flows youthful valley through the Newer Volcanics into of the Newer Volcanics completely obliterated them the underlying rocks. The valleys of these three (Condon, 19 51) . The surface of these earlier lava streams are often entrenched, have ingrown flows still reflected the slope of the buried coastal meanders, occasional hanging valleys, and are plain and on this surface the early Werribee River, actively eroding (James, 1920). Below Braybrook, Skeleton Water Holes Creek, Maribyrnong River, the valley of the Maribyrnong River is broader, Moonee Ponds Creek and Kororoit Creek developed more mature, with wide paired river terraces at the as consequent streams. Then a later phase of 40 feet level standing above the present flood plain vulcanism, in which smaller tongue-like flows were between Braybrook and Maribyrnong. The terraces outpoured, modified the courses of these streams­ are noted by Hills (1939) from West Essendon and substantially in some cases-and gave them their Maribyrnong. Downstream from Essendon, basalt present positions. The tongue-like basalt flows came of the Newer Volcanics is absent from the eastern from cones, found typically near Digger's Rest and side of the valley, which then shows a more gradual at Mount Cotteril and Mount Atkinson on the profile. Werribee Plains, all of which are still high points on the volcanic plains. The volcanic landscape of Moonee Ponds Creek is much smaller than the Williamstown, Footscray, Essendon, Keilor and Maribyrnong River, though between Broadmeadows Bulla districts is the eastern extremity of the and Strathmore it has a rather similar deep youthful Werribee Plains Lava Field, sometimes known as valley bordered by: Newer Volcanics. Below the Keilor Plains Lava Field. Strathmore, however, with Newer Volcanics absent, its valley broadens, becomes more mature and The Werribee Plains Lava Field has been down between ·Strathmore and Flemington shows raised faulted and possibly warped by movements on the paired river terraces, which appear to correlate with Rowsley Fault at Bacchus Marsh and the Selwyn those of the Maribyrnong River. Downstream from Fault near Mornington. The graben thus formed, Moonee Ponds and Flemington Bridge, the present which is named the Port Phillip Sunkland by Fenner flood plains of these streams show estuarine traits, ( 1918) , drowned the lower parts of the lava field, and are continuous with the surface of the Y ana betrunked the lower reaches of the streams crossing Delta, a low-lying area of marine and estuarine it and gave Port Phillip Bay its present configura­ deposits whose surface is now only a few feet above tion. Condon (1951) places the faulting within the sea-level. time between the outpouring of the Newer Volcanic flows of the Werribee Plains and the later tongue Further east, both Merri Creek and Darebin flows. Evidence for a local post-basaltic warp at Creek now flow across the basalt which came down Footscray, which Keble and Macpherson (1946) their ancestral valleys, while in contrast, the Yarra 16

River has become marginal to the basalt. Merri Bridge. Continued sedimentation-with the final Creek and Darebin Creek both have youthful factor of the late Holocene fall in sea-level-has valleys which are moderately deep. Merri Creek linked these three streams and extended the mouth (Hall, '1909 ; Cook, 1916) has rapids along its of the combined stream, so that the united stream course and east of Pentridge, follows the boundary now enters Hobson's Bay near Williamstown. Hall betwe~n the basalt on the west and the Tertiary (1909) and Pritchard (1910) believed that an old sands on the east. At this locality, the resistant bed of the Yarra River went behind Victoria basalt forms a steep bank, while the sands make a Barracks to Albert Park Lake, and thence to the gently sloping opposing bank. At Northcote, basalt sea through Beaconsfield Parade. Pritchard stated on both banks causes a gorge-like valley. that a flood of 1891 followed that course. Though occasional floods may have found this route, it is The youngest lava flow in the. Melbourne area is doubtful whether this was ever an established stream that of the Yarra valley (Hills, 1939). The course, for Tertiary sands of the Brighton Group, physiographic effects of this lava have been discussed shown on the geological map of Melbourne and earlier in these notes. suburbs (Mines Department, 1959), cross this route along Albert-road and have been confirmed there 4. THE YARRA DELTA (see Frontispiece). recently. North-westerly longshore drifting finally fixed the mouth of the Yarra River against the basalt In its lower estuarine section, the Yarra River, at Williamstown (Hall, 1909). during the Quaternary, has extended its mouth seawards by the deposition of sediments. The The Quaternary Coode Island Silt is the upper­ resulting landform constructed is the Yarra Delta, most material in the West Melbourne Swamp to which, beginning at Princes Bridge, spreads out to Princes Bridge section of the delta. Occurring Hobson's Bay. Its fiat surface, only a few feet 7 feet above present sea-level at Kings Bridge, above present sea-level, is exposed by a minor late the Coode Island Silt there gives proof of late Holocene fall in sea-level. Quaternary emergence. Overlying the Coode Island Silt in the Fishermen's Bend-Port Melbourne area The Yarra Delta is bounded on the west by low are sands of the Port Melbourne Sand. These cliffs between North Williamstown and Footscray, sands, described in the Quaternary section of this then passes up the Maribyrnong valley to the bulletin, consist of bedded marine sands overlain Flemington Racecourse, its northern extremity. by beach ridges and aeolian sands. The sand Eastwards, the old shore bounding it can be ridges reached 7 feet above sea-level (Lucas, 1887), followed past Kensington and North Melbourne, but they have been exploited as sand deposits and then past Spencer Street Railway Station to Princes no longer exist. The ridges are interpreted as Bridge. South of Kensington, a lagoon known as beach ridges-with some dune sand-formed on the the West Melbourne Swamp formerly received the margin of a retreating sea. waters of Moonee Ponds Creek. The swamp has now been artificially filled, and a channel has been COASTLINE. cut to drain Moonee Ponds Creek directly into the Port Phillip Bay and Hobson's Bay lie within the Yarra River. The delta deposits cover parts of down-faulted area known as the Port Phillip Sunk­ South Melbourne, and probably exist in the Albert land (Fenner, 1918), the structure, tectonics and Park area almost to St. Kilda. Tertiary stratigraphy of which are discussed in the The genesis of the Yarra Delta and its stratigraphy Tertiary section of this bulletin. have been discussed in the Quaternary section of In general, down-warping characterized the Port this bulletin, where it is shown that the phases of Phillip Sunkland during Tertiary time, but as already sedimentation involved in its growth are related to stated, late Tertiary movements raised the north­ the changing sea-level of the Quaternary. Although eastern section of the Sunkland, thereby forming there may be old channels of the Yarra River and the Brighton Coastal Plain, elevating the Nillumbik the Maribyrnong River buried beneath the surface Terrain, and producing the Carrum Swamp on the of the delta, drilling has not yet definitely located southern side of the Beaumaris Monocline. It is any such channels. Keble ( 1946) postulated earlier probable that downwarping movements occurred at outlets of the Yarra at Port Melbourne and close this time in the western part of the Port Phillip to St. Kilda, but the writer finds the evidence for Sunkland, thereby betrunking Kororoit Creek, these from submarine contours to be inconclusive. Skeleton Water Holes Creek and the Werribee Earlier in the Quaternary, the Yarra River, River. By the beginning of Quaternary time, Port Maribyrnong River and Moonee Ponds Creek all Phillip Bay must have had its basic present entered the sea separately: the Yarra near Princes configuration. Bridge, the Maribyrnong at Flemington Racecourse The western shores of Port Phillip Bay contrast and the Moonee Ponds Creek near Macaulay. with much of the eastern shores of the Bay. The A shallow bay then extended as far inland as Princes western shores are flat and prograding over long 17 stretches, with a very low hinterland, while the REFERENCES. eastern shores are often cliffed and retrograding (Jutson, 1931). CoNDON, M. A., 1951.-The Geology of the Lower Wer­ ribee River, Victoria. Proc. Roy. Soc. Viet., Vol. 63, The coast fronting the Yarra Delta is low, with pp. 1-24. a broad sweeping sandy beach which is interrupted CooK, G. A., 1916.-Notes on the Geology of the Coburg by a headland of Silurian bedrock at St. Kilda. Area. Proc. Roy. Soc. Viet., Vol. 28, pp. 173-182.

From St. Kilda to Beaumaris the coastline is an CooKsoN, IsABEL, C., 1954.-The Cainozoic Occurrence emerged one, characterized by cliffs and active of Acacia in Australia. Aust. Jour. Sci., Vol. 2, pp. erosion. Along this stretch, the coast is crenulate, 52-59. with crescentic sandy sections and pocket beaches DAVIS, W. M., 1909.-Geographical Essays. Dover ed. separated by headlands-such as Point Ormond and republ. 1954 Red Bluff-which are composed of resistant ferruginous sandstone of the Brighton Group. FENNER, C., 1918.-The Physiography of the Werribee Erosion at headlands has often produced shore River Area. Proc. Roy. Soc. Viet., Vol. 31, pp. platforms, such as the wide platform at Rickett's 176-313. Point (Hills, 1946). A shore platform 8 · 5 feet GILL, E. D., 1950.-The Geology of Picnic Point, Port above present sea-level at Picnic Point indicates Phillip Bay, Victoria. Proc. Roy. Soc. Viet., Vol. 62, a minor late emergence (Gill, 1950). A strong pp. 121-127. structural control for this section of coastline is GILL, E. D., 1950.-Nomenclature of Certain Tertiary outlined in the Tertiary section of this bulletin, Sediments near Melbourne. Proc. Roy. Soc. Viet., where it is shown that headlands are situated near Vol. 62, pp. 165-171. anticlines, which raise the harder Black Rock Sandstone above sea-level, while the bays coincide GILL, E. D., 1953.-Palaeoecological Interpretation of with synclines which carry the softer Red Bluff some Victorian Fossil Diatom Floras. Mem. Nat. Member into the zone of wave attack. The Mus. Melbourne, Vol. 18, pp. 141-153. coincidence of the rather straight north-westerly GILL, E. D., 1961.-Eustasy and the Yarra Delta, Vic­ trending sides of the bays with the anticlinal axes toria, Australia. Proc. Roy. Soc. Viet., Vol. 74, pp. is also noted in that section. 125-133. Between the Yarra mouth and Seaholme, the sea GREGORY, J. W., 1903.-The Geography of Victoria. 8 is fronted with low basalt cliffs, and beach deposits vo, Whitcombe and Tombs, Melbourne. are not prominent. HALL, T. S., 1909.-Victorian Hill and Dale. 8 vo, Lothian, Melboume. At Williamstown, the coast is of basalt, with a platform 20 to 30 yards wide between the cliff and HART, T. S., 1913.-0n the Country between Melbourne the shoreline (Hills, 1940). The platform is above and the Dandenong Creek. Proc. Roy. Soc. Viet., the level of normal wave attack, and seems to have Vol. 25, pp. 268-285. originated during a period of higher sea-level. HILLS, E. S., 1934.-Some Fundamental Concepts in Williamstown beach, nearby, is a pocket beach in Victorian Physiography. Proc. Roy. Soc. Viet., Vol. an indented coastline of basalt cliffs. In the lower 47, pp. 158-174. reaches of Kororoit Creek, in the Altona area, and HILLS, E. S., 1939.-The Age and Physiographic Relation­ near the mouth of Skeleton Water Holes Creek, ships of the Cainozoic Volcanic Rocks of Victoria. late Quaternary emerged shell beds and sand ridges Proc. Roy. Soc. Viet., Vol. 51, pp. 112-139. overlying the basalt provide further evidence of a minor fall in sea-level during late Quaternary time HILLS, E. S., 1940.-The Question of Recent Emergence of the Shores of Port Phillip Bay. Proc. Roy. Soc. (Hills, 1940; Gill, 1961). Viet., Vol. 52, pp. 84-105.

Though the last movement along the coastline HILLS, E. S., 1946.-The Physiography of Victoria. 2nd was one of minor emergence, probably of about ed., 8 vo, Whitcombe and Tombs, Melbourne. 10 feet, the coastline cannot be simply classified as an emerged coastline. As the main movement JAMES, A. V. G., 1920.-The Physiography and Geology responsible for the genesis of the coastline fronting of the Bulla-Sydenham Area. Proc. Roy. Soc. Viet., the Brighton Coastal Plain is uplift, this section Vol. 32, pp. 323-349. should be classified as an emerged coastline. The JursoN, J. T., 1910.-A Contribution to the physical remaining portions of the coastline have originated history of the Plenty River and of Anderson's Creek, basically by submergence, which is the movement Warrandyte, Victoria. Proc. Roy. Soc. Viet., Vol. responsible for the present general configuration of 22, pp. 153-171. Port Phillip Bay. If the coastline were to be JursoN, J. T., 1911.-A Contribution to the physiography classified as a whole, it would have to be designated of the Yarra River and Dandenong Creek Basins as a compound coastline. Victoria. Proc. Roy. Soc. Viet., Vol. 23, pp. 469-515: 2288/66.-2 18

REFERENCES-continued.

JuTSoN, J. T., 1913.-0n the age and physiographic relations LucAs, A. H., 1887.-0n the sections of the delta of the of the Older Basalts of Greensborough and Kangaroo Yarra, displayed in the Fishermen's Bend cutting. Ground, and of certain basalts at Bundoora and Trans. and Proc. Roy. Soc. Viet., Vol. 23, (old series) Ivanhoe. Proc. Roy. Soc. Viet., Vol. 26, pp. 45-56. pp. 165-173.

JuTSON, J. T., 1931.-Erosion and Sedimentation in Port PRITCHARD, G. B., 1910.-The Geology of Melbourne. 8 Phillip Bay, Victoria, and their bearing on the theory vo, Tait, Melbourne. of a Recent relative uplift of the sea floor. Proc. PRITCHARD, G. B., 1944.-0ld Yarra History. 8 vo, Roy. Soc. Viet., Vol. 43, pp. 130-153. Cheshire, Melbourne. KEBLE, R. A., 1946.-The sunklands of Port Phillip and SELWYN, A. R. C., 1854.-0n the geology, palaeontology Bass Strait. Mem. Nat. Mus. Melbourne, Vol. 14, and mineralogy of the country situated between Mel­ pp. 69-122. bourne, Western Port Bay, Cape Schanck and Point Nepean. Parliamentary Paper. KEBLE, R. A., 1950.-The Mornington Peninsula, Geol. SINGLETON, F. A., 1941.-The Tertiary geology of Aus­ Surv. Viet., Mem. 17. tralia. Proc. Roy. Soc. Viet., Vol. 53, pp. 1-125. KEBLE, R. A., and MACPHERSON, J. H., 1946.-The con­ THIELE, E. 0., 1906.-An example of stream capture near temporaneity of the river terraces of the Maribyrnong Melbourne. Vic. Nat., Vol. 23, pp. 101-104. River, Victoria, with those of the Upper Pleistocene of Europe. Mem. Nat. Mus. Melboume, Vol. 14, THOMAS, D. E., and BARAGWANATH, W., 1950.-Geology pp. 52-68. of brown coals of Victoria, Pt. 3, Min. & Geol. Jour. Viet., Vol. 4, part 2, pp. 41-63. KITSON, A. E., 1902.-Further notes on the River Yarra WHINCUP, S., 1944.-Superficial sand deposits between improvement sections at the Botanical Gardens, Mel­ Brighton and Frankston, Victoria. Proc. Roy. Soc. bourne. Proc. Roy. Soc. Viet., Vol. 15, pp. 41-46. Viet., Vol. 56, pp. 53-76. 19

CHAPTER 3. GENERAL GEOLOGY OF THE MELBOURNE AREA

In this chapter the various rock formations represented are considered in conventional order of decreasing age. 3-1 SILURIAN Rocks of Silurian age form the basement or " bedrock " of the entire Melbourne area. They outcrop at the surface over extensive areas in the eastern suburbs where they give rise to distinctive soil types and may be seen in various stages of weathering in shallow excavations. Elsewhere they underlie to depths of many thousands of feet all the other formations recognized with the exception of the granitic intrusions. The rocks of the Silurian System are described in two parts :­ (1) Structure and Stratigraphy. (2) Sedimentary Petrology and Palaeontology.

STRUCTURE AND STRATIGRAPHY R. G. Whiting. 1

GEOLOGICAL STRUCTURE. section by Thomas and Keble ( 1933) illustrating The structure shown on the map is a broad their work in the Jackson's Creek-Keilor area, interpretation based on a limited number of exposures though it was not there specifically designated as the especially in the more settled areas of the city and Keilor anticline. The detailed structure at Keilor is suburbs. Interpolation and extrapolation have been somewhat complex, but there is little doubt that the freely indulged in for the sake of presenting a overall picture is that of a highly crenulated anticline reasonably complete picture. In many instances with a north-south strike. near the margins, information outside the boundaries The general strike of the folds over most of the of the map has had a bearing on the interpretation Melbourne area is N 20°-25°E with a tendency presented. The field work has in the main been of for a group of folds to assume a strike of N 10°- a reconnaissance nature and many of the obser­ 150E in the south central part of the map. The vations shown have been estimated. In the latter Keilor anticline assumes the normal regional strike stages of the work many strikes and dips were where it crosses the Moonee Ponds Creek near measured. In a few instances information from the Broadmeadows. Quarter Sheets of the Geological Survey of Victoria was used where exposures are not now available. The synclinoria are the Bulleen syncline (Jutson 1911 b), the J anefield synclins, the Merriang Folding. syncline (Jutson 1908) and the Bulla syncline The general structure is shown to consist of (Thomas and Keble 1933). The latter two are not concertina type folding of an average wave length shown on the map as the area where they would of about three quarters of a mile. Four anticlinoria occur is covered by basalt. The Merriang syncline and four synclinoria are recognizable, the former is a deep structure where mapped to the north by being the W arrandyte anticline (Jutson 1911 b) , the Jutson and in view of the remarkable continuity of Templestowe anticline (Jutson 1911 b), the Whittle­ most of the folds it is reasonable to assume its sea anticline (Jutson 1908) and the Keilor anticline. existence and structural importance under the basalt Jutson's Whittlesea anticline was mapped by him about 5 miles east of the Keilor anticline. The Bulla in the immediate vicinity of Whittlesea and syncline was mapped by Thomas and Keble just passes under Newer Volcanics not far south of this outside the boundaries of the map and would cross area. There is little doubt however that the structure the extreme north-west corner under the basalt. The shown here as the Whittlesea anticline is the same J anefield syncline is also not clearly indicated on as that mapped by Jutson and that it has retained the map, but shows in a gully east of Plenty-road its structural significance in the Melbourne area. The near Janefield a little to the north of the boundary Keilor anticline is indicated at the east end of a of the map.

1 Manuscript dated 13th March, 1959. 20

There are two characteristics which are worth south independently and not in alignment with each special mention. The first is that between the Jane­ other before the Studley Park zone suffered any field syncline and the Templestowe anticline the appreciable compression. As the folding movement west dips are generally somewhat steeper than the progressed this severe lack of alignment required east dips. This characteristic applies also between some compensation where the folds approached each the Bulleen syncline and the W arrandyte anticline, other from north and south. The Studley Park fault while the eastern limb of the Templestowe anticline zone is seen then as a zone of adjustment between exhibits steep easterly dips. The second notable these independent folding movements. This hypo­ feature in the eastern half of the map is the general thesis is not in disagreement with Hills' mapping proximity of the synclines to the anticlines on their and accords with his remark quoted above con­ west. The combined effect of these two features is cerning the genetical relationship of the folding and to give a step like structure in which the flatter faulting (See Plates 9, 10). easterly dips form the short " treads " of the steps The nearest known major fault to the Melbourne and the steeper westerly dips form long " rises ". area is the Selwyn fault. This has a general N 20°E. Few observations are available in the western half, trend and passes up the eastern side of Port Phillip but so far as can be seen this general pattern Bay from Dromana to Frankston. Originally appears to be reversed. regarded as of Tertiary age, the line of this fault The relative crowding of folds in the southern passes up the western edge of the Dandenongs and portion of the area probably results in much less through the Yering area. West of this line folding structural relief here than in the north. of the Silurian rocks is on a N 20°E strike, while east of it the folding strikes N 35°W. This suggests Much minor folding is observable particularly in that this line represents a Palaeozoic fault on each brick pits, but these folds do not appear to persist side of which are more or less independent fields far in strike. of folding, the Tertiary movements having followed the old line of weakness. Faulting. Faults and warps which appear to be subsidiary Throughout Victoria folding of the type occurring movements to the Selwyn fault, though not neces­ in the Melbourne area is observed to be accom­ sarily any older than Tertiary age are the Brushy panied by minor faults. Small reverse strike faults Creek fault (Jutson 1911a) which passes east of and transverse faults termed " cross-courses " in the Wheelers Hill and the Beaumaris monocline which mining fields are usually common. Such faults can be seen in the cliffs at Beaumaris. These undoubtedly occur also in Melbourne. There is structures are sub-parallel to the Selwyn fault. evidence of one of these transverse faults in the New The marked difference in elevation between the Northcote brick pits at Tally Ho. Larger strike western suburbs with their basalt flats and the faulting may be present but has not been observed. eastern suburbs with their more dissected Silurian An area of intense faulting worthy of special note rocks with occasional Tertiary capping, suggests that is the Studley Park fault zone. This area is marked the western area may be downfaulted by another on the map with purely arbitrary boundaries. It such subsidiary movement sub-parallel to the Selwyn has been mapped by Hills on a scale too detailed to fault. This movement may approximate in position be presented here. On the origin of faulting here to that of the Janefield Syncline. he remarks : " It . · . appears that the faults and folds are genetically related " (Hills, 1941). Pitch Effects. A glance at the map indicates that the anticline On the basis of the limited available information. in the Barkers-road cutting south of. the fault zone on the pitch of the folds Figure 1 shows a reduced fails to align with what is apparently the matching scale plan divided into a number of areas exhibiting anticline north of the zone by about half a mile. regional pitches. The central area, comprising the The same discrepancy would appear to apply to the northern part of Melbourne City and some northern syncline west of this anticline. The syncline is not and eastern suburbs, exhibits a predominantly exposed north of the fault zone due to the basalt southerly pitch while the southern part of Melbourne cover in this area, but Hills' mapping indicates that is north pitching. Two other regions occur to the it must lie to the west of the sharp bend in the north and a fifth region shown coming into the river a little over half a mile west of the Chandler north-east corner is based on information outside Highway bridge. Other folds adjacent to the fault the area. The lines bounding these regions are zone appear to have no such lack of alignment. It designated as "Pitch Crests" and "Pitch Troughs". is difficult to imagine therefore that the unaligned The terms are self explanatory. These lines are folds have suffered any translational movement of the shown as being relatively straight, but such pitch order of half a mile due to faulting. An explanation changes where detailed observations are available that is suggested is that, for this part of the field, in goldfield areas are seen to be somewhat irregular. the folding movements commenced to the north and However, the zones are of the order of 4 miles 21 wide and deviations of the lines by the order of As continuous exposures are not available, half a mile would have no important bearing on the accurate estimates of thickness of beds cannot be general structural picture. Pitches observed are given, but it may be inferred from the cross section sometimes as high as 30°, but probably average that the total stratigraphic thickness of Silurian 10°-15°. The lowest beds stratigraphically might rocks in the area of the map is of the order of be expected to occur where the main anticlinoria 12,000 feet of which 6,000 to 7,000 feet may be cross the pitch crests and the highest beds where Keilorian and 5,000 to 6,000 feet Melbournian. pitch troughs cross synclinoria. Such limited palaeontological evidence as is available appears REFERENCES CITED. generally to confirm this picture. GEOLOGICAL SURVEY OF VICTORIA, 1860.-Quarter Sheets Nos. IN.W., IN.E., IS.W., IS.E. STRATIGRAPHY. GILL, E. D., 1952.-0n the Age of Bedrock between The Silurian rocks are regarded as resting con­ Melbourne and Lilydale, Victoria. The Victorian formably on Upper Ordovician rocks to the north­ Naturalist, Vol. 69, No. 4, pp. 41-47. west of Bulla and Sydenham (Thomas and Keble, GREGORY, J. W., 1902.-The Heathcotian-a pre-Ordo­ vician Series and its Distribution in Victoria. Proc. 1933). Roy. Soc. Viet., Vol. 15, Pt. 2, pp. 148-175. Within the Silurian the stratigraphic sequence HILLS, E. S., 1941.-The Silurian Rocks of the Studley recognized in the Melbourne area is (descending Park District. Proc. Roy. Soc. Viet., Vol. 53, Pt. 1, order):- pp. 167-191. Melbournian. JuTsoN, J. T., 1908.-The Silurian Rocks of the Whittle­ sea District. Proc. Roy. Soc. Viet., Vol. 21, Pt. 1, Keilorian. pp. 211-225. The Keilorian was defined by Thomas and Keble JUTSON, J. T., 1911a.-A contribution to the physiography (1933) from their work in the Keilor area and is of the Yarra River and Dandenong Creek Basins, Victoria. Proc. Roy. Soc. Viet., Vol. 23, Pt. 2, pp. regarded as being equivalent to the Llandovery of 499-515. the British sequence. The Melbournian, defined JuTSON, J. T., 1911b.-The Structure and General Geology by Gregory ( 1902), is regarded by Thomas and of the Warrandyte Goldfield and Adjacent Country. Keble as being equivalent to the Ludlow in the Proc. Roy. Soc. Viet., Vol. 23, Pt. 2, pp. 515-554. British sequence. So far no equivalent to the British THOMAS, D. E., 1947.-The Geology of the Eildon Dam middle member, the Wenlock, has been determined. Project. Memoir No. 16, Geological Survey of Vic­ It may be absent, present but unfossiliferous, or the toria, 57 pp. fossiliferous equivalent may yet be found. It may THOMAS, D. E., and KEBLE, R. A., 1933.-The Ordovician and Silurian Rocks of the Bulla, Sunbury Area and perhaps be equivalent to the unfossiliferous interval a discussion of the Sequence of the Melbourne Area. referred to by Thomas as Eildonian (Thomas, Proc. Roy. Soc. Viet., Vol. 45, Pt. 2, pp. 33-84. 1947). As might be expected in a heavily built up area the palaeontological evidence is yet rather OTHER REFERENCES. sparse. GILL, E. D., 1940.-The Silurian Rocks of Melbourne and Keilorian beds occur at the type area at Keilor. Lilydale. A discussion of the Melbournian-Y eringian Upper Ordovician or Lower Silurian rocks occur boundary and associated problems. Proc. Roy. Soc. near the old Diamond Creek mine on the Temple­ Viet., Vol. 52, Pt. 2, pp. 249-261. stowe anticline just north of the map boundary. GILL, E. D., 1942.-0n the Thickness and Age of the Type Yeringian strata, Lilydale, Victoria. Proc. Roy. Illaenid forms found on the western flank of the Soc. Viet., Vol. 54, Pt. 1, pp. 21-58. Templestowe anticline (Gill, 1952) in the vicinity HAUSER, H. B., 1923.-The Geology of Studley Park. of Koonung Koonung Creek indicate beds low in Proc. Pan. Pac. Sci. Congr., Vol. II., pp. 1648-1654. the Silurian~probably Keilorian. JuNNER, r-:. R., 1913.-General and Mining Geology of Melbournian beds occur in the Bulla syncline, the Dramond Creek Area. Proc Roy. Soc Viet., Vol. in the Yarra valley in the vicinity of Melbourne City 25, Pt 2, pp. 323~353. and Richmond, on the Moonee Ponds Creek and NICHOLLS, ANN, 1930.-The Structural Features of the in the Studley Park area. Silurian Rocks in the Melbourne District Proc. Roy. Soc. Viet., Vol. 42, Pt. 2, pp. 129-134. The fossil content of these stages is described in the next section of this bulletin. ILLUSTRATIONS. Figure 1 shows the area divided into a shaded TEXT FIG. 1.-Idealized plan showing structure of the and an unshaded portion. The dividing line cannot Silurian bedrock and the approximate relationship be regarded as a boundary as there is not sufficient between the Melbournian and Keilorian stages. palaeontological information available for this. It TEXT FIG. 2.-Cross-sections of the Silurian rocks. is rather a structure contour drawn in such a position Section A. Through Doncaster Junction and Merlyn­ that the shaded area includes all the known Mel­ stan Station. bournian fossil localities and the unshaded area all Section B. Through Camberwell Station parallel to the Keilorian localities. Section A. /,?\..0/ ? ~If . Thomastown I ':'-."~" ? tl/)('-( t~0/J..? ' • 0

N N

fvfelbournian 0 I 2 Keilorian Scale of Miles / Jackson's Creel<. / / Deep Creel<. < / / /Bullo Syncline "' " "" Merriang Syncline < I " " Keilor Anl/clt'ne" ~ " /" > \ Moonee Ponds Creek. ( "' ( \ ~ ) < <> Whittlesea Anticline ) _ 1 1-<---+-)_Moonee Ponds Creek, I > / 0 / '"'0.. I A 0 < < "' < << > 0 >~ ~. I 0 I i:T 0 0 ::l < ::l <. c s. ) / . I > 20 / Yarra Rrver. I ::l Merr/ong I syncline I (j) >-:1 m Merlynston Station. tTl <( Is:~ () ...... o- ( ...... 0 k---'''--- ~Mrn' Creek. q 0 I ::J \ \ I~ A ')I; 'TI ro I ~-· \ \ 0 -· ' 0 llD Q '{::J ~ N c;· . ' Whlttleseo Anticline\ ~ ::l I. ' camberwe/1 Station. _... I / // I // Templestowe Anticline < <:. Bulleen Syncline < I ~ _...'> I ..-> Janefleld<(/Syncllne <'~Oorebin Creel<...... "> 1,-/ Creek / <') \ / ~>~Yarra River. <.. <...... Warrandyte Anticline ' ') ) <... / ...... 0 Templestowe Anticline'

(f) 5 n c ...... _... <1> - -dUI!een Syncli - 0 - ...... _ 4-- Doncaster Junction. N _, ...... 3 z ~ ...... (JJ "''" '< ...... I ~ +> >

~ ...... Warrandyte Anticline '-...

sz 24

SEDIMENTARY PETROLOGY AND PALAEONTOLOGY

John A. Talent.

SEDIMENTARY PETROLOGY. Keilor contain well rounded pebbles and even The Palaeozoic rocks of the Melbourne area cobbles of silty sandstones as well as pebbles of consist of thousands of feet of monotonous pelitic reef quartz and black chert. The most striking and psammitic sediments of Silurian age charac­ feature of these sediments is that within the same terized by the apparent absence of well washed beds there are angular and partly rounded fragments quartz sandstones, by the general absence of very of siltstone of sizes up to about 6 or 7 ems. with coarse sandstones and conglomerates, by the domi­ some fragments " frozen " in such a position as to nance of pelitic over psammitic sediments, and by demonstrate that they were being torn from the a general paucity of fossils. underlying bed. The deposit owes its origin to slumping and in this locality the slumping mass had The pelitic beds are composed of non-calcareous been ripping up the substratum. dark blue-grey and occasionally greenish-grey clay­ stones and clayey siltstones weathering to pale-grey, If one omits from consideration the fossiliferous yellowish and brownish tints with segregation of beds containing brachiopods, mollusks and corals limonite along bedding planes, joints and fractures. there is a remarkable rarity of beds containing an The mudstones may be laminated, and between appreciable propo!tion of carbonate. Two excep­ individual laminae there may be a pronounced tiOns are sandy siltstones from the foundations of oscillation in grain size and in the proportion of fine the I~ings Bridge (Table 1, column 5), and quartz grains to the ever dominant paste. Fissile matenal from beneath the water table in a sediments are invariably subordinate to fairly mas­ sewerage excavation in College-crescent, Carlton. sive structureless clayey siltstones, or clayey siltstones The former is unfossiliferous, but in the latter there possessing only poorly developed bedding plane is an abundance of recognizable shell material fissility. There are high alumina claystones and (brachiopods and bryozoans) in addition to isolated calcite crystals scattered through the matrix. Both silty claystones with more than 22% Al20 3 , but there are no carbonaceous types, although irregular examples are from beneath the water table and films of carbon may occur along the bedding planes ser~e to emphasize. that, in dealing with psammitic at some localities. The siltstones are occasionally sediments outcroppmg at the surface or exposed in micaceous along the bedding planes, and at a few shallow excavations in the Melbourne area, localities, e.g., in the cliff immediately downstream allowance should be made for possible leaching of along Moonee Ponds Creek from Dawson-street carbonates. bridge, Brunswick, there are clearly defined ovoid Tables 1 and 2 chemically and mineralogically bodies of siltstone corresponding in composition to demonstrate the compositional immaturity of the the host rock. The inorganic problematica " Can­ coarser grained sediments of the Silurian of the cellophycus " and "Spirophyton " were abundant in Melbourne . area. The general close intermixing of a belt of clayey siltstones exposed in excavations the sand-sized quartz grains with the silt- and along Burke-road, Ivanhoe. clay-sized debris indicates deposition from viscous Most of the psammitic sediments of the Melbourne me~ia-turbidity flows, with little or no subsequent area are carbonate-free silty sandstones with between sortmg. 25% and 65% of the rock composed of rounded TABLE L quartz grains distributed through a paste of sericite, Mineralogical Composition of Silurian "Sandstones" of quartz, chlorite and clay minerals. Flakes of the Melbourne District. muscovite over 0 · 1 mm. in length are a common Mineral 1 2 3 4 5 6 7 component but rarely exceed 0 · 5% of the rock. ------The muscovite tends to be concentrated along the ---- bedding planes. Fresh felspar is found only in the Quartz .. 63·5 56·3 44·7 27·4 25·3 15 ·1 11·6 deeper parts of brick pits, and when present does Felspar . . .. 0·7 . . . . 0·3 2·7 6·8 Muscovite tr. 1·9 .. .. 0·7 tr. 0·2 not exceed 1% of the rock. Exceptions to this rule Rock Fragmen:t~ ...... are the sandstones associated with the conglomerate Calcite .. 3·6 .. at Keilor (Table 1, columns 6 and 7) where felspar Paste .. .. 36·5 41·1 55·3 72·6 70·1 82·7 81·4 is an appreciable component indicating either a more felspar-rich source than usual, or a lesser 1. Dight's Falls, Studley Park, Kew. degree of maturity. The irregular beds of conglo­ 2. Dight's Falls, Studley Park, Kew. merate associated with these latter sandstones at 3. At 130 feet in a bore at Austral Bakeries. Clayton. 25

4. South bank of Maribyrnong River, at the old Geological Some species of plectambonitid, chonetid and Survey of Victoria fossil locality Ba 29 and 36, rhynchonellid brachiopods are characteristic of the approximately one mile SSW of the bridge over Melbournian beds of central Victoria. Numerous the Maribyrnong River at Keilor. species of mollusks have been " desqribed from 5. Foundations of Kings Bridge, Melbourne. the Melbournian of the Melbourne area, but 6. Associated with conglomerate outcropping on the south none of these belong to short ranging genera bank of the Maribyrnong River one half mile and none of the species, with the possible NNW of the bridge over the Maribyrnong River exception of Ctenodonta (s.l.) victoriae, can at Keilor. be described as being a distinctive zone fossil. 7. Same locality as 6. Pelmatozoans are an important element in the Melbournian fauna, but the apparent restriction of TABLE 2. each species to a single locality makes them of Chemical Analyses of Silurian Sedimentary Rocks from little stratigraphic use. No corals have yet been New Nortlzcote Brick Pit, Croxton, compared with found with the shell material preserved, so that all Analyses of Two "Well Washed" Sandstones from the forms described to date defy adequate treatment. Ordovician of Victoria. The graptolites, occurring al\ke in the Keilorian and Melbournian, are stratigraphically the most im­ 1 1 2 portant group. _-_ \__3~-4 \_s __6 \_7 1 The best locality for collecting Silurian fossils in sio. 76·7o 65·10 67·00 43·20\51·4095·10 92·18 the Melbourne area is the cliff immediately up­ Al20 3 12·24 19·06 17·26 17·57 22·56 0·42 1·59 stream along Moonee Ponds Creek from the 2 13 Fe20 3 } 3·46 3·57 4·44 19·91 4·67 2·03 { ' Ormond-road-Brunswick-road bridge, Brunswick. FeO 2·00 The older descriptions of Melbourne fossils from Ti02 0·70 O· 87 0·80 0·17 0·17 MgO 1·37 2·28 1·88 1·44 2·13 0·17 0·27 " Flemington ", " Moonee Ponds Creek " and CaO tr. tr. tr. tr. tr. nil tr. "West Brunswick" refer to this locality. It yields an f 0·15 Na.o} 1·73 4·20 3·32 5·51 4·67 undet. l_ abundance of moulds of rhynchonellid brachiopods K.o tr. long referred to as Rhynchonella decemplicata H 20+ 2·85 3·90 3·70 6·70 6·50 1·81 1·86 H 20- 0·95 1·02 1·60 5·50 7·90 0·17 0·19 Sowerby in association with occasional other rhynchonellid brachiopods, comparatively rare 100·00 100·001100·00 100·00 100·00199·70+ 100·37 plectambonitid, orthotetid, dalmanellid and inarti­ culate brachiopods, occasional lamellibranchs, par­ NoTE.-Analyses 1 to 5 appear to have been recalculated ticularly Ctenodonta (s.l.) victoriae, gastropods, on a 100% basis. The chemical analyses given in this cephalopods, moulds of rugose corals and bryozoans, table are old analyses. No sample of the silty sandstone and the remains of trilobites. It is the type locality, from New Northcote brick pit was preserved so that no for instance, of the trilobite Trimerus harrisoni corresponding mineralogical composition could be listed in Table 1. The locality is described by Bain and Spencer­ McCoy. Jones (1952, Min. and Geol. Jour. Viet., 4, pt. 6, pp. 14, 15). Other permanent exposures to yield occasional 1. Silty sandstone, New Northcote Brick Pit. Silurian shelly fossils are : the railway cutting wesu 2. Blue-grey "mudstone", New Northcote Brick Pit. of Royal Park railway station, the outcrops along 3. Pale yellow "mudstone ", New Northcote Brick Pit. Moonee Ponds Creek about Dawson-street bridge, 4. Ferruginous "mudstone", New Northcote Brick Pit. and the west end of Studley Park, particularly the 5. Grey claystone, New Northcote Brick Pit. old road from Johnston-street bridge to the Pump­ 6. White Ordovician quartz sandstone, Bradshaw Creek. ing Station. This last locality was the source of 7. Ordovician quartz sandstone, Ironbark Mine, Eag!ehawk. the graptolites described by 0. A. Jones (1927). Lower Silurian graptolites have been collected from several localities about Keilor; these are indicated PALAEONTOLOGYo on the geological map. Otherwise the chief localities As a general rule fossils are uncommon in the are brick pits and temporary excavations for foun­ Silurian sediments of the Melbourne area and more­ dations and the laying of pipes. These will occa­ over there are some thousands of feet of section sionally yield brachiopods and graptolites and on which have yet to yield a single fossil. Benthonic rare occasions a starfish or two, the shelly fossils fossils are extremely rare in the Keilorian being typically concentrated in the basal conglome­ (Llandovery) rocks of the mapped area, but in the ratic or mud-clast-bearing part of graded beds. Melbournian (Lower Ludlow) beds of Melbourne, Exotic forms, for example, the jellyfish South Yarra, Carlton and Brunswick they are " Discophyllum " mirabile found in Hoffman's brick reasonably common at restricted localities and in pit, Brunswick, and the carpoid echinoderm general are more common than graptolities. As a Victoriacystis aff. wilkinsi found in the City Brick general rule the preservation is poor and it is often Co. pit, Camberwell-road, Hawthorn, are discovered impossible to make meaningful determinations. every few years. 26

Faunal and Floral Lists. ECHINODERMATA. The following lists include only those indentifica­ CARPOIDEA. tions which have been supported by a figure or some Victoriacystis afl wilkinsi Gill & Caster. form of descriptive citation. An attempt has been made to bring the generic placements of the various MOLLUSCA. species up to date, but in many cases reassignment must await a monographic investigation. Where an GASTROPODA. identification has been made with a species originally Straparollus (Euomphalus) holzeri (Pritchard). described from outside Victoria and the identifica­ tion appears to be in error, reference to the species MELBOURNIAN has been omitted and only a generic identification PLANTAE. has been included. The descriptions and figures of the various species can be found in the works Buthotrephis gracilis Hall. listed in the bibliography. B. sp. It will be seen from these lists that a great COELENTERATA. number of species of invertebrates have been HYDROZOA. described from the Melbournian of the Melbourne Conularia ornatissima Chapman. area, but many of these forms are in need of 5 restudy, preferably on better preserved material "Discophyllum" mira bile (Chapman) • than was available to their original describers. It 0 Ref~rred to Parapsonema Clarke, 1902, by H. J. Har­ is therefore a matter of some importance to examine nngton and R. C. Moore (1956, Treatise Invert. Paleont. Part F), but differs from Parapsonema in all new excavations in the quest for better preserved having but a single cycle of "knotted" radial bands, material, and in particular any material that has and from Discophyllum Hall, 1847, in having the the shell preserved. bands " knotted ". ANTHOZOA. KEILORIAN "Columnaria" flemingtonensis (Chapman). 1 ARTHROPODA • "Lindstroemia" conspicua (Chapman). TRILOBITA. Rugosa indet. Asaphus sp. 2 Cheirurus sp. 2 ECHINODERMATA. Thomastus jutsoni (Chapman). CRINOIDEA. Botryocrinus longibrachiatus Chapman. 1 A wide variety of invertebrates has been recorded by F. Chapman (1932, Roy. Soc. Viet., 44, pt. 2) from Hapalocrinus victoriae Bather. Keilorian beds west of the mapped area. Heliocrinus plumosus Chapman. 2 Note at township of Keilor on quarter sheet 1 N.W. of the old geological survey. The locality has not been ASTEROIDEA. relocated. Baliactis flemingtonensis (Withers & Keble).

3 Eoactis stachi (Withers & Keble). GRAPTOLITHINA • Petraster angustior Withers & Keble. Monograptus exiguus (Nicholson). P. smythi McCoy. M. spp. Promopalceaster meridiana lis (Etheridge). Stomatograptus australis (McCoy). P. meridionalis parvior Withers & Keble. s Numerous species of graptolites have been recorded by Schuchertia macrarta Withers & Keble. D. E. Thomas and R. A. Keble (1933) and described by W. J. Harris and D. E. Thomas (1949, Min. and Yarravaster yarraensis (Withers & Keble). Geol. Jour. Viet., 3, pt. 5) from Keilorian beds west of ue mapped area. OPHIUROIDEA. Eospondylus tenuis Withers & Keble. ? KEILORIAW. Furcaster leptosomoides (Chapman). 4 From the City Brick Co. pit, Camberwell-road, Hawthorn. Gregoriura spryi Chapman. Lapworthura pulcherrima Withers & Keble. COELENTERATA. Stiirtiaster sp. aff. S. mitchelli Etheridge. RUGOSA. Stiirtzura. brisingoides (Gregory). ? "Lindstroemia " scalm·is (Chapman). Urosoma? bakeri (Withers & Keble). 27

VERMES MOLLUSCA INCERTAE SEDIS. Keilorites crassituba (Chapman) Hyolithes spryi Chapman H. sp. BRYOZOA Indeterminate Trepostomata SUPPOSED MOLLUSCA. "Capulus melbournensis" Chapman BRACHIOPODA INARTICULATA" ARTHROPODA Lingula? fiemingtonesis (Chapman) TRILOBITA. L. ? spryi (Chapman) L. ? yarraensis (Chapman) Raphiophorus jikaensis (Chapman) L. ? sp. R. yarraensis (Chapman) Petrocrania? lata (Chapman) Calymene sp. "Siphonotreta" australis (Chapman) Encrinurus spryi Chapman 6 The generic location of the seven species of inarticulate Otarion spryi (Gregory) brachiopods cannot be determined from published descriptions and figures. Phacops sp. Trimerus harrisoni (McCoy) ARTICULATA " Chonetes " melbournensis Chapman MEROSTOMATA. Dalmanellacea-an undescribed species Pterygotus australis McCoy Orthotetacea-an undescribed species Plectambonitacea-several species SUPPOSED PHYLLOCARIDA. Rhynchonellida-several species "Aptychopsis victoriae " Chapman 7 Stegerhynchus sp. " Ceratiocaris pinguis " Chapman 7 Known as Rhynchonel/a (or Camarotoechia or Plagior­ "Xiphidiocaris falcata" Chapman hyncha) decemplicata Sowerby in previous lists. MACHAERIDIA LAMELLIBRANCHIATA Plumulites sp.8 Actinopteria? sp. s The paratype median plate of Turrilepas ornatus Chapman Aviculopecten? spryi (Chapman) from South Yarra cannot be correlated with the Conocardium sp. holotype of the species, a single lateral plate from Ctenodonta? australis (Chapman) Yan Yean, Victoria, and so is excluded from that species. C. ? arcaeformis (Chapman) C. ? melbournensis (Chapman) GRAPTOLITHINA C. ? perobliqua (Chapman) C. ? portlocki (Chapman) Monograptus chimaera Barrande C. ? producta (Chapman) M. colonus Barrande C. spectabilis (Chapman) (? syn. C. lW. crinitus Wood victoriae) M. dubius (Suess) C. ? taylori (Chapman) M. roemeri Barrande C. ? spp. varians Wood9 C. ? (s.l.) victoriae (Chapman} M. Ditichia maccoyianus (Chapman) g Further species and varieties of Monograptzw from localities . within the Melbourne area are listed by " Grammysia" abbreviata Chapman D. E. Thomas and R. A. Keble (1933). Modiolopsis? melbournensis (Chapman) M. ? sp. "Modiolopsis" australis Chapman REFERENCES.

GASTROPODA. SEDIMENTARY PETROLOGY Several undescribed, but poorly preserved species. HILLS, E. S., 1941.-The Silurian rocks of the Studley Park district: Proc. Roy. Soc. Victoria, Vol. 53 (n.s.), .. pp. 167-191. CEPHALOPODA. LANGFORD, W. G., 1916.-The petrology of the Silurian Dawsonoceras? sp. sediments near Melbourne: Ibid., Vol. 29 (n:s.), Orthocones indet. pp: 40-A9. . 28

PALAEONTOLOGY OF THE SILURIAN GREGORY, J. W., 1901.-Cyphaspis spryi, a new species of trilobite from the Silurian of Melbourne: Proc. Roy. BATHER, F. A., 1897.-Hapalocrinus victoriae n.sp., Soc. Victoria, Vol. 13 (n.s.), pp. 179-182, Pl. 22. Silurian, Melbourne, and its relation to the Platycrinidae: Geol. Mag., dec. 4, Vol. 4, pp. 337- HALL, T. S., 1899.-The grapto•lite-bear:ing rocks of Victoria, 345, Pl. 15. Australia: Geol. Mag., 1899, pp. 438-451. BLANDOWSKI, W., 1858.-0n extensive Infusoria deposits HARRIS, W. J., and THOMAS, D. E., 1937.-Victorian in the Mallee scrub, &c., and on the presence of Graptolites (New Series)-Pt. IV: Mining and Geol. Fucoidae in Silurian rocks near Melbourne: Trans. Jour. Viet., Vol. 1, Pt. 1, pp. 68-79. Phil. Inst. Victoria, Vol. 2, pp. 141-146, 2 Pls. LucAs, A. H. S., 1927.-0n an additional occurre~ce _of CHAPMAN, F., 1903.-New or little-known Victorian fossils Bytlzotrephis in Victoria: Mem. Nat. Mus. V1ctona. in the National Museum: Pt. 1, Some Palaeozoic No. 7, pp. 157, 158, Pl. 14. species: Proc. Roy. Soc. Victoria, Vol. 15 (n.s.), JoNES, 0. A., 1927.-Silurian graptolites from Studley pp. 104-122, Pls. 16-18. Park, Melbourne: Geol. Mag., Vol. 64, pp. 101-105, CHAPMAN, F., 1903.-Ibid.: Pt. 2, Some Silurian Mollus­ Pl. 5. coidea: Ibid., Vol. 16 (n.s.), pp. 60-82, Pls. 10-12. McCoY, F., 1874-1882.-Prodromus of the palaeontology CHAPMAN, F., 1904.-Ibid.: Pt. 3, Some Palaeozoic of Victoria: Geol. Surv. Victoria, decades 1-8. Pteropoda: Ibid., Vol. 16 (n.s.), pp. 336-342, Pl. 31. McCoY, F., 1899.-Note on a new Australian Pterygotus: CHAPMAN, F., 1904.-Ibid.: Pt. 4, Some Silurian Ostracoda Geol. Mag., dec. 4, Vol. 6, pp. 193-194. and Phyllocarida: Ibid., Vol. 17 (n.s.), pp. 298-319, PRITCHARD, G. B., 1944.-0ld Yarra history as told by Pls. 13-17. the geology of Burnley, Heyington, Tooronga: CHAPMAN, F., 1905.-Ibid.: Pt. 6, Notes on Devonian Cheshire, Melbourne, 32 pp. Spirifers: Ibid., Vol. 18 (n.s.), p. 19-Note on Lingula. SPENCER, W. K., 1950.-Asterozoa and the study of the Palaeozoic faunas: Geol. Mag., Vol. 87, pp. 393-408. CHAPMAN, F., 1907.-Ibid.: Pt. 8, Some Silurian brittle­ stars of the Melbournian Series: Ibid., Vol. 19 THOMAS, D. E., and KEBLE, R. A., 1933.-The Ordovician (n.s.), pp. 21-27, Pls. 6-8. and Silurian rocks of the Bulla-Sunbury area, and discussion of the sequence of the Melbourne area: CHAPMAN, F., 1908.-A monograph of the Silurian Proc. Roy. Soc. Victoria, Vol. 45 (n.s.), pp. 33-84. bivalved Mollusca of Victoria: Mem. Nat. Mus. Melbourne, No. 2, 62 pp., 6 Pls. WITHERS, R. B., and KEBLE, R. A., 1934.-The Palaeozoic starfish of Victoria: Ibid., Vol. 46 (n.s.), pp. 220-249, CHAPMAN, F., 1910.-A synopsis of the Silurian fossils of Pls. 10-12. South Yarra and the Yarra Improvement Works: Victorian Naturalist, Vol. 27, No. 4, pp. 63-70. WITHERS, R. B., and KEBLE, R. A., 1934.-The Palaeozoic brittlestars of Victoria: Ibid., Vol. 47, pp. 196-212. CHAPMAN, F., 1910.-New or little-known Victorian fossils Pl. 11. in the National Museum: Pt. 10, Some Palaeozoic worms and Crustacea: Proc. Roy. Soc. Victoria, Vol. 22 (n.s.), pp. 101-112, Pls. 27-29. CHAPMAN, F., 1911.-Ibid.: Pt. 13, Some Silurian species EXPLANATION OF PLATE 1. of the genus Lingula, &c.: Ibid., Vol. 24 (n.s.), pp. FIG. I.--Monograptus dubius (Suess), X 2, Royal Park 179-186, Pl. 45. (after Harris & Thomas, 1937). CHAPMAN, F., 1912.-Ibid.: Pt. 14, Some Silurian trilobites: Fro. 2.-Monograptlls chimaera (Barrande), X 3·5, Studley Ibid., Vol. 24 (n.s.), pp. 293-200, Pls. 61-63. Park (after 0. A. Jones, 1927). CHAPMAN, F., 1914.-0n the palaeontology of the Silurian FIG. 3.-Monograptlls roemeri (Barrande), X 3 · 5, Studley of Victoria: Rep. Aust. New Zealand Assoc. Adv. Park (after 0. A. Jones, 1927). Sci., 14th meeting, Melbourne 1913, pp. 207-235. FIG. 4.--Monograptus varians Wood, X 3 · 5, Studley Park ETHERIDGE, R., 1891.-0n the occurrence of the genus (after 0. A. Jones, 1927). Palaeaster in the Upper Silurian rocks of Victoria: Rec. Australian Mus., Vol. 1, No. 10, pp. 199-200, Fro. 5.--Hapalocrinus victoriae Bather, X 5, holotype, Pl. 30. South Yarra (after Bather, 1897). GILL, E. D., 1945.-Trilobita of the family Calymenidae FIG. 6.--" Discophyllum " mira bile (Chapman), X 0 · 5 from the Palaeozoic rocks of Victoria: Proc. Roy. approx., reconstruction of upper surface based Soc. Victoria VoL 56, pp. 171-186, PL 7. on holotype figured by Chapman (1926), GILL, E. D., 1945.-Chonetidae from the Palaeozoic Brunswick. rocks of Victoria and their stratigraphical signifi­ FIG. 7.-Aviculopecten? spryi Chapman, X 3, holotype, cance: Ibid., Vol. 57, pp. 125-150, Pl. 8. South Yarra (after Chapman, 1908). GILL, E. D., 1949.-Palaeozoology and taxonomy of some FIG. 8.-" Chonetes" melbournensis Chapman, X 3, Australian homalonotid trilobites: Ibid., Vol. 61, exterior of pedicle valve, South Yarra (after pp. 61-73, Pis. 8, 9. Chapman, 1903). GILL, E. D., 1952.-0n the age of the bedrock between Fro. 9.-Petraster smythi McCoy, X 2, holotype, Moonee Melbourne and Lilydale: Victorian Naturalist, Vol. Ponds (after McCoy, 1874, Pl. 10). 69, pp. 41-47. Fra. 10.-Trimerus harrisoni (McCoy), X 1, holotype, GILL, E. D., and CASTER, K. E., 1960.-Carpoid echino­ Moonee Ponds (after McCoy, 1876, Pl. 23). derms from the Silurian and Devonian of Australia: Bull. Amer. Paleontology, No. 185, 71 pp., 10 Pls. FIG. 11.-Lingula? spryi Chapman, X 3, Swanston-street, GREGORY, J. W., 1889.-0n a new species of the genus · Melbourne (after Chapman, 1903). Protaster (P. brisingoides) from the Upper Silurian of Fro. 12.-Ctenodonta (s.l.) victoriae (Chapman), X 2, Australia: Geol. Mag., dec. 3, Vol. 6, pp. 24-27. holotype, South Yarra (after Chapman, 1908). 29

2

6

8

10 II 12 PLATE 1. 30

VICTORIAN INTERNATIONAL MELBOURNE AREA TIME SCALE STAGE NAMES

Holocene (Recent) Alluvium,estuarine deposits, sand dunes etc: (see section on Quaternary) ....;:... 0...c Q) 0 -:::J Pleistocene 0

Werribee Plains Phase LEGEND NEWER VOLCANICS IIIII 172' Conformable or Transitional Greensborough Phase Upper contact. Pliocene ----Disconformity, diastem etc.

Lower RED BLUFF SANDS KALIMNAN ~ Unconformity. u Pliocene 78' ·a BRIGHTON GROUP N I [=SANDRINGHAM I LATERifiTiON ?I Period of erosion and I or 0 BLACK ROCK .E SANDS) I I I I non- deposition 0 ICHEL TENHAMIA N SANDSTONE u 48' Horizontal gradation or MITCHELL! AN? ~ I ensing. BAIRNSDALIAN? Miocene NOTE: Times 8 thicknesses are not ;:... ._ NEWPORT drawn to constant scale . ....0 BALCOMBIAN b. Q) I- BATESFORDIAN G;E~ ~L~ ~M;ST-;N£ 5,____> 169' FORMATION LONGFORDIAN? --- = Thin impure brown cool member-- Oligocene JANJUKIAN? ALTONA COAL SEAM 141'

WERRIBEE FORMATION (upper part)

IIIIIIIrrr ~- Eocene 1 OLDER VOLCANICS 139 241'?

WERRIBEE FORMATION (lower part) I J I J I 1 _l _l l MAJOR UNC[NFORMITY I I

Palaeozoic "'"'DEVONIAN ~"'"" SANDSTONES S. ~RANITIC ROCKS MUDSTONES

Stratigraphic table of Tertiary rocks in the Melbourne area. TABLE 3. 31 3-2 TERTIARY

1 P.R. Kenley • INTRODUCTION AND GEOLOGICAL the St. Kilda Silurian inlier where initial dips are SETTING. presumably radial, the Tertiary sediments generally exhibit a very low regional dip to the south-west Melbourne is situated in the north-eastern part or west-south-west of the order of 50-75 feet per of a sedimentary trough known as the Port Philip mile, each formation in turn passing down dip Sunkland, in which sedimentation proceeded beneath the waters of the Bay. This dip evidently with only minor interruptions throughout most of represents the combined effect of initial dip and Cainozoic time. gentle basinward tilt imparted during the sinking A wide range of marine and terrestrial deposits of the basin. The regional picture is modified in was laid down in this trough and a number of the southern and south-eastern suburbs by a series distinct formations, each distributed over a wide of low amplitude undulations or minor folds. area, has been recognized (Table 3). The stratigraphic relationships of the various deposits Detailed accounts of these geological structures are illustrated in idealized fashion in Fig. 3. This are given later in this section. diagram summarizes features shown in detail in Plate 7. General Featmes of the Tertiary Sediments and their Relationships with the Older Rocks. Major Structural Features. Broadly speaking the area to the south and south­ A broad gentle N.W.-S.E. directed flexure west of Melbourne is underlain by a wedge-shaped known as the Melbourne Warp (Gill 1961, p. 131; section of marine and near shore terrestrial Tertiary Plate 2) forms the north-eastern margin of sediments and lavas which achieve a thickness of continuous outcrops of the Tertiary sediments 662 feet at Altona and probably considerably more south-east of Melbourne. This flexure has evidently beneath the waters of the Bay. These rest un­ served repeatedly as a hinge structure separating conformably on a comparatively level fossil erosion predominantly land areas to the north-east from the surface (the Nillumbik Terrain) which was planed generally subsiding sedimentary basin to the south­ in Silurian sediments and Upper Devonian granitic west. rocks. Only minor topographic irregularities have The triangular Brighton-Cheltenham block (Plate been recognized in this surface (e.g., St. Kilda inlier). 2) experienced a somewhat different geological Generalized contours drawn on the surface at the history from the adjoining parts of the basin as a base of the Tertiary sediments are shown in Plate 2. result of movements of elevation on small bounding flexures (the Beaumaris Monocline and Anonyma Variation of Sedimentary Facies. Flexure) which occurred several ·times during the Several features of the sediments show a regional Cainozoic Era. These movements resulted south-westerly trend. For example, the grain size in non-deposition or erosion of the thick sands of of particular formations tends to decrease and the the Werribee Formation on the structurally raised formation thickness increase as the distance from Brighton-Cheltenham block. There are also the margin of the basin increases (Gill, 1947). lithological differences between the Newport Forma­ Other characters such as the quartz content of the tion in this area and in the area to the west of Newport Formation vary from place to place parallel Hobson's Bay. to the Tertiary coastline, presumably due to lateral Except in the vicinity of the Beaumaris Monocline changes in the character of the adjoining hinterland where dips are locally south-easterly, and around and of the sea floor. r- sw NE -1 Nt.WER VQLCANICS (GreensbDrough Phase)

TEXT FIG. 3.-Diagrammatic cross-section illustrating the stratigraphic relationships of the principal Tertiary formations in the Melbourne area. (Not to scale. Vertical dimension greatly exaggerated.)

1 Manuscript completed 1960, revised 1964. 32

Marine Transgression and Regression. tlons are comparatively well-known from bores and Two period& of marine transgression in which shafts there. Most of the formation names stem the sea advanced to about the general position of from this area. The formations generally persist the Melbourne Warp can be recognized. At other with reduced thickness or modified lithology into times a fall of sea level in relation to the land the southern and south-eastern suburbs, but because in the basin caused marginal regression of the seas. of the paucity of good sub-surface data, are less These regressions are generally marked by erosional well known in this area. breaks, terrestrial sediments or lavas. Reworking and scouring of soft sediments in the newly formed The various formations will be described in shallows produced smaller breaks in the sedimentary conventional order of decreasing age, only passing sequences. reference being made to the economic significance of the deposits as this has been treated in other One or more minor marine incursions or sections of this bulletin. New or amended ingressions appear to have taken place in W erribee stratigraphic terms are explained in the text or the Formation time, but there is no evidence that the accompanying appendix. J anjukian1 transgression, which is of major impor­ tance elsewhere in Victoria, ever extended into the northern part of the Port Phillip Basin. The main Werribee Formation. marine transgression here occurred in Oligocene Lithology and Definition and Miocene (Longfordian to Bairnsdalian) time and this was followed by regression in stages giving Resting directly on the eroded surface of the rise first to shallow seas in late Miocene Silurian rocks in the south-western suburbs of ( Cheltenhamian) time and eventually to terrestrial Melbourne are a thick series of sands, coarse sands and brown coals with lesser amounts of clay and conditions in Pliocene time. carbonaceous clay and occasional lenses of gravel Comparison with Bacchus Marsh. and conglomerate. The sands are generally angular and typically contain abundant pyrite. These Bacchus Marsh occupies a position in the north­ sediments are known as the Werribee Formation vvest part of the Port Phillip Sunkland analogous (Thomas and Baragwanath, 1950, p. 50). to that of Melbourne in the north-east and the rock sequences in the two areas have much in common At Spotswood extensive flows of basalt of the (Thomas and Baragwanath, 1950, p. 50). Several Older Volcanics are developed about the middle of the formations in the two areas are probably of this formation. The sediments above and below continuous beneath the lavas of the Keilor-Werribee the Older Volcanics and present as intercalations plains. between some of the basalt flows are essentially similar in character except that brown coals are STRATIGRAPHY. common above the Older Volcanics and rare or Within the area of the Melbourne map the absent below (Table 4). Gravels are slightly more sedimentary sequence is better developed on the frequent and coarser grained below the strati­ western side of Hobson's Bay and the main forma- graphic level of the Older Volcanics.

TABLE 4.-Approximate frequency of occurrence of lithological types in the Werribee Formation, south-western and western suburbs (based on data from bore logs).

l Approximate Frequency in Bores. Number Total Lithological Unit Fine Clayey of Bores Sand and Carbona~ Brown Footage Conglo- Sand Sandy Clay ceous Clay Coal Total mer ate Clay

% % % % % % % Werribee Fm. (upper part) .. 2 36 7 8 6 41 100 19 1,335 Werribee Fm. (upper part) excluding brown coal seams more than 20 ft. thick .. 3 60 12 14 9 2 100 19 796 Werribee Fm. (lower part) .. 3 52 10 22 13 0·3 100·3 20 1,136 Werribee Fm. (total) .. 4 42 8 12 10 24 100 44 3,234

1 For details of the stages of the Victorian Tertiary, see Singleton (1941) and Carter (1959). 33

Although marginal movements of elevation and Age and Correlation. erosion or non-deposition must have preceded or The Werribee Formation may be correlated with accompanied the extrusion of the Older Volcanics, the Yaloak Formation of the Bacchus Marsh area which are partly if not entirely terrestrial, no break which it resembles closely. in sedimentation has as yet been recognized where the Older Volcanics are absent. For this reason it Coalified wood is abundant in the carbonaceous seems preferable at present to continue to regard clays in the upper part of the formation, but as yet the beds above and below the Older Volcanics as the fossils found have been of little value for age parts of a single rock unit. determination. The beds are regarded for the present as having been deposited during an unknown In the Altona-Laverton area the thick lenticular interval of Eocene and early Oligocene time. coal seam known as the Altona Coal Seam (Thomas and Baragwanath, 1950, p. 50) is present at or Aquifers. near the top of the formation. This thick coal Several important aquifers occur in this formation. seam and a number of thin seams which develop One is generally present in the sands and coarse by splitting from the main seam are here regarded sands above the Older Volcanics and one or more as belonging to the same lithological group as the occur in the coarse sands, gravels and pebble beds Werribee Formation (see below). below the Older Volcanics. The waters in these aquifers are artesian or near artesian near the coast Distribution and Thickness. between Williamstown and Werribee. The Werribee Formation is not known to outcrop Sub-Older Volcanic Alluvials. at the surface within the area of the Melbourne Thin deposits of sands, silts, sandy clays and map, but bores show it to have a wide sub-surface clays with minor bands of conglomerate are distribution west of Melbourne. It attains a developed beneath the Older Volcanic rocks at a thickness of 241 feet in the Truganina No. 1 bore number of places in the valleys of the Moonee at Altona (Department of Mines, Victoria, 1903, Ponds and Merri Creeks and their tributaries. The p. 69 ; 421-662 feet), but wedges out rapidly to beds are commonly iron-stained, but the limonite the east and north-east and is sparingly developed cement is unevenly distributed and some beds are or absent in the southern and south-eastern suburbs. practically devoid of iron. Well-preserved fossil leaves occur at Pascoe Vale, Flemington and South of the Beaumaris Monocline it is elsewhere. represented by thin sands underlying basalts of the Older Volcanics at Mordialloc (Plate 7, Section 4). These sediments have been mapped by the Geological Survey (Quarter Sheet No. 1, 1863) The maximum development of the formation is and Hanks ( 1934). They are best exposed at a probably to the south and south-west of Melbourne locality on the south-west bank of the Moonee in the central parts of the Port Phillip basin. Ponds Creek, approximately 1 t miles north-west of Pascoe Vale railway station (Sunbury military map Grid Ref. 950 475 ; see Hanks, 1934, p. 145, and Sedimentary Environment. Gill, 1949). The beds are usually of the order of The Werribee Formation is generally thought to 10 to 20 feet in thickness and are thought to be have been deposited in coastal swamps and estuaries of fluviatile origin. They are probably lateral which were periodically inundated by encroachment equivalents of the lower part of the Werribee of the sea on the low-lying sub-coastal areas. Formation. Shell-bearing sands have been recorded from near The fossil leaves from outcrops on the Moonee the top of the formation in the Truganina No. 1 Ponds Creek at Pascoe Vale have been described bore in the depth range 437-493 feet (Department by Paterson ( 1934) and are referred to in the of Mines, Victoria, 1895, 1899, 1903), and are chapter on fossil plants. The fossils are not present at about the same horizon in the Truganina diagnostic as to age, but are comparable with early No. 3 bore near the Skeleton Waterholes Creek, Tertiary floras from other parts of the State. Similar Laverton (depth 517 ft. 5 in., Department of Mines, sands beneath the Older Volcanic rocks at Arundel, 1903, p. 70; Kitson, 1902, p. 261 ; Thomas and north of Keilor and elsewhere may be correlated Baragwanath, 1949, p. 33). The fossils at Laverton with these deposits. include two species of polyzoa, Dentalium mantelli Zittel and two species of gasteropods. These indicate Older Volcanics ("Older Basalts"). a marine origin. Marine fossils were also reported from fine quartz sands immediately underlying the Lithology, Distribution and Thickness. Older Volcanics at 295 feet in the Port Phillip Oil Under the heading of Older Volcanics are Company Limited bore at Williamstown (Strevens, grouped the early Tertiary basalts of the South 1924). Melbourne, North Melbourne, Royal Park, 2288/66.-3 34

Essendon, Pascoe Vale, Keilor and Tullamarine bourne and Altona Colliery Company in the period areas and of bores at Spotswood, Brooklyn, 1910-1919, is known as the Altona Coal Seam Williamstown, Deer Park, Kings Bridge, Mordialloc (Thomas and Baragwanath, 1950, p. 50). and elsewhere. Most of these rocks are olivine The Altona Seam is 69 feet thick in the Altona basalts. Shaft, the top of the coal occurring at a depth of These old lavas form an extensive sheet at least 329 feet. The coal attains a maximum recorded 6 miles wide, which in most areas overlies a near­ thickness of 140 ft. 7 in., with one 17 in. clay split, level surface consisting of sediments of the Werribee in the Truganina No. 3 bore on the Skeleton Water Formation. The prominent belt of Older Volcanics Holes Creek just beyond the western margin of the extending N.N.W.-E.S.E. through the west side of map (Department of Mines, Victoria, 1903, p. 70; the city represents the outcropping edge of this 356-498 feet). It thins out to the south-west, sheet which now dips gently to the W.S.W. Minor north and east. To the north-east as many as four irregularities appear in the sub-Older Volcanic coal seams are present in bores and shafts at surface where the Older Volcanics overlap the lower Newport, presumably as a result of " splits " Tertiary sediments. developing in the main Altona Seam (Thomas and The Older Volcanics are a little over 120 feet Baragwanath, 1950, p. 50). thick in several of the bores drilled for the proposed As at Bacchus Marsh (Baker, 1946) marcasite Lower Yarra Crossing and a number of flows and doubly terminated quartz crystals are locally showing different degrees of weathering, vesicular abundant in the upper part of the coal (Truganina zones and thin sedimentary intercalations have been No. 3, Department of Mines, Victoria, 1903). recognized (J. L. Neilson and W. E. Bamford, personal communication). The petrography and For reasons given below the writer considers that general character of the Older Volcanic rocks are none of the " brown coals " recorded from the described in a separate chapter. eastern side of Hobson's Bay (e.g., Point Ormond), are to be correlated with the Altona Coal Seam. Age and Correlation. Definition. The question of the age of individual occurrences The Altona brown coals are intimately associated of Older Volcanic rocks throughout the State has with the sediments of the upper part of the Werribee been considered by Hills (1939) and Singleton Formation. They differ from the thin impure (1941) . In the sub-surface south-west of Melbourne " brown coal " developed in the lower part of the the Older Volcanics are interbedded between lower Newport Formation in that they have a different and upper parts of the Werribee Formation and are chemical character and distribution and appear to probably of Eocene to early Oligocene age. In be separated from it by an unconformity. outcrop the Older Volcanics rest on sub-Older Mr. W. Baragwanath (in Thomas and Baragwanath, Volcanic alluvials or equivalent Werribee Formation 1949, p. 55) has made a similar distinction between beds and are overlain by fossiliferous marine the lower brown coals at Bacchus Marsh and the limestones of Batesfordian age at Green Gully, highest " impure brown coal " which is there Keilor (Crespin, 1926) and by fossiliferous iron­ interbedded with marine Batesfordian sediments stones of Balcombian age at Royal Park (Hall and equivalent to part of the Newport Formation. If Pritchard, 1897; Singleton, 1923, 1941). Although this distinction is valid the true brown coals of the the outcrop data extends the possible upper age Altona Coal Measures are entirely pre-Newport limit of the Older Volcanics into thE\ Miocene, the Formation in age. evident continuity of the various occurrences with the basalts interbedded with the Werribee Formation Sedimentary Environment makes it probable that they are all of about the The brown coals and associated clays were same age. presumably deposited in extensive low-lying coal The Older Volcanic rocks of the Melbourne area swamps situated adjacent to the sea. They are can be correlated with the early Tertiary basaltic among the last deposits of a cycle of sedimentation lavas at Bacchus Marsh (the Pentland Hills Vol­ which had been predominantly terrestrial to this canics), the Mornington Peninsula and elsewhere. stage. The immediately ensuing sediments of the Newport Formation are of marine origin. Altona Coal Seam. Age and Correlation. Distribution and Thickness. Cookson (1959) has described pollens of three In the southern and south-western part of the new species of Nothofagus from the Altona brown Melbourne map brown coal has been encountered coal, but pal::eontological data is as yet insufficient in bores and shafts at Newport, Williamstown, to enable a reliable dating of the coals. Following Altona and Laverton (Department of Mines, Vic­ Thomas and Baragwanath (1949, p. 32) the brown toria, 1895, 1899, 1903, 1938). The principal coal coals are here regarded as mainly Oligocene in age seam which was worked unprofitably by the Mel- with some probably extending down into the Eocene. 35

The Altona Coal Seam is generally regarded as ( 4) Light greenish-grey micaceous siltstones being contemporaneous with the Maddingley Coal with marine fossils containing occasional Seam of the Bacchus Marsh area and the two seams thin impersistent limestone and argil­ are probably continuous beneath the basalts and laceous limestone bands (14-18 feet) . sediments of the Werribee Plains (Thomas and ( 3) Dark-grey to black carbonaceous siltstones Baragwanath, 1949, p. 35). with marine fossils (2-27 feet). The Werribee Formation, Older Volcanics and ( 2) Impure " brown coal " (1-6 feet) . Altona Coal Seam form a natural lithological group ( 1) Greenish-grey to grey, calcareous clay or analogous to the N arracan Group of Gippsland. sandy clay with marine fossils (3-7 This group has not been named in the Melbourne feet). area.

-UNCONFORMITY­ The Wen-ibee Formation-Newport Formation Contact. Werribee Formation. The base of the Newport Formation rests on a This sequence is closely paralleled in bores and slightly uneven surface and overlies in turn, the mines workings in the parish of Parwan near Altona Coal Seam in the Laverton-Altona area, Bacchus Marsh, where an " upper impure brown the sands and clays of the upper part of the Werribee coal " occurs as an intercalation in dark-grey marine Formation in the Brooklyn-Newport area and the clays (?Longfordian) which are overlain by lime­ basalts of the Older Volcanics in the Spotswood­ stones and sandy limestones of Batesfordian age Yarraville area. This transgressive relationship is interpreted as indicating minor earth movements (Parr, 1942). contemporaneous with or subsequent to the deposi­ At Brooklyn the impure brown coal is thin, tion of the upper part of the Werribee Formation persistent and in contact with sediments containing and concomitant non-deposition or erosion in the marine fossils both above and below. Above it elevated areas prior to the deposition of the Newport grades into highly carbonaceous siltsones which Formation. progressively decrease in carbon content toward the top. The impure brown coal consistently has a high Newport Formation. ash content and contains occasional marine fossils Distribution and Thickness. at Brooklyn. For these reasons the writer accepts Overlying the Altona Coal Seam in the Altona Baragwanath's view (put forward for the Parwan Shaft at depths of 160-330 feet is a sequence of coal, in Thomas and Baragwanath, 1949, p. 55) that richly fossiliferous light to dark-grey micaceous, the upper " coal " represents redistributed brown partly glauconitic silts (" marls ") containing bands coal eroded from older coal seams. In the opinion of limestone and calcareous concretions. These of the writer it was probably deposited in a marine sediments are known as the Newport Formation environment. (Thomas and Baragwanath, 1950). A similar thin impure brown coal, usually con­ Similar beds have been recognized in bores at taining quartz sand or grit is widespread near the Brooklyn and Spotswood and extend beneath the base of the marine sequence in the south-eastern waters of the Bay where their lateral equivalents suburbs. It is probable that this horizon will prove occur in bores from Oakleigh to Mentone and in to be a useful marker bed in the northern part of outcrop at the base of the cliff section at Beaumaris. Port Phillip Basin. The lower fossiliferous ironstones and ferruginous grits outcropping at Royal Park (Balcombian) are Sequence South-Eastern Suburbs considered to represent this formation in the The Newport Formation appears more variable oxidized condition and the thin Green Gully Lime­ in lithological character south-east of Melbourne stone Member at Keilor (see below) is regarded as and is distinctly more arenaceous in its sub-surface a facies variant of part of the formation. development than is the case to the south-west. Sequence South-Western Suburbs. A representative sequence is as follows:­ In the Brooklyn-Spotswood area the sequence Brighton Group. within the Newport Formation is as follows:- -UNCONFORMITY- Brighton Group. ( 3) Olive-green, olive-brown and grey glauconitic (?) silts and clays typically -UNCONFORMITY- becoming sandy towards the north­ ( 5) Light greenish-grey to yellow-brown east. Commonly contain one or more fossiliferous silts, clays and marls in limestone bands, but limestones may places containing limestone bands. locally predominate (e.g., Clarinda). 36

(2) Carbonaceous silts or clays in places con­ Aturia australis McCoy. They have been listed taining thin impure brown coals ( 1-7 and described by Crespin (1926). The larger feet). foraminifera which include Lepidocyclina (Try­ ( 1) Shelly quartz sands or sandy limestones, bliolepidina) batesfordensis Crespin indicate that usually containing some quartz grit and the deposit is contemporaneous with the thick gravel (2-11 feet). polyzoallimestones at Batesford, near Geelong.

-UNCONFORMITY- The Green Gully Limestone rests directly on basalt of Older Volcanic age and is in turn overlain Silurian. with local unconformity (Crespin, 1926) by Silts of unit (2) contain the large Batesfordian fossiliferous ferruginous grits believed to be of Bal­ foraminifera Lepidocyclina howchini, Operculina combian age (Singleton, 1941). victoriensis and Cycloclypeus victoriensis at 105-120 The extent of the Green Gully Limestone feet in a bore at "Oakleigh Drive-In " theatre, beneath the younger deposits to the south and Clarinda (Carter, 19 58). south-west of Keilor is not known. Batesfordian Beds of unit (3) contain a Balcombian micro­ sediments were probably once quite widespread as fauna at Hughesdale (115 feet, Melbourne and Batesfordian Lepidocyclinae have been recorded Metropolitan Board of Works Bore No. S.E. 4; from sands and limestones in bores at Cheltenham, Reed, 1960) and Mordialloc (110-115 feet, Country Heatherton and Lara (Crespin, 1943, p. 169 ; Roads Board Bore No. 2; Taylor, personal com­ Gill, 1957, p. 184; Carter, 1958). Remanie munication). Lepidocyclinae from the Batesfordian are present in the basal nodule bed of the Black Rock Sand­ Aquifers South-Eastern Suburbs. stone at Beaumaris (Parr, in Singleton, 1941, p. Lenses of sand are present at several levels in the 78; Gill, 1957, p. 184). formation, but particularly in the lower part and Fossils in the Newport Formation. these constitute sources of good quality underground water in this area. No comparable aquifers have The fossils in the Newport silts include beauti­ yet been found at this stratigraphic level south-west fully preserved foraminifera, siliceous sponge of Melbourne. spicules (characteristic), brachiopods, pelecypods and gastropods. They have been listed by Hall and Pritchard (18 97), Thiele and Grant (1902), GREEN GULLY LIMESTONE MEMBER. Dennant and Kitson (1903) and Colliver (193 7b) At Green Gully near Keilor on the western edge and indicate that the beds may be correlated with of the map and on the Maribyrnong River down­ the marls at Balcombe Bay (the type Balcombian) stream from Green Gully there are several small and at Grice's Creek near Mornington. Blue clays isolated exposures of polyzoal limestones which and marly sands of about the same age occur together constitute the only recognized occurrence beneath the shingle beach near the Beaumaris boat of rocks of Batesfordian age outcropping near Mel­ sheds (Hall and Pritchard, 1897; Singleton, 1941 ; bourne. For convenience these limestones are here Gill, 1957 ; Colliver, 1937a). These have recently given the name of Green Gully Limestone and are been assigned to the Bairnsdalian (Wilkins, 1963, regarded as a member of the Newport Formation. p. 55). All of these occurrences of Balcombian The type section of the formation is on the south to Bairnsdalian sediments are probably continuous side of Green Gully and is that described by Hall beneath the waters of Port Phillip Bay. and Pritchard (1897, p. 211) and Crespin (1926, The fossiliferous ironstone bed 1-2 feet thick p. 104). The outcrop is only 120 feet long and near the base of the Tertiary sediments in the Royal achieves a maximum exposed thickness of 5 feet­ Park railway cutting ; similar rocks at various tapering to zero at either end of the exposure. localities near Moonee Ponds and Essendon (Hall and Pritchard, 1897; Pritchard, 1901 ; Singleton, The limestone is cream in colour and consists 1923 ; Gill, 1950 and Colliver, 1936) and the mainly of foraminifera and polyzoan tests and lower 3 feet of fossiliferous ferruginous grits at echinoid spines. Quartz grains are abundant in the Green Gully, Keilor directly overlying the Green lower part and at the base the rock contains pebbles Gully Limestone, are regarded as littoral facies of of basalt and calcareous grit. In the lower part of the Balcombian (Hall and Pritchard, 1897 ; Single­ the Green Gully section and towards the southern ton, 1941). end of the outcrop some of the carbonate has been replaced by limonite giving rise to ferruginous The fossils from these littoral deposits consist limestone. principally of marine pelecypods and gastropods. Those from Royal Park have been listed by Hall The fossils present are all of marine organisms and Pritchard (1897, " Lower Beds "), Singleton and include a variety of algae, foraminifera, corals, (1923, "Lower Beds") and Colliver (1936). echinoderms and polyzoa and the nautiloid species Those from Keilor have been listed by Hall and 37

Pritchard (1897) and Crespin (1926, "Janjukian" Brighton Group (=Sandringham Sands). fossiliferous ironstone). The gastropods Haliotis Lithology, Distribution and Thickness. naevosoides McCoy and Cerithium flemingtonense McCoy, the pelecypod Cucullaea corioensis McCoy Poorly bedded sands, soft sandstones and gravels and the nautiloid A turia australis McCoy are some are exposed in rail cuttings and excavations through­ of the more common or better known forms out the southern and south-eastern suburbs and present at these localities. extend in an almost unbroken sheet from Gardiner's Creek to the coast. These rocks which are commonly known as the " Red Beds " (Hall, 1909) Sedimentary Environment and Facies Changes. are shown in a yellow colour on the Melbourne The Newport Formation is an entirely marine geological map. They have recently been named sequence. As at Geelong (Bowler, 1963) the the Sandringham Sands (Gill, 1950, 1957) but for Batesfordian limestones appear to have developed reasons given at length in the Appendix to this near the margin of the Newport seas and basin­ section are here referred to as the Brighton Group. ward evidently give way to impure limestones, marls In common with the other formations these and silts. deposits generally have an exceedingly low regional The limestones in the lower part of the bores in dip to the south-west and are found at progressively the south-eastern suburbs tend to be sandy and greater elevations towards the north-east. The grade laterally to shelly sands. beds become steadily thinner to the north-east and eventually wedge out against the Nillumbik Terrain (Fig. 3, Plate 7). Age of the Newport Formation. To the north and north-east of Gardiner's Creek Sediments in the Werribee Park bore (Deutgam the topography is more dissected than to the south­ No. 1) regarded as part of the Newport Formation west and in many places the streams have cut down have been shown to be of Longfordian age (Taylor, through the originally continuous sheet of Brighton 1963 ; 392 and 430 feet) and rocks of this age Group sediments into the underlying rocks, leaving are probably also present in the lower part of the remnants of the sands capping the higher undissected Newport section near Melbourne. Batesfordian areas. The higher areas in the eastern and north­ sediments occur higher in the Werribee bore (230 eastern suburbs as for example Kew, Camberwell, and 344 feet; Taylor, 1963); and at Keilor, Clarinda Bm·wood, Mount Waverley, Doncaster and Heidel­ and Cheltenham (Crespin, 1943 ; Gill, 19 57). berg owe their sandy soils and comparatively level Balcombian sediments have been recorded at Altona summits to these remnants. and the marls and impure limestones at the top of the formation at Beaumaris are assigned to the In the north-western and western suburbs the for­ Bairnsdalian (Wilkins, 1963, p. 55.) There is no mation is of similar lithological character, but is known stratigraphic break in this sequence and all largely obscured by flows of Newer Volcanic basalts. of these beds are included in the Newport Forma­ The deposits thicken to the south-west of the Moonee tion. Ponds Creek and pass down dip beneath the basalts of the Keilor-Werribee Plains where they are repre­ sented by red-brown silts, sandy silts and clayey silts Newport Formation-Brighton Group Contact. with occasional gravel bands in bores and shafts. Beds of Mitchellian age are lacking from the The Brighton Group occurs in the Altona Coal Shaft Beaumaris cliff sections and a phosphate nodule in the depth range 3 8-111 feet. The cream and bed containing remanie fossils occurs at the base of yellow sandy clays and calcareous sandstones from the Brighton Group resting disconformably on the 111-160 feet which contain marine fossils from marls and impure limestones of the Newport 111-131 feet, are of uncertain affinities, but Formation. probably also belong to this unit. At Spotswood Melbourne and Metropolitan Board of Works Detailed cross-sections drawn between Brooldyn Pumping Station the group occurs from 29-100 and Spotswood show that the Brighton Group rests feet and at the Brooklyn Pumping Station it occurs on an irregular surface and near Spotswood the from 103-1 7 4 feet. Newport Formation has been completely removed by erosion exposing the upper beds of the Werribee Formation and the Older Volcanics. The extent Subdivisions. of erosion in this area suggests that it was caused Deposits resembling the Brighton Group are wide­ by subaerial agencies. Marine erosion and re­ spread in the Port Phillip area and various attempts working of older sediments in shallowing seas have been made to subdivide them. As the literature caused by marine regression probably accounts for of the subject is voluminous and somewhat involved the development of the phosphatic nodule bed at a resume of the more important contributions is Beaumaris (Bowler, 1963, p. 120). given in the accompanying appendix. 38

The subdivisions adopted in these notes are as A nodule bed about 3 inches thick occurs follows (modified from Gill, 1957) :- at the base of the formation at Beaumaris. This f Red Bluff Sands consists of quartz grit and gravel containing nume­ Brighton rous rounded phosphatic concretions up to 6 inches Group i -DISCONFORMITY- l Black Rock Sandstone. in length. Sharks' teeth and pieces of whale bone and fish bones are common, but many of these are These units have been recognized in the coastal abraded indicating a remanie origin (Singleton, sections between Brighton and Beaumaris. In places, 1941, page 32). These derived remains have notably west of Hobson's Bay there is some difficulty evidently accumulated as a result of marine action in distinguishing two formations and in such areas reworking part of the Newport Formation as have subdivision of the Brighton Group is not justified at also the worn Lepidocyclinae noted by Parr (in present. Singleton, 1941, page 7 8) . Other inverterbrates are rare at this level. Black Rock Sandstone (Plates 13, 14). Lithology, Distribution and Thickness. Definition and Age. In outcrop these beds consist of yellowish-red and The Cheltenhamian Stage as defined by Single­ reddish-brown ferruginous sandstones and marly ton (1941, page 35) represents the total time sands, with local development of ironstone bands. which elapsed during the deposition of the richly Coarse ferruginous grits are present near the top fossiliferous basal 20-22 feet of the Black Rock of the sequence at Mordialloc. The strata are Sandstone at Beaumaris. This stage is probably of moderately lithified and calcareous in the lower uppermost Miocene age. Singleton regarded the part of the unit, and the casts of shells in the upper succeeding 19-28 feet of sparingly fossiliferous beds part indicate that originally it must also have been as being probably Kalimnan (Lower Pliocene) in somewhat calcareous (Gill, 1957). Samples of age. The fossils from these upper beds (Hall and the formation from bores consist largely of glau­ Pritchard, 1897) are evidently inconclusive as to age conitic and calcareous silty sands and shelly sands. and on rock stratigraphic grounds Gill (1957) in­ The heavy limonite cement characteristic of these cluded them within the Black Rock Sandstone. rocks in outcrop is evidently due to oxidation of This interpretation is accepted here (see Appendix), the original glauconite at the surface. The but the exact age of these upper beds remains un­ mineralogy of these beds at Beaumaris has been certain. described by Carroll (1949). The Black Rock Sandstone is reasonably well Correlation. stratified and shows only minor development of cur­ The Black Rock Sandstone may be broadly cor­ rent bedding. The formation crops out in the cliffs related with similar ferruginous sandstones on the at Beaumaris where it achieves a total thickness of Mornington Peninsula (Baxter Sandstones, Keble, 41-48 feet. Further north the upper beds form the 1950) and the Bellarine Peninsula ("Lower Plei­ base of rocky headlands and shore platforms at Black stocene" of Jutson and Coulson, 1937). They are Rock, Sandringham, Hampton, Brighton and Point probably also equivalent to the Rowsley Formation Ormond. The formation also occurs in the lower at Bacchus Marsh. part of the cliffs between Mentone and Bay-street, Mordialloc. Fossils. On the land it extends under the Red Bluff Sands Fossils in the 20 feet of beds above the nodule throughout the southern suburbs and is probably bed include a variety of molluscs, brachiopods, represented by ferruginous sandstones containing foraminifers, echinoderms, corals, polyzoans and shelly fossils in some of the deeper railway cuttings crustaceans. Especially common or stratigraphically as for example, at Elsternwick, Windsor and South important forms include the cephalopod Aturia Yarra. It is also probably represented by the australis McCoy, the pelecypods Limopsis beawna­ sparingly fossiliferous upper ferruginous beds at riensis Chapman, Neotrigonia acuticostata (McCoy), Royal Park and Ascot Vale (see Hall and Pritchard, Placunanomia cf. ione (Gray) and Eucrassatella cf. 1897; Gill 1950, 1957) and by the unfossiliferous camura (Pritchard) ; and the echinoids Lovenia upper parts of the ferruginous grits at Green Gully, forbesi (Woods) and Monostychia cf. australis Laube Keilor. Rich shell beds typical of this formation (Singleton, 1941, pages 33, 35). Plant remains were recently found in sewer excavations at Land­ consisting of leaves of Cinnamomum (Singleton cox Park, North Brighton where the shells occur in 1935, 1941; page 51) and fossil wood (Hart, 1893, ferruginous sandstones at a depth of about 15 feet page 157) occur near the top of the formation. (Personal communication R. C. Glenie and M. Hall) Other details of the fossils recorded from these and at W~ight-street, Bentleigh where they occur in beds are given by Hall and Pritchard (1897), soft green glauconitic silty sandstone at a depth of Cudmore (1926), Singleton (1941) and Gill (1950, 40-45 feet. 1957). 39

Red Bluff Sands (Plates 13, 14). The gravels and coarse sands developed north­ Lithology, Distribution and Thickness. east of the Melbourne Warp are generally considered to be of fluviatile origin. This formation is well-exposed in the valley of the Maribyrnong River and in railway cuttings and The Red Bluff Sands are probably of Middle to coastal sections south of Gardiner's Creek and the Upper Pliocene age (Singleton, 1941, page 78). Yarra River. Excellent exposures are visible in Deposits which m\).y be correlated with them are recently enlarged and deepened rail cuttings at widespread in other parts of the Port Phillip area. Moorabbin and Elsternwick and in sand pits at Aquifers. Clayton and Clarinda. Bands of coarse sand and gravel in the Red Bluff The formation is the chief source of moulding Sands have yielded useful supplies of groundwater sand in the Melbourne area. It consists of poorly at some localities in the south-eastern suburbs, but consolidated sands, fine sands, grits and gravels generally the water quality at this stratigraphic level which usually contain sufficient clay matrix to enable is poor. them to stand at steep angles of rest in cliffs and cuttings. Lenses of carbonaceous material are Brighton Group-Newer Volcanics Contact. present near the base of the formation ( cf. Hart, A period of uplift and erosion followed the deposi­ 1893, page 158; Gill, 1957) and the carbonaceous tion of the Red Bluff Sands and streams developed horizon can often be recognized in bores and sand which dissected a land surface of somewhat greater pits in the south-eastern suburbs. Irregular pale relief than that prevailing at present. Part of this yellow to light-brown staining with iron oxide is fossil surface is now preserved beneath the basalts prevalent in the formation, but the beds are markedly of the Newer Volcanics and sufficient is known of less ferruginous in outcrop than those of the Black its shape to enable a reconstruction of the drainage Rock Sandstone. The deposits are generally poorly pattern to be attempted. This is shown in orange bedded and the bedding planes are usually sub­ lines on the geological map of Melbourne (1959). horizontal with gentle undulations. Cross bedding is common especially towards the north-east, but becomes less conspicuous towards the south-west. The rocks considered below range from late Plio­ cene to Pleistocene in age. The type section of the formation is at Red Bluff, Sandringham where it achieves a thickness of 78 Sub-Newer Volcanic Alluvials. feet (Gill, 1957). Hart (1893) estimated that these Basalt flows of the Newer Volcanic series (Exford beds are more than 100 feet thick south of the Beau­ Volcanics) flowed down some of the pre-existing maris monocline, but recent bores show a maximum valleys deeply burying the old alluvial deposits and thickness of only 7 5 feet at Mordialloc. At Red soils. These and other underlying rocks have fre­ Bluff, Gill recognized the following sequence-a quently been baked brick red by the basalts. basal clayey sand, a median clayey gravel and The buried alluvial deposits or " deep leads " coarse sand, and an upper clayey sand. He claimed range in age, as do the superimposed basalts in the that this sequence of beds within the formation is Port Phillip area, from Upper Pliocene to about maintained throughout the Melbourne area (Gill Middle Pleistocene, but within the area of the map 1957, page 166). most are probably of Lower to Middle Pleistocene In the northern and north-eastern suburbs the Red age. Bluff Sands appear to overlap the Black Rock Sand­ Deposits of this type contained fossil trees and stone and extend with interruptions as far north as other plant remains in quarries at Collingwood, Greensborough and St. Helena. Burnley (Chapman, 1905) and Clifton Hill (Prit­ chard, 1910, page 110; 1944; Armitage, 1910, Fossils, Age and Sedimentary Environment. page 28). Fossil leaf beds of lacustrine origin, The formation is only sparingly fossiliferous and which are probably contemporaneous with these organic remains recorded consist of fossil wood, deposits, occur on the Maribyrnong River between fresh water sponge spicules and fresh water pele­ Bulla and Keilor (See Chapter 5). cypod fragments at Green Gully, Keilor; fresh water sponge spicules at Coburg; and fossil wood, pollen Newer Volcanics (Exford Volcanics). (including N othofagus spp.) and a hystrichos­ Distribution and Nomenclature. phaerid at Red Bluff, Sandringham (Crespin 1926; The younger basalts or "Newer Basalts" of the Hanks 1934, page 150; Gill 1950, page 170; 1957, Melbourne area represent the eastern fringe of the page 173). Gill (1957, page 170) considers the extensive basalts of the Keilor-Werribee Plains. The flora to be indicative of a Pliocene age and on the name Exford Volcanics has been applied to these basis of the fossils and the type of sediment postulates rocks by Condon (1951), but "Newer Volcanics" (page 183) a partly fluviatile, partly near-shore has been retained here in deference to accepted lagoonal or paludal origin for the deposits. usage. 40

Subdivisions. the Older Volcanics than the later phase Newer From a detailed study of the stratigraphy of the Volcanics and for this reason have been repeatedly Exford Volcanics Condon recognized two main grouped with the Older Volcanic rocks in maps and phases of volcanic activity:- reports including the present edition of the geological ( 1) An early phase in which extensive sheet­ map of Melbourne and Suburbs. like basalt flows were poured out over From the evidence cited it would appear that an the pre-existing surface ; and Upper Pliocene age is most probable for these (2) A later phase in which smaller tongue-like Greensborough Phase basalts and that a prolonged flows from central vents were extruded. period of quiescence and erosion preceded the extru­ The younger flows rest on the eroded sion of the later central eruption flows. A planed­ and weathered surface of the older flows off scoria cone revealed in the Brooklyn trunk sewer and on a variety of older rocks. They excavations west of Spotswood at a depth of about outcrop at or near the surface through­ 100 feet probably also belongs to this early phase out the lava field. of vulcanicity. Two distinct periods of post-Older Volcanic (sensu stricto) vulcanicity have also been recognized in the Basalts of the W en:ibee Plains Phase. Melbourne area (Aplin 1868, Quarter Sheet No. 2 S.E., Hart (1894), Jutson, 1913) and although the The bulk of the younger basalts to the north earlier flows of the Melbourne area are not recog­ and west of Melbourne are little dissected and nizably of the sheet flow type a correlation of the individual flows can often be mapped reliably two Melbourne phases with those of the W erribee throughout their length. In such cases the volcanoes Plains is suggested both by the stratigraphic and the from which they originated can be established beyond lithological evidence. The terms Greensborough doubt. Most of the extinct centres of eruption lie Phase and W erribee Plains Phase are here proposed to the north and north-west of the area covered by as informal terms to distinguish these two phases of the map. In some cases there has been sufficient volcanic activity. dissection for lateral streams to have developed alongside individual flows and, with the possible The age of some of these basalt flows and of other exception of the Mount Fraser scoria cone at Cainozoic volcanic rocks throughout Victoria has Beveridge, volcanic activity seems to have ceased been discussed by Hills (1939) and is considered much earlier in the Melbourne-Werribee Plains further below. area than it did in parts of the Western District or Daylesford volcanic areas. Basalts of the Greensborough Phase. The basalts of Greensborough, J anefield, Heidel­ Late Pleistocene to Recent silts cover the basalt berg and Kangaroo Ground overlie coarse sands and flows of this group in the fossil estuaries of the gravels which have been correlated with the Brighton Yarra and Maribyrnong Rivers (see Section 3-3, Group (Aplin, 1868, Note 3; Jutson, 1913). In Quaternary). From the stratigraphic and physio­ addition thin decomposed basic dykes evidently re­ graphic relations of these younger flows they are lated to these lavas intrude the gravels in Lucas's and thought to be not younger than Middle Pleistocene Sinclair's gravel pits at St. Helena (Pers. comm. Dr. and probably range from Lower to Middle A. D. N. Bain). In the Readymix Concrete sand Pleistocene in age. pit situated about one mile west of Kangaroo Ground township, K. G. Bowen (Pers. comm.) has recorded Detailed accounts of the basalts of the Newer a two foot conglomerate band containing rounded Volcanics are given in other sections of this Bulletin. cobbles of strongly weathered basalt in sands six The greatest thickness of these rocks recorded is 172 feet below typical Kangaroo Ground basalt. The age feet in the Truganina No. 3A bore. As in most other of the cobble basalt can only be conjectured at the areas, this thickness is made up of three or more present stage, but this exposure may well hold the separate basalt flows. key to relationships between the Older Volcanics and the Greensborough Phase basalts. DETAILED GEOLOGICAL STRUCTURE OF If the correlation of the sands and gravels in these THE TERTIARY DEPOSITS. areas with the Brighton Group is correct it follows that the Greensborough and Kangaroo Ground Monoclines and flexures. basalts must be Upper Pliocene in age or younger. Melbourne Warp. On the other hand, these early flows differ from the typical Newer Volcanic basalts of the later phase The Melbourne Warp is an exceedingly broad both petrologically (see Section 3-4) and in showing gentle flexure with the downthrown block lying a much more advanced stage of dissection. In these to the south-west (Gill, 1961, page 31). It characters the basalts show a closer resemblance to is responsible for the pronounced lineation in 41 the Tertiary-Silurian contact between Heying­ Beaumaris Monocline. ton and Dandenong and the low topographic The regional importance of the Beaumaris Mono­ escarpment which parallels this contact a little cline was recognized by Hart ( 1913) and later by to the east of the Oaldeigh-Dandenong railway. Whincup ( 1944). The structure is seen in outcrop In the western part of the city this structure swings at Beaumaris where the cliffs are locally parallel with to the N.N.W., parallel with the trend of the Moonee the turnover of the monocline. Flexing of the beds Ponds Creek, and continues northerly to about has produced dips of up to 30° to the south-east Pascoe Vale where the displacement is taken up by near Charman-road and minor faulting is present at a gentle N.E.-S.W. trending structure of similar some places (Plate 13) . general character (Plate 2). The Beaumaris Monocline forms a low diminish­ Shore lines in both Newport Formation and Black ing escarpment which can be traced from the coast Rock Sandstone times roughly coincided in position inland for some distance to the north-east. Data with the Melbourne Warp and this and the present from water bores indicates that it persists through topographic expression of the structure suggest that Mentone and Heatherton to Clayton and probably a repeated movements took place on this line. During little beyond. The overall trend of the structure is Cainozoic time the warp appears to have acted as a 34° (magnetic), approximately perpendicular to the hinge separating a predominantly rising area in the axes of the Tertiary " folds " (see below). Total north-east from a predominantly subsiding area in stratigraphic displacement on the base of the Tertiary the south-west. due to this monocline is about 132 feet over a dis­ tance of 1,600 feet at Clayton, 104 feet over 3,700 The total vertical displacement on the base of the feet at Clarinda, and 116 feet over 3,000 feet at Men­ Tertiary due to the Melbourne Warp ranges from tone. The full thickness of the Black Rock Sand­ 190 feet over a distance of 5,000 feet at North Mel­ stone and the very top of the Newport Formation bourne to 135 feet over 6,900 feet at Oakleigh. are raised above sea level in the Beaumaris cliffs immediately on the upthrown side of the monocline. Anonyma Flexure. Feeble back tilt on the Beaumaris Monocline has The following features suggest that the western led to the formation of a drainage divide (the Notting side of the Brighton-Cheltenham block is probably Hill-Cheltenham axis; Hart, 1913) a little to the controlled by a geological structure lying offshore north-west of the monocline. The last movements from the present coast:- on this monocline took place after the deposition of the Red Bluff Sands and are probably of late Plio­ 1. The coast maintains an overall N.N.W. trend cene to Pleistocene age (Kosciusko Uplift ; Hills, between St. Kilda and Beaumaris despite the regional 1940, page 276). north-westerly strike of the outcropping Tertiary sediments. "Gellibrand Fault." 2. Comparatively high land adjoins the coast to Condon ( 19 51, page 4) postulated the existence the east with continuous cliffs of up to 90 feet in of a structure, which he named the Gellibrand Fault, height between Middle Brighton and Rickett's Point. to explain an apparent offset in the Tertiary strata 3. The Brighton Group which forms the cliffs on between Newport and Altona; but Thomas and the east lies well below sea level on the western side Baragwanath (1950, page 51) and Gill (1961, page of Hobson's Bay. 129) showed that the subsurface data used by Condon was not valid. Gill ( 1961) suggested 4. The sediments of the Werribee Formation are retention of the name in the form " Gellibrand evidently absent from the Brighton-Cheltenham Warp " for a slight steepening in the dip of the block. Tertiary sediments between bores at Spotswood and Newport. However, information obtained from 5. Structure contours on the base of the Tertiary recently drilled bores has failed to confirm the (Plate 2) broadly parallel the coastline and indicate existence of this local steepening (Plates 2, 7). a slight steepening in the gradient of this surface near the coast. The depth to Silurian basement reported in the Port Phillip Oil Co., Williamstown well (approx. 767 These features appear to be best explained by feet, personal coll1111unication, Mr. J. Strevens) sug­ assuming a N.N.W.-S.S.E. trending flexure or fault gests the presence of a fault or monocline down­ downthrown to the west. The name Anonyma thrown to the south-west between Newport and Flexure is here suggested for this hypothetical struc­ Williamstown. The trend of such a structure, if ture. The name is given after the Anonyma Reef present, would however be at a considerable angle which is situated near the western edge of the sub­ to the Gellibrand Fault proposed by Condon and it marine outcrop of the Black Rock Sandstone. appears desirable that this term should lapse. 42

Folding.1 sandstone and the creeks which at this point trend A series of undulations or gentle folds in the strata north-west coincide with "synclines". The ampli­ of the Brighton Group between Rickett's Point and tude of these folds is approximately 12 feet. St. Kilda have controlled the development of head­ Unlike Hart (1913, page 279) the wnter con­ lands and pocket beaches in this area (Plate 2) . As siders that the larger and more persistent topo­ outlined by Hart (1913, page 277) and Gill (1957, graphic ridges correspond to the main anticlines on page 170) the headlands are situated near the crests the coast and the larger valleys to the synclines. of anticlines which raise the harder Black Rock According to this interpretation the surface Sandstone above sea level. The crescentic bays co­ expression of the folds must be considered as incide with the synclines which carry the softer more having been modified to some extent by erosion easily eroded Red Bluff Sands into the zone of wave and later deposits of wind blown sand. A sug­ attack. gested correlation and naming of folds mapped on the coast and their probable counterparts The coastal exposures of these folds have been inland is given in Plate 2. The interpretation inland mapped by the writer on aerial photographs at a is based on field observations and an analysis of scale of 500 feet to one inch. The dips on the Lands Department (1885, 1896) contour plans and limbs of the folds are generally of the order of 3- Melbourne and Metropolitan Board of Works 10° and the prevailing strike is north-west. The (1960) drainage plans. Similar features are un­ long north-east sides of the bays approximate closely doubtedly present in the intervening areas, but much in position to the anticlinal axes, the beaches gene­ further work is required to delineate them properly. rally being situated on the eastern side of the shore platforms formed in the harder rocks exposed at The trends defined by the ridges and headlands the crests of the folds. are continued for some distance offshore by sub­ merged rock platforms and reefs formed in ferrugi­ The stream pattern between Gardiner's Creek and nous sandstones of the Black Rock Sandstone. The Rickett's Point shows pronounced N.W.-S.E. struc­ Anonyma Reef is situated on the Black Rock or the tural control (Hart, 1913). This control is inde­ Quiet Corner anticlinal trend, and Y orkies Rock and pendent of the back tilt on the Beaumaris monocline a number of lesser shoals occur on the Red Bluff referred to above and was considered by Hart anticline (Bathymetric charts-Cox, 1861; Taylor, (pages 279, 284) to be due to "lines of easy ex­ 1962). cavation parallel to the strike of the folds " or other " structural features ". The folds are typically simple symmetrical folds of amplitude 2 to 15 feet. The fold spacing varies Whincup ( 1944) considered the remarkable set from about 30 feet to 2,500 feet (anticline to anti­ of parallel valleys and ridges present in the Brighton­ cline), most folds occurring at intervals of 1, 000- Cheltenham area to be controlled by a series of 1,500 feet. longitudinal sand ~unes. However, as she herself In the Brighton-Cheltenham block the strike of observed, many of the supposed dunes have flat tops, the fold axes generally ranges from 299-314° (mag­ show a peculiar type of horizontal bedding in their netic) with 308 ° the predominant direction. From upper parts and contain a core of Tertiary sediments Quiet Corner south to Rickett's Point the folds at shallow depth. For these reasons the writer re­ swing to 320-323°, but appear to revert to about gards the undoubted dune sands present around their original trend further south. Between Mentone Cheltenham and Sandringham as forming only a and Bay-street, Mordialloc the folds are more closely capping to the Red Bluff Sands and considers that spaced and strike at about 292° magnetic. slight surface expression of the broad low amplitude folds in the Tertiary sediments was the controlling The fold axes are generally parallel and many factor in the development of the topography and maintain their entity for distances of several miles drainage. (Plate 2). Locally, particularly at places where there are changes in the trend of the folds, a series Support for this hypothesis is provided by recent of lesser folds is developed on and between the bores arid excavations for the Melbourne and Met­ main folds (e.g., Rickett's Point). Gentle reversals ropolitan Board of Works, Bentleigh intercepting of pitch are common along the length of the anti­ sewer along Wright-street and Eddy's-grove between clines in outcrop. Streams such as the tributaries of Elster Creek and its south branch. Here the crest Elster Creek which locally cut across the trend of of the topographic ridge corresponds in position to the fold axes, appear to do so at pitch reversals an " anticline " in the shell beds of the Black Rock or places at which folds die out along their strike.

1 It is conceivable that the structures described here represent a series of parallel submarine banks developed towards the close of Black Rock Sandstone time. Whatever their true origin, the external form as revealed from outcrops and the practical con~equence~ are essentially the. same.. The writer has favoured the hrpoth~sis of an origin due to structural deformatwn (foldmg) rather than sedimentatiOn largely because of the relatiOnship of the joint pattern to the long axes of the structures. 43

The Red Bluff Sands are thinner above the The Beaumaris Monocline appears to have little anticlines in the Black Rock Sandstone than in effect on the joint pattern and it seems probable the adjacent synclines and the amplitude of the that the main jointing was imposed prior to the undulations in the stratification planes decreases formation of the monocline. upwards from the .base of the formation. At this stratigraphic level the small structural relief is Structure Contours-Base of Tertiary. considered to be due to supratenuous folding The contours drawn on this surface are based probably arising from differential compaction of on data compiled from bores and show the general the sediments. Regardless of origin, at least part form of the Tertiary basin in the Melbourne area. of the relative displacement on the top of the Black In some areas the bore data is inadequate and Rock Sandstone between adjacent anticlines and modification of the contours will be necessary as synclines is reflected at the land surface. new data becomes available. The folds are surprisingly long and regular and The bores are too widely spaced and in many have every appearance of being normal compres­ cases the bedrock surface cannot be located with sional folds pre-dating the last movement on the 1 sufficient precision to enable the contours to give Beaumaris Monocline which truncates them. The an indication of the fold pattern. folding post-dates the Black Rock Sandstone and probably pre-dates the deposition of the Red Bluff Sands as these beds are unaffected by the jointing ACKNOWLEDGEMENT. described below. The writer wishes to acknowledge his indebted­ ness to J. L. Neilson and W. E. Bamford for Folds of similar morphology are developed in the subsurface data on the Lower Yarra Crossing and Lower Pliocene and older Tertiary deposits at to J. L. Neilson for geological logs of bores from Curlewis, but these appear to have been caused the M.M.B.W. south-east trunk sewer. B. E. Wells solely by movements on the adjacent Curlewis and J. B. Coulsell assisted respectively in the Monocline (Coulson, 19 3 3 ) . compilation of some of the bore data and the drawing of the joint rose diagrams. Mr. E. D. Gill Jointing. provided stfmulating discussion on the nomenclature Several sets of vertical or near-vertical joint of the Brighton Group ( = Sandringham Sands of planes are developed in the Black Rock Sandstone Gill, 1957) even though he disagreed with the and were studied in cliffs and shore platforms. views expressed here. Because of the nature of the outcrops measure­ Thanks are due to Mr. A. J. Wagglen, Chief ments were largely restricted to the anticlinal areas Engineer, Ports and Harbours Branch, Public except in the Mentone-Mordialloc area. Works Department for permission to inspect unpublished bathymetric charts prepared by that Measurements of joint trends were grouped into Department and to Mr. J. J. Fryer for bringing areas of broadly similar joint pattern and joint this information to notice. Messrs. C. S. Gloe and frequency roses were constructed (Plate 2). The A. H. Bartlett kindly provided new information main sets of joints on the Brighton-Beaumaris from bores in the Mordialloc area. coast are developed in the sectors 295-300° ; 25-35°; 40-50°; 85-90°; 330-335°; 305-310°; 315-320° and 0-5° (whole circle magnetic bearings APPENDIX. arranged in order of decreasing abundance). At Subdivisions of the Brighton Group. Mentone the main joint sets are developed in the sectors 65-75°, 325-335° and 0-5°. These sediments were originally mapped by the Geological Survey of Victoria and in Quarter Sheet The joint sets were found to be arranged No. 1 (Melbourne and Suburbs) issued in 1863 symmetrically with respect to the fold axes and they were grouped together under the naine of presumed axis of main stress. The appearance of "Flemington and Upper Brighton beds". Later these joints in the field and their relationship to ( 1868) the term "Brighton beds " was applied to the presumed stress axes suggest that they are the same formation on Quarter Sheet No. 2 S.E. mostly typical shearing joints genetically immediately to the north of Quarter Sheet No. 1 related to the folding. Joints developed parallel N.E. In subsequent Quarter Sheets the Flemington to the main stress direction are more common and Upper Brighton beds ("Newer Pliocene") between Mentone and Mordialloc and are con­ were distinguished from the Brighton beds ("Older sidered to be tension joints. Pliocene") and it is probable that these units were

1 Contrary to expectations these folds or fold-like undulations are not conspicuous in the Beaumaris cliffs. This is probably due to the overriding influence of the Beaumaris Monocline, 44

the same as the two subdivisions of the beds in the Jutson and Coulson (1937, p. 319) also recog­ Brighton cliffs recognized by later workers. Un­ nized a group of apparently unfossiliferous sediments fortunately, the boundary between the two forma­ overlying fossiliferous marine late Tertiary deposits tions was not marked on published maps of the on the Bellarine Peninsula and elsewhere through­ Melbourne area and the criteria by which they out the Port Phillip area, and drew attention to were distinguished are not known. Hart's (1893) recognition of an unconformity between these two units. An analysis of the stratigraphic terminology em· played by the Geological Survey under Selwyn is On the basis of a detailed study of the strata given by Thomas and Baragwanath (1950, Pt. 3, represented in the cliffs at Beaumaris Singleton p. 43). In their discussion of the stratigraphy of ( 1941, pp. 3 3, 78) recognized a sequence above the Altona area Thomas and Baragwanath adopted the " Balcombian " essentially similar to that pro­ the old term Flemington and Upper Brighton beds. posed by Hart (1893). This comprised- This term has clear priority and was undoubtedly used in a truly stratigraphic sense by the early ( 1) A basal nodule bed immediately overlying officers of the Geological Survey, but as the com­ the "Balcombian" marls, and the ensuing pound name does not conform with the requirements 20-22 feet of brown calcareous sandstone of the Australian Code of Stratigraphic Nomen­ and sandy marl containing abundant shells. clature its use has been abandoned in these notes. These fossiliferous beds were made the basis of the definition of the Cheltenhamian In 1893 Hart proposed a threefold subdivision of Stage (Upper Miocene). the Tertiary rocks of the Beaumaris area and (2) 19-28 feet of ferruginous sandstone with recognized a fourth " upper sand " unit which hard ironstone bands, apparently uTI­ clearly belongs to the Quaternary. From the fossiliferous. These were regarded as Beaumaris cliffs he described a lower unit ( 1) of being Kalimnan (Lower Pliocene) or ferruginous and calcareous sandstone and shelly younger. marls containing an abundance of marine fossils. ( 3) 4-10 feet of white sands. These beds were These were considered to be about 45-feet thick considered to be similar to beds through­ on the basis of evidence from bores at Mordialloc. out the southeastern suburbs of Melbourne This lower unit was considered to be overlain with­ and were regarded (p. 78) as being out stratigraphic break by about 70 feet of " Middle or Upper Pliocene or even ferruginous sandstones with ironstone bands (unit Pleistocene ". 2). Fossils were stated to be absent from this unit at Beaumaris, but Hart recorded fossil marine The marked differences from the thicknesses cited shells from near its top at Brighton and Red Bluff, for the corresponding units by Hart (1893) evidently and shells and wood from Black Rock. These two arise because Hart has attempted to estimate the units were considered to have been uplifted and maximum thickness of each unit over the whole denuded to some extent before deposition of the Beaumaris-Mordialloc area whereas Singleton's poorly cemented, often coarse, grey, white, yellow values are based on measurements of particular and red sands which he termed the " lower sand " cliff sections. (unit 3). This third unit was believed to attain a stratigraphic thickness of more than 100 feet Later Gill (1950, p. 168) proposed the name between the south end of Charman-road and Sandringham Sands for all of these deposits, and Mentone. No fossils were recorded from unit 3. included the basal Balcombian shell bed of Royal Park in his original definition. In (1957) he It is apparent from Hart's descriptions (1893, recognized a twofold subdivision of the Sandringham p. 156 and 1912, p. 278) that he did not recognize Sands-a lower stratigraphic unit consisting of the "Balcombian" ( =Bairnsdalian) at the foot of ferruginous sandstone and marly sands which he the Beaumaris cliffs and that his unit ( 1) is the same named the Black Rock Member, and an upper unit as the Cheltenhamian of Singleton · ( 1941, see of clayey sands, grits and gravels named the Red below). Bluff Member and separated from the Black Rock Member by a disconformity. Hall and Pritchard (1897, p. 190) accepted the existence of the unconformity recognized by Hart, Thus Gill's proposal groups the lower two units of but considered it to be of local importance only Hart (1893) and Singleton (1941) together. As and not indicative of an appreciable time break. described the Black Rock Member is considered They recognized (p. 223) fossiliferous lower beds to be marine and ferruginous and the Red Bluff and unfossiliferous upper beds, but treated the Member terrestrial and essentially non-ferruginous deposits as a unit which was regarded as marine or only slightly ironstained. The two members were near the coast and becoming terrestrial and fresh­ mapped separately along part of the Sandringham water inland. coast by Gill (1957, p. 168, map). 45

Recently Gill (19 58) suggested that a period of CHAPMAN, F., 1905.-Excursion to Burnley. Viet. Nat., ferruginization (laterization) intervened, in Lower Vol. 21, No. 12, p. 173. CoLLIVER, F. S., 1937a.-Fossil Localities in and about Pliocene time, between the times of deposition of Melbourne Part L-Royal Park Cutting. Viet. Nat., the Black Rock Member and the Red Bluff Member. Vol. 53, No.7, pp. 131-132. According to Gill therefore the two members are CoLLIVER, F. S., 1937a.-Fossil Localities in and about lithologically distinct, contain different fossils­ Melbourne Part IL-Beaumaris. Viet. Nat., Vol. 53, one marine and the other terrestrial-and are No. 9, pp. 151-153. separated by a disconformity which marks a definite CoLLIVER, F. S., 1937b.-Fossil Localities in and about Melbourne Part IV.-Altona Brown Coal Mine. Viet. time break. For these reasons it is suggested here Nat., Vol. 54, No. 5, pp. 80-81. that the two members should be accorded full CoNDON, M. A., 1951.-The Geology of the Lower formation rank (Black Rock Sandstone and Red Werribee River, Victoria. Proc. Roy. Soc. Viet., Bluff Sands) and that the Sandringham Sands should Vol. 63, pp. 1-24. be elevated to Group status to be consistent with the CooKsoN, IsABEL C., 1959.-Fossil Pollen Grains of recommendations of the Australian Code of Strati­ Nothophagus from Australia. Proc. Roy. Soc. Viet., graphic Nomenclature (1959). The term Sandring­ Vol. 71, Pt. 1, pp. 25-30. CouLSON, ALAN, 1933.-The Older Volcanic and Tertiary ham Group thus becomes almost synonymous with Marine Beds at Curlewis, near Geelong. Proc. Roy. the term " Brighton Group " also proposed by Gill Soc. Viet., Vol. 45, Pt. 2, pp. 140-149. (1950, p. 167) "to refer to all beds outcropping in CRESPIN, IRENE, 1926.-The Geology of Green Gully, the cliff sections " between Elwood and Mordialloc. Keilor, with special reference to the Fossiliferous As the term Brighton Group is merely a formalized Beds. Proc. Roy. Soc. Viet., Vol. .38, pp. 100-124. version of the old Geological Survey term " Brighton CRESPIN, IRENE, 1943.-The Genus Lepidocyclina in Vic­ toria. Proc. Roy. Soc, Viet., Vol. 55, Pt. 2, pp. beds " which was employed on several 157-180. published Quarter Sheets, the term Brighton Group CuDMORE, F. A., 1926.-Extinct Vertebrates from is preferred to Sandringham Group and is adopted Beaumaris. Viet. Nat., Vol. 43, No. 3, pp. 78-82. in these notes. DENNANT, JoHN, & KITSON, A. E., 1903.-Catalogue of It is unlikely that the transition from fossiliferous the Described Species of Fossils (except Bryozoa and Foraminifera) in the Cainozoic Fauna of Victoria, marine beds to sparingly fossiliferous marine beds South Australia and Tasmania. Rec. Geol. Surv. of similar lithology in the Black Rock Sandstone Viet., Vol. 1, Pt. 2, pp. 89-147. will prove to be conveniently mappable in the field DEPARTMENT OF MINES, VICTORIA, 1895.-Annual Report and it seems undesirable to formally name the two of the Secretary for Mines, for 1894. subdivisions recognized by Hart (1893) and DEPARTMENT OF MINES, VICTORIA, 1899.-Report on the Singleton ( 1941) until such time as surface and Brown Coals and Lignites of Victoria. Prog. Rept. subsurface stratigraphic work reveals further details Geol. Surv. Viet., No. 10, pp. 73-83. DEPARTMENT OF MINES, VICTORIA, 1903.-Annual Report of the vertical relationships and horizontal of the Secretary for Mines and Water Supply for distribution of these two units. In the meantime, in year 1902. the cause of simplicity, Gill's members are retained DEPARTMENT OF MINES, VICTORIA, 1904.-Annual Report here, but with the new status suggested above. Regret of the Secretary for Mines and Water Supply for is nevertheless expressed that the Black Rock Sand­ year 1903. stone is named from a locality in which only the top DEPARTMENT OF MINES, VICTORIA, 1938.-Records of sparingly fossiliferous part of the formation is Boring Operations 1923-30. represented and that the names Beaumaris and DoRMAN, F. H., & GILL, E. D., 1959.-0xygen Isotope Cheltenham of the classic Beaumaris cliff sections Palaeotemperature Measurements on Australian Fossils. Proc. Roy. Soc. Viet., Vol. 71, Pt. 1, pp. do not appear in the nomenclature. 73-98. DouGLAS, J. G., 1958.-Palynological Examination of REFERENCES CITED. Sample from Brooklyn Pumping Station Project. ARMITAGE, RICHARD W., 1910.-Notes on the Occurrence Mines Dept., Viet., Unpublished Report 31.1.58. of Plant Remains in Olivine Basalt, Clifton Hill DouGLAS, J. G., 1960.-Palynological Examination of Quarry. Viet. Nat., Vol. 27, No. 2, pp. 21-30. ~amples from the North Pump Well, Brooklyn Pump­ BAKER, GEORGE, 1946.-Microscopic Quartz Crystals in mg Station. Mines Dept., Viet., Unpublished Report Brown Coal Victoria. American Mineralogist, Vol. 21.7.60. 31, pp. 22-30. GILL, E. D., 1949.-Early Tertiary Plant Beds near Pascoe BowLER, J. M., 1963.-Tertiary Stratigraphy and Sedi­ Vale, Melbourne, Victoria. Viet. Nat., Vol. 66, No. 4, mentation in the Geelong-Maude Area, Victoria. pp. 69-73. Proc. Roy, Soc. Viet., Vol. 76, Pt. 1, pp. 69-137. GILL, E. D., 1950.-Nomenclature of Certain Tertiary CARROLL, DoROTHY, 1949.-Mineralogy of the Chelten- Sediments near Melbourne, Victoria. Proc. Roy. Soc. hamian beds at Beaumaris, Victoria. Jour. Viet., Vol. 62, Pt. 2, pp. 165-171, Pl. X. Sedimentary Petrology, Vol. 19, pp. 104-111. GILL, E. D., 1957.-The Stratigraphical Occurrence and CARTER, A. N., 1958.-Report on Private Bore in Elder­ Palaeoecology of some Australian Tertiary Marsupials. road, Clarinda. Mines Dept., Viet., Unpub. Rept. Mem. Nat. Mus. Viet., Vol. 21, pp. 135-203, Pls. 1-4. No. 1958/23. CARTER, A. N., 1959.-Guide Foraminifera of the Tertiary GILL, E. J:?., 1958.-Dating of Cainozoic Non-Marine Stages in Victoria. Min. & Geol. Jour., Viet., Vol. 6, Rocks m Australia. A.N.Z.A.A.S., Adelaide. Ab­ No. 3, pp. 48-54. stracts of Lectures and Papers, 4 pp. 46

GILL, E. D., 1961.-Eustasy and the Yarra Delta, Vic­ STRATIGRAPHIC NOMENCLATURE, 1959.-Australian Code toria, Australia. Proc. Roy. Soc. Viet., Vol. 74, Pt. 2, of Stratigraphic Nomenclature, Third Edition. Jour. pp. 125-133. Geol, Soc. Aust., Vol. 6, Pt. 1, pp. 63-70, May. 1959. HALL, T. S., 1909.-" Victorian Hill and Dale." T. C. STREVENS, J. L., 1924.-Report on the Port Phillip Oil Co. Lothian, Melbourne. Ltd. bore at Williamstown. Unpublished Report, HALL T. S., & PRITCHARD, G. B., 1897.-A Contribution Mines Department Petroleum Records. t~ our knowledge of the Tertiaries in the neighbour­ TAYLOR, D. J., 1963.-Micropalaeontological Examination hood of Melbourne. Proc. Roy. Soc. Viet., Vol. 9, of Samples from Deutgam No. 1 Bore. Mines Dept., pp. 187-229. Viet., Unpublished Report 1963/62. HART, T. S., 1893.-Notes on the Rocks of Brighton and THIELE, E. 0. & GRANT, F. E., 1902.-0n the Fossil Moorabbin and the surrounding districts. Viet. Nat., Contents of the Eocene Clays of the Altona Coal Vol. 9, pp. 156-159. Shaft. Proc. Roy. Soc. Viet., Vol. 14, Pt. 2, pp. HART, T. S., 1894.-Volcanic Rocks of the Melbourne 145-152. District. Viet. Nat., Vol. 11, pp. 75-78. THOMAS, D. E., & BARAGWANATH, W., 1949-51.-Geology HART, T. S., 1913.-0n the Country between Melbourne of the Brown Coals of Victoria. Min. & Geol. Jour., and the Dandenong Creek. Proc. Roy. Soc. Viet., Viet., Pt. 1, Vol. 3, No. 6, pp. 28-55, Sept. 1949. Vol. 25, Pt. 2, pp. 268-285. Pt. 2, Vol. 4, No. 1, pp. 36-52, March 1950 (a). Pt. 3, Vol. 4, No. 2, pp. 41-63, Sept. 1950 (b). HILLS, E. S., 1939.-The age and Physiographic Rela­ Pt. 4, Vol. 4, No. 3, pp. 36-50, March 1951. tionships of the Cainozoic Volcanic Rocks of Victoria. Proc. Roy. Soc. Viet., Vol. 51, Pt. 1, pp. 112-139. WHINCUP, SYLVIA, 1944.-Superficial Sand Deposits between Brighton and Frankston, Victoria. Proc. HILLS, E. S., 1940.-" The Physiography of Victoria." Roy. Soc. Viet., Vol. 56, Pt. 1, pp. 53-76. Whitcombe & Tombs Pty. Ltd., Melbourne and Sydney, 292 pp. WILKINs, R. W. T., 1963.-Relationships between the Mitchellian, Cheltenhamian and Kalimnan Stages in JuTsoN, J. T., 1913.-0n the Age and Physiographic the Australian Tertiary. Proc. Roy. Soc. Viet., Vol. Relations of the Older Basalts of Greensborough 76, Pt. 1, pp. 39-57. and Kangaroo Ground, and certain Basalts at Bun­ doora and Ivanhoe. Proc. Roy. Soc. Viet., Vol. 26, Pt. 1, pp. 45-56. MAPS. JuTsoN, J. T., & CouLSON, ALAN, 1937.-0n the Age of APLIN, C. D. H., 1868.-Quarter sheet 2 S.E. Geol. Surv. certain Marine Deposits at Portarlington, Victoria, Viet. Scale 1 : 31,680, Notes 1-12. with a Proposed Subdivision of the Post-Tertiary BLACK, GEORGE, 1885.-Melbourne and Suburbs, Contour Rocks of the Port Phillip Bay District. Proc. Roy. plans. Lands Dept., Viet., scale 10 chains to 1 inch, Soc. Viet., Vol. 49, Pt. 2, pp. 314-326. contour interval 10 feet. Plan Nos. M386, M386A JUTSON, J. T., & CouLsoN, ALAN, 1940.-Further Notes and M386F. on Certain Marine Deposits at Portarlington, Vic­ CUNINGHAM & PICKETT, 1896.-Parish of Moorabbin, toria. Proc. Roy. Soc. Viet., Vol. 52, Pt. 2, pp. Contour plan. Lands Dept., scale 20 chains to 1 inch, 342-344. contour interval 10 feet. Plan No. M386P. KEBLE, R. A., 1950.-" The Mornington Peninsula." LANDS DEPARTMENT, VICTORIA, 1962-63.-Port Phillip Geol. Surv. Viet., Memoir 17. Bay, Eastern Shore, Miscellaneous Photomap No. 119, KENLEY, P. R., 1960.-The Tertiary Deposits of the Mel­ Sheets 3-8, scale 500 feet to 1 inch. bourne Area-Stratigraphy. Mines Dept., Viet., Un­ MELBOURNE AND METROPOLITAN BOARD OF WoRKS, 1960. published Report No. 1960/41, pp. 1-21. -Melbourne and Suburbs, Drainage Record Plan as KITSON, A. E., 1902.-Remarks on the Brown Coal Beds at 1st April, 1960. M.M.B.W., scale 1 mile to 1 inch. and Associated Deposits of the Werribee Plains, Vic­ toria. Trans. Aust. Inst. Min. Eng., Vol. 8, Pt. 2, BATHYMETRIC CHARTS-PORT PHILLIP pp. 255-267. BAY. PARR, W. J., 1942.-The Age of the Lignite Deposits at Parwan. Min. & Geol. Jour., Viet., Vol. 2, No. 6, Cox, COMMANDER HENRY L., 1861-62.-Pojnt Ormond pp. 363-364. to Red Cliff (Sheet VII.). Coast Survey Plan No. 25 (1861). Red Cliff to Sand Station (Sheet VIII.). PATERSON, HELEN T., 1934.-Notes on some Tertiary Coast Survey Plan No. 24 (1862). Lands Dept., Viet., Leaves from Pascoe Vale. Proc. Roy. Soc. Viet., scale 6 inches to a nautical mile (6,069 feet). Vol. 46, Pt. 2, pp. 264-273. Cox, CoMMANDER HENRY L., 1864.-Admiralty Chart of PRITCHARD, G. B., 1901.-Eocene Deposits at Moonee Port Phillip No. 1711, with corrections and additions Ponds. Viet. Nat., Vol. 18, No. 4, pp. 61-63. to 1961. Scale 1 : 100,000. PRITCHARD, G. B., 1910.-" The Geology of Melbourne." LARKIN, J. P., 1930.-Point Ormond-Brooks Jetty, St. Peter G. Tait, Melbourne & Sydney. Kilda. Public Works Dept., Viet., Ports and Harbours PRITCHARD, G. B., 1944.-" Old Yarra History as told by Branch, Plan No. 13134, Sept. 30th, 1930. Scale the Geology of Burnley, Heyington, Tooronga." 1 : 1,800. 8vo., Cheshire Pty. Ltd., Melbourne. TAYLOR, S. B., 1962.-Green Point-Half Moon Bay. Public REED, K. J., 1960.-Micropalaeontological Examination of Works Dept., Viet., Ports and Harbours Branch, Plan samples from M.M.B.W., South-east Trunk Sewer No. 1962/363, 165; May, 1962. Scale 600 feet to Bore S.E.4. Mines Dept., Viet., Unpublished Report 1 inch. No. 1960/116. SINGLETON, F. A., 1923.-The Geology of Royal Park. Proc. Pan. Pacific Science Congress, Australia, Vol. 2, ILLUSTRATIONS. pp. 1626-1631. TEXT FIG 3.-Diagrammatic cross-section illustrating the SINGLETON, F. A., 1941.-The Tertiary Geology of Aus­ stratigraphic relationships of the principal Tertiary tralia. Proc. Roy. Soc. Viet., Vol. 53, pp. 1-125. formations in the Melbourne area. STIRLING, lAMES, 1899.-Report on the Brown Coals and PLATE 2.-Base of Tertiary structure contours and Lignites of Victoria. Geol. Surv. Viet., Progress geological structure of the Tertiary rocks, Melbourne Report, No. 10, pp. 73-83. area. Plate 2.

--700

PORT PHILLIP

Point Cook

Bore ~S1t~:~~ !i~u;~:J.:t:/d: 'ol line) Strudure contours o.n hue ollhe Terfit ry

An lidine) Positions ol lo/Js on ,,,d bued Syndlne f on inlerptel•lion ol !opogrephy

_ 1-fonoclil111111ellure or w~rp ~ (AxiJ of srndlnt l bend)

Suit ol Hilu

M TnndoiAtllkllnti A.o l• BM Tr•nd of S.111m.,h Monodln. J_ '"''North ....JtM 1gne Uc North 47 3-3 QUATERNARY

J. L. Neilson and J. J. Jenkin. 1

No attempt has been made to sub-divide the Keble and Macpherson's lower terrace (Braybrook) Quaternary into Recent (Holocene) and Pleistocene, is cut in sediments which are older than the sedi­ owing to the absence of satisfactory criteria on ments of the higher Keilor terrace (see Fig. 4) . which to base this boundary. For the same reason, correlation of the Melbourne Quaternary The original deposition of the terrace material deposits with the established sequences from was probably controlled by a local base level due to a basalt bar across the river in the vicinity of Europe has not been attempted. Flemington, or to a general higher base level due to a higher sea level. ALTONA AREA. Shell beds, several feet above present sea-level, Gill (19 53, b) has distinguished three distinct occur associated with sand ridges parallel with the lithological units, which together, make up what present coastline at Altona and Seaholme, though have been known as the Maribyrnong Terraces. they have been obscured considerably by recent Gill used the term terrace in the sense of " bodies building (Plate 15, Fig. 3) . of sediments ", not topographic forms, but has since ( 1962) defined these " bodies of sediments " The shell beds contain only living species, some as formations. of which, e.g., Anadara trapezia, are not as common in Port Phillip Bay to-day as when the beds were Gill's three formations are, from oldest to formed. The sand with which the shells are found youngest:- is very variable in grain-size. The shells are some­ ( 1) Arundel Formation. (From the Arundel times worn or broken, sometimes entire.. The Terrace) . This formation consists of shell beds rest upon a surface of basalt of the dark-brown clays with thin sandy and Newer Volcanics. gravelly lenses, and near the base generally contains many pebbles and Overlying the shell beds are low sand ridges, boulders of basalt and Silurian bedrock. which are probably beach ridges modified by wind action. At Altona, the sand ridges reach a maxi­ (2) Doutta Galla Silt. (From the Keilor mum elevation of 12·2 feet above low-water mark Terrace). Overlying the Arundel Forma­ of the present sea level (Hills, 1940). The upper tion unconformably, these sediments are surface of the shell beds is exposed 9 · 5 feet above light coloured silts, of rather uniform sea level in the railway cutting near the Williams­ lithology. town racecourse (Pritchard, 1909; Grant and A number of diastems occur, the most Thiele, 1902) . prominent being in the middle of the The distinction between the shell beds and the formation. sand ridges is made by Gill ( 1961), who believes ( 3) Maribyrnong Alluvium. (From the Mari­ that the shell beds were deposited in a normal byrnong Terrace). Consists of grey to shallow-water marine environment, and exposed by black sandy and clayey silts. a Holocene eustatic change of sea level. In the Doutta Galla Silt have been found Near the mouth of Skeleton Water Holes Creek, aboriginal hearths, artefacts, the Keilor skull, and emerged stratified shell beds are well displayed, a few other vertebrate remains. Radiocarbon covered by thin deposits of black mud. Shell beds dating has been carried out on charcoal from the are found in black muds behind ridges of the hearths in the Keilor Formation. Two such deter­ Altona type at Point Cook. minations have been made, with results of 8,500 -+- 250 years and 3,100-+- 160 years (Gill, 1955a). MARIBYRNONG VALLEY. Considering the wide variation in these results little reliance can be placed in them. Further deter­ Keble and Macpherson ( 1946) described three minations and ancillary checks are required. terraces along the Maribyrnong River, and corre­ lated them with the classic sequence of the European Gill (1955b) records a marine deposit from the Alps. This correlation, depending on terrace levels Maribyrnong River at Essendon, containing only and not on the stratigraphy of the deposits, molluscs, barnacles, and wood bored by marine is doubtful, but is too big a question to be discussed borers, and gives a radiocarbon dating of 4,820 here. The section at Dry Creek, Keilor, shows that -+- 200 years.

1. Manuscript completed 1959, revised 1964. 48

Crespin ( 1926) mentions a small deposit of The development of the Yarra Delta, as Gill Coxiella limestone at Green Gully, Keilor and a (1953, 1961) has shown, appears to depend mainly carbonaceous sandy clay with diatoms and other on the fluctuating sea level of the Quaternary. plant remains from the same locality. Direct evidence for tectonic effects here is lacking. Alluvial deposits also occur in the valleys of the The Quaternary sediments of the Yarra Delta Moonee Ponds Creek, the Merri Creek and are sub-divided into four main units, each of which Darebin Creek. Stillwell ( 1911 ) has described a has been proved to have wide geographical extent. fresh-water limestone occurring in tributaries of The upper three units were recognized, but not Moonee Ponds Creek north-east of Broadmeadows. named, by Lucas (1887), though they have since The limestone, which is younger than the Werribee been named by Gill (1962). The lowest unit, com­ Plains basalt, has an irregular distribution and is posed largely of sands and gravels, was first noted very variable in chemical composition. It contains by Learmonth (1957) from the preliminary drill­ shells of living species. Near the mouth of Moonee ing for the Kings Bridge ; he did not name Ponds Creek, at the Arden-street crossing, a frag­ it, and was uncertain whether it was of Tertiary ment of the lower jaw of Diprotodon australis was or Quaternary age. Unpublished work by J. L. found in fawn to brownish sandy clay 25 to 35 feet Neilson has since established the wide extent of below the surface (Pritchard, 1899). Marine these sands and gravels over the Yarra Delta ; shells of Recent species were found in the same they are named the " Moray Street Gravels " from excavation 200 feet to the west, and appear to their prominent development at Kings Bridge. overlie the Diprotodon bed. Unpublished work by W. E. Bamford and J. L. Neilson and published work by Donald and Ellwood The alluvial material in the terraces of Moonee (1962), on the Fishermen's Bend-Spotswood area, Ponds Creek shows a prominent diastem like that have added to the stratigraphic knowledge of that in the Doutta Galla Silt of the Maribyrnong Valley, area. and the deposits can probably be correlated. The stratigraphy of the Yarra Delta is given Other finds of bones of extinct marsupials have in Table 5. been made in the valley of Merri Creek at Coburg, in a clay overlying the basalt, and Hanks (1934) TABLE 5-STRATIGRAPHIC TABLE, YARRA DELTA AREA. found further remains in deposits under the basalt. Beach ridges and aeolian sands LOWER YARRA AREA. Port Melbourne A low lying area of Quaternary sedimentation Sand Stratified sands with shell spreads seawards from Princes Bridge. This area, beds known as the Yarra Delta, covers much of South Coode Island Silt Including Whiteman Street Melbourne and embraces the West Melbourne Quaternary Carbonaceous Member Swamp, Fishermen's Bend and Port Melbourne. Newer Volcanics (stratigraphic position not Situated near the head of the Port Phillip Basin, certain). (Basalt of the Flinders Street area) a basin of Tertiary sedimentation, the Quaternary Fishermen's Bend Silt deposits of the Yarra Delta represent the last phases of sedimentation within this basin. The Moray Street Gravels Port Phillip Basin and its structure have been Newer Volcanics (Basalt of the Werribee Plains discussed in the Tertiary section ( 3-2) of this Phase) bulletin. Recent drilling now makes it possible to see the general structure and stratigraphy of the Brighton Group Yarra Delta, which are shown on the accompanying cross-sections (Fig. 5, Plate 3). Tertiary . . Newport Formation The Quaternary Yarra Delta sediments rest on Older Volcanics a very gently south-westerly sloping, but somewhat Werribee Formation irregular, terrain. This terrain is composed generally of Older Volcanics, Tertiary sediments Silurian .. Interbedded siltstone, mudstone and sand- of the Werribee Formation and in a limited area stone adjacent to Spotswood, of the Tertiary Newport Formation, as well as Silurian bedrock. The varied nature of this terrain is due to pronounced erosion Port Melbourne Sand. during a glacial low-sea level. At that time, sedi­ The Port Melbourne Sand covers the Fishermen's ments of the Tertiary Brighton Group were com­ Bend-Port Melbourne area, with increasing thick­ pletely removed from this area, with denudation ness to the south-west. On the Yarra Delta adjacent extending down into the older rocks. to Spotswood, these sands are about 20 feet thick, 49 while at Port Melbourne, they reach a thickness below sea level at the site of Spencer Street Bridge, of about 40 feet. Where found in bores adjacent gave an age of 8,780 +- 200 years (Gill, 1955). to Spotswood, the sands are medium to fine in The stump probably comes from the Whiteman grain-size, and often silty or clayey. Street Carbonaceous Member. A later radiocarbon The sands appear to conformably overlie the determination on this stump (Gill, 1957) gave black Coode Island Silt. From the Coode Canal 8,300 ± 210 years. excavations, Lu,cas (1887) describes the major The lateral extent of the Whiteman Street part of the sands as bedded, sometimes cross­ Carbonaceous Member is limited. It has been bedded and with some shell bands. This portion found at the foundations of the Spencer Street of the sands is clearly marine, and would appear Bridge and the Kings Bridge. to have been deposited close to the margin of the The age of the Coode Island Silt is given as retreating sea after the last post-glacial higher belonging to the mid-Holocene thermal maximum eustatic sea-level. Overlying these marine sands, by Gill ( 19 53), and its elevation agrees with the Lucas recognizes thin superficial aeolian sand ridges well-known mid-Holocene 10 feet high sea-level. running parallel with the present coast. In It thus, in part at least, belongs to the Flandrian unpublished note books in the possession of the Transgression. Mines Department, J. T. Jutson estimates that the bedded marine sands reach about 3 feet above The sediments of the Coode Island Silt are present sea-level. As well as describing dune sands deposited disconfonnably on an irregular surface overlying the marine sands, Jutson describes sub­ cut by sub-aerial erosion in the underlying Fisher­ parallel beach ridges trending W.S.W. close to the men's Bend Silt. An appreciable time interval is Williamstown ferry. indicated between these two formations. The Coode Island Silt always overlies the basalt of the Newer The Port Melbourne Sand may be correlated with Volcanics which came down the Yarra valley. the Altona shell beds and sand ridges. Newer Volcanics. Coode Island Silt. Basalt of the Newer Volcanics flowed down the The Coode Island Silt is very widespread over ancestral valleys of the Merri Creek and Darebin the delta, though its thickness varies considerably. Creek, into the old valley of the Yarra, and flowed It extends up the Yarra valley at least as far as on below Princes Bridge to Spencer Street Bridge, the Church-street bridge, and also extends up the beyond which is has not been found in bores. Maribyrnong valley. At Olympic Park and adjacent to King Street The accompanying sections (Plate 3) indicate along Flinders Street, this basalt is overlain by the the variation in thickness of this formation. At Coode Island Silt. Beneath Flinders Street in this Kings Bridge, it is about 60 feet thick, while vicinity, barnacles are seen on the upper surface at the Mines Department Store site, Fishermen's of the basalt. Bend, it is not represented at all. At Coode Canal, The stratigraphical position of this basalt is not Lucas (1887) states that its thickness varies from quite certain. It is certainly overlain by the Coode 5 to 8 feet. Island Silt, and probably it is underlain by the The Coode Island Silt is a soft dark grey silt, Fishermen's Bend Silt, but inadequate descriptions clayey silt and silty clay. Its physical characteristics of bore materials make the latter uncertain. It is are discussed by Donald and Ellwood ( 1962). certain, however, that this basalt is younger than Marine shelly fossils, including Anadara trapezia; the Moray Street Gravels. A Quaternary age for foraminifera, occasional plant fragments and this basalt is also indicated by Pritchard's observa­ abundant spores indicate a marine and estuarine en­ tion ( 1944) of silts containing Quaternary marine vironment (Learmonth, 1957). Lucas (1887) fossils beneath the basalt at Richmond and Burnley. remarks that at West Melbourne Swamp this silt is rich in brackish water and marine diatoms, and has Fishermen's Bend Silt. even yielded dolphin remains at 10 feet depth. The Fishermen's Bend Silt is very widespread Gill (19 53) has recorded marine diatoms from over the Yarra Delta. It is found in the Yarra these silts in the Yarra Valley as far upstream as Valley as far upstream as Princes Bridge. Church Street Bridge. Its thickness varies considerably. At Kings Within this formation, in the vicinity of the Bridge, it is mostly between 5 feet and 25 feet in Kings Bridge, is a prominent carbonaceous band thickness, while at Fishermen's Bend, it reaches a about 5 feet thick. In this band, here named thickness of 70 feet. The variation in thickness is the Whiteman Street Carbonaceous Member, plant largely due to erosion, which occurred during a fragments are very abundant, so that it varies from glacial low sea-level, when this formation was a carbonaceous silty clay to a peat. A radiocarbon exposed to sub-aerial weathering and erosion dating of a red gum stump, excavated from 63 feet (Gill, 1953). 2288/66.-4 50

The Fishermen's Bend Silt is best described as The irregular upper surface of the Moray Street a stiff silty clay. In parts, it is a fairly pure clay, Gravels as revealed by boring at Kings Bridge, is while in others it is a sandy clay. Sometimes it probably due to moderate erosion of these deposits, is a clayey silt, or a silt. Its colour varies from perhaps under tidal conditions, as sea-level rose and pale grey to yellow and pale brown, frequently with deposition of the Fishermen's Bend Silt began. mottling in its upper zone. When the material is a fairly pure clay, its upper zone often shows fissuring, as Donald and Ellwood ( 1963) observe. HEIDELBERG ALLUVIAL TERRACES. The colour and fissuring are indicative of sub­ Broad river terraces are conspicuous along the aerial weathering, during an interval of exposure Yarra River, above its junction with Darebin before the marine incursion which deposited the Creek. They are particularly prominent at Heidel­ overlying Coode Island Silt. It was probably during berg and Templestowe. They originated as a this interval of time, that the basalt of the Newer result of the lava flows of the Newer Volcanics Volcanics which flowed down the lower Yarra which, flowing down the ancestral valleys of Merri valley was extruded. In contrast to the Coode Creek and Darebin Creek into the old valley of Island Silt, the Fishermen's Bend Silt it much more the Yarra River, caused damming of the river. consolidated and has a far lower organic content.

The appearance of the Fishermen's Bend Silt AEOLIAN DEPOSITS. suggests a marine environment of deposition, though In the western part of the area, the Newer marine or estuarine fossils from it are not common. Volcanic basalts of the W erribee Plains are covered Gill (1953) has stated that it is marine. Plant by a thin blanket of red coloured fine sandy clay fragments are sometimes present at Kings Bridge, which is probably of aeolian origin. but are not common. An extensive belt of sand-ridges and dunes The age of the Fishermen's Bend Silt is placed occurs between Cheltenham and Frankston. These within the Riss-Wiirm Interglacial (about 100,000 occur as ridges parallel to the present coastline years ago) when the sea-level was 25 feet higher and as crescentic lunette-like ridges on the eastern than at present, (Gill, 1961). side of swamps (Whincup, 1944). Dunes to the north of this area were regarded by Whincup as Moray Street Gravels. longitudinal dunes, but an alternative explanation of these dunes is given in the Tertiary section of The lowest Quaternary formation consists of this bulletin. gravels and sands, together with included mi~or silts and clays. Generally, the sequence begms with coarse gravels, or even cobbles, and rises through a varied succession of the other materials. REFERENCES. Lateral variation is quite pronounced. The sands, CRESPIN, I., 1926.-The Geology of Green Gully, Keilor, and to a lesser extent the gravels, often have a with special reference to the fossiliferous beds. Proc. small clay content. Minor thin lenses of carbon­ Roy. Soc. Viet., Vol. 38, pp. 100-124. aceous clay are known from the Kings ~ridge site. These sands and gravels are, almost Without DONALD, I. B., and ELLWOOD, R. B., 1962.-Geotechnical Investigation for the proposed Road Crossing of the exception, uncemented, and the pebbles in the Lower Yarra River, Melbourne. Aust. Road Res. gravel are well rounded. Both the sands and Board, Vol. 1, Pt. 2, pp. 1173-1212. gravels are predominantly of quartz. GILL, E. D., 1953 (a) .-Palaeoecological interpretation of some Victorian fossil diatom floras. Mem. Nat. Mus. The Moray Street Gravels are of wide geo­ Melbourne, Vol. 18, pp. 141-153. graphical extent, but bores at West Melbourne Swamp, between Dynon Road, and Footsc:ray Roa1, GILL, E. D., 1953 (b) .-Current Quaternary studies in in some cases passed directly from Fishermen s Victoria, Australia. Actes du IV. Congres Inter­ Bend Silt into Silurian bedrock or basalt of the national du Quaternaire. Older Volcanics. The thickness of the Moray GILL, E. D., 1955(a) .-Radiocarbon dates for Australian Street Gravels varies considerably. It is not known archaeological and geological samples. Aust. J. Sci., to be more than 50 feet, and is usually very much Vol. 18, pp. 49-52. less. GILL, E. D., 1955(b).-The Australian "Arid Period", The. Moray Street Gravels, with their rapid Aust. J. Sci., Vol. 17, pp. 204-206. lensing and variation, are fluviatile deposits, brought GILL, E. D., 1957.-Report of the A.N.Z.A.A.S. com­ down by very vigorous streams during a time of mittee for the investigation of Quaternary strandline glacial low sea-level. changes. Aust. J. Sci., Vol. 20, pp. 5-10. 51

GILL, E. D., 1961.-Eustasy and the Yarra Delta, Vic­ KITSON, A. E., 1902.--;-Further notes on the River Yarra toria, Australia. Proc. Roy. Soc. Viet., Vol. 74, pp. improvement sectiOns at the Botanical Gardens, 125-133. Melbourne. Ibid., Vol. 15, pp. 41-46.

GILL, E. D., 1962.-Report on Victoria, for the LEARMONTH, A. P., 1957.-Geological Groundwork for A.N.Z.A.A.S. Committee for the Investigation of the Melbourne's King Street Bridge. Min. and Geol. Quaternary Strandline Changes (Sections C and P). Jour. Viet., Vol. 6, No. 2, pp. 7-10. Aust. ]. Sci., Vol. 25, pp. 203-4.

GRANT, F. E., and THIELE, E. 0., 1902.-Notes on some LucAs, A. H. S., 1887.-0n the sections of the delta of Recent marine deposits in the neighbourhood of the Yarra, displayed in the Fishermen's Bend cutting. Williamstown. Proc. Roy. Soc. Viet., Vol. 15, pp. Proc. Roy. Soc. Viet., Vol. 23, pp. 165-173. 36-40. PRITCHARD, G. B., 1899.-0n the occurrence of Dipro­ HANKS, W., 1934.-The Tertiary sands and Older Basalt todon australis (Owen) near Melbourne. Proc. Roy. of Coburg, Pascoe Vale and Campbellfield. Proc. Soc. Viet., Vol. 12, pp. 112-114. Roy. Soc. Viet., Vol. 46, pp. 144-152.

HILLS, E. S., 1940.-The question of Recent emergence PRITCHARD, G. B., 1909.-The Recent shell-beds of of the shores of Port Phillip Bay. Proc. Roy. Soc. Williamstown. Viet. Nat., Vol. 26, pp. 20-24. Viet., Vol. 52, pp. 84-105. KEBLE, R. A., and MACPHERSON, J. H., 1946.-The con­ PRITCHARD, G. B., 1944.-0ld Yarra history, as told by temporaneity of the river terraces of the Maribyrnong the geology of Burnley, Heyington, Tooronga. River, Victoria, with those of the Upper Pleistocene Cheshire, Melbourne. 32 pp. 8 vo. in Europe. Mem. Nat. Mus. Melbourne, Vol. 14, pp. 52-68. STILLWELL, F. L., 1911.-Notes on the geology of Broad­ meadows. Proc. Roy. Soc. Viet., Vol. 24, pp. 156-178. KITSON, A. E., 1900.-Geological notes on the River Yarra improvement sections at the Botanical Gardens and vicinity, Melbourne. Proc. Roy. Soc. Viet., WHINCUP, S., 1944.-Sand deposits between Brighton and Vol. 13, pp. 243-252. Frankston. Proc. Roy. Soc. Viet., Vol. 56, pp. 53-76.

ILLUSTRATIONS

TEXT FIG. 4. Generalized section showing the relationship of the alluvial formations on the Maribyrnong River near Dry Creek, Arundel. TEXT FIG. 5. Plan of Yarra Delta area, showing positions of bores and Cross-sections A, B, C (see Plate 3). PLATE 3. Cross-sections A, B and C, Yarra Delta area (see Text Fig. 5 for positions of sections).

s K N 100 ~---'"------..

FEET 50

100

Maribyrnang Alluvium K Keilor Terrace

B Broybrook Terrace Quaternary Oouta Galla Sill M Moribyrnong Terrace of Keble and Macpherson 0946) Arundel Formal/on

Interbedded SandstoMS Silurian and Mudslont:s

TEXT FIG. 4. Generalized section showing the relationship of the alluvial formations on the Maribyrnong River near Dry Creek, Arundel. 52

SOUTH

PRINCES PIER

HOBSON BAY

BREAKWATER PIER SCALE OF CHAIN~ 0 40 60 80 Plate 3 )Q )Q t'! :;:; 0 9 u UJ ,_ ...... o~ltl ...... ( e; 0 UJ • » > • {t • . ~" -o ~_.Vl UJ _.VlO::~ ~ 0~ ~ ~ ~ mm~ ~ ~0. ~~~ "oo ~~ iJ~ u~ ,;• ,;g • • .,_·--·------a~------100 Tb \------_ --~_:::' _ .::_:-- --=---==~:-...:.:- =.:-::.=:.:.-=-==------=--=--=--==- - !~-=-=~~:--~:~~~~~~-;.:_-_::::..;:~Om :~.:J:Zo=-=~~~:~~':: Om _____ ---_ -----:.:::-:. ------____ :..o:.------5 --... - .... ____ Tw _-_-::;;: ___-_- __-;-_:-:-:-_-==:.-::::-_- __- T ----- ,... Tw ------__ _ - ..,!1 ___ --- -- Tvo ______--7------.... ---··· Tvo - 200 ------7------Tw ------~------s Tw ...... -··------· ------HOR IZONTA L SCALE 0 10 20 CHAINS ------______., ___ _ ------········ s SECTION A I I Beach ridges and aeolian sands VERTICAL SCA LE 0 100 200I FEET PORT MELBOURNE SANDS Stratified marine sands with shell beds VERTICAL EXAG GERATION 6·6 TIMES R.L (Feel) ll! ;.. 0 COODE ISLAND SILT Dark gray-brown solt silts, silty clays, clayey sills + ·100_ ltl '1- "' ('f Ill UJ .f¥~ LiJ ~ ~ ~ ~ WHITEMAN STR EET Dark gray -brown peal, peaty silts, silty peal ~ ~ ~ Ill Ill Ill (lj CARBONACEOUS MEMBER (,j -'l'- (,j (,j (,j ~ i O livine basalt ol the Flinders Street area Q uaternary NEWER VOLCANICS ,_ ~)l! ~~ ~ ~ ~~ "! _1_8ea Level ~ ~ ~ ~- (Stratigraphic position not certain) Pale gray, pale brown and mottled gray-brown still 0 __;._ _ __ ...= ... Tw FISHERMENS BEND SILT o-Ll~tl~l~:~~L"""'"""'==0=='p=a==:O::==p=m===_=_=__= _J~~·~~l_=_=_=_=_ =__=_=_=_=_=_=_=::=:_= __= _ _=-_-~--~ --=-~--~--~-_:_::.~:.~:.~--~--~--~~~:.~--~-~--~--~=;:-~:.~-~-~-~-~-~-~-~-~.::~p~~~::~-~~~~~·~~-~~~· -~~?.-~~~~~~~~-~--~~~-~~f._-~:~~0~~~~;-~~~t·~:::-:~:~;~=~-~~-=:~:~~-~:~-_::__::_:::_:=:_~~f-~_;::_:_: _=_=_=_::_:: ::;~;~;;;~;_;_;;::;: ~~~;~;-~_;_~-~~~~=-=-=~~-f-~~~~:~~~~~~~~-~_=_:::_~-~~;~;-~~:;-_;:::::_=_:;;:_~:::::::_::_=_=::.=_=,= =_r_=_=_=_==~=:::-~:;~;::-:::;- :~~~f~~~r,i~~~~~~::~r~,;~:~;~-~t~~-;~;~:.,:~!~"!~0 clayey silts, silty clays, clays, silts and sandy clays 1 =~t--~~=9._~-:_-_-_-:;:_-:.:::::.::: :: -- ---t------Of ______o!______- - --=:~_-:_.9~- -1- ---- _-:.;- .. -01, MORAY STREET GRAVELS Gravels, sands, with some clayey and silty horizons Of -100- - - ' Om t::-_------NEWER VOLCANICS Basalts and scoria, ol the W erribee Plains Phase ''-_....:::..._ ---___ ----=--,._-- _ -•-__ ----:'":.-:..--:..-..:.;---:~-.:.-=--~~-Tn s - --? · ------=------.:.:..:.~- 7:.=::.:..:...-;.:-?---~----~" 1 BRIGHTON GROUP Red-brown sills, clayey sands, silty sands ------Tvo ·------0------;~:;.::._ ---~?~- Tvo __:-:_--_ -_-.::=------Tw ---- (UNSUBDIVIDED) and minor grits -- ~...... _ ___ ...!!!..~· Tn ___ ;___ ------._,~-..::..- ----? ------Greenish·gray micaceous siltstones, with marine fossils ------HORIZON TAL SCA LE 0 10 20 CHAINS NEWPORT FORMATION -200------tvlinor limestones grading to carbonaceous siltstones ------s lr------t-1----, 1 and thin impure brown coal near base Tw 7------VERTICAL SCALE O 100 200 FEET Tertiary ------SECTION B ALTONA COAL SEAM Thick brown coal, locally spliffin g to thin seams ------VERTICA L EXAGGERATION 6·6 TIM ES with clay intercalations ------7------s Pyritic sands, ligneous sands, clays and carbonaceous -300- WERRIBEE FORMATION clays, minor thin brown coals and conglomerates near base R.L. (Feel) + 40- OLDER VOLCANICS Basaltic clay and basalt

Sil urian Mudstones and sandstones

-40-

-eo- NORTH SECTION c SOUTH - 120- s

HOR IZONTAL SCALE Oil---i'i----li l-0----jlr ~ FEET VERTICAL SCALE 0 I 50 100 FEET 53

3~4 IGNEOUS ROCKS GRANITIC ROCKS. are fresh enough for complete petrological examina­ tion. Because of their decomposed nature it is P. R. Kenley. only in road cuttings, clay pits, building excavations Small stock-like granitic intrusions occur at etc, that the dykes are noticeable and hence the Broadmeadows (adamellite) and South Morang extent and strength of the dyke swarm is largely a (granite). The rocks at both localities intrude matter of conjecture. the Silurian bedrock discordantly and contact metamorphic rocks are developed in the sediments Add and Intermediate Dykes. adjacent to the intrusions (Stillwell, 1912 ; Tattam, Quartz and felspar porphyry dykes occur at 1925 ; Edwards and Baker, 1944). Diamond Creek (Junner, 1913) and Broadmeadows Other small granitic intrusions occur at South (Stillwell, 1911) and also in many of the Melbourne Yarra and Toorak (Quarter Sheet 1 S.E.). The brick pits (Bain and Spencer-Jones, 1952-3). occurrence at South Yarra was worked for many Acid dykes and other small igneous intrusions years as a source of fireclay by the South Yarra occur at South Yarra (Hills, 1941, Kitson, 1901, Fire-Brick Co. (Bell, 1961). Other developments Mines Department Quarter Sheet 1SE.), Mont of granitic rocks were recognized in sewerage Park (Jutson and Chapman, 1913), and Royal excavations in the Toorak--South Yarra area, and Park (Singleton, 1923). recent sewerage bores drilled by the M.M.B.W. in The dykes from the Diamond Creek area have the St. Kilda Junction-Prahran area have shown been intensely altered and only the outlines of the that a granitic mass underlies thin Tertiary original minerals are now preserved. deposits in this area (J. L. Neilson, Pers. comm.). The Mont Park dyke is approximately 300 yards Granitic rocks have also been recorded from long and varies in width from about 6 to 30 feet. directly beneath the Tertiary sediments in bores In thin section it is seen to consist of altered felspar, at Clayton and Clayton South. The granitic rocks small blebs of quartz, sericite, and occasional tour­ in this area are thought to be associated with the maline. Harkaway granodiorite intrusion which outcrops east of Dandenong. Granodiorite also outcrops in The close association of the quartz porphyry the Frankston-Mt. Eliza area. dyke at Broadmeadows with the Bulla-Broad­ meadows granodiorite intrusion suggests that the These rocks are considered to be of late Upper two are probably related and like the other acid Devonian age by analogy with well-dated rocks of and porphyry intrusions of the Melbourne area similar petrological character in other parts of the probably belong to the epi-Devonian period of State. igneous activity. REFERENCES. Basaltic Dykes. BELL, G., 1961.-Victorian Fire-Clays and Fire-Bricks, Pt. III, The South Yarra Fire-Brick Co. Pty. Ltd. J unner ( 1913) described the only known fresh Min. and Geol. Jour. Viet., 6 (4), pp. 9-16. basaltic dyke from the Melbourne area. The dyke EDWARDS, A. B. and BAKER, GEORGE, 1944.-Contact was exposed in a shaft near where the Maroondah Phenomena in the Morang Hills, Victoria. Proc. Roy. Aqueduct crosses Diamond Creek north of Greens­ Soc. Viet., 56 (1), pp. 19-34. borough. It consists of phenocrysts of olivine STILLWELL, F. L., 1912.-Notes on the Geology of Broad­ meadows, Proc. Roy. Soc. Viet., 24 (1), 156-178. and titanaugite in a ground mass of felspar, granular TATTAM, C. M., 1925.-Contact Metamorphism in the augite, olivine, magnetite and apatite. Bulla Area and Some Factors in Differentiation A number of small decomposed dykes intruding of the Granodiorite of Bulla, Victoria. Proc. Roy. Soc. Tertiary gravels at St. Helena aTe reported by Viet .. 37 (2), 230---247. Crohn ( 1950). These dykes are of considerable DYKE ROCKS. interest in that they are the only known dykes in the Melbourne area to intrude Tertiary sediments. K. G. Bowen. Near the intersection of Clifton and Sweyn The Silurian of the Melbourne area has been Streets, Balwyn a limburgitic volcanic plug has intruded by a large number of dykes varying in been described by Chapman and Thiele (1911). composition. The majo:11ity of these dy1ces are The rock was exposed over an area measuring completely decomposed and now consist almost approximately 230 feet by 100 feet and rising entirely of clay minerals. The presence or absence slightly above the surrounding ground level. In the of quartz in these decomposed dykes is the only hand specimen it is a dense, dark blue or black indication as to original composition. Occasionally rock. Microscopically it consists of numerous relict felspar or ferromagnesian phenocrysts are olivine and occasional augite phenocrysts set in a recognisable in thin section, and rarely the dykes ground mass of augite, labradorite laths, numerous 54

small crystals of magnetite, some ilmenite and brown REFERENCES. glass. This plug is regarded as being related to the BAIN, A. D. N. and SPENCER-JONES, D., 1952-53.-" Mel­ Older Volcanics (Chapman and Thiele 1911, bourne Brick and Tile Industry." Min. and Geol. Edwards 1939). Jour., Vol. 4, Nos. 5 and 6, Vol. 5, No. 1. CHAPMAN, F. and TmELE, E. 0., 1911.-" On a Limbur­ Alkaline Dykes. gite Rock Occurring as a Volcanic Plug at Balwyn, Hills (1941) describes an alkaline suite of dykes near Doncaster." Proc. Roy. Soc. Viet., Vol. 24, Pt. 1, from the Studley Park district. These dykes pp. 124-134. CROHN, P. W., 1950.-" Flintoff's Hill Greensborough, which range from 1 foot or less up to about 10 feet Preliminary Report." Mines Departi1Jent, Un- in thickness intrude the Silurian, but not the overly­ published Report 1950/18. ing Tertiary gravels. Of all the dykes exposed in the EDWARDS, A. B., 1934.-" Tertiary Dykes and Volcamc area only one, an anorthoclase trachyte is fresh Necks of South Gippsland, Victoria." Proc. Roy. enough for complete examination. The rock con­ Soc. Viet., Vol. 47, Pt. 1, pp. 112-134. sists of phenocrysts of anorthoclase, occasional EDWARDS, A. B., 1939.-" The Petrology of the Tertiary Older Volcanic Rocks." Proc. Roy. Soc. Viet., Vol. biotite flakes, small chloritic or serpentinous 51, Pt. 1, pp. 73-9ti. pseudomorphs after pyroxene (aegirine) set in a HILLS, E. S., 1941.-" The Silurian Rocks of the Studley ground mass of fresh sanidine laths. Another dyke Park District." Proc. Roy. Soc. Viet., Vol. 53, Pt. 1, although too decomposed for examination contained pp. 167-191. numerous xenoliths of a soda rich graphic granite, JuNNER, N. R., 1913.-" General and Mining Geology of and a felspathic xenolith consisting almost entirely the Diamond Creek Area." Proc. Roy. Soc. Viet., of anorthoclase. Vol. 25, Pt. 2, pp. 323-353. JuTsON, J. T. and CHAPMAN, F., 1913.-" On the Occur­ rence of a Felsitic Dyke and Associated Breccias at Lamprophyre Dykes. Sugar Loaf Hill (Mont Park), near Heidelberg." Lamprophyre dykes, one of which occurs near the Proc. Roy. Soc. Viet., Vol. 26, Pt. I, pp. 57-62. intersection of Alexandra Avenue and Church KITSON, A. E., 1901.-" Geological Notes on the River Street, South Yarra, have been regarded as Tertiary Yarra Improvements Sections at the Botanical Gardens and Vicinity, Melbourne." Proc. Roy. Soc. Viet., in age because of their similarities with the presumed Vol. 13, Pt. 2, pp. 243-252. Tertiary lamprophyres of the Midlands goldfields SINGLETON, F. A., 1923.-" The Geology of Royal Park," (Stillwell, 1912; Edwards, 1934). Proceedings of the Pan-Pacific Science Congress Australia, pp. 1626-1631. Age of the Dykes. STILLWELL, F. L., 1911.-"Notes on the Geology of The dykes at St. Helena intrude gravels which Broadmeadows." Proc. Roy. Soc. Viet., Vol. 24, Pt. 1, may be correlated with the Brighton Group. These pp. 156-178. and the dyke near the Maroondah Aqueduct STILLWELL, F. L., 1912-" Preliminary Notes on the Monchiquite Dykes of the Bendigo Goldfield." Proc. probably belong to the same phase of volcanic Roy. Soc. Viet., Vol. 25, Pt. 1, pp. 1-14. activity as the nearby basalts, i.e., the Greens­ borough phase of the Newer Volcanics. The alkaline dykes at Studley Park which do not intrude BASALTS the Brighton Group equivalents are therefore pre­ Brighton Group in age, i.e., pre-Upper Miocene, G. Bell, P. R. Kenley, and D. Spencer-Jones. and can probably be correlated with the Older Volcanics. GENERAL REMARKS Thus it is possible to recognize at least three Two main periods of volcanic activity, in each periods of igneous activity in the Melbourne area of which large quantities of basalt and associated during which dykes have been intruded. The first tuffs were ejected, have long been recognized in associated with the epi-Devonian period of igneous the Cainozoic rocks of the Melbourne area. The activity when the acidic and porphyritic dykes were rocks of the earlier major vulcanicity are of intruded, the second with the Older Volcanics when Eocene to early Oligocene age and are known the alkaline dykes of Studley Park were intruded generally as the Older Volcanics. The rocks of and the third with the Greensborough phase of the the later major vulcanicity are of Upper Pliocene Newer Volcanics, when the dykes at St. Helena and to Pleistocene age and are commonly referred to Greensborough were intruded. The lamprophyric as the Newer Volcanics. dykes were also probably intruded during the Although the majority of basalts clearly belong Tertiary. There are no known dykes which may be to one group or the other, it is evident that stages correlated with the Werribee Plains phase of the of prolonged volcanic activity and prolonged Newer Volcanics. dormancy intervened during each of these main In addition to the dykes described above there periods of vulcanicity, and it is apparent that are numerous completely decomposed dykes which volcanic activity did not entirely cease in cannot be placed with any certainty in any of the the long period of time between the main vulcan­ above groups. isms. Where reliable age evidence is lacking the 55

age of a particular basalt flow is frequently difficult Jointing. Both columnar and sub-horizontal to determine, and some basalts, notably those of laminar or platey jointing are well-developed, with the Greensborough-Kangaroo Ground area have the columns typically more closely spaced than in been regarded variously as belonging to:- the Newer Volcanics. The laminar joints in some ( 1) The Older Volcanics. This view is based flows appear to parallel incipient flow laminae. mainly on petrological evidence and was Weathering and Alteration. In a relatively fresh expounded by Edwards (1939) ; or condition they are typically divided by fractures (2) An intermediate period of vulcanicity. This lined with thin films of limonite. In the course view is due to J utson (1913) and is based of weathering the rock adjacent to these fractures on physiographic and stratigraphic lines decomposed and the resultant zone of alteration of argument ; or extended progressively outwards from the fractures. At a fairly advanced stage of weathering this ( 3) An early phase of the Newer Volcanics. process gave rise to a series of more or less This view is mainly due to Alpin (1868) concentric shells of crumbly, decomposed basalt and depends on stratigraphic evidence that the basalts overlie sediments corre­ surrounding residual kernels of fresh basalt. The lated with the late Cainozoic Brighton resulting structure is known as " onion " or Group and therefore fall within the time " spheroidal " structure. interval represented by the Newer Locally, weathering of the basalts has progressed Volcanics. beyond this stage to the point where the basalt has None of these arguments can be re­ completely decomposed to a poorly crystallized garded as conclusive, but for reasons set kaolinitic clay in which only faint relics of the out elsewhere (Sect. 3-2) the third view original basaltic texture are preserved (e.g., Royal has been adopted in this volume. Park). . Un?er co~d~tions of poor drainage, montmonllomte and Illite tended to form (Briner, 1963) resulting in sticky soils which exhibit high OLDER VOLCANICS (P.R.K. & G. B.). shrinkage on drying. The rocks included under this heading are mainly dense black basalts which form a subsurface sheet Petrology. The petrology of these rocks has with only limited outcrops to the west of Mel­ been considered at some length by Edwards (1939) bourne. The outcrops extend north-west from who included the Kangaroo Ground and Greens­ South Melbourne, generally along the line of the borough occurrences (here assigned to an early Melbourne Warp to Essen don, Pascoe Vale and phase of the Newer Volcanics) with the Older Keilor and are best developed in the valleys of Volcanics. the Moonee Ponds Creek and Maribyrnong River. Th~ Old~r Volcani~ rocks for~ a distinct petro­ These rocks are also represented extensively in graphic smte recogmzable practically throughout bores in the Yarra delta, Footscray, Newport and the State. The ~ost common petrological types Spotswood areas. To the south-east of Melbourne represented are titanaugite basalts and olivine minor developments have been recognized in bores basalts, the latter being the predominant type in at Mordialloc and the formation is again represented the Melbourne district. Analcite is sometimes at the surface in the Frankston-Cranbourne area. abundant in these rocks. Characteristically the The stratigraphic position and age of these rocks Older Volcanic basalts lack iddingsite, are glassy, has been considered in Section 3-2. and only rarely are vesicular or porous. They are generally black in colour as compared with the light-grey, blue-grey or dark-grey of the Newer Physical Features of the Rocks (Plates 4, 6). Volcanic basalts. Thickness. The Older Volcanics achieve a maxi­ mum thickness of approximately 120 feet in bores The bulk of the Older Volcanic olivine basalts east of Spotswood where they are represented by a in the Melbourne area were assigned by Edwards series of basalt flows of varying degrees of vesicu­ to the Keilor type. This petrological type occurs larity and state of weathering with thin sands and at. Keilor, Tullamarine and along the Maribyrnong carbonaceous clays separating some of the flows. River. The type has been described as consisting of small phenocrysts of olivine in a fine-grained Appearance. These rocks are typically hard, ground mass of laths of labradorite, pyroxene iron dense, glassy, tough black basalts in which vesicles oxide and considerable brown glass, but th~re is are usually rare or absent. Specific gravities of considerable textural variation. At Green (Taylor's) the basalts are generally in the range 2.8-3.1. Gully (Plate 4, Fig. 2), the top flow of Older The physical properties of these basalts which Volcanic basalt is decomposed into a white friable are relevant to their behaviour as aggregate ro~k. The next lovyer flow from the quarry is materials are considered in Section 4-1 of this fairly fresh and typical of the Older Volcanics. volume. Thin sections show it to be fairly fine-grained, 56 containing abundant clear brown glass (Plate 5, Centres of Eruption. Unlike the Newer Figs. 1, 2). The bottom flow visible lower in the Volcanics, few definite points of eruption of the gully is a fine-grained basalt containing much iron Older Volcanics have been recognized. It is con­ oxide with medium-sized phenocrysts of olivine. sidered that the weathered basaltic dykes which The rocks from Steele's Creek at Keilor East, intrude the Silurian bedrock of the Melbourne area Tullamarine and Campbellfield, show marked are hypabyssal equivalents of the Older Volcanic similarities. The two latter are coarse grained rocks and some of these dykes may represent with large phenocrysts of olivine partly altered to feeder channels which supplied the extensive early serpentine, set in a ground mass of labradorite, Tertiary basalt flows. pyroxene, olivine, iron oxide and abundant dark­ brown opaque glass. The dense black basalt at Campbellfield in the REFERENCES CITED. Merri Creek south-east of Mellody's clay pit is APLIN, C. D. H., 1868.-Quarter sheet No. 2 S.E. Geol. petrologically almost identical to the Tullamarine Surv. Viet., Scale 1:31,680, Notes 1-12. basalts. It underlies the Newer basalt and is BRINER, G. P., 1963.-Survey of Clay Minerals in some separated from it by a thin layer of ferruginised Victorian Soils. Proc. Roy. Soc. Viet., Vol. 77 ( 1), clay. At Tullamarine boring data also shows pp. 191-195. sepaJ:ation from Newer basalt by a considerable thickness of Tertiary sands and clays (Plate 12, CoNDON, M. A., 1951.-The Geology of the Lower Werribee River, Victoria. Proc. Roy. Soc. Viet., Vol. Fig. 2). 63, pp. 1-24. Chemical composition. Anaylses of basalts from Royal Park and Keilor are given in Table 6. CRESPIN, IRENE, 1926.-The Geology of Green Gully, Keilor. Proc. Roy. Soc. Viet., Vol. 38, pp. 100-124. TABLE 6. CROHN, P. W., 1953.-Lilydale Limestone Deposit. Min. - I. 2. 3. and Geol. Jour., Vol. 5, No. 1, pp. 37-41. sio. 0 0 0 0 45·64 44·95 46·43 EDWARDS, A. B., 1939.-Petrology of the Tertiary Older 0 0 0 0 14·35 15·50 17·60 Al20 3 Volcanic Rocks of Victoria. Proc. Roy. Soc. Viet., 0 0 0 0 8·51 Fe.Oa 2·08 2·04 Vol. 51, Pt. 1, pp. 73-98. FeO 0 0 0 0 10·32 10·47 2·44 MgO 0 0 0 0 9·50 7·43 8·03 GILL, E. D., 1942.-Bearing of Tertiary Sub-Basaltic 0 0 0 0 8 ·12 CaO 7·87 8·24 Deposits on the Palaeogeography of the Lilydale 0 0 0 0 2·17 3·04 3·56 Na20 District. Proc. Roy. Soc. Viet., Vol. 54, Pt. 2, pp. 0 0 0 0 1·23 1·98 0·92 K20 245-256. H.o+ 0 0 0 0 1·29 2·60 1·20

H.o- 0 0 0 0 1·92 0·52 0·81 HANKS, WALTER, 1934.-Tertiary Sands and Older Basalts 0 0 0 0 0·47 0·18 n.d. co. of Coburg, Pascoe Vale and Cainpbellfield, Victoria. Ti0 0 0 0 0 2·74 2·77 2·25 2 Proc. Roy. Soc. Viet., Vol. 46, Pt. 2, pp. 144-152. P205 0 0 0 0 0·42 0·52 0·37

0 0 0 0 0·13 0·21 0·22 MnO HILLS, E. S., 1939. The Age and Physiographic Relation­ Li,O 0 0 00 0 0 0 0 0 0 ships of the Cainozoic Volcanic Rocks of Victoria. 0 0 0 0 0·02 0 0 0 0 Cl Proc. Roy. Soc. Viet., Vol. 51, Pt. I, pp. 112-139. s 0 0 0 0 0·14 0 0 0 0

0 0 0 0 Nil 0 0 0 0 BaO JuTSON, J. T., 1913.-Age and Physiographic Relations of Other 0 0 0 0 0·11 0 0 0·07 the Older Basalt of Greensborough and Kangaroo Ground, &c. Proc. Roy. Soc. Viet., Vol. 26, Pt. 1, Total 0 0 0 0 100·40 100·45 100·53 I pp. 45-56. 1. Olivine basalt (Flinders type of Edwards, 1939) Royal Park cutting. Analyst W. McCance 1932, Proc. LEARMONTH, A. P., 1958.-Geological Ground Work for Roy. Soc. Viet. 44 (2), p. 247. Melbourne's King St. Bridge. Min. and Geol. Jour. 2. Olivine basalt (Keilor type of Edwards, 1939) Viet., Vol. 6, No. 2, pp. 7-10. Quarry, Sect. XV, parish of Tullamarine. Analyst F. L. Stillwell, 1912. Proc. Roy. Soc. Viet. 24 (1), p. 177. MuRRAY, R. A. F., 1887.-Geology and Physical Geography 3. Olivine basalt (Greensborough phase of Newer of Victoria. Melbourne, 8 vo., 150 pp., 1st Ed. 1887. Volcanics. Flinders Type of Edwards 1939). Quarry near northern end of Flintoff's Hill, Greensborough. PATERSON, _HELEN T., 1934.-Notes on some Tertiary Analyst N. R. Junner, 1913, p. 335. Proc. Roy. Soc. Leaves from Pascoe Vale. Proc. Roy. Soc. Viet., Vol. Viet. 25 (2). 46, Pt. 2, pp. 264-273. 57

EXPLANATION OF PLATES 4-6. (See pages 58-60.)

PLATE 4. Older and Newer Volcanic rocks. Fig. 1. Newer basalt (top) overlying Tertiary sands in a small quarry near the Keilor-St. Albans­ road, at Green (Taylor's) Gully, Keilor. Fig. 2. Relationship of Older basalts ( O.B.) and Newer basalts (N.B.) to the Miocene sands and limestones at Green Gully. The lepidocyclinal limestones of the Green Gully Limestone Member occur at the base of the sands, immediately to the right of the photograph. Fig. 3. Older and Newer basalt flows separated by a sand layer two feet thick, Standard Quarries, Footscray.

PLATE 5. Thin section of Older basalt from Keilor. Fig. 1. Ordinary light. The brown glass (G) is characteristic. The ground mass consists of labradorite laths (L), pyroxene grains (P) and magnetite ( M). Phenocrysts are of olivine ( 0). Magnification xl 00. Fig. 2. As above, crossed nicols.

PLATE 6. Newer and Older Volcanic rocks. Fig. 1. Flat-lying basalt of the Newer Volcanics over­ lying Silurian mudstones dipping to the East (right) at 35-40°. Butler's Brick Pit, Albion-st. East, East Brunswick. Looking north. Fig. 2. Columnar jointing in basalts of the Older Volcanics, eastern quarry, Bayview Quarries, Tullamarine. Granodiorite tors crop out on Mt. Gellibrand in the background. Looking north-east.

2288/66.-5 58

PLATE 4.

FIG. 1.

FIG. 2.

FIG. 3. 59

PLATE 5.

FIG. 1.

FIG. 2. 60

PLATE 6.

FIG. 1.

FIG. 2. 61

NEWER VOLCANICS. Werribee Plains Phase (D.S.-1.). Greensborough Phase (P.R.K. & G.B.). The extensive basalt lava flows which form the relatively fiat areas to the north and west of Mel­ Rocks similar in appearance to the Older bourne belong to the younger or W erribee Plains Volcanics are represented at Greensborough, Jane­ Phase of the Newer Volcanic Suite in Victoria. The field and Kangaroo Ground. These rocks overlie basalt lavas and pyroclastics of this phase are com­ sands and gravels which are here regarded as cor­ paratively young in terms of geological time ; this relatives of the Brighton Group and which, as first fact being deduced from the present physiographic noted by Dr. A. D. N. Bain (Pers. comm.), are expression of the rocks, their thin soil cover and the intruded by occasional thin basaltic dykes. In the evidence that they overlie Quaternary alluvial and Readymix Concrete sand pit about one mile west estuarine sediments (Pritchard, 1944). of Kangaroo Ground, K. G. Bowen (Pers. comm.) observed conglomerate bands containing rounded cobbles of deeply weathered (? Older) basalt in Sections through the basalts in quarries and other the sands beneath these basalts. excavations indicate that many separate flows took place, some separated by considerable intervals of time. Hanks (1955) concluded that the eruptions The available evidence thus appears more con­ from the volcanic centres north of Melbourne were sistent with a late Tertiary age for the basalts at spasmodic and took place over a long period. Greensborough and Kangaroo Ground, but as noted by J utson (1913) these basalts cap comparatively high land and are distinctly older than the indis­ North and northwest of the City basalt flows putable Newer Volcanic flows present in the were extruded over a dissected land surface eroded adjacent valleys. For these reasons the basalts in basalts of the Greensborough Phase, Tertiary considered here have been regarded as belonging to sediments, Older Volcanic basalts and the Silurian an early phase of the Newer Volcanics such as is bedrock. The basalt flows partially filled the ancestral valleys of the Merri and Darebin Creeks represented in the W erribee plains (Condon, 19 51) and flowed down the ancestral valley of the Yarra and elsewhere in western Victoria. These rocks River from near the present site of Alphington to are here referred to as the Greensborough phase of vvhere Spencer Street Bridge crosses the river. The the Newer Volcanics. basalts did not completely blanket the old topography with the result that low hills such as Clifton Hill, The basalts of this group in the Plenty River­ Northcote Hill and Royal Park protrude through the Greensborough district are dense, blue-grey basalts flows as Silurian bedrock inliers. with columnar jointing. At both Greensborough and Kangaroo Ground the basalt rests partly on The alluvial gravels, sands and clays which had Silurian sediments and partly on sands, gravels and been deposited in the old valleys were covered by clays infilling an uneven surface carved in the the basalt lavas and these sediments have been Silurian bedrock. exposed by quarrying operations, e.g., Corporation Quarry, Clifton Hill (Mitchell, 1942), and in the These rocks comprise titanaugite basalts of the valleys of the present streams. Moorooduc petrological type and olivine basalts of the Flinders petrological type (Edwards, 1939). The maximum thicknesses of basalt are found Both of these types contain olivine phenocrysts, where the old stream valleys have been filled by the which are generally corroded to some extent and lavas. A thickness of 190 feet has been proved in partly altered to serpentine. In the Moorooduc the Albion Quarrying Company's quarry, Victoria­ type these phenocrysts are set in a ground mass of street East, Brunswick. titanaugite ophitically intergrown with labradorite laths, and abundant interstitial glass. In the West and southwest of the City the basalt flows Flinders type the groundmass is an intergranular have completely blanketed the old topography which growth of pyroxene granules, labradorite laths and was composed mainly of gently-dipping Tertiary iron oxide together with interstitial glass. and Quaternary sediments. Thicknesses of 170 feet and 151 feet were proved in the Truganina No. 3A and No. 4 bores respectively. Brown to green basaltic glass is abundant in both types, and is generally more or less devitrified, showing alteration to serpentinitic or chloritic Physical features of the basalt rocks. alteration products. The basalts of the W erribee Plains Phase are usually vesicular or honeycombed and often the Chemical composition. An analysis of basalt from surface of the flows is scoriaceous. Fresh exposures Greensborough is included in Table 6. of these rocks exhibit many physical features which 2288/66.-6 62

are characteristic of basic volcanic rocks. The of a fiat surface the upper surface of the joint in following are some of the more common features : a single column is convex and the lower surface is concave. The result is a ball and socket contact. 1. Vesicles. Many of the basalt flows are vesicular, tha~ is, Composition of the basalts. they are full of cavities of varying size from fractwns The basalts of the Werribee Plains Phase are of an inch in diameter to several inches. These grey to bluish-grey when fresh, a~d alth~mgh cavities have resulted from the trapping of bubbles variable in texture they are fine to medmm gramed. of gas when the lava was still in a molten state. The basalts in the Melbourne area are largely un­ Sometimes long cylinders of vesicles, pipes or differentiated and for composition can be grouped "corks" (Mcinerny, 1929), can be observed with the basic members of the Central Victorian extending vertically through the flow. These Volcanic Suite (Edwards, 1938). The two dominant pipes may be due to the sudden release of types are labradorite basalts containing olivine and gases and steam as the molten lava passes over are distinguished by the presence or absence of the wet sediments or water in the bed of a stream. The mineral iddingsite. individual vesicles or amygdales are often filled or partially filled with secondary minerals such as (a) Iddingsite labradorite basalt (Footscray Type). members of the Zeolite group and carbonates. In thin section these rocks are fine grained 2. Ropy structure. consisting of laths of plagioclase (labrad?r.ite­ bytownite) with subhedral crystals of ohvme, On the surface of a flow which has not been interstitial augite set in a groundmass of colourless deeply weathered the lava is wrinkled or ropy felspathic glass and disseminated grains of iro~ ore exhibiting corded structures which have resulted mineral. The olivine has been altered margmally from the movement of the molten flow when the to reddish-brown iddingsite. Some alteration to surface exposed to the atmosphere had become iddingsite has also occurred along cleavage planes viscous. (Mcinerny, 1929). 3. Spheroidal or onion weathering. (b) Olivine labradorite basalt. This is a weathering phenomenon exhibited by In thin section these rocks consist of phenocrysts basic volcanic rocks and some fine-grained sedi­ of corroded olivine with lime rich pyroxenes set ments where curved sheets of decomposing rock in a fine-grained groundmass of labradorite laths exfoliate from the main mass. The result is that (An55), pyroxene prisms, gree~ felspathic .glass the rock breaks up into spherical masses with the and minute rods and blebs of uon ore mmeral exfoliating sheets coming off like the skins of an (Edwards, 1938). onion. The weathering is initiated along the joint planes of the rock. Table 7 lists some chemical analyses of these rocks.\ 4. Jointing. TABLE 7. The jointing of basalt rocks is very characteristic -- Merri Creek, Eldridge's Merri Creek, and usually results from shrinkage during cooling East of Quarry, Coburg. Maribyrnong. from a molten lava to solid rock. In some areas Type. Pentridge. Footscray. jointing in basalt may be due to earth movements 01. Lab. Ol. Lab. Id. Lab. Id. Lab. and is therefore of tectonic origin, however the Basalt. Basalt. Basalt. Basalt. jointing described below is primary and due to cool­ % % % % ing. SiO, .. 49·01 50·86 51·05 49·60 Al,03 .. 16·60 13·84 12·75 15·14 Fe203 .. 2·97 4·70 9·75 3·94 (a) Mural joints. FeO .. 8·55 6·56 3·02 6·97 MgO .. 7·81 8·94 6·15 6·73 These joints occur near the surface of a basalt CaO .. 8·21 8·45 9·27 8·22 flow and consist of three sets, two being vertical Na,O .. 2·91 2·59 2·76 2·98 K,O .. 0·85 0·75 0·39 1·35 and the other horizontal. H,O+liO'C. 0·44 0·82 1·52 1·08 H,0-110' C. 1·24 0·57 2·23 2·40 co, .. .. 0·30 (b) Columnar joints (Plate 6, Fig. 2). TiO, .. 1:56 1:93 1·01 P2 05 .. 0·32 0·23 0·23 0·11 These are vertical joints spaced from several MnO .. .. 0·20 0·66 0·32 Cl .. .. Tr. Tr; Nil inches to several feet apart, cutting through the s .. .. 0·03 Nil so, .. .. Tr. Nil .. flows. The columnar jointing is perpendicular to Li,O .. .. Tr. .. the surface on which the lava rests so that in a BaO .. .. Tr. .. 0·01 NiO .. .. 0·01 .. .. confined valley the columns would be perpendicular Cr20 3 .. .. 0·05 .. .. to the valley sides. The columns if projected Total .. 100·47 100·53 99·78 100·16 would converge to a point above the valley centre. Analyst .. G. A. Cook A. G. Hall / P. G. W. Bayly A. B. Edwards Horizontal joints cut across the columns, but instead 63

Zeolite minerals. REFERENCES. The specimens of zeolite minerals collected from EDWARDS, A. B., 1938.-Tertiary volcanic rocks of Central Victoria. Quart. Jour. Geol. Soc. Lond., Vol. XCIV, these basalts were probably some of the best found Pt. 2, pp. 243-320. in the world. For many years the samples were HALL, r. s., 1911.-Victoria Hill and Dale. Thomas c. collected from the lower faces of the old Corporation Lothian, Melb., pp. 19-27. Quarry, Clifton Hill, and from quarries at Burnley HANKs, WALTER, 1955.-Newer volcanic vents and lava and Richmond. These quarries have now been fields between Wallan and Yuroke. Proc. Roy. Soc. Viet., Vol. 67, Pt. 1, pp. 1-16. filled with rubbish and debris consequently this HART, T. · S., 1894,-Volcanic Rocks of the Melbourne source is no longer accessible. The zeolite district. Viet. Nat., Vol. XI, No. 5, p. 76. minerals were well developed in the deeper sections HILLS, E. S., 1946.-Physiography of Victoria. Whitcombe of the flows where the basalts had filled the old and Tombs, Melbourne, pp. 189-192. valleys. The more common minerals of the zeolite MciNERNY, K., 1929.-Building stones of Victoria, Pt. 2. group found were analcite, gmelinite, mesolite, Proc. Roy. Soc. Viet., Vol. 41, Pt. 2, pp. 121-159. phacolite and phillipsite. In some of the larger MITCHELL, S. R., 1942.-Minerals of the Suburban Area. Viet. Nat., Vol. LIX, No. 7, pp. 116-118. cavities a clay-like mineral, halloysite was found PRITCHARD, G. B., 1944.-0ld Yarra history. 8 vo., in the lower part of the vugh. The carbonate Cheshire, Melbourne. mineral, aragonite, often is associated with the STILLWELL, F. L., 1911.-Geology of Broadmeadows. zeolites. Proc. Roy. Soc. Viet., Vol. 24, Pt. 1, pp. 156-178. 64

CHAPTER 4.

ECONOMIC GEOLOGY

In this chapter the various economic minerals of the Melbourne area are considered briefly. These include the commonplace, but economically important aggregate materials obtained by quarrying and other forms of extractive industry. Information on the underground water potential of the various rock formations is also presented.

4-1 AGGREGATES

K. G. Bowen.

Crushed rock aggregates play an important part The Older Volcanics in contrast to the light­ in the modern community and plentiful supplies of grey vesicular Newer Volcanics are typically dense, good quality aggregates close to the point of use black, glassy olivine basalts. Columnar jointing is are an important economic factor in road and generally much more pronounced and regular with building construction. individual columns up to about 1 foot across. Several different rock types and rocks of The average specific gravity of the Older different ages are quarried and crushed for use in Volcanics is 2 · 95 and the average crushing road and concrete aggregates within the metropolitan strength 20,000 lb./sq. in. compared with 2 · 80 and area. The most widely used stone is basalt which 16,000 lb./sq. in. for the Newer Volcanics. amounts to approximately 70 per cent. of the total production. Scoria. Although scoria and tuffs from the numerous Basalt. extinct volcanoes of the Western District have been widely quarried and used particularly for road­ Basalts of three different ages are quarried, the making materials, it is only in recent years that most widely used being those of the Werribee this material has been used in Melbourne, and is Plains Phase of the Newer Volcanics. These obtained from Mount Fraser near Beveridge. basalts are obtained mainly to the west and north Because of its lightweight, but still reasonable of Melbourne at places such as Williamstown, strength, it can be used as aggregate in concrete Footscray, Essendon and Epping. Former quarries blocks, or lightweight concrete. It is widely used at Richmond and Collingwood were located in on secondary roads, on shoulders of main roads basalts of this age. and for private pathways and drives. Pliocene basalts of the Greensborough phase of the Newer Volcanics are quarried at Greensborough Acid Igneous Rocl{s, and also at Bundoora where a recently opened The Upper Devonian acid igneous rocks of the quarry is probably located in similar basalts. Dandenong Ranges are quarried at Coldstream (Lower Toscanite), at Kilsyth (Lower Toscanite) Oligocene basalts of the Older Volcanics are and at Ferntree Gully (Lower Dacite). Rocks quarried at Tullamarine, Berwick and N arre Warren. of this series are very tough and compact, but because of their high silica content (approximately The Newer Volcanics are generally grey, fine to 25 per cent.) they are very abrasive in crushing coarsely vesicular, ophitic olivine basalts. Indivi­ plants. dual flows are generally thin and up to eight different flows with an average thickness of Besides the general use of these rocks as aggre­ approximately 20 to 30 feet are exposed in some gates, dacite is used for the manufacture of rock quarries. The flows generally exhibit columnar wool insulation. A mixture of crushed dacite, hard jointing with individual columns 3 or more feet coke and certain fluxes is added to a continuous across. Considerable variation in the hardness, flow cupola furnace. The charge which melts at number and size of vesicles, and degree of weather­ about 1,400° to 1,450° C. is tapped off and dis­ ing exists between different flows and for this reason tributed on a spinning disc which transforms the individual flows are generally quarried separately. melt into long fibres. The fibres are annealed by 65 spraying with light oil and are subsequently sprayed millisecond delay fuses. These fuses ensure that with resin which binds the fibres into a pad or there is a very slight delay of usually about 0.025 batt. The loose fibres are collected on a conveyor of a second in the detonation of each successive belt, compresesd into batts and passed through hole. This method not only produces far more an oven where the product is cured. rock with much better fragmentation, but is also comparatively quiet and free from vibration. Sedimentary Rocl.:s. The broken stone is then carted to the crushing Sedimentary rocks because of their inferior plant where it is crushed and screened to produce hardness and frequent presence of clay minerals are the various product sizes. generally not used for aggregates. Exceptions to this are where the rocks have been hardened by Physical Properties. metamorphism or have become silicified. A hard blue hornfels formed by the thermal metamorphism Modern road and concrete design requires strict of normal Silurian sediments by the Lysterfield control on the properties of the aggregate used. granodiorite is quarried at Lysterfield. Indurated For concrete the important properties are the Silurian sediments are quarried at Doncaster North strength of the stone, its cleanliness and freedom and at Frankston. from clay and dirt, its grading, i.e. the quantity of stone retained on a series of standard sieves ; the Lower Devonian limestone is quarried at Lilydale shape of the particles and its Los Angeles abrasion primarily for the manufacture of agricultural lime, loss. The Los Angeles abrasion loss is a measure but small quantities are used for other purposes of the resistance of the stone to abrasion and impact. particularly for ornamental stonework. It is the percentage of material passing a No. 10 B.S. test sieve produced after rotation at a speed of 30 to 33 r.p.m. in a machine similar to a ball mill. Production. The size of the test sample, and the total number of revolutions depends upon the grading of the Complete production figures are not available, material. but approximate figures for the years 1951 and 1961 are 1·6 million and 6·4 million cubic yards respectively. The percentage of the total produc­ For road making as well as the factors mentioned tion (19 61 ) for the different rock types are given above the plasticity index is particularly important. in Table 8. It is usually determined on the material passing a No. 36 U.S. test sieve or equivalent and represents TABLE 8. the range in moisture content through which the material is plastic. At higher water contents the material ceases to be plastic and behaves as a Percentage of - Production. liquid, and at lower water contents it behaves as a semi-solid. Werribee Plains Phase 61 Considerable variation in the physical properties exists not only between the different types of aggre­ Basalt .. Greensborough Phase 3 gate, but also in the same type of aggregate from different locations. Some typical values for Los Older Volcanics 19 Angeles loss are given in Table 9.

Devonian Lavas ...... 10 TABLE 9 .

Sedimentary Rocks ...... 6 Rock Type, Los Angeles Loss .

% Method of Working. Toscanite .. 10-14 Basalt is generally quarried from a number of Dacite 10-20 benches, each bench usually corresponding to an individual flow. In the other rock types which are Basalt­ usually of a more uniform composition bench heights are determined by economic and safety Older 11-14 factors. Drill holes are put down behind the quarry Newer 19-25 face, charged wtih explosive and fired usually by 66 4-2 SAND DEPOSITS

K. G. Bowen.

Approximately 2 · 5 million cubic yards of sand and Clarinda. Eroded remnants of the Brighton valued at about $2 · 8 million are used annually in Group are worked at Kangaroo Ground and St. the metropolitan area. Sand is used as a basic raw Helena. material in industries ranging from the finest glass­ ware to road making. The biggest single use, In contrast to the even grained uniform dune amounting to approximately 50% of the total sands these are quite variable in grading and production is in all forms of concrete. Other uses frequently contain a high percentage of clay. include brick, plaster, glass, foundry, and as a filler in hot mix. Concrete Sand. The bulk of Melbourne's concrete sand produc­ Sand like many other non-metallic products is tion comes from the Springvale and Clayton areas of little value unless it is located within reasonable with lesser amounts from Kangaroo Ground, St. distance of the markets to which it is to supply. Helena and Bacchus Marsh. Some very coarse Strictly speaking sand refers to particles of a granitic sands are transported to Melbourne for particular size (2 mm.-1/16 mm. diameter) but blending purposes from Garfield and Pyalong. of any composition. The grains are most commonly Most of the pits are worked hydraulically and the composed of silica or quartz and the sands of sand is washed and classified. Melbourne are of this type. Elsewhere the par­ The grading of a concrete sand should be within ticles may be composed of rock fragments, calcite, the limits as .set out in Fig. 6. It should be free olivine and many other minerals. Silica sands, from harmful materials such as clay, mica, organic because of the inherent properties of hardness and matter and soluble salts and should consist of resistance to abrasion of the particles, are most equidimensional, strong, rounded or sub-rounded desirable. particles rather than sharp angular particles which produce a harsh concrete difficult to work. The Classification. particular grading used has considerable effect on Sand may be classified in a number of different the cement and water contents of the mix which effects both the ultimate strength and cost of the ways, e.g., by origin :-wind blown, fluviatile, or mix. river deposits, by age:-Tertiary, Pleistocene, Recent, by use:-concrete, glass, foundry sand, etc., or by composition:-silica sand, calcite sand. etc. Since the same sand may be used for a number of different uses, or sands with similar gradings may have formed in a number of different ways during different geological ages the classifications are arbitrary ones of convenience.

Pleistocene to Recent Sands. Extensive wind blown Pleistocene to Recent dune sands occur in the Frankston, Cranbourne and Langwarrin areas. Further areas of dunes occur at Lang Lang. The sands of these dunes which rise to about 100 feet in height are pale yellow in colour and are comparatively evenly graded. TYLER MESH Unlike the Tertiary sands they lack any coarse TEXT Fm. 6. Examples of grading limits for concrete sand particles and are therefore of little use for concrete and the grading for a typical washed concrete sand work. Approximately one third of total production from Springvale. comes from these dune sands. Glass Sand. Tertiary Sands. The main requirement for glass sand is that it The bulk of Melbourne's sand, approximately must have a high silica content and have an 60%, comes from Brighton Group sediments or exceptionally high degree of purity. The presence their equivalents. The main areas being to the of even very minor amounts of iron and titanium south east of Melbourne at Springvale, Clayton are sufficient to colour the glass. 67

Formerly the grey to white sands immediately to 10 per cent. of clay which is usually bentonite below the soil of sand dunes was used. This sand with clean graded sand. The big advantage of which is usually about 2 feet in thickness owes its synthetic sands is that it is possible to more closely purity to the downward percolation of humic acid control the properties of the sand. from the soil, which leaches the iron from this horizon. The particular grading of sand used, which effects both the surface finish and the permeability Production of glass sand now comes entirely depends upon the metal being cast, the size of the from sand dunes at Lang Lang where the dune casting and the position of the sand in the mould. sands undergo a complex treatment which involves sluicing with a weak caustic soda solution to Approximately 60,000 cubic yards of foundry remove iron salts and a flotation process to remove sands are used annually in Melbourne. Of this any heavy minerals. total about 8,000 yards are of naturally bonded sands obtained from Brighton Group sediments, the remainder is synthetic sand mostly obtained Hot Mix Filler. from the sand dunes at Cranbourne and Carrum Sand which is used for hot mix filler has a Downs. These sands are carefully washed and grading very similar to that of concrete sand (see classified to meet the desired specifications. Fig. 6) . The sand used in Melbourne is generally a blend of the dune sands from the Frankston, Miscellaneous Sands. Cranboume area with coarser sands from nearby country areas to meet the required specification. As well as the sands mentioned above there are relatively small quantities of sand which are used for rather specialized purposes. Some of these Brick Sand. uses include sand for abrasive papers, traction sands, Brick sand as used in Melbourne is generally sand for soaps, and sand for silica flour. Large a blend of two different sands. The clay free or quantities of packing sand are used annually for " hungry " sands from Cranbourne and Frankston laying pipes, underground cables and tanks. are mixed with clayey or " fatty " sands which occur in the Springvale and Clayton areas. The Methods of Working. two sands are generally combined by mixing from separate hoppers into a rotary or vibrating screen The loose unconsolidated dune sands can be where the sand is mixed and then passes through readily excavated using a small tractor type front the screen into another hqpper or into a stockpile. end loader, loading directly from the face into a waiting truck. For larger outputs a more sophis­ In general there are no set specifications for ticated type of excavator is used. In some pits brick sand except that the coarser sizes must be the sand is put through a rotary screen mounted absent. The particular blend of " fatty " to over a storage bin or hopper. Plant roots, leaves " hungry " sand can be varied to suit the user. and hard cemented lumps are removed by the screen. Moulding Sands. In the production of washed sand three separate A sand used for moulding purposes must have steps are involved :- the following properties :- 1. Mining of the sand (usually by hydraulic 1. Sufficient cohesiveness to hold together when monitoring) and pumping of the sand to moist. the washing plant. 2. Washing and classifying of the sand. 2. Sufficient refractoriness to withstand the heat 3. Dewatering and elevating the washed sand to of the metal being cast. overhead hoppers or stockpiles. 3. Sufficient strength to resist the pressure of the metal. In hydraulic monitoring a jet of water at high pressure is directed at the face which washes the 4. Sufficient permeability to permit water vapour sand down into a sump in the floor of the pit. and gas generated during cooling to escape. From the sump the sand is then pumped to the 5. Proper texture and composition so that the washing plant. mould will produce a smooth surface on The washing plants differ in detail, but in the casting and will not react with the metal. general the sand from the sump passes through a trommel or a vibrating screen to remove any Formerly sands containing clay which bonded oversize material and thence it either passes directly the grains together were used. In later years or through a series of intermediate stages into a these naturally bonded sands have been replaced settling tank in which the sand settles to the by synthetic .sands which are made by mixing up bottom. Screws or bucket conveyors are used to 68 dredge the sand from the bottom of the tank and 100 allow the water to drain back into the tank. The ---- Before wash~ng sand is elevated to either overhead bins or stock­ -- After washing 80 v 20 piles where further drying takes place and from ;7 which the material is loaded. Two stockpiles or / bins are generally used, one being built up while / 60 40 the other having dried is being loaded. I // The water overflowing from the settling tank / // which contains clay and fine sand is either returned 40 / 60 directly to a settling pond or in some cases is pumped to a cyclone classifier. The sand removed ~/ / by the cyclone may be fed back to the main product 20 / 80 or marketed separately. The wash water generally passes through a number of settling ponds and ~/ after clearing is recycled through the plant. 0 ~ 1 00 Ya 4 14 28 48 100 The changes in the grading of a sand after TYLER MESH washing in a plant similar to that described are TEXT FIG. 7. Change in grading of sand produced by shown in Fig. 7. washing.

4-3 CLAY AND SHALE DEPOSITS G. Bell. INTRODUCTION AND HISTORY. floor-tile manufacture had become well established, Industrial expansion in Victoria has seen a sharp it was not until after the 1914-18 European War rise in demand for all types of clay. Among when supplies of roofing slate and iron were re­ notable developments in the past few years, is the stricted, that manufacture of pressed clay roofing­ increased demand for white kaolin for paper filler tile developed. Today this type of roofing accounts and ceramic-whiteware, while abandonment of dry­ for the greater proportion of Melbourne's housing press methods of brick production in favour of requirements. extrusion methods has resulted in a sharp increase Most clays for the white-ware, sanitary-ware, in demand for fine-grained plastic clays. porcelain and electrical porcelain industries of The earliest brick buildings in Melbourne were Melbourne are brought in from other areas. Clays built of brick impo!t'ted from England and the of this type are mined from lacustrine deposits of Netherlands but transportation difficulties and kaolinite-quartz clays at Axedale, near Bendigo, economic considerations necessitated brick making and from Mulwala and Oaklands in southern New in the young settlement. John Pascoe Fawkner is South Wales. Pure, highly-reflecting, well crystal­ reputed to have been the first maker of local hand­ lised kaolinite is mined at Mt. Egerton and Gordon moulded bricks and buildings built of these still near Ballarat. stand. Refractory residual clays developed from grano­ After 1858, the development of the Hoffman diorite are mined from Bulla and kaolinite obtained kiln revolutionised brick manufacture by providing by washing these clays is used as paper filler. a continuous-output chamber kiln which utilised Similar clays are mined from Hallam for the manu­ the hot gases from cooling or firing chambers for facture of fire brick. Imported kaolinites having a drying and pre-heating the bricks. The simulta­ high alumina content are blended with the Hallam neous introduction of dry-press methods of brick material to increase the alumina content of the fire manufacture made possible use of the local deeply­ brick from 25% to 32% or more. weathered silica-rich mudstones and siltstones with which Melbourne is particularly well-endowed. PRODUCTION OF SHALE AND SILTSTONE. With the introduction of this raw material the city Weathered shale and siltstone deposits of Silurian saw the foundations of such companies as Hoffman age are used as the basis of all Melbourne's brick, Brick and Potteries Ltd. (1870), Butlers Brick tile and pipe manufacture. Of the total amount Works (1879), Fritzsch Holtzer & Co. (1880), of material mined for heavy-clay ware, at least two­ and Northcote Brick Co. (1882), which together thirds falls into the shale category. In recent produced the majority of bricks for city buildings years, the proportion of red-burning shale used has during the latter part of the nineteenth century. steadily declined due to the increasing demand for Plastic clays were first found in the Mitcham lighter coloured brick. However, tendencies to area and the Australian Tesselated Tile Company " Modern ", " Georgian " or " American Colonial " was established there in 1886. Although brick and styles of architecture could reverse this trend. 69

Production of red-burning shale is confined to the 31. Klay Co., Campbellfield ; Hoffman's Brick and Keilor, Templestowe, East Burwood, Glen Iris and Pottery, Campbellfield. Scoresby areas, mining having ceased at Brunswick, 32. Melbourne Pottery Co., Campbellfield. Oakleigh and City Brick Pits, Camberwell due to 33. Campbellfield Clay Co., (Hotchkiss), Camp­ either the depletion of reserves or difficulty of bellfield. mining. 34. Mellody and Sons, Campbellfield. Large deposits of weathered shale and siltstone, 35. City Brick; Co-op. Brick; Commonwealth which burn buff or pale-pink have been developed Potteries, Scoresby. at Campbellfield and Craigieburn. Smaller deposits 36. Clifton Brick Holdings, (included with Hoff­ of similar material are mined at East Preston and man Brick) Summer Hill, Craigieburn. Keilor. 3 7. Rio-Tinto Extractive Industries (Rio Tinto Brick Pty. Ltd.), Campbellfield. PRODUCTION OF PLASTIC CLAY. 38. Dome Oil and Mineral Syndicate N.L., Bulla. Plastic clay deposits, suitable for making red-tiles and pipes are restricted to limited areas at Black~ Below are generalised figures for clay production burn, Mitcham, East Burwood and Scoresby~ in the metropolitan area for the period 1960-1963. Wantirna. TABLE 10. White plastic clays have been mined at Campbell­ field, but lateral and vertical variation coupled with Red White - Clay and Clay and Kaolin. Fire Clay. high rate of extraction have depleted reserves. Shale. Shale. Text Fig. 8 shows the main areas from which clay has been produced. The following list provides the Tons. Tons. Tons. Tons. key to the numbers used on the map. 1. Northcote Brick (Co-operative Brick Co. Pty. 1960 .. n.a. 659,281 . . 10,707 Ltd.) Pit and New Northcote (Brick Indus­ 1961 . . n.a. 462,192 . . 22,046 tries). 1962 . 842,175 343,589 23,019 2. New Gamble Pit, Oakleigh (Brick Industries). . . . 3. Brick Industries, East Burwood. 1963 .. n.a . 505,753 2,027 23,978 4. Clifton Brick, Preston. 5. Barldy Brick, Brunswick. 6. Auburn Brick Works, Auburn (Co-operative Silurian Clay Shales Brick Co. Pty. Ltd.). The mineralogical composition and particle 7. Glen Iris Brick, Thornbury. size distribution of clays determine their suitability 8. Blackburn Tile Works, Blackburn (Co-operative for fabrication of heavy-clay ware. Materials Brick Co. Pty. Ltd.) containing chlorite, if heated too rapidly or in a 9. City Brick Works, Hawthorn. reducing atmosphere, will bloat and prematurely 10. Evans Bros, Tally Ho. fuse, while materials which have been subject to 11. Auburn Brick Pit, Vermont. natural leaching are essentially kaolinitic, semi­ 12. Builders and Roofing Co. Pit, Vermont. refractory and white burning. Surface clays consist 13. Wunderlich Tile, Vermont. largely of kaolinite or halloysite-metahalloysite of 14. Number not used. poor crystallinity and small particle size and are 15. Standard Brick, Box Hill. particularly plastic. They may be used in varying 16. Glen Iris Brick, Templestowe. proportions to bind and plasticize less-plastic silty 17. Templestowe Brick, Bulleen. materials occurring beneath the surface zone. 18. Ceramic Brick and Tile (Evans Bros. Holdings, In general, shaley materials are not suitable Scoresby). for the manufacture of pipe unless a high proportion 19. Evans Bros., Oakleigh. of fine-grained kaolinitic clay is added. This is 20. Fritsch Holzer, Camberwell. due to the paucity of particles of less than 2 micron 21. City Brick, Camberwell. size and the abundance of silica in the silt size 22. Oakleigh Brick, Oakleigh. range. These characteristics lead to fabrication 23. Glen Iris Brick, Oakleigh. difficulties, poor green- and dry-strength and high porosity, when fired at temperatures up to 24. Hoffman Brick and Potteries, Brunswick. 1100°C. The Silurian shales, siltstones and sand­ 25. Daniel Robertson Tile Co., Nunawading. stones are strongly folded, indurated sediments 26. Builders Roofing and Trading Co., Mitcham. which may be traversed by occasional hard-quartz 2 7. Australian Tesselated Tile, Mitcham. veins, or decomposed igneous dykes. The latter, 28. Council Shale Quarry, Broadmeadows. if incorporated in the brick mix, result in lowered 29. Knotts Pit, Craigeburn. fusion point. Variations in the character and 30. Bain's Shale Pit, Keilor. permeability of adjacent beds in steeply dipping. 70 and folded strata may result in varying development seventeen feet. These rest on brown coal and ligne­ of kaolinite and varying degrees of leaching of iron ous clay of which five feet is exposed in a pit on and soluble salts. In some materials soluble iron the west of the railway track, 1700 feet north of salts migrate to the surfaces of the brick during Camp Road. drying and fire to a darker colour than faces which have not been free to the atmosphere. If the design On passing farther eastward some ten feet of of kiln car hacking is such that faces of bricks high quality white plastic clays lie directly on the remain protected during drying, but shrinkage deeply leached eroded surface of Silurian shales. exposes butted brick ends to the atmosphere, bricks with dark returns result. This problem can be CAINOZOIC PIPE AND TILE CLAYS overcome by stabilising iron salts or drying in Tertiary, residual and transported (lacustrine and Keller dryers where all faces are free during the fluviatile) plastic clays occur in restricted, thin, drying. but important deposits to the east and south-east Before the advent of extrusion methods of of Melbourne. These red and white or brown and fabrication, Melbourne brick manufacturers relying white mottled clays overlie Silurian shales and are on small additions of fine-grained kaolinite-halloy­ mined together with upper layers of the latter for site surface clays to give the required bond to the the manufacture of red roofing tile, sewer pipe and mix, were able to mine deep into unweathered blue red, sienna or brown face brick. shales to depths of 70-100 feet. Such clays are found at Tally Ho, Cheltenham, In general, most leached Silurian shales are Scoresby, Mitcham and Ferntree Gully. kaolinitic, but materials at Craigieburn are characterised by the presence of halloysite, illite Scoresby and Femtree Gully and hydrous mica, with 40% quartz. (Handel, Plastic clays of probable Pliocene age resulting 1960). Thirty percent of this material lies in the from deep weathering of Silurian shales extend from minus 2 micron size range accounting for a fair Ferntree Gully to Scoresby as thin deposits which degree of plasticity. Shales, where leached, result appear to have been formed over extensive areas of in a pleasing fired colour of cream or pink, while the Lower Pliocene land surface. Upper Pliocene iron rich materials fire to a deep terra-cotta colour. earth movements and subsequent erosion have had Admixtures of the two can be made to produce the effect of depressing and dissecting the clay pleasant shades of pink, buff, salmon or orange, between Croydon and Wheelers Hill. Residual but unless dry-pressed, brick with a high proportion clay deposits at present being exploited at Scoresby of weathered shale is porous and weak. Some and Ferntree Gully on the eastern and southern specimens, particularly if underfired, exhibit water slopes of Blind and Dandenong Creeks reach a absorption figures in excess of 15% and this only maximum thickness of fifteen feet or so and have a serves to accentuate moisture expansion phenomena general dip to the north-west of 2 o. (Hosking and Hueber, 1960). For this reason, high proportions of Tertiary plastic clays must be Grain size of the clays is exceptionally small, added to shales in soft column extrusion plants. being of the order of 1000 Angstrom or 0 · 1 micron Shales which have been metamorphosed such (Darragh, 1963). As a result the clay shows as those close to granitic intrusions at Bulla, Broad­ marked thixotropic properties. The clay from a meadows and Morang tend to exhibit a development pit in Cathies Lane (Text Fig. 8, No. 35) is a of discrete particles of hematite which when fired, characteristic red and white mottled quartz-kaolinite result in a poor, pale to medium grey-pink colour. clay. In spite of the extremely fine particle size, drying shrinkage is not excessive, being of the order CAINOZOIC SEMI-REFRACTORY CLAYS. of 8% for 15.6% Hp. Thick deposits of pre-Newer Volcanic, semi­ refractory, lacustrine clays occur at Campbellfield. Tally Ho. These deposits which are possibly of Lower Ultra fine-grained residual clays similar in Tertiary age, are associated with brown coals and composition to those at Scoresby (Darragh, 1963) show considerable lateral variation. They cover a occur at Tally Ho: Iron is present as goethite. wide area extending from Fawkner, northward along The clays are plastic, mottled brown and white the Hume Highway to Campbellfield where they are

Shrinkage Locality Strata Colour fired Colour fired References ~-2)J Dey rroo rtso tzoo at J050°C. at ttoooc. "C "C "C I Buff to deep terra Brunswick Silunan shales 35-63 lr0-6 o 47-77 6.3~13o j cotta (hard). ov45 I j Oatmeal to terra Burwood Silurian shales 3 14-18 10-17 1 r0-17 cotta, hard. Oatmeal to tan, hard. .6 1 36 I ::=_f~-i-----1- ~ ' ~- I Campbellfield I .... I. Piastre 4000 I 4330 10 17.43 17·1 I Tl off white to buff, hard.loff white to buff, hard. IHandel 1960 2Weathered 13·7-18·0 7·2-14·0'3·5-13·2 2·8-13·1 off white to pink, firm. Ivory to pale pink, firm. Bell e. Kennedy 0"' 1962-1964. ~- f------~~+-::-c-~- I Silunan shales­ /!?.. Comberwell ] Surface 13 14 Bell B Kennedy I 13 9.8 Terra cotta. 'Terra cotta. 0 2Weathered 3 6 11.8 I"75 6. 7 Terra cotta Terra cotta. 1962-1964. 0 3.Portly weathered shale 1-3 3-7 I 3-9 12-20 9-20 9-18 I 1 Fawn t.~.ter~o~~otto Terra cotta. .g f------1 ------J I ·-·-f-· 1 4.5- 145- 145- IJ~--~- ~--~ Cheltenham , ~--~ ~~~--~~~·t__ ~ _,__~ --~~~- 6.0 6.0 17.0 f~rea~~--~~~~~-cotta.,White to buff medium., Keble, ~~~=-~- ~ ----~~~·+--~ ~~~+------+--+---+ g: f-- Craigie burn Srlurian shale Hondel,l960 t:! Weathered and I 40 moj 39 29 18-3.3 : 2.5 ll83183 !I 222022 !2500 Light buff. Bell 6 Kennedy Whrte shale to nil-1 Oatmeal, hard. 1962-1964, -..J--l--~~-t~---~~~~~ v. pale pink, hard t ~~~~~~~+-~~~~-{ "' I · -~1-----.J-i --1 ----' - -I 8. j Bell a Kennedy Keiter Silunan shales 27 20 3-4 i 3.5- Cream to buff. 1962-1964. 19-21 l_~j_~_ 'g. --+------11-----t----1'· -·-·· i 5.7 'a Scoresby §" ,.., J Mottled 20 Handel, 1960 -;... 34-44156-~6i sa 1 s-1o 13 II 16 14-16.7110-11.416·1-7 515.3-6.910range to tan, hard Red, hard. 2 S!lurran Betl 8. Kennedy '0 o:; ffiOJ.. ffiOJ. I 12 47 8 1D 13.9 8.8 2.5 0.3 Fble red,hord. Sienna, hard 3 Srlurran shale ma,. I ma1 r 23 36 14.6 9. 9 3.4 Pole pink to red,hord. Pole prnk to red, hard. 1962-1964 8 1:"' 7 I 9 -...1 '0 tti Darragh, 1963 tv

8 Chemical Analyse's Locality Strata References W' I ~ I Broadmeadows I Weath~-~e~~--~~~~ 67·3BII6·2t l3·93lo·7t lo·29l2·3slo-aslr·4 15·72 6: (I) 0 Bulla Weathered granite I maj. I maj. I min. § ~ 1 f------l-+--+------l-+--+-+--+----+-+--+-1"-""'"4---+--+--+--+-+--1-t--t---~-t--t- Oandenong Weathered granrte 3-4 I 6-7' 57·05129·01 I0·991 nil. I "- I0·21 I D 071 0·84110·6,(2) Ross U.

~ 6~·~823·52 3·0 niL tr. 0-43 0·12 J-45 8·88 (3)0rdishvVest U.

jv i v i ·-~...l~-----~

v

@1!8

Scale of Miles 0 4 8

SEDIMENTARY ROCKS D Pleistocene

lW/:/1 Pliocene

1===:1 Silurian IGNEOUS ROCKS· 0 Newer Volcanic c==J Older Volcanic 8 Granite

Plastic clay pit ] Pit numbers - see lex!. 11i16 Shale quarry (14 no! used)

Municipal boundaries

TEXT FIG. 8. Clay and shale deposits, Greater Melbourne area. 74 4-4 THE BRICK AND TILE INDUSTRY D. Spencer-Jones. The City of Melbourne has been particularly well­ Raw Material. endowed with suitable raw material for the manu­ In the past when red bricks were practically the facture of bricks and terracotta tiles. In the early only bricks available, all the ingredients for the mix days of the settlement residual clays and colluvial or " pug " were obtained from the manufacturers' clays were available and later the actual mudstones local pit. The brickmaker by experimenting with (clay shales, Keble and Watson 1952) or "reef" mixtures of the surficial or residual clay and the clay of the Silurian bedrock were used. The mudstones, shale, arrived at a satisfactory color and bond for either weathered or partially weathered, now form the burnt product. The proportions of the ingre­ a large percentage of the mixture used for red bricks dients were purely empirical, as they probably are and terracotta tiles. at the present time. In recent years the cream and pink bricks have Historical Comment. become increasingly popular. As a result the brick The first bricks made in Melbourne were hand manufacturers have been forced to obtain white or made and it is a tribute to the old brickmakers and grey clays to add to their mixture. For this reason the raw materials they used that some of the the white fluviatile and residual clays at Campbell­ buildings made of these bricks are still standing. field have been used in large quantities. These bricks were burnt in crude ~ilns, using TABLE 12. green timber as a fuel. Chemical Composition of Some Typical Clay Shales Following the development of the Hoffman kiln from the Melbourne Area (after Keble and Watson, 1952). in the mid 19th Century and the supply of black coal from New South Wales, the brick industry Sample No. 721/04 722/04 723/04 727/04 728/04 developed rapidly in the 1870's and 1880's.

Pioneer companies such as the Hoffman Brick % % % % % and Potteries Ltd. (1870), Fritsch Holtzer and Co. (1880), Northcote Brick Co. (1882) and sio. .. 73 ·12 74·52 72·87 64·97 65·04 Butler's Brick Works (1879), produced the majority Al 0 15·61 16·19 15·35 18 ·19 of the bricks for city buildings constructed during 2 3 .. 16·07 the latter part of last century. Fe20 3 .. 3·00 1·01 2·05 2·88 5·76 The early brick clay pits were opened up as FeO .. 0·13 0·12 0·20 0·20 0·43 close as possible to the building area hence the industry was concentrated in Brunswick, Coburg MgO .. 1·02 .. 0·93 1·67 2·39 and Northcote. With the expansion of the city CaO . . 0·55 ...... and the increased demand for private dwellings, other companies commenced at Oakleigh, Box Hill Na.o .. 1·11 2·47 2·03 0·12 0·55 and Camberwell. K.o .. 1·36 1·14 0·56 1·76 Trace

The rapid growth of the city has led to the H 20 at 110 building over of areas of possible clay reserves and oc. .. 0·62 0·63 2·39 5·31 3·75 the manufacturer has been forced to seek clay from H 20 below areas at Campbellfield, Templestowe and Burwood. 110 °C ... 3·08 3·58 3·33 4·07 5·43 The tile industry, although in some instances an Cl .. 0·41 0·46 0·23 0·28 Nil offshoot of the brick industry, developed mainly in the Blackburn, Mitcham and Nunawading areas. Total . . 100·01 100·12 99·94 99·45 99·42 The tile industry is comparatively young compared with the brick industry, the first full scale production If these analyses are representative of the clay developed during and after the first World War. shales in the Melbourne area it can be seen that Because of the war the established materials used some variation does occur in composition. This is for roofing, such as slates and corrugated iron, were understandable because the samples are from unobtainable and a substitute was necessary. different horizons in the Silurian bedrock The development of the durable and much more sedimentary succession. attractive terracotta tile continued through the The straight clay shale from the bedrock is not depression years and is now the most popular particularly plastic and without the mechanical roofing medium for private dwellings. pressing used in the process, clay would have to be 75 added for satisfactory moulding. The increase in Production. clay composition has to be carefully controlled Some production figures for the industries over because it tends to increase the percentage shrinkage the past years are tabulated below : and consequently amount of distortion of burnt product. Conversely an increase in the silica sand TOTAL PRODUCTION FOR VICTORIA. content reduces shrinkage, but increases porosity Roofing Tiles and the necessary temperature for incipient vitri­ Year. Clay Bricks. (Terracotta). fication. By carefully controlling the temperature of the kiln to produce incipient vitrification, the brickmaker 1938-39 .. 197·2 mill. 13·74 mill. can make allowance for variation in clay com­ 1948--49 .. 153·1 mill. 10·98 mill. position of the " pug ". 1956-57 .. 208·1 mill. 14· 98 mill. The temperature control during burning of roofing tiles is even more critical than that for 1957-58 .. 236·4 mill. 15 ·19 mill. bricks. The tiles are taken to a temperature 1958-59 .. 257·4 mill. 16·98 mill. approaching vitrification. Excessive firing tem­ peratures will induce warping and fracturing of the burnt product. REFERENCES As iron is the main colouring medium in the BAIN, A. D. N. and SPENCER-JONES, D., 1952-53.­ burning of clays, the intensity of colouration is to Melbourne Brick and Tile Industry, Pt. 1. Min. and Geol. Jour. Viet., Vol. 4, No. 5, pp. 20-28; Pt. 2, some degree proportional to the percentage of Vol. 4, No. 6, pp. 13-20, Pt. 3, Vol. 5, No. 1, ferrous and ferric iron in the raw material. The pp. 24-29. brickmaker adds chemicals to the kiln during burning KEBLE, R. A. and WATSON, J. C., 1952.-Clay and Shale to obtain special coloring effects. Deposits. Mem. Geol. Surv. Viet., No. 18, 76 pp.

4-5 EXPANDED SHALE AGGREGATE R. G. Whiting. MATERIALS USED AS LIGHTWEIGHT EXPANDED SHALE. AGGREGATES. The artificial bloating of rocks is carried out by The use of light weight aggregates for concrete passing a crushed or pelletised product through an is a modern engineering development now finding oil fired inclined rotating cylindrical kiln. The wide application in structural concrete work. A exterior of the rock fragments fuses causing the number of different materials have been used surface to be sealed and a reaction producing a including scoria and various types of bloated clays gas takes place internally causing expansion of the and shales. Scoria is lava which has been fragments. In the case of clays these are usually naturally bloated by the contained gases at the ground and pelletised, often with addition of ·time of its extrusion. Though it has been used to material suitable for producing a gas reaction. With some extent for manufacture of light weight suitable shales they are crushed and screened and building blocks it has not found wide application fed directly into the kilns, as they already possess in Victoria for various reasons. Besides the fact the necessary chemical composition for gas produc­ that it may not be very high in strength compared tion. The temperature normally required for ex­ to normal crushed aggregate, crushed scoria has panding shales is of the order of 1100°C to 1300°C. the disadvantage that its surface has open pores During 1954 the Mines Department was which may connect to some extent with the internal approached by a Melbourne consulting engineer pores. Under these conditions water, sand and regarding suitable shale deposits for this industry. cement may penetrate sufficiently to reduce the It is an important requirement for suitable shales effect of the lightweight of the aggregate. Further­ that they be fairly fresh (i.e., unweathered) and more, although scoria is of common occurrence, relatively free from sandy layers. An area which deposits of even grade and large tonnage within appeared to meet these requirements was located suitable distance of major markets have not yet in the Plenty River Gorge between South Morang been located.1 Bloated clays and shales-although and Plenty. A belt of shaly rocks outcrops in the more expensive-are more satisfactory in use and bed of the Plenty River in this area just off the can be produced with an even and reliable grade. northern edge of the map and probably extends

1 A scoria deposit in the Geelong district was investigated after the above was written. 76 some distance to the south in the area westwards Little has been said above on the question of the from Greensborough. Considerable testing and properties of material suitable for bloating. The research was carried out on this material by Mr. important factor appears to be chemical rather than R. Hill of the C.S.I.R.O. Building Research mineralogical composition. A brief bibliography on Laboratory at Highett, Victoria. Subsequently this question is given in which the latest and Melbourne's first expanded shale plant was opened probably the most significant paper is that by R. D. in 1959 by Reids Quarries Ltd., in the vicinity of Hill and D. N. Cook (1960). Plenty. By comparison with concrete made with normal crushed aggregate concrete made from expanded REFERENCES. shale has substantially the same strength but is BLAKEY, F. A. and HILL, R. D., 1955.-" Further Tests about one third less in weight. In combination on Materials for Light Weight Structural Concrete." with pre-stressing techniques2 components can be Constructional Review, Vol. 28, No. 5, pp. 19-26. produced with equal strength but of the order of CoNLEY, J. E. et al, 1948.-" Production of Light Weight half the weight of standard reinforced concrete. Concrete Aggregate from Clays, Shales, Slates and It will be appreciated that the weight saving achieved Other Materials." U. S. Bureau of Mines Report of by appropriate use of such members in multistoried Investigations, No. 4401. buildings is very considerable. The saving is HILL, R. D. and BLAKEY, F. A., 1953.-" Expanded Clay cumulative in that not only is there a considerable Aggregates for Concrete." Constmctional Review, weight saving in the members themselves but the Vol. 26, No. 6, pp. 22-26. whole supporting structure can be scaled down in HILL, R. D. and CooK, D. N., 1960.-" Some Causes of design due to the smaller weight requiring support. Bloating in Expanded Clay and Shale Aggregates." To date appreciable use has been found for concrete Australian Journal of Applied Science, Vol. 2, No. 3, floor beams made in this manner. Pre-stressed pp. 374-384. beams using lightweight aggregate are at present RILEY, C. M., 1951.-" Relation of Chemical Properties being constructed for this purpose in spans up to to Bloating of Clays." British Clay Worker, Vol. 60, 40 feet in length. p. 78.

2 For those who are not familiar with pre-stressing of concrete the following brief explanation is given. In normal beams under load, the lower half of the beam is under tension. The reinforcing rods are placed in this section in a reinforced concrete beam to provide tensile strength. However some tension still occurs in the concrete with the beams under load and as the tensile strength of concrete is very low this a severe limiting factor in load carrying capacity. In the case of prestressed beams the concrete is poured into a mould in which the reinforcing rods or wires have previously been placed under tension (within the elastic limit). After the concrete has finally set, the tension on the reinforcing wires is released. As they tend to spring back to their original length they produce compression in the concrete. We now have a beam in which the underside is under compression before load is applied and to which considerable load may be applied before tension is produced in the concrete of the underside. It will be readily seen that other factors being equal, strength for strength a prestressed beam may be constructed somewhat lighter than a standard beam. When this technique is combined with the use of expanded shale aggregate the saving in weight is quite considerable.

4-6 GOLD R. G. Whiting. LOCATION AND STRUCTURAL No gold occurrences comparable with the above ENVIRONMENT. fields have been worked within the area of the map Gold producing areas just outside the northern but a few small diggings exist. Two quartz reefs margins of the geological map are the Warrandyte, have produced gold, one near Hill Street, North Diamond Creek and Y arrambat goldfields. The Balwyn, south of Koonung Koonung Creek and the other east of Thompson Road about :i mile south first is associated with the W arrandyte Anticline, of Templestowe. Both of these reefs occur in the the second with the Templestowe Anticline and general vicinity of the Templestowe Anticline, the the last with an anticline about 2~ miles west of the Templestowe Anticline. The Ringwood Antimony former near a " pitch crest " and the latter in a and Gold mine was associated with an anticline north pitching area. about 3 ~ miles east of the W arrandyte Anticline off the eastern margin of the map. These four fields HISTORICAL. occur near the " pitch crest " line portion of which shows near the northeast corner of the small scale The following particulars concerning the last two map (Text Fig. 1). These areas of mineralization reefs are taken from " The Colonial Mining are therefore associated with structural " highs ". Journal" of September 1858, where these occur- 77 rences referred to as " recent discoveries " are Victoria". He quotes from a letter by Mr. Nicholls called the Boroondara and Bulleen gold mines as follows " The probability of a deep lead round respectively. Melbourne was pointed out by me in the Ballarat Star newspaper, February 23rd, 1862; and on May The first of these to be discovered was the Bulleen the 29th I corroborated what I had previously reef. It was 4-14" wide and dipped 60°E approxi­ written, having found a coarse speck of gold in the mately parallel to the bedding. It was worked by gravel at Studley Park, on the high ground. . . a party of four miners who paid a percentage of the I ...was informed that gold had been obtained in gold won to the agent for the ground, the owner small quantities in the alluvial drifts of North being absent in England at the time. Crushings Melbourne, at the Flagstaff Hill, at a sawpit at were carted eleven miles to Andersons Creek battery Emerald Hill, at St. Kilda, on the footpath Hoddle­ and are said to have yielded 22 oz. per ton. Each street, in gravel brought from Studley Park, at miner is said to have earned £200-after deducting Greville-street Station", at Chambers' Foundry, all expenses-for eight weeks work. The ore is Prahran, on Batman's Hill, and on Richmond Hill, stated to have contained antimony and copper as near the Hawthorn Railway cutting, in sinking the well as gold. cellar of Mr. Hancock's house, and by the same man in cutting a drain on the opposite side of the The Boroondara reef was discovered by Messrs. Yarra River, on Colonel Anderson's land. . . At Manuel and Teague who obtained a lease from the Collingwood a shaft was sunk on the basaltic flat, owner Mr. Henry Roberts. Three shafts were and bottomed at about 130 feet on a greenish slate opened and the reef found to be up to 5 feet wide reef . . . a little gold was found ". but apparently averaged much less than this. It dips 60°E. Small scale tests are said to have It is of interest to add that during 1959 gold was indicated a grade of from 2 to 5 oz. per ton. A said to have been found under the basalt in a company known as the Woodfield Boroondara building foundation excavation in Rokeby Street Gold Mining Co. was formed. near Victoria Parade, Collingwood. Passing reference is made in the same Journal to another mine about two miles east of Templestowe Stirling (1899) records the discovery of gold in but the location of this is not given precisely. a sewerage excavation at the corner of Albert and St. David Streets, St. Kilda. A small piece of The only other recorded gold mining effort in the quartz containing gold was taken from a vein in Melbourne area was an attempt to locate a deep Silurian strata. lead under the basalt in the Collingwood area. Dicker's Mining Record of January 1863 carries a Under the heading "Discovery of Gold at Frank­ report of the Collingwood Gold Mining Company ston" in the Australian Mining Standard of 1897, Ltd. in which reference is made to a bore put down a report by Lidgey refers to Porter's Reef and near Hoddle Street behind the Royal George Hotel. White Reef being discovered. The fact that these This hotel, now delicensed, was situated on the south­ reefs occurred in granite suggests that the locality west corner of Gipps and Hoddle Streets, Colling­ was probably south of Frankston where granite is wood. The bore went through 67 feet of basalt and exposed beneath the Tertiary in some gullies hit bedrock (Silurian) at 132 feet. Black sand on between Frankston and Mt. Eliza. the bedrock yielded a few colours of gold. It was proposed to sink a shaft on the site of the bore. According to Stanley Hunter (1909) "In 1865 REFERENCES. Mr. C. F. Nicholls wrote two letters to the Ballarat BROUGH SMYTH, R., 1869.-Goldfields and Mineral Districts Star stating he was convinced that a deep lead of Victoria, 644 pp. existed between Studley Park and Princes Bridge CoLONIAL MINING JoURNAL, 1858.-Vol. I, p. 2, September . . .Mr. Nicholls was convinced that beneath the 1858. basalt of Collingwood Flat an auriferous gutter DICKER'S MINING RECORD, 1863.-Vol. II, No. 3, p. 52, existed. The Collingwood Mining Company was January 1863. formed which sank a shaft 111 feet deep through 62 feet of basalt, finding at the bottom black sand HuNTER, STANLEY, 1909.-Deep Leads of Victoria. Geol. and a little gold resting on the Silurian bedrock. . . Surv. Viet., Mem., No. 7. the company collapsed through insufficient capital ". LIDGEY, E., 1897.-Discovery of Gold at Frankston, Victoria. Australian Mining Standard, Vol. 13, That both reports refer to the same events, the p. 1881. date in the latter report being in error, is shown STIRLING, JAs., 1899.-Report on Gold Discovery at St. by reference to Brough Smyth's " Gold Fields of Kilda. Geol. Surv. Viet., Progress Report, No. 11, p. 6.

1 Now Prahran Station. 2288/66.-7 78 4-7 BROWN COAL

J. L. Knight1 The Altona area was originally opened up for Calorific Value (B.T.Us. per lb. gross)- settlement by the Altona and Laverton Bay Free­ As received . . 4,370 hold and Investment Co. Ltd. The company Dry basis 10,505 constructed the railway line from the Williamstown Racecourse to Altona Beach and sold land for up to Ultimate Analysis - Dry Basis. £8 per foot in 1888. When the land boom burst train services were cancelled late in 1890. % Carbon .. 60·61 In 1890 or 1891 Mr. J. S. Hosie sunk a shaft Hydrogen at Altona and extracted an unrecorded quantity of 4·49 coal. This shaft was deepened but struck the Nitrogen 0·59 underlying artesian water and the workings flooded. Sulphur 1·94 In 1894 Hosie sank another shaft 10 ft. x 5 ft. Oxygen 24·61 to a seam of coal 73 ft. thick, 333 ft. below the Ash 7·76 surface, but no further work was done until 1908 when the Melbourne and Altona Colliery Co. Total 100·00 enlarged this shaft to 15 feet diameter. They secured the top 59 ft. 9 ins. with brickwork and took precautions to exclude the water which was In 1920 the Directors of the Altona Beach flowing in beneath the basalt at a rate of between Estates Ltd. and Altona Brown Coal Co. published 1000 and 1500 gallons per hour. The shaft was a booklet entitled " Production of Electrical Energy carried down as a 12 sided regular polygon to a from Brown Coal, Morwell or Altona?" In it they depth of 353 feet. claimed that the Altona field produced 75,000 tons This shaft was intended to be used for ventilation of coal and that the cost of producing power from only but was equipped with hauling gear to deal Altona brown coal would be cheaper than that with an output of 500 tons of coal per 8 hour produced from Morwell. The Morwell area referred shift. A spur railway line was built from Altona to here is that which subsequently became the to the mine. In 1910, 600 tons of coal were pro­ Yallourn undertaking of the S.E.C. H. C. Jenkins, duced and between 1910 and 1919 when the mine Government Metallurgist at the time, suggested that closed the recorded production was 31,160 tons the Altona coal would be suitable for briquetting valued at about £7,300. and also stressed its value as a deodorant. The Altona Bay Estates Co. sank three bores in The Williamstown and Newport Coal Prospecting 1928 with the following result- Co. sank a shaft 225 feet deep near Newport in Bore 3-65 feet of coal at 354 feet ; the basalt 1894. A bore was sunk from the bottom of the being 172 feet thick. shaft and in all five seams of coal were passed Bore 4-62 feet of coal at 348 feet ; the basalt through- being 50 feet thick. 6 ft. at 198 ft. Bore 5-77 feet of coal at 321 feet; the basalt 8 ft. at 252 ft. being 151 feet thick. 6 ft. at 275 ft. A new shaft to the north-west was sunk in 1928 2 ft. at 299 ft. to obtain coal for experimental purposes. After 4 ft. 6 ins. at 306 ft. some driving on the coal all work ceased in 1931. The Hobson's Bay Coal Co. drilled a bore near An analysis of the brown coal at Altona is the Yarraville Sugar Works cutting 8 feet of brown given below :- coal at 221 feet. Neither of these companies Proximate Analysis- apparently produced any quantity of coal. Another As received. Dry Basis. bore near Newport struck three seams of brown % % coal intercalated with clays at 212 feet. Total Moisture 58·40 thickness of coal was 22 feet. Volatile Matter 20·00 48·1 Fixed Carbon 18·65 44·8 Brown coal has been recorded further east in bore Ash 2·95 7·1 holes along St. Kilda Road and at Point Ormond a 4 ft. 6 ins. seam was struck in a drill hole at a 100·00 100·0 depth of 101 ft. 6 ins.

1 Manuscript dated 29th March, 1960. 79 4-8 THE UNDERGROUND WATER RESOURCES

P. R. Kenley and J. S. Hancock.

INTRODUCTION. Formation water temperatures of 65°F. and This report reviews the occurrence of under­ 88°F. have been recorded -from Brooklyn and ground water in the Melbourne Metropolitan area south-west of Altona respectively. and briefly sets out available information as to The waters of the Werribee Formation are con­ the nature, distribution, yields and water qualities fined above by the impervious Altona Coal Seam of the various aquifers represented. and Newport Formation and are under substantial The main targets for drilling in future search for pressure. A number of bores yield artesian water underground water have been indicated wherever from these aquifers at Altona. Recorded pumping possible and questions affecting the development, yields from seven bores range from 500 to 42,000 exploitation, life and use of the aquifers are discussed gallons per hour with four of the seven yielding briefly. close to 10,000 gallons per hour. The higher yields were obtained from wells in which screens were OCCURRENCE OF GROUND WATER IN THE installed. VARIOUS STRATIGRAPHIC UNITS. The range of composition shown in available SILURIAN. analyses of waters from this formation is given in The Silurian rocks are tightly folded mudstones Table 13. and sandstones of low porosity. The sediments TABLE 13.-Range of composition in thirteen Werribee themselves have little potential as water bearing Formation waters, south-western suburbs. media but locally open joints and fractures in the Parts per million rocks provide a significant volume of voids which Ca++ 72-137 may contain water. Mg++ 156-398 The majority of bores sunk into the Silurian (Na+ + K+) as Na+ 840-1,417 rocks for water are shallow, generally less than Fe (Soluble) 0·1-0·3* 100 feet. Yields from these depths are usually RzOa 0·11-4·4* low, normally averaging between 200 and 400 Cl- 1,260-2,130 gallons per hour. In the inner suburbs the salinity C03-- 0-57 HC0 - 9-262 in total dissolved solids varies from 7,000-11,000 3 parts per million ; but in the higher rainfall areas N03- 0-5* of the hills north-east of Melbourne salinities as low 6-28* Si02 as 3,000 parts per million have been recorded. Total solids (hypothetical) 3,150-5,857 (average 4,160) Recent drilling at Fairfield has obtained yields pH 7-8·8 of 1,500-2,000 gallons per hour at 140 feet in fresh * Not determined in all cases. sandstone, the water having 3,264 parts per million total dissolved solids. This water differed in type The consistently high yields of these aquifers, from the shallower waters, in containing more coupled with their temperature and location, under­ magnesium than sodium. lying the industrial areas from Footscray through to The salinities of waters from the Silurian rocks Altona, gives these waters a high potential usefulness limit their use to salt tolerant stock and cold water for industrial cooling and washing. It seems likely washing processes. that consumption will increase in the future with the growth of industry in these suburbs. TERTIARY. Werribee Formation. Older Volcanics. The Werribee Formation contains thick beds of The Older Volcanics are very variable in their coarse sand at a number of levels, both stratigraphic­ water potential, the controlling factor tending to be ally above and below the Older Volcanics (Plate 7, the state of weathering in which the rocks are found. Cross Sections 1 and 2). Gravels and fine conglo­ Yields encountered in the northern suburbs vary merates are also present in the lower part of the from 14,000 gallons per hour to 500 gallons per formation. Most of these porous layers contain hour in scoria and decomposed basalt respectively. water, and good aquifers are usually present at one The quality of the water is generally poor, values or more horizons. An upper fairly persistent aquifer from 4,000-8,000 parts per million total solids occurs at a depth of about 150 feet at Spotswood, being the most common. Because of the high 236 feet at Brooklyn and 437 feet at Altona. Lower yields obtained from some bores, these rocks are aquifers occur at depths of 300 feet (Spotswood) generally worthy of investigation where water of to 578 feet (Altona). poor quality will suffice. ---

80 Recent drilling in the Mordialloc area has revealed Brighton Group. the presence of supplies of good quality water in the South-eastern Suburbs. Older Volcanics and the underlying sands equivalent In this area underground water occurs in coarse to the Werribee Formation (Personal communica­ sand or fine gravel lenses within the Red Bluff Sands, tion C. Gloe). The Older Volcanics in this area typically near the base of the formation. Near occur at depths of 180-190 feet. Cheltenham some underground water is probably also derived from the sandy limestones of the Black Newport Formation. Rock Sandstone. South-western Suburbs. The water in the Brighton Group is generally South-west of Melbourne the Newport Formation under only slight to moderate head except along the lacks the permeability necessary for the develop­ foot of the Beaumaris monocline where at least one ment of good aquifers. bore is artesian. Water qualities and yields are very variable from South-eastern Suburbs. place to place. In 21 bores for which information Equivalent sediments in this area are more sandy on this aquifer is available, yields generally range and contain the principal aquifers of the Melbourne from very small to about 3,200 gallons per hour area. These are developed in sandy limestones, with one value of 12,000 gallons per hour obtained shelly sands and sand beds in the lower part of the from the artesian bore mentioned previously. The formation. average yield is of the order of 1,600 gallons per hour. The formation underlies the Brighton Group over Nine analyses of waters from this aquifer show most of the area to the south and south-west of a range of composition from 850-7,500 parts per Dandenong-road and ranges in thickness from about million total solids with an average of about 3.500 35 feet (Oakleigh to Keysborough) to 70 feet at parts per million. It is doubtful if these figures can Heatherton and 80 feet at Mordialloc. be regarded as representative as waters from a Yields and water qualities vary from place to number of good bores have not been analysed. place, but experience has shown the formation to be South-western Suburbs. a more dependable source of water than the over­ The Brighton Group sediments in this area are lying Brighton Group. Recorded yields in 32 bores generally more silty and clayey than in the south­ for which data are available range from zero to more eastern suburbs and are represented by red-brown than 14,000 gallons per hour with values of 500 to clayey sands and silty sands with occasional more 5,500 gallons per hour typical. The average yield porous and permeable layers. The group is generally is about 2,800 gallons per hour. from 70-90 feet in thickness in this area but locally The water ranges in composition from 180 to has been completely removed by pre-Newer Volcanic 4,800 parts per million total solids with an average erosion. composition of about 1,500 parts per million. Practically all the available data on the waters in Hardnesses of up to 300 parts per million calcium this group come from samples obtained from the carbonate have been recorded. Unfortunately, too Melbourne and Metropolitan Board of Works ex­ few dependable analyses are at present available to cavations for the Spotswood-Brooklyn trunk sewer permit systematic study of the variation in water and the Brooklyn Pumping Station. Yields of water quality. Generally, however, the areas with to large excavations have been moderate (of the waters containing less than 1,000 parts per million order of 2,000-3,500 gallons per hour) and have total solids and with yields in excess of 1, 000 frequently been accompanied by large inflows of gallons per hour are roughly co-extensive. They suspended silt. Yields to bores would probably be embrace large sections of the market garden small although local gravelly lenses may occasionally and golf course areas of Clarinda, Heatherton, provide larger supplies. Keysborough, Mentone and Cheltenham. The Ten analyses of waters from the Brooklyn waters of these areas are under pressure and rise sewerage workings showed a range of composition 80-150 feet in the bores. In a few cases flowing from 4,274-7,476 parts per million total solids. (artesian) bores have resulted. One analysis of 27,907 parts per million at Spots­ wood Pumping Station is suggestive of local Future search for large supplies of good quality contamination by sea water. underground water in this formation will require better delineation of the zones of high porosity and Northern and North-western Suburbs. permeability in this unit. The present bore distribu­ The Brighton Group sediments contain a high tion is highly irregular and there are considerable proportion of clays in this area and the occasional areas in which no data are available, especially in sand lenses present are generally of small dimensions. the inner southern and south-eastern suburbs. Waters from these beds have proved to be of good Future drilling should extend the known area of quality but supplies seldom exceed 400 gallons per good quality waters in this formation. hour. 81

Eastern Suburbs. QUATERNARY. Thin deposits of Brighton Group sediments cap Yarra River Alluvials (Excluding the Yarra Delta the Silurian rocks north of Gardiner's Creek. These Sediments) . include coarse gravels, sands and clays and are generally less than 50 feet in thickness, but The main development of these deposits near occasionally may attain 100 feet. Melbourne is between the Chandler Highway and Templestowe where they attain thicknesses of 30-50 Some of these Tertiary remnants contain small feet and occupy alluvial fiats up to a mile in wi?th. supplies of underground water, but generally the The lower beds in this area were probably deposited areal extent is so limited and the present day re­ in a lake dammed by lava flows which entered the charge rate so reduced by artificial surface drainage Yarra Valley via the ancient valley of the Darebin that the potential of these rocks as a source of Creek. These lacustrine deposits were later covered ground water is very slight. by normal flood plain deposits. The deposits consist of fine sands, silts and clays, but lenticular channel TERTIARY-QUATERNARY. sands and gravels may occur in parts of the section. Newer Volcanics. The silts are unlikely to provide good aquifers South-western Suburbs. due to the problems of developing bores in fine The basalt and scoria of the Newer Volcanics sediments, but the gravels and sands may eventually rest on an erosion surface carved in the Brighton yield useful supplies of good quality water. At Group sediments. They are closely jointed and in present the underground water potential of the Yarra general have a comparatively high bulk porosity and River alluvials is largely untested. permeability, although the permeability values vary considerably, even from flow to flow, depending on Yarra Delta Sediments. the nature of the basalt. High permeabilities often In parts of the Yarra delta the Tertiary and exist in the rocks between basalt flows, permitting Quaternary sediments attain a thickness of 140 feet. high yields to be obtained from a short vertical The detailed lithological sequence of thes~ rocks h~s interval of the bore. These conditions are difficult been described in the Quaternary sectiOn of this to predict underground, but water prospects in these volume. Of the several formations recognized, only rocks are generally good enough to justify test the Moray Street Gravels provide good aquifers. drilling. Where water is encountered it can usually The waters in this formation are sub-artesian to be developed in open hole with casing needed only artesian but few records are available as to yields to protect the pump. obtainable and the quality of the water. Quite large yields of underground water have been obtained from bores situated along the lines of pre­ A bore at the Mines Department Drill Store in basaltic drainage where the basalt may be up to Cook-street Port Melbourne, yielded in excess of 17 5 feet thick. Recorded yields in bores range from 5,000 gallons per hour of ":'a!er contain~ng 300-13,000 gallons per hour with values of less approximately 12,000 parts per mllhon total sohds than 1,000 gallons per hour typical. from a depth of 120 feet in these gravels. A bore at the A.P.M. works in South Melbourne yielded Very few Newer Volcanic bore waters have been water with a total solids content of 16,07 6 parts per analysed. The five analyses available to the writers million from a depth of 122 feet. Field observations show a range of total solids contents from 2,890 on other waters encountered in drilling for parts per million at Laverton to 22,300 parts per engineering investigations have also indicated very million at Brooklyn. In the industrial areas it is saline waters. probable that the waters in these rocks have locally been contaminated to some extent by underground The other four formations of the Yarra delta discharge of chemical wastes. sediments are clayey and have low porosities and The best recorded production from these rocks in consequence have very little potential as sources is from a well at Laverton. This yielded 13,500 of underground water. gallons per hour of water containing 2,890 parts per million total solids, under sustained pumping Dune Sands between Mordialloc and Frankston. for seven days. Small supplies of near surface waters have been produced from the Recent dune sands of this area Northern and North-western Suburbs. notably at Aspendale and Carrum. Many of these Unfortunately, little information is available as to have been tapped by means of " spear points " and the subsurface geology of this area. The basalt some of the water has proved suitable for use in ranges in thickness from zero to a maximum home gardens. The number of such bores will recorded value of 190 feet. undoubtedly increase in the near future and as the Although as yet virtually untapped, good supplies storage of small aquifers of this type is limited, some of underground water are likely in the deeper parts control on pumpage or. bore spacing w~ll eventually of pre-existing valleys. It is considered that the be necessary if the aqmfers are to contmue to serve water qualities would probably be poor. a useful purpose. 82

AQUIFER CHARACTERISTICS. approach to the choice of screens or slotted casing Intake Areas. and their positioning in the wells should enable Practically the whole of the south-eastern suburbs increased yields to be obtained. lie in an intake area for underground water. Within Utilization of Water. this area the main aquifers appear to take up the Present. bulk of their water at the up-dip extremity of the beds in the region of the Melbourne flexure. The underground water found in the Melbourne (Plate 7, Cross Sections 3 and 4) . area is too high in dissolved solids to be of general use, although the good quality waters in parts of the Intakes for the south-western suburbs are partly south-eastern suburbs are suitable for most purposes. concealed by basalt, but are evidently in the vicinity These waters are used extensively for both flood of the Maribyrnong River. and spray irrigation of vegetable crops. Many of In the other areas the intakes are mostly either Melbourne's larger golf clubs have successfully used local, or upstream on the same system of drainage underground water for watering fairways and greens, or in the case of the Newer basalts, the pre-Newer and an ever increasing number of homeowners are Volcanics drainage. making use of underground water in gardens. The use of " spear points " to tap shallow underground Natural Recharge. waters is the most common method of obtaining Under natural conditions sub-surface aquifers are such garden supplies. recharged by meteoric waters which either enter the Industry is making limited use of underground aquifers through their up-dip outcrop or by water for cooling and washing purposes and some percolation down through porous beds overlying them. domestic use is made of poor quality waters for filling swimming pools. In city areas, the intensity of settlement and the resulting complex artificial drainage systems greatly Future. reduce the area available for surface waters to enter Many of the limitations on the use of ground the aquifers and also the volume of water available water in Melbourne may be overcome in the future to enter the aquifers as compared with natural by mixing appropriate amounts of fresh surface conditions. This tendency is partially offset by water with groundwater to make " shandies " suit­ garden watering, but relatively little of this water able for the required usage. Such water could be finds its way into the permanent underground used for watering golf courses, playing fields, market storages. gardens, &c. In industry, it is feasible to use If intensive use is to be made of underground groundwater for some phases of the operations and water around Melbourne, a stage will eventually be fresh water for others. In these ways it should be reached when there is insufficient water entering the possible to save considerable amounts of fresh aquifers to replace the water pumped out in bores water for use where high quality water is essential. and the aquifers will become depleted unless special It should be pointed out that at present blending protective measures are taken. of bore water with mains water is not permitted in Water Quality Distribution. reticulation systems connected direct to the The pattern of water quality distribution in the Melbourne and Metropolitan Board of Works various aquifers is at present known only in outline supply. in a few places. Much additional work is required Sources of Information. to put future search for underground water on a better basis. Most of the information used in the writing of this report has been derived from Mines Department The available data on some of the aquifers to the records and private bore logs held by the Depart­ south-east shows the typical gradual deterioration ment. Full use has been made of the unpublished in water quality down-dip towards the coast. reports written on the area and observations made The only evidence of salt water intrusion in the by other members of the Geological Survey. metropolitan area is in the shallow aquifers of the Yarra delta area and the Carrum Swamp. Acknowledgements. The writers wish to thank Dr. D. Spencer-Jones Bore Distribution and Construction. for information in connection with the Newer basalts Bores are at present both widely spaced and and Messrs. J. L. Neilson and W. E. Bamford for sporadic in their distribution. Clusters of bores information concerning the geology of the Yarra occur in certain areas-notably around Clarinda, delta. but in other places almost equally worthy of Messrs. I. Nicholls and L. Milton assisted in the investigation, bores have either not been drilled or drawing of cross sections 3-5. no information is available concerning them. Special thanks are due to private drilling The quality of the design and construction of the contractors who made their boring records available wells varies considerably and a more scientific to the Mines Department. Plate 7

.. ~ ~ ~ ;/ 200 200 l ~o.."'(J $ Tb / ~0 ______j ___~-~-=~ , 100 9" ------~Q~y-.------S L. ------y ..::::- -~~ s ------~------~ Tvo .:.---- ___ ------;:::;.::::----- 1-0.. ~ I --- ~ ------·100 q'.'.S .§ ~· ~ ~ "# ? $ ~~ ~ 100 ,'1'::-. ~ .q~~l ---~ ------~ ~ ~ ----- l" SL. -----__::::----~------T~ -- ·200 Tvn ~_::::::::----- SL f- - -~ L'or- .. 200 ---- " Tvn ~ b r------~~ - .100 ------·300 -~=Tfu--·.·r- ': - •.·--••- ·~ -100 +- --~ - t------Tw ---- r- r------Tb---=--=------~ 200-300LL--+--~ SECTION No. 2 ALTONA- BROOKLYN - BRUNSWICK ------Tvo s ---- -400 ------~::;...- - .!::::... _ _ -- ·20 0 Tn ----- ·4ooLl- --t---r Tw ----- Tw ------.---- 300 -- To ___ •300 f------1-· ------400 ------s - - Tw ·600 ------·S 0 =-'? r-=--..--....__..._, ------s SECTION No. I LAVERTON- BROOKLYN- SPOTSWOOD --- ·100 -- •O $ --- -- LEGEND ·800 Or

13&•..1 Recent Or 17~+320° "'' 300 "'' 300 Pleistocene to Ovn Ovn Upper Pliocene Tob Tob <;I 200 200 Tb Brigtllon Group Lower Pliocene Tor 100 Red Bluff Sond.s. W!tt't1 I() y~I/(Jir.btown Dtld li91lt-btowtt Sflndl Md cltlfiY 1011ds. TO "" l « o l/y 14? /h grDVIJ, &OOrsl SOI1d Dr COI/)(IIf(IU OUS Sill Of bDU.

TOb Block Rock Sondslont. Rrd-IN'wn srmds!M#(llv# 9"#M glt>VCDhl.,i'C SL Upper Miocene TbO SDhdS (JtN:/ SDttdy lihi#SIDMS (SubsvriDU) with lfNNiM fossilS. l.CCD!Iy wii/J s pMsp/UJtk n

Ntwporl F« moflon. Ct##ttllh · ~'Y m leoe#ovs sills/on# ond m/nor implr~ ·100 Tn · 100 s l•'m#Sitiii#S, 9t'Odlll9 IO COt'bMOUeyclinq/ SECTION No. EAST MALVERN TO KEYSBOROUGH l1m#Sit>tt# in *'"'"' port, All lilhologlu 9rod# /t3t,·olly lnttt silty sonds tlhd 3 sqnd#. fSqulh#OSI#t'h sufHirbs)

To AUono Cool Stom. Brown ct~IJI, Jttcql/y , .,h cloy int#rCDIOiiM I .

Tw Wectibu Formorion lupp#rPiJrl) Pyrili'c sqnds, Jlgnl t/t sOlids rmd ~'nor til/A Oligocene to brown cools. 179• Eocene (?) Tvo Older Volconiu . Bosa/1/c c!Dy ond bosoll. ~58. 400

400 Tw Wtrribe. Formorion fi----' 9rq"' 's emd ct>n9t"m"q'' ""or tHu#. 300 ------.._,.._~ ____ Silurian 09 Dw<~n•'qn grqnil# qnd gront~dlt~r/1# 011d t>ssqc/ouddyk# r«ks. l 200 S11vrian st>ndstt>n# qnd mv dsl<1n#s. 200 c! Tertiary --- 100 100 s s s SL SL. ,__ _,_-L ===---=-= ==- ~~~- -=-=.~--=---=-===::.~------· 100 -100 ------===-Tn ?- -$ -==-~;:;) --~- Tw . --- --.::- -200 ·200 SECTION No. 4 BOX HILL TO MORDIALLOC Scale

300 Coburg R.S. 80 120 160 CHAINS -"\milt ro n01 th Horizontal ~ 200

FEET 100 Verlicol co====~~~2300====300~==·~00~==5500E=~600 Tvo s ------SL Verttcol exoggerolion 13·2 SL

SECTION No.5 KEILOR TO HEIDELBERG - 100 - 100 83 ILLUSTRATIONS. TEXT FIG. 9. Sketch map showing position of geological PLATE 7-continued. cross-sections of the Tertiary rocks (see Plate 7). Cross-section 2. Altona to Brunswick. PLATE 7. Geological cross-sections of the Tertiary rocks, Cross-section 3. East Malvern to Keysborough. Melbourne area. (See Text Fig. 9 for positions of Cross-section 4. Box Hill to Mordialloc. sections). Cross-section 1. Laverton to Spotswood. Cross-section 5. Keilor to Heidelberg.

TEXT FIG. 9. Sketch map showing position of geological cross-sections of the Tertiary rocks (see Plate 7). 84

CHAPTER 5. FOSSIL PLANTS IN THE MELBOURNE AREA

J. G. Douglas.

Fossilized plants are sparsely distributed in the Altona. sediments of the Melbourne area. The main plant ANGIOSPERMAE. fossil localities and their floras are listed below :- DICOTYLEDONAE. FAGACEAE. Silurian. Nothofagus emarcida Cookson. Unidentified plant fragments are found scattered Nothofagus falcata Cookson. throughout the Silurian rocks of Melbourne, and Nothofagus deminuta Cookson. are usually present in greatest abundance at shelly Nothofagus vansteenisi Cookson. fossil localities. An algal species, Buthotrephis GYMNOSPERMAE. gracilis Hall, has been identified from Hoffman's PODOCARPACEAE. Clay Pit, Brunswick (Lucas, 1927). Buthotrephis Mesembrioxylon sp. tenuis and B. intermedia recorded from South The following calcareous algae have been Yarra, are probably not of algal origin. recorded from the Green Gully Limestone of No microfloras have been recorded from the Batesfordian age at Green Gully, Keilor (Crespin, Silurian beds. 1926) :-

Tertiary. Keilor. Lower Tertiary floras occur in the Altona brown ALGAE. coals and in sub-Older Volcanic Alluvial deposits at RHODOPHYCEAE. Flemington and Pascoe Vale. Lithophyllum hydractinoides Crespin. The coals are composed of a great variety of Lithothamnion amphiroaeformis Roth. plant tissues, only a few of which have been identi­ L. ramosissimum Reuss. fied. Described forms consist of four species of Probable lacustrine beds of pre-Newer Volcanic fossil pollen (Cookson, 1946; 1959) and pieces of age at Keilor contain leaves of eucalyptus, acacias, fossil wood. ferns and other plants, together with stems and The floras at Pascoe Vale and Flemington occur fruits of unidentified plants (James, 192 7). The principally as fragmentary leaf impressions. The Eucalyptus leaves have been described by Patton forms present include broad leaved angiosperm (1919). At a number of other localities, sub­ genera referred to Magnolia and Nothofagus Newer basaltic sands have yielded pyritized and (Paterson, 1934) which are not indigenous silicified wood. members of the modern flora and sclerophyllous angiosperms similar to the present day plants of the Tertiary-Quaternary. area, such as Eucalyptus sp. Weathering has The Newer basalts of the Melbourne area destroyed microspores in the sediments from these occasionally contain pieces of wood which have localities. been preserved with only partial damage to the woody tissue. These were incorporated into the Plant remains from the Lower Tertiary of the lava while it was still molten. Identifiable wood Melbourne area include :- (e.g., Casuarina sp., Gill and Baker, 1950) has been recorded from several localities. Pascoe Vale. ANGIOSPERMAE. Quaternary. DICOTYLEDONAE. Plant reproductive bodies or microspores are MORACEAE. plentiful in the Quaternary clays and silts of the Ficonium nitidum Paterson. Yarra valley. Excavations for many engineering MYRTACEAE. projects along the Yarra have revealed beds Eucalyptus kitsoni Deane. containing extensive pollen and spore microfloras. FAGACEAE. These are valuable for strata correlation and Nothofagus muelleri Ettinghausen. geological age determination. Well preserved fossil MAGNOLIACEAE. woods have also been obtained from the Yarra silts. Magnolia microphylla Paterson. Stumps and trunks identified as Eucalyptus camal­ LAURACEAE. dulensis (River Red Gum) were found during the Cinnamomum sp. Spencer Street Bridge and Kings Bridge excavations. 85

Carbon dating tests carried out on one such Bacillariophyceae have also been recorded from specimen indicated an age of nearly 9,000 years Coburg, Brunswick, Fairfield (Y arraford Avenue), (Gill, 1955). Richmond (Church Street Bridge) and Mitcham. Microscopic siliceous plants lmown as diatoms The Quaternary sands and gravels in the south­ are found at numerous localities, and the following eastern part of the area also contain some silicified have been identified (Tindale, 1953) woods. BACILLARIOPHYCEAE. CENTRALES. REFERENCES. Actinocyclus barklyi Coates. CooKsoN, IsABEL C., 1946.-Pollens of Nothofagus Blume A. duodenarius. from Tertiary deposits in Australia. Proc. Linn. Soc. Campylodiscus bicostatus. N.S.W., Vol. 71, 1-'2, pp. 49-63. C. clypeus. CooKsoN, IsABEL C., 1959.-Fossil Pollen Grains of Nothofagus from Australia. Proc. Roy. Soc. Viet., C. cribrosus. Vol. 71, Pt. 1, pp. 25-30. C. hodgsonii. CRESPIN, IRENE, 1926.-The Geology of Green Gully, C. parvulus. Keilor, with special reference to the Fossiliferous Beds. Coscinodiscus eccentricus. Proc. Roy. Soc. Viet., Vol. 38, pp. 100-124. C. radiatus. DurGAN, SuzANNE L., 1951.-A catalogue of the Au;;tralian Cyclotella rectangula. Tertiary flora. Proc. Roy. Soc. Viet., 63, pp. 41-56. Hya/odiscus subtilis. LucAs, A. H. S., 1927.-0n an additional occurrence of Hydrosera triquetra. Bythotrephis in Victoria. Mem. Nat. Mus. Mel­ bourne, 7. Orthosira marina. GILL, E. D., 1953.-Palaeoecological interpretation of PENNALES. some Victorian fossil diatom floras. Mem. Nat. Mus. Achnanthes brevipes. Melbourne, 18, pp. 141-153. A. subsessilis. GILL, E. D., 1955.-Radiocarbon dates for Australian Cocconema lanceo/atum. archaeological and geological samples. Aust. Jour. Cymbella sp. Sci., 18, 2. GILL, E. D. and BAKER, A. A., 1950.-Fossil plants in Epithemia turgida basalt at Maribyrnong, Victoria. Viet. Nat., 67, 6. E. westernannii JAMES, A. V. G., 1920.-The Physiography and Geology Gomphonema cymbiforme of the Bulla-Sydenham area. Proc. Roy. Soc. Viet., G. gracile Vol. 32, Pt. 2, pp. 323-349. G. lanceolatum PATERSON, H. T., 1934.-Notes on some Tertiary Leaves Himantidium arcut from Pascoe Vale. Proc. Roy. Soc. Viet., Vol. 46, pp. 264-268. H. bidens PATTON, R. T., 1919.-Notes on Eucalypt Leaves occurring H. gracile in the Tertiary Beds at Bulla. Proc. Roy. Soc. Viet., H. undulatum Vol. 31, Pt. 2, pp. 362, 363. Navicula amphisbaena TINDALE, B., 1953.-Some Victorian fossil diatoms. Mem. N. elliptica Nat. Mus. Melbourne, 18. N. minitula N. ovalis DESCRIPTION OF PLATE 8. N. pusilla Fig. 1. Ficonium nitidum, Paterson. Moonee Ponds Creek, N. tumens Pascoe Vale. Leaf impression, natural size. After Nitzschia sp. photograph by A. A. C. Carter, in Paterson, 1934. Pinnu/aria accuminata Fig. 2. Angiosperm leaf impression. Moonee Ponds Creek, P. distans Pascoe Vale. Natural size. G.S.V. Reg. No. 59345. P. major Figs. 3, 5-14. Microspores, King-street Bridge excavations, Yarra River. Figs. 6, and 8, X 300; Figs. 3, 5, 7, P. nobilis 9-14, X 400. P. stauroneiformis Fig. 4. Nothofagus emarcida, Cookson. Pollen, Altona Pleurosigma balticum brown coal mine. X 400. P. spp. Fig. 15. Epidermal tissue, King-street Bridge excavation, Stauroneis acuta Yarra River X 400. S. pulchella Figs. 16-17. Bacillariophyceae, Mitcham. X 400. S. splendida Fig. 18. Fungal hypha, King-street Bridge excavations, S. striatula Yarra River X 300. NoTEs.-1. Figs. 3-15, 18. Drawn from specimens in S. spp. acid insoluble residue obtained using the Schulze's solu­ Tabellaria sp. tion-hydrofluoric acid method. Tryblionella gracilis 2. All figures are camera Iucida drawings by Miss T. marginata A. C. Moore.

2288/66.-8 86

PLATE 8.

I / I ' , ~~. / l>\ .:·..··;····.~·.··.·'\ .. '·:· ~~ ! 3 4 / ~ 2 6

10

7 8

14

12

~ -~ 16 ' 17 87

GENERAL ACKNOWLEDGEMENT

In the preparation of this bulletin information was drawn from a wide range of sources, both within the Mines Department and from outside organizations and individuals. Sincere thanks are tendered to all those who contributed in this way. Special assistance given to authors of particular articles are acknowledged in the body of the text. Fair drawings of illustrations were prepared in the Mines Department drawing office under the direction of Mr. D. Mcinnes, M.A.I.C. Mr. R. G. Williams assisted with the photography. 88

EXPLANATION OF PLATES 9-15.

PLATE 9. Fig. 2. Basalt of the Older Volcanics (below quarry bench) overlain by Tertiary sands (white). Rubbly SILURIAN SANDSTONES, CLAYSTONES AND SILTSTONES. basalt of the Newer Volcanics occurs at the top of Fig. 1. East dipping strata in outcrop on the south bank the quarry face (dark). Western quarry, Bayview of the Yarra River at Dight's Falls, Studley Park. Quarries, Tullamarine. Fig. 2. Minor thrust faulting and jointing in steeply dipping strata exposed on the Boulevard, west of Yarra-street, PLATE 13. Studley Park. BRIGHTON GROUP SEDIMENTS. PLATE 10. Fig. 1. Cliffs east of Wells-road, Beaumaris, viewed from the south-west. Ferruginous sandstones of the Black SILURIAN SANDSTONES, CLAYSTONES AND SILTSTONES. Rock Sandstone dipping at 20-30° to the south-east adjacent to the Beaurnaris monocline. Fig. 1. An anticline exposed in a road cutting in Barker's­ road, Kew, immediately east of the Yarra River. The Fig. 2. Cliffs at Red Bluff, Black Rock, viewed from the concrete on the left side of the photograph (smooth) south-west. The sands and clayey sands of the Red masks a soft decomposed dyke. Bluff Sands form the upper part of the bluff (light colour) and the harder ferruginous sandstones of the Fig. 2. A large anticline exposed in the south face of the Black Rock Sandstone form its base which is located Oakleigh Brick Co. Pit, Stamford-road, Oakleigh. on the crest of the Re-d Bluff anticline. The beds Occasional faint traces of the bedding persist in the at the top of the Black Rock Sandstone dip at a intensely weathered zone at the top of the pit face. few degrees towards the observer (apparent dip to right) into the Half Moon Bay syncline (See Plates PLATE 11. 2, 14 ). SILURIAN SEDIMENTS, TERTIARY SEDIMENTS AND NEWER VoLCANics. PLATE 14. Fig. 1. Deeply weathered Silurian mudstone (claystones and siltstones) in the S. and I. Franklin Pty. Ltd. BRIGHTON GROUP SEDIMENTS AT RED BLUFF, BLACK RoCK. Clay Pit, Camp-road, Campbellfield. The bedding planes which dip at about 50° to the east (left) Fig. 1. Red Bluff viewed from the south-west. Detail of can be traced from the relatively fresh Silurian the disconformable contact between the Red Bluff sediments (dark coloured) in the bottom of the pit Sands above (light-coloured) and the Black Rock into the weathered sediments (light coloured) above. Sandstone below. A thin capping of rubbly basalt of the Newer Fig. 2. Red Bluff from the north-west, looking south-east Volcanics (dark) occurs at the top of the pit face. along the axis of the Red Bluff anticline. The sand­ stones of the Black Rock Sandstone dip gently beneath Fig. 2. Deeply weathered Silurian mudstones dipping at the sea to the left and right of the headland. about 35-40° to the south-east (right), overlain unconformably by a wedgeshaped deposit of Tertiary clays locally dipping at about 10° to the southwest (right). Flat-lying rubbly basalt of the Newer PLATE 15. Volcanics (dark) caps the Silurian on the left side of the photograph and the Tertiary on the right. RED BLUFF SANDS AND QUATERNARY SHELL BEDS. Campbellfield Clay Co. Pty. Ltd. Pit, Sydney-road, Fig. 1. Rowlands Quarries Ltd. Sand Pit, Clayton. Look­ Campbellfield. ing north-west. Sluicing operations in poorly bedded fiat-lying sands of the Red Bluff Sands. PLATE 12. Fig. 2. As above, looking south-east. The bedding in the SILURIAN SEDIMENTS, TERTIARY SEDIMENTS AND BASALTS. pit face rises gently to the north (left) from the south-east corner of the pit (centre). Carbonaceous Fig. 1. Flat-lying Tertiary sands and gravels of the sands are exposed in the floor of the pit at the Brighton Group unconformably overlying Silurian extreme left of the photograph. siltstones, claystones and sandstones dipping at 30-40° to the east (apparent dip about 13 o to the left). Fig. 3. Shell beds and shell-bearing sandy limestone of South-east face of railway cutting immediately north­ Quaternary age exposed in a small railway cutting east of Royal Park station. north-east of Seaholme. 89

PLATE 9.

2288/66.-9 90

PLATE 10. 91

PLATE 11.

Fig. 1.

Fig. 2. 92

PLATE 12.

Fig. 1.

Fig. 2. 93

PLATE 13.

Fig. 1.

Fig. 2. 94

PLATE 14.

Fig. 1.

Fig. 2. 95

PLATE 15.

Fig. 1.

Fig. 2.

Fig. 3. ------By Authority: A. C. BRooKS, Government Printer, Melbourne.