FOSSIL PLANTS.

Cambrian Plants.—

The oldest Australian plant-remains belong to the genus Girvanella. This curious little tubular unicellular organism, once thought to be a foraminifer, shows most affinity with the blue-green algae (Cyanophyceae), an important type of plant even now forming calcareous deposits such as the calcareous grains on the shores of the Salt Lake, Utah, and the pea-grit of the Carlsbad hot springs. Girvanella problematica occurs in the Lower Cambrian limestones of South Australia, at Ardrossan and elsewhere.

Silurian Plants.—

Amongst Silurian plants may be mentioned the doubtful sea-weeds known as Bythotrephis. Their branch-like impressions are fairly common in the mudstones of Silurian age found in and around Melbourne. They generally occur in association with shallow-water marine shells and crustacea of that period.

The genus Girvanella before mentioned is also found in the Silurian (Yeringian) of Lilydale and the Tyers River limestone, Victoria (Fig. 54).

Haliserites is a primitive plant of the type of the club-mosses so common in the rocks of the Carboniferous period. This genus is found in some abundance in the Yeringian stage of the Silurian in Gippsland (Fig. 55).

Devonian and Carboniferous Plants.—

Plant-life was not abundant, however, until Upper Devonian and Carboniferous times. In the rocks of these periods we meet with the large strap-shaped leaves of Cordaites and a fern, Sphenopteris, in the first-named series; and the widely distributed Lepidodendron with its handsome lozenge-scarred stems in the later series (Fig. 56). Cordaites has been found in Victoria in the Iguana Creek beds (Upper Devonian), and it also probably occurs at the same horizon at Nungatta, New South Wales. Lepidodendron occurs in the Lower Carboniferous sandstone of Victoria and Queensland (Fig. 57): in New South Wales it is found at Mt. Lambie, Goonoo, Tamworth and Copeland in beds generally regarded as Upper Devonian. Both of these plants are typical of Carboniferous (Coal Measure) beds in Europe and North America. The fern Rhacopteris is characteristic of Upper Carboniferous shales and sandstones near Stroud, and other localities in New South Wales as well as in Queensland (Fig. 58). These beds yield a few inferior seams of coal. Girvanella is again seen in the oolitic limestones of Carboniferous age in Queensland and New South Wales.

Carbopermian Plants.—

The higher division of the Australian Carboniferous usually spoken of as the Permo-carboniferous, and here designated the Carbopermian (see Footnote 2, page 48), is typified by a sudden accession of plant forms, chiefly belonging to ferns of the Glossopteris type. The lingulate or tongue-shaped fronds of this genus, with their characteristic reticulate venation, are often found entirely covering the slabs of shale intercalated with the coal seams of New South Wales; and it is also a common fossil in Tasmania and Western Australia. The allied form, Gangamopteris, which is distinguished from Glossopteris by having no definite midrib, is found in beds of the same age in Victoria, New South Wales, and Tasmania. These plant remains are also found in India, South Africa, South America and the Falkland Islands. This wide distribution of such ancient ferns indicates that those now isolated land-surfaces were once connected, forming an extensive continent named by Prof. Suess “Gondwana-Land,” from the Gondwana district in India (Fig. 59).

Triassic Plants.—

The widely distributed pinnate fern known as Thinnfeldia is first found in the Trias; in the Narrabeen shales near Manly, and the Hawksbury sandstone at Mount Victoria, New South Wales. It is also a common fossil of the Jurassic of South Gippsland, and other parts of Victoria. The grass-like leaves of Phoenicopsis are frequently met with in Triassic strata, as in the upper series at Bald Hill, Bacchus Marsh, and also in Tasmania. The large Banana-palm-like leaves of Taeniopteris (Macrotaeniopteris) are common to the Triassic and Lower Jurassic beds of India: they are also met with in New Zealand, and in the upper beds at Bald Hill, Bacchus Marsh.

Jurassic Plants.—

The Jurassic flora of Australasia is very prolific in plant forms. These range from liverworts and horse-tails to ferns and conifers. The commonest ferns were Cladophlebis, Sphenopteris, Thinnfeldia and Taeniopteris. The conifers are represented by Araucarites (cone-scales, leaves and fruits), Palissya and Brachyphyllum (Fig. 60). The Ginkgo or Maiden-hair tree, which is still living in China and Japan, and also as a cultivated plant, was extremely abundant in Jurassic times, accompanied by the related genus, Baiera, having more deeply incised leaves; both genera occur in the Jurassic of S. Gippsland, Victoria, and in Queensland. The Jurassic flora of Australasia is in many respects like that of the Yorkshire coast near Scarborough. In New Zealand this flora is represented in the Mataura series, in which there are many forms identical with those of the Australian Jurassic, and even of India.

Cretaceous Plants.—

An upper Cretaceous fern, (?) Didymosorus gleichenioides, is found in the sandstones of the Croydon Gold-field, North Queensland.

Plants of the Cainozoic.—Balcombian Stage.—

The older part of the Cainozoic series in Australasia may be referred to the Oligocene. These are marine beds with occasional, thick seams of lignite, and sometimes of pipe-clay with leaves, the evidence of river influence in the immediate neighbourhood. The fossil wood in the lignite beds appears to be a Cupressinoxylon or Cypress wood. Leaves referable to plants living at the present day are also found in certain clays, as at Mornington, containing Eucalyptus precoriacea and a species of Podocarpus.

Miocene Leaf-beds.—Janjukian Stage.—

Later Cainozoic deposits, evidently accumulated in lakes, and sometimes ferruginous, may be referred to the Miocene. They are comparable in age with the Janjukian marine beds of Spring Creek and Waurn Ponds in Victoria. These occur far inland and occupy distinct basins, as at the Wannon, Bacchus Marsh (Maddingley), and Pitfield Plains. Leaf-beds of this age occur also on the Otway coast, Victoria, containing the genera Coprosmaephyllum, Persoonia and Phyllocladus. In all probability the Dalton and Gunning leaf-beds of New South Wales belong here. Examples of the genera found in beds of this age are Eucalyptus (a species near E. amygdalina), Banksia or Native Honeysuckle, Cinnamomum or Cinnamon, Laurus or Laurel, and Fagus (Notofagus) or Beech (Fig. 61). In the leaf-beds covered by the older basalt on the Dargo High Plains, Gippsland, leaves of the Ginkgo Murrayana occur.

In South Australia several occurrences of leaf beds have been recorded, containing similar species to those found in the Cainozoic of Dalton and Vegetable Creek, New South Wales. For example, Magnolia Brownii occurs at Lake Frome, Bombax Sturtii and Eucalyptus Mitchelli at Elizabeth River, and Apocynophyllum Mackinlayi at Arcoona.

Fruits of the “Deep Leads.”—

The Deep Leads of Victoria, New South Wales and Tasmania probably begin to date from the period just named, for they seem to be contemporaneous with the “Older Gold Drift” of Victoria; a deposit sometimes containing a marine fauna of Janjukian age. This upland river system persisted into Lower Pliocene times, and their buried silts yield many fruits, of types not now found in Australia, such as Platycoila, Penteune and Pleioclinis, along with Cupressus (Spondylostrobus) and Eucalyptus of the existing flora (Fig. 62).

Pleistocene Plants.—

The Pleistocene volcanic tuffs of Mount Gambier have been shown to contain fronds of the living Pteris (Pteridium) aquilina or Bracken fern, and a Banksia in every way comparable with B. marginata, a species of the Native Honeysuckle still living in the same district.

The siliceous valves of freshwater diatoms constitute the infusorial earths of Victoria, Queensland, New South Wales and New Zealand. The commonest genera met with are Melosira, Navicula, Cymbella (or Cocconema), Synedra, Tabellaria, Stauroneis and Gomphonema. They are, generally speaking, of Pleistocene age, as they are often found filling hollows in the newer basalt flows. In Victoria diatomaceous earths are found at Talbot (See Fig. 42), Sebastopol and Lancefield; in Queensland, at Pine Creek; in New South Wales, at Cooma, Barraba, and the Richmond River; and in New Zealand at Pakaraka, Bay of Islands. In the latter country there is also a marine diatomaceous rock in the Oamaru Series, of Miocene age.

COMMON OR CHARACTERISTIC FOSSILS OF THE FOREGOING CHAPTER.

Girvanella problematica, Nicholson and Etheridge. Cambrian: S. Australia.

Bythotrephis tenuis, J. Hall. Silurian: Victoria.

Haliserites Dechenianus, GÖppert sp. Silurian and Devonian: Victoria.

Cordaites australis, McCoy. Upper Devonian: Victoria.

Lepidodendron australe, McCoy. Lower Carboniferous: Victoria and Queensland. Up. Devonian: New South Wales.

Rhacopteris inaequilatera, GÖppert sp. Carboniferous: New South Wales.

Glossopteris Browniana, Brongniart. Carbopermian: New South Wales, Queensland, Tasmania and W. Australia.

Gangamopteris spatulata, McCoy. Carbopermian: Victoria, New South Wales and Tasmania.

Thinnfeldia odontopteroides, Morris sp. Triassic: New South Wales. Jurassic: Victoria, Queensland and Tasmania.

Cladophlebis denticulata., Brongn. sp., var. australis, Morris. Jurassic: Queensland, New South Wales, Victoria, Tasmania and New Zealand.

Taeniopteris spatulata, McClelland. Jurassic: Queensland, New South Wales, Victoria, and Tasmania.

(?) Didymosorus gleichenioides, Etheridge fil. Upper Cretaceous: Queensland.

Eucalyptus precoriacea, Deane. Oligocene: Victoria.

Eucalyptus, Banksia, Cinnamomum, Laurus and Fagus. Miocene: Victoria, New South Wales and Tasmania.

Spondylostrobus Smythi, von Mueller. (Fruits and wood). Lower Pliocene: Victoria and Tasmania.

Pteris (Pteridium) aquilina, LinnÉ, and Banksia cf. marginata, Cavanilles. Pleistocene: Victoria and South Australia.

LITERATURE.

Girvanella.—Etheridge, R. jnr. Trans. R. Soc. S. Australia, vol. XIII. 1890, pp. 19, 20. Etheridge, R. and Card, G. Geol. Surv. Queensland, Bull. No. 12, 1900, pp. 26, 27, 32. Chapman, F. Rep. Austr. Assoc. Adv. Sci., Adelaide Meeting (1907), 1908, p. 337.

Devonian Ferns and Cordaites.—McCoy, F. Prod. Pal. Vict. Dec. V., 1876, p. 21. Dun, W. S. Rec. Geol. Surv. New South Wales, vol. V. pt. 3, 1897, p. 117.

Lepidodendron.—McCoy, F. Prod. Pal. Vict., Dec. I. 1874, p. 37. Etheridge, R. jnr. Rec. Geol. Surv, New South Wales, vol. II., pt. 3, 1891, p. 119. Idem, Geol. and Pal. Queensland, 1892, p. 196.

Carboniferous Fungi.—Etheridge, R. jnr. Geol. Surv. W.A., Bull, No. 10, 1903, pp. 25-31.

Carboniferous Ferns.—Dun, W. S. Rec. Geol. Surv. New South Wales, vol. VIII. pt. 2, 1905, pp. 157-161, pls. XXII. and XXIII.

Glossopteris.—Feistmantel, O. Mem. Geol. Surv. New South Wales, Pal. No. 3, 1890. Arber, N. Cat. Foss. Plants, Glossopteris Flora, Brit. Mus., 1905.

Gangamopteris.—McCoy, F. Prod. Pal. Vict., Dec. II. 1875, p. 11.

Jurassic Plants.—McCoy, F. Prod. Pal. Vic., Dec. II. 1875, p. 15. Woods, T. Proc. Linn. Soc. New South Wales, vol. VIII. pt. I. 1883, p. 37. Etheridge, R. jnr. Geol. Pal. Queensland, 1892, p. 314. Dun, W. S. (Taeniopteris), Rep. Austr. Asso. Adv. Sci., Sydney, 1898, pp. 384-400. Seward, A. C. Rec. Geol. Surv. Vic., vol. I. pt. 3, 1904; Chapman, F. Ibid., vol II. pt. 4, 1908; vol. III., pt. 1, 1909. Dun, W. S. Rec. Geol. Surv. New South Wales, vol. VIII. pt. 4, 1909, p. 311.

Older Cainozoic Plants.—McCoy, F. Prod. Pal. Vic., Dec. IV. 1876, p. 31. Ettingshausen, C. von. Mem. Geol. Surv. New South Wales, Pal. No. 2, 1888. Idem, Trans. New Zealand Inst., vol. XXIII. (1890), 1891, p. 237. Deane, H. Rec. Geol. Surv. Vict., vol. I. pt. 1, 1902, pp. 15, 20.

Lower Pliocene Deep Leads.—McCoy, F. Prod. Pal. Vict., Dec. IV. 1876, p. 29. Mueller, F. von. Geol. Surv. Vic., New Veg. Foss., 1874 and 1883.

Pleistocene and other Diatom Earths.—Card, G. W. and Dun, W. S., Rec. Geol. Surv. New South Wales, vol. V. pt. 3, 1897, p. 128.