Page:1902 Encyclopædia Britannica - Volume 25 - A-AUS.pdf/847

 geology]

AUSTRALIA

791

■ Glossopteris, Phyllotheca, Verte animal world as we know it to-day,—types which are in no sense braria, Splienopteris, Annularia embryonic. We cannot here, any more than elsewhere, work back Spirifer, PachydomuSj Productus far enough to get near to the beginnings of life. The Cambr!anOrthoceras, Conularia, Martiniopsis ^Permo-Carboniferous Eurydesma, Platyceras, Leaia, Gan auimals on the Cambrian sea-shores were graded and gamopteris, Aviculopecten, Notomya grouped no less exactly and definitely than the invertebrate fauna -Sanguinolites. the present coast-line. Mammals, birds, reptiles, and fishes are, I Rhacopteris, Lepidodendron, Gala of of course, absent; but it must strike one as remarkable that J mites, Archaeopteris, Sigillaria, Loxo Carboniferous VLeptaena, Phyllotheca, Fenestella. lamellibranchs, gasteropods, and pteropods, should f Lepidodendron, Cyclostigma, Spiri brachiopods, be present in that far-off epoch pretty much as we see them to-day. J fer, Rhynchonella, Atrypa, Orthis Devonian j Orthoceras, Asterolepis, Pteronites Cambrian rocks are known in Yorke’s Peninsula, South Australia, VMurchisonia. near Leigh’s Creek, 300 miles to the north of Adelaide.^ /■ Atrypa, Pentamerus, Halysites and rocks have been described in the Kimberley district of jp-i Graptolites, Phacops, Bronteus, Caly Cambrian mene, Cyathophyllum, Spirifera West Australia containing such world-wide forms as Salterella and Didymograptus, Lingulocaris, Lin Olenellus. The Macdonnell Ranges of Central Australia are congula, Mucophyllum, Stromatopora also of Cambrian age, and, like all the Australian Cambrian, K Favosites, Heliophyllum, Phillipsas sidered Silurian. trea, Rhizophyllum, Columnaria are of marine origin. Some of the Cambrian beds were laid down Petraia, Lichas, Syringopora, Cyclo in shallow waters, as ripple-marked quartzites and current-bedded nema, Bellerophon, Palseaster, Niso sandstones are known to occur. No contemporaneous igneous Trochus, Asaphus, Beyrichia, Cyph rocks are known. The Cambrian shows evidence of much foldv aspis. f Conocephalites, Dolichometopus ing, and it is evident that the earth movements giving rise to the -[ Dikelocephalus, Dinesus, Olenellus folds took place before the deposition of the succeeding Silurian. ^Cambrian l.Salterella, Orthisina, Leperditia. The Macdonnell Range, usually regarded as Cambrian, consists of conglomerates, limestones, and slates, and these conglomerates SHOWING THE GENERAL SUCCESSION OF AUSTRALIAN Table, are the first evidence of the existence of any land in Australia. Strata. The Silurian system is well represented over Australia. Quite PerSome Typical Examples. System. one-thirtieth of the area of the continent is covered by rocks of iod. / Raised beaches.—Victoria and West Australia this age. In the colony of Queensland, however, the S]Iur!an_ ^ r Recent have sand loams for forming these. f Alluvial flats and great plains of the interior. Silurian is not developed to any considerable extent. -[ Raised beaches of the north-west coast, Tasmania. The Australian Silurian consists of sandstones, mud-stones, conqH '-Pleistocene L Large area in the south-east of South Australia. Limestone creek beds,south-west Victoria,contain- glomerates (rare), “slates,” and limestones. Over a great area of ing about 80 per cent, of living mollusca. V olcanic ash the country highly inclined mud-stones are known as Silurian beds of Mount Gambier. Mammaliferous sandy clays “slates.” The cleavage of these rocks corresponds to the bedding containing diprotodon, &c., Mammaliferous cave de- planes, and they are, therefore, not true slates. Nowhere has the Pliocene posits of New South Wales and Victoria; freshwater Australian Silurian been subjected to such intense metamorphism v limestones of the Geelong district. Newer basalts at as to develop cleavages across the deposition planes. The Silurian .tH Werribee, Geelong, and Camperdown, Victoria. V 2=5 Marine sands of the Dry Creek and Croydon bores, beds have been tilted, folded, and broken ; but the conditions South Australia. Oyster beds of the Murray river necessary for the production of rocks resembling, say, the Bangor NOSS , cliffs and Aldinga Bay, South Australia. Calcareous slates, were not present. The mud-stones of Victoria have yielded •zig ^ Miocene i sands and clays of Jemmy’s Point, Gippsland, and ^H I the upper beds at Murray Creek, near Hamilton, an abundance of Graptolites, and these interesting fossils have also o t. VWest Victoria. found in New South Wales. The richest fauna, however, Generally—limestones, clays, and sands from the beenbeen discovered in the limestones. European forms, made I Snowy river, Gippsland, to the Great Australian has ] Bight; also from Geraldton to Shark Bay, Western familiar by text-books, are well represented, as, for instance ' Eocene Australia; and Table Cape,T Tasmania (all1 marine). —Halysites, Favosites, Syringopora, Phillipsastrea, amongst the (Plant beds of Emmaville, New South Wales, lr ' —w ~ corals ; Phacops, Bronteus, and Calyviene, amongst the trilobites. No marine beds of Eocene, Miocene, or Pliocene Beceptaculites is also known, together with Pentamerus, and a age are known east of the Main Dividing number of Spirifers. So far as is known, the Silurian beds are Range in New South Wales or Queensland. Upper Cretaceous.—Desert sandstone of marine. No contemporaneous igneous rocks have been discovered. £ £ £o Queensland. Victoria the Upper and Lower Silurian have an aggregate thickLower Cretaceous.—Rolling Downs for- In o 2 ^ mation of Queensland. Artesian water- ness of 35,000 feet. In New South Wales a section has been meaCretaceous bearing beds of north-western New South sured at Molong showing a thickness of 3000 feet. The ‘ ‘ slates of Wales. Kennedy Range and Gascoyne Silurian age are often seen to rest directly on granite, their bedding -P3S* river, West Australia. Beds with fossil fish, Talbragar river, planes standing vertically and rising directly from the granite. The Op Jurassic New South Wales. Oolitic limestone of granite is not, therefore, the original bed-rock on which the slates ^ St? Champion Bay district, West Australia. were laid down. There is abundant evidence to show that much of oo aiO ^ The Hawkesbury sandstones and granite was intruded amongst the “ slates ” after the latter were associated shales of New South Wales. the Lower Mesozoic rocks of the Clarence left highly inclined by intense folding. These granites are therefore river. The Ipswich and Burrum beds of younger than Silurian, and, as they do not intrude on the CarbonTriassic, or TriQueensland with Tceniopteris. The Upper iferous higher up in the series, they are probably of Devonian age. as-Jura. Coal Measures of Tasmania, and the '■d Some interesting caves have been discovered in the limestones of £§ o > g Australia are considered to be of Meso- this age. The Australian black-fellow has left us no history in connexion with them. Certain rock shelters have been used by oq "3 ^ zoic age. f Coal Measures of New South Wales, Newcastle, the aboriginals, but of the limestone caves they evidently made no I Illawarra, and Lithgow, with Glossopteris. Upper use. The living aboriginal avoids even their vicinity. The ("Permo - Carbon- J and Middle Bowen river formations, Queensland. Wellington caves of New South Wales have been eroded through iferous . . I Collie river and Irwin river, West Australia. TasI manite beds, Mersey and coast about the estuary limestones of Silurian age. Breccias accumulated through openl^of the Derwent, Tasmania. from the surface, and yielded a series of most interesting giant 1 Port Stephens district, New South Wales. Gym- ings pie, Lower Bowen, and Star formations, Queens- marsupials, first drawn attention to by Sir Richard Owen. In Carboniferous J1 land. Also the Lower Coal Measures of Tasmania. fact, the whole importance of these caves lies in the scientific value f Mount Lambie sandstones, Rydal, New South attached to the fossils referred to. From a scenic point the I Wales. Avon river and Mount Tambo beds, Victoria. are uninteresting. The Jenolan caves of New South Wales J Burdekin beds, Queensland. Sandstones and grits, caves Devonian I Kimberley, West Australia. Fingal slates, Tas- are also eroded from limestones of the same age. They have 0>h 1 mania. yielded no fossils of especial interest, but are widely known for r Highly-inclined clay slates and talcose slates, beauty. Geologically, the existence of the caves depends on I New South Wales, South Australia, and West their I Australia and Victoria. Graptolite beds of the fact that a bar of limestone runs almost directly across a J Victoria. Yass and Molong limestones, New deeply eroded valley, — water, the giant sculptor of mountains, Silurian South Wales. “ Larapintine ” limestones, Mac- having found it easier to make for itself a passage by dissolving 04 £ donnell ranges. Queen river schists and slates, the limestones than by eroding them to the valley level. land the Gordon river group, Tasmania. In Australia there is a great development of stratified rocks up r Olenellus and Salterella beds of Kimberley, West Australia. Ardrossan beds of South Australia. to 23,000 feet in thickness, unconformable to the older Silurian Cambrian Magog and Caroline creek groups, Tasmania. and the overlying Carboniferous. The life of the period [)evonian Yorke’s Peninsula series, South Australia. Kim- is also clearly distinct from that of the preceding and Iberley, West Australia. Heathcote, Victoria. / Quartzite and some metamorphic rocks of Tas- the succeeding rocks. Here for the first time in the geological ^Pre-Cambrian mania. Mount Lofty Ranges, South Australia. record we meet with contemporaneous igneous rocks. The Snowy Of the seven sub-kingdoms of living things, no less than five are river porphyries of Victoria and certain felsites in the Braidwood represented in the Australian Cambrian. If we except vertebrates, district, New South Wales, must be considered the results ^ of we have therefore at the very dawn of life representatives of the volcanic outbursts in Devonian times. In Queensland, Devonian
 * nema, Euomphalus, Spirifer, Orthis foraminifera, sponges, corals, hydrozoans, entomostraca, trilobites,