Page:1902 Encyclopædia Britannica - Volume 25 - A-AUS.pdf/848

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PERMO-CARBONIFEROUS.

AUSTRALIA [geology rocks quite 20,000 feet in thickness have been measured, forming Quite fifteen seams of workable coal, with an aggregate thickone unbroken series. Devonian rocks are developed largely in ness of 150 feet, have been opened up around Newcastle, New Western Australia. There is one belt 200 miles long, from the South Wales. It has been estimated that at the present rate of Saw Ranges to the Lubbock Range. Interbedded igneous rocks, consumption the known coal beds would last 3000 years. The breccias, and ash-beds are known, up to 100 feet in thickness. In same series with similar fossils is known to occur in West the Kimberley district of the same colony there are grits, con- Australia, lasmania, and Queensland. A considerable amount of glomerates, and limestones and slaty shales of Devonian age, 1100 volcanic activity manifested itself at many points over what is feet in thickness. The earliest land plant indicating a land flora now East and West Australia in Permo-Carboniferous times. for Australia is Dicrartophyllum Australicum from the middle Jurassic beds are said to underlie the Cretaceous to the north of Devonian of Queensland. Remnants of old land areas which Champion Bay, West Australia. Oolitic limestones, grits, sandsupported a land flora are also preserved near Jlansfield in stones, and clay ironstones make up the series. Some Victoria, also near Twofold Bay, and at Rydal in New South fossils have been described from Shark Bay, whfere Jurassic. Wales. Rocks with a thickness of quite 10,000 feet are developed they occur in ferruginous and variegated limestones, at Rydal (New South Wales). They contain the well-known fossils, clays, and ironstones, not unlike rocks of the same age occurrin0Spirifera disjuncia, and Ithynclionellcipleurodon, occurring mostly in in England. These interesting stratified rocks are all of marine quartzites. The series is made up for the most part of reddish and origin. In other parts of Australia freshwater desposits containpurple shales, mud-stones, grit, and conglomerates. These show ing abundant plant remains are classed as Jurassic. A remnant a strong unconformability with the underlying Silurian. The of rocks of this age occurs near Gulgong (New South Wales). Here occurrence of Lepidodendron is remarkable, being found as it is some yellow ferruginous shales were found to contain abundant exactly in the same horizon as the Spirifer named. fish remains. The fish belonged for the most part to the LeptoIhe Carboniferous of Europe is remarkable for the great develop- lepidce, and on the same slab could be seen land-shells, and ment of workable coal-seams in the series. In Australia the impressions of Tmniopteris. The fossiliferous shales are in situ, Carbon- gre-atest accumulation of coal is found in a subsequent being laid down in an eroded hollow in the Hawkesbury sandstone. The type district for Triassic rocks in Australia is immediately iferous. seiaes °[ rock known as the Permo-Carboniferous. The Australian Carboniferous is characterized by such forms around Sydney. Here the rocks are divided into three groups : as Lqtidodewlron, llluioopttris, Cordicites, Archccopteris, Sphenopteris, (1) Wianamatta shales, 700 feet; (2) Hawkesbury and Palozoniscid fish, and also by well-marked marine shells. The sandstone, 1000 feet ; (3) Narrabeen shales, 1600 feet. Triassic. rocks are therefore partly marine and partly fresh-water, and whole series is characterized by the absence of evidence of contemporaneous igneous activity is left by a great The marine fossils and an abundant and decided Mesozoic flora. Fish aiiety of rocks ranging from felsites to basalt. Carboniferous remains have also discovered. Much of the beauty of Sydney beds rich in fossil plants can be traced from Queensland through as a city is due to been the excellent building material supplied by the New South Wales. The Carboniferous rocks of Queensland are Hawkesbury sandstone. Ascending Permo-Carboniferous to conveniently divided into (1) Gympie series, which has been Iriassic rocks we at once lose the from Coal Measures measured up to 21,000 feet in thickness, on the Hodgkinson gold- fossil, Glossopteris. Quite another ferncharacteristic characterizes Triassic rocks field. The chief fossils are the marine forms—PTotoreteporct avipla, Ttcniopteris. In searching for artesian water in Western New I roductus cora and Mccrtinia subradiata—associated with LepidoWales, Tmniopteris beds have been discovered (underlying dendron : (2) the Star formation, made up of slates, conglomer- South Cretaceous). After boring through these beds abundant supplies ates, sandstones, and a thin band of limestone—the Avhole reaching of artesian water were struck. The presumption, therefore, is that up to a thickness of 1353 feet. Lepidodendron is also abundant, Iriassic and not Cretaceous, are the source of artesian water, and Cyclostigma, with the marine forms, Phillipsia dubia and if not in rocks, Queensland, certainly in New South Wales. Rhynchonella pleurodon. The Carboniferous rocks of West Queensland has a great series of coal-bearing rocks, known as Australia consist of limestone beds interbedded with shales, layers Burrum formation. The lower Burrum coalfield extends of gypsum, and traces of rock salt 1000 to 1300 feet in thickness, the the eastern coast-line from Point Cartwright on and a series of freshwater sandstones, with a thickness of 1800 feet along the south, to Littabella Creek on the north, and Trias-Jura. . The Silurian, Devonian, and Carboniferous, with their associated inland for an average distance of 25 miles. iqneous rocks, are the sources of all the metalliferous deposits in stretches Its area is estimated at 3000 square miles. The Coal Measures of Australia, the alluvial leads being of course derived from the wearing this formation contain several workable coal-seams, of excellent down of these formations. The well-known Mount Morgan mine may quality for steaming purposes. No marine fossils have been perhaps be noted as an exception, for we have here a geyser deposit discovered, plants of the usual Mesozoic aspect are plentiful. of Upper Mesozoic or Tertiary age, in a Permo-Carboniferous area. Newer than but the Burrum is the Ipswich, also classed as Trias-Jura. JSo rocks newer than the Carboniferous are known to have had This formation an area of quite 12,000 square miles in metalliferous deposits in the shape of lodes formed amongst them. the south-easternoccupies corner of Queensland. The Ipswich formation Permo-Carboniferous is a term originally proposed by Mr Robert contains excellent coal-seams. These beds contain no marine Etheridge, jun., for a formation “ distinguished by a copious marine fossils, the whole being laid down under freshwater conditions. Permo- faaunaa partaking of a Carboniferous and Permian nature, There is an abundant flora, prominent forms being—Lquisctum, Carbon. ^ora from,which lycopodiaceous plants were almost Sphenopteris, Thinnfeldia, and Tmniopteris; but Glossopteris, so iferous. entirely absent. Anyone familiar with the Carbonifer- characteristic of the Newcastle Coal Measures, is absent. The .' °^s rocks of Europe will remember that the most char- Collie Creek Coal Measures of West Australia may be proacteristic fossil plant is Lepidodendron. This is absent in the Coal visionally classed here. There is an important series of rocks in Measures of eastern Australia ; and in its place we find plants and one form in particular, with quite a Mesozoic aspect. The lasmania, undoubtedly of Mesozoic age, composed mainly of sandstones, shales, and blue and white clays. "The tern referred to is Glossopteris. This beautiful fossil plant is found variegated frequently contains seams of coal of good thickness and fair associated with workable Coal Pleasures over great areas of the series quality. There are no marine fossils, but a great abundance of continent The Permo-Carboniferous rocks of Eastern Australia ate quite 10,000 feet m thickness. The lower beds contain coarse plant remains with a decidedly Mesozoic aspect. Mr R. M. Johnstone considers that these beds probably cover the whole conglomerates m great abundance and a very distinctive marine period from the close of the upper Palaeozoic Coal Measures to fauna, the upper beds are made up for the most part of finer the beginning of the Tertiary period. Some of these beds are materials and are of freshwater origin. The whole series is thus probably of the same age as the Trias-Jura of Queensland. divided m the type district, Newcastle, as follows Certain beds in Victoria, about Cape Paterson, Barabool Hills, and a series known as the Bellarane beds, consisting of sandstones,* Qbelong seams coal worked at Newcastle to theofUpper Coal Measures. The coal, and carbonaceous shales, may belong to this series. They best known in the Newcastle Coal Measures contain an abundant fossil flora, but no marine fossils. The descending order—(1) Parbury’s seam : leading forms are Tmniopteris, Alethopteris, and Zamites. These Upper Coal Measures (4) [C Dirty seam Northern (3) Burwood seam ; rocks occupy four distinct areas, and contain all the known Yard; seam seam. Glossopteris abundant. The Dempsey coal-bearing rocks in Victoria. They cover, at least, 4000 square Series, 2000 feet in thickness, separate these coal seams from the underlying Tomago Coal miles. The Cretaceous rocks cover an immense area in New South ^Measures. Wales, Queensland, North, West, and Central Australia. They [ffeet mVpper Marine Beds are about 5000 thickness. The following divisions may be grouped into three series—the lower, developed recognized in descending order(1) Beds Upper Marine Series 1 are in Western Australia ; the middle, in North- Cretaceous. with Crmoids and Sanguinolites ; (2) beds with chiefly abundance of Spirifers ; (3) Muree rock : v(4) Western New South Wales ; and the upper, in Queens'.conglomerates. ’ land and over Central Australia generally. The Upper Cretaceous, ( Greta Coal Measures, with no marine which belongs the widely - spread formation known as desert Lower Coal Measures 1 shells. Fossil plants abundant. Glossopteris to sandstone, must have covered more than one-fourth of the whole (common. ^ The AJJ-IAVAJ-JO isAO about CAUUUU 200< continent. This sandstone, it has been remarked, is a monument . Lower Marine —Series Lower Marine Series lf feet in thickness. of the power of denudation. It is now found only in isolated Eurydesma cordata (characteristic. iiagmentary table-lands. Taken as a ■whole, the desert sandstones
 * (5) seam
 * (6) Borehole