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JURASSIC
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gold-bearing, metamorphic slates are of this age. Marine Jurassic rocks have not been clearly identified on the Atlantic side of America. The Patuxent and Arundel formations (non-marine) are doubtfully referred to this period. Lower and Middle Jurassic formations occur in Argentina and Bolivia. Jurassic rocks have been recognized in Asia, including India, Afghanistan, Persia, Kurdistan, Asia Minor, the Caspian region, Japan and Borneo. The best marine development is in Cutch, where the following groups are distinguished from above downwards: the Umia series = Portlandian and Tithonian of south Europe, passing upwards into the Neocomian; the Katrol series = Oxfordian (part) and Kimeridgian; the Chari series = Callovian and part of the Oxfordian; the Patcham series = Bathonian. In the western half of the Salt Range and the Himalayas, Spiti shales are the equivalents of the European Callovian and Kimeridgian. The upper part of the Gondwana series is not improbably Jurassic. On the African continent, Liassic strata are found in Algeria, and Bathonian formations occur in Abyssinia, Somaliland, Cape Colony and western Madagascar. In Australia the Permo-Carboniferous formations are succeeded in Queensland and Western Australia by what may be termed the Jura-Trias, which include the coal-bearing “Ipswich” and “Burrum” formations of Queensland. In New Zealand there is a thick series of marine beds with terrestrial plants, the Mataura series in the upper part of Hutton’s Hokanui system. Sir J. Hector included also the Putakaka series (as Middle Jurassic) and the Flag series with the Catlin’s River and Bastion series below. Jurassic rocks have been recorded from New Guinea and New Caledonia.

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1 Purbeckian from the “Isle” of Purbeck. Aquilonien from Aquilo (Nord). Bononien from Bononia (Boulogne). Virgulien from Exogyra virgula. Pteroceran from Pteroceras oceani. Astartien from Astarte supracorollina. Rauracien from Rauracia (Jura). Argovien from Argovie (Switzerland). Neuvizien from Neuvizy (Ardennes). Divesien from Dives (Calvados). Bathonien from Bath (England). Bajocien from Bayeux (Calvados). Toarcien from Toarcium (Tours). Charmouthien from Charmouth (England). Sinemourien from Sinemurum, Semur (Côte d’Or). Hettangien from Hettange (Lorraine).

Life in the Jurassic Period.—The expansion of the sea during this period, with the formation of broad sheets of shallow and probably warmish water, appears to have been favourable to many forms of marine life. Under these conditions several groups of organisms developed rapidly along new directions, so that the Jurassic period as a whole came to have a fauna differing clearly and distinctly from the preceding Palaeozoic or succeeding Tertiary faunas. In the seas, all the main groups were represented as they are to-day.