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demonstrates that Earth expansion is a viable process and gives justification to extending modelling studies back to the Archaean aeon. Extending models to the Archaean involves recognising that continents are made up of ancient granite-greenstone crustal frag- ments called cratons, ancient eroded mountains or fold belts called orogens, and ancient sedimentary basins of various ages. Earth expansion occurs within the continents as crustal extension in the network of continental sedimentary basins and rift zones. Moving backwards in time, sediments deposited within extension- al basins and rift zones are progressively removed and crust is restored to a pre-extension configuration. By removing all basin and rift sediments, a primordial Earth is reconstructed for the Mesoproterozoic era (1,600 million years ago), comprising assembled Archaean cratons and Proterozoic basement rocks at about 1,700 kilometres radius. Expanding Earth models reveal that the distribution of conti- nental sedimentary basins and shallow seas, continental magma- tism and concentration of crustal movements form a global net- work surrounding assembled Precambrian crust. The Precambrian global network forms the loci for ongoing continen- tal crustal extension, basin sedimentation and crustal mobility during the Proterozoic and Palaeozoic eras and represents the pri- mary loci for continental break-up and opening of the modern oceans during the Mesozoic and Cenozoic eras. This process of progressive continental crustal extension during Earth expansion demonstrates a simplified development of conti- nents and oceans throughout Earth history, as continental crust progressively extends prior to continental rupture, break-up and dispersal of continents to the present. All rocks contain an immense amount of geological and geo- physical information which, to the trained eye, has a complex but variable history of formation, metamorphic change, chemical and erosive weathering, climatic influence, biotic activity and metallic worth to tell us. On a global scale, we can piece together geologi- cal and geophysical information about locations of ancient poles and equators (palaeomagnetics), ancient distributions of exposed land, mountains, ice-caps, seas and shorelines (palaeogeography), ancient distribution, dispersal patterns, climatic requirements and extinctions of flora and fauna (palaeobiogeography), distribution of ancient climatic zones distinguished by latitude-dependent rocks located from polar ice-caps to equatorial zones (palaeocli- matology), and formation and distribution of metallic and hydro- carbon resources (metallogeny). On an expanding Earth, the information available from each of these geological and geophysical disciplines can be visualised as they happen and where they happen, and we can see what has subsequently happened. Biotic species and climatic zones established before continental break-up, for instance, are fragmented and dispersed in sympathy with dispersal of continents. New biotic species will either displace or interact with existing species, and climatic change will superimpose on established climatic patterns. A good example is Antarctica, which straddled the equator throughout most of Earth history and has preserved an essentially tropical-to-temperate range of fossilised plant and animal species and rock types. Since the Permian period (260 million years ago), Antarctica migrated south to its present location straddling the present south pole, with extreme changes to climatic patterns and Figure 1: Expanding Earth models from the Archaean to Future, showing ancient coastlines (heavy lines), emergent land surfaces and shallow continental seas. Each image advances 15 degrees longitude throughout the sequence to show a broad coverage of geographical development during the Precambrian and Phanerozoic aeons. 2200006000080 1-Archaean to Mesoproterozoic = §-Cambrian 7-Silurian 9-Late Devonian 11-Permian 2-3-4-Neoproterozoic 6-Ordovician 8-Early Devonian 10-Carboniferous 12-Triassic 13-Early Jurassic 15-Early Cretaceous 17-Late Cretaceous 19-Eocene 14-Late Jurassic 16-Mid Cretaceous 18-Paleocene 20-Oligocene 21-Miocene 22-Pliocene 23-Recent 24-Future 2200000000000 12-Triassic 18-Paleocene 54 = NEXUS APRIL — MAY 2001 THE EARTH IS A GEOLOGICAL ENTITY www.nexusmagazine.com