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increase in Earth radius and cease expansion in the distant future. increase in Earth radius and cease expansion in the | What about Subduction? distant future. As mentioned earlier, subduction of crusts beneath continents is an artefact of the basic Plate Tectonics What about the Supercontinents? requirement for a static-radius Earth. To maintain a On an Expansion Tectonics Earth, during the Triassic Plate Tectonics static-radius Earth, the new oceanic Period the modern deep oceans did not exist. All crusts accumulating along the mid-ocean spreading continental crust was united to form a single ridges must then be continuously disposed of supercontinent called Pangaea, enclosing the entire elsewhere, displacing and recycling pre-existing crusts ancient Earth at about 3,200 kilometres radius— into the mantle by subduction. Modern planetary approximately 52 per cent of the present Earth radius. studies have shown this process to be unique to planet Geographical studies show that, prior to the Triassic Earth, and hence, without subduction, Plate Tectonics Period, oceans were represented by a network of cannot exist. continental seas, with sediments deposited within In Plate Tectonics theory, subduction zones mark sites continental basins masking all of convective down-welling of the evidence of sea-floor spreading. Earth's crust as well as part of the Exposed lands and varying coastal upper mantle. Subduction zones are outlines prior to this time were . postulated to exist at convergent similarly represented by the ancient All subduction- plate boundaries around the margins Gondwana, Laurentia, Baltica and related of the Pacific Ocean, where oceanic Laurussia supercontinents, and prior b . l d and continental crustal plates o that again by the ancient Rodinia observational data converge with other plates and sink supercontinent and smaller sub- simply record the below to depths of approximately 100 continents. . . kilometres, thereby recycling crust, crustal Interaction sediment and trapped water into the What about the Ocean Water and ion] deep mantle. Atmosphere? between adjoining On an Expansion Tectonics Earth, Researchers elsewhere have argued thick continental subduction of between 5,000 to that, before the Triassic Period, a crusts and 15,000 kilometres of Pacific oceanic crust beneath North America, for instance, is unnecessary. All subduction-related observational data simply record the crustal interaction between adjoining thick continental crusts and relatively thin oceanic crusts during ongoing changes in surface curvature. Instead, as the Earth's radius increases with time, the surface curvature of the volume of the ocean water has Earth flattens, giving rise to been constant throughout crustal interaction and jostling of geological history. On an Expansion Tectonics Earth, _ plates along their margins as they stretch and distort he sea-floor crust, ocean water and atmosphere all _—_ during gravity-induced flattening. originate from deep within the Earth's mantle and have been added to the surface crust at an accelerating rate | What about Mountain-Building? hroughout geological time. The increase in new ocean In Plate Tectonics theory, it is generally assumed that water and atmosphere is considered to have resulted mountain-building results from the collision between rom a process of mantle out-gassing as a natural ancient plates as they randomly move over the Earth's response to a decrease in mantle temperature and surface under the influence of mantle convection pressure conditions with time. currents. Researchers elsewhere have therefore The distribution of ancient coastal outlines on concluded that because Earth expansion is a radial Expansion Tectonics models demonstrates implicitly | process, and hence extensional, the process cannot hat ocean waters did not cover the entire Earth, as has explain the compression required for mountain-building. been suggested, but instead formed a network of While seemingly logical from a Plate Tectonics relatively shallow continental seas which, in turn, perspective, this conclusion is illogical from an defined the location and distribution of the ancient Expansion Tectonics perspective. As the Earth's radius supercontinents and intervening ancient seas. increases, the continental crust must distort, bend, twist small ancient Earth with a continuous continental crust would have been covered by an ocean with an average depth of 6.3 kilometres. If this were the case, then terrestrial life-forms would not have evolved and continents would only have been exposed to erosion fairly recently in Earth history. This argument assumes that the relatively thin oceanic crusts during ongoing changes in surface curvature. related simply record the crustal interaction between adjoining thick continental crusts and during ongoing changes in surface curvature. What about Mountain-Building? In Plate Tectonics theory, it is generally assumed that mountain-building results from the collision between ancient plates as they randomly move over the Earth's surface under the influence of mantle convection currents. Researchers elsewhere have therefore concluded that because Earth expansion is a radial process, and hence extensional, the process cannot explain the compression required for mountain-building. While seemingly logical from a Plate Tectonics perspective, this conclusion is illogical from an Expansion Tectonics perspective. As the Earth's radius increases, the continental crust must distort, bend, twist JUNE - JULY 2010 NEXUS ¢ 37 All subduction- observational data relatively thin oceanic crusts www.nexusmagazine.com