Plate tectonics for curious kiwis

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Aitken, J.J. 1996 Plate tectonics for curious kiwis. Lower Hutt: Institute of Geological & Nuclear Sciences. Institute of Geological & Nuclear Sciences information series 42 76 p.

Abstract: The theory of plate tectonics explains the whys and wherefores of major geological activity on, and within, the earth. It accounts for earthquakes, volcanoes, mountain ranges, and the creation of many minerals, oil and gas. The theory is based on the fact that the outermost layer of the earth is divided into a patchwork of a dozen major thin and rigid plates that move relative to each other. Tectonics refers to the architecture and major structural features of the outer part of the earth. Tectonic plates carry continents and ocean basins about the surface of the planet on a relatively soft and mobile layer that is driven by heat from within the earth. The plates move apart from each other at enormous cracks along the top of almost continuous mountain chains in most major oceans, and new magma wells up from within the planet to solidify at these oceanic ridges. Where plates move together, something has to give way: they either slide past each other, or one plate sinks under the other, or they collide and crumple into chains of mountains. One of the most glorious aspects of plate tectonics is its user-friendliness. Understanding the theory does not require senior mathematics, microchip technology, familiarity with the speed of light, or a jargon dictionary. All of which is just as well for the average Kiwi: New Zealand straddles a plate boundary, and plate tectonics affects our lives every day. Compared with other landmasses, New Zealand is barely adolescent, and it only exists because of the collision of the Australian and Pacific plates. The tectonic forces which move these plates together cause the edges of both plates to wrinkle up and deform. The highest wrinkles are New Zealand's mountains, volcanoes, land areas and coastal islands. The deformed remainder of the ancient New Zealand subcontinent is submerged and includes the Chatham Rise and the Campbell Plateau, some 1000 km east and south of the South Island. This location astride two tectonic plates makes New Zealand one of the most geologically exciting countries on earth, and one where the consequences of plate tectonics are highly influential, and unavoidable. Our volcanoes, boiling mud pools, hot springs, geysers, earthquakes, active faults, and the Southern Alps, as well as many massive landslides, are all the results of plate tectonics in action. (auth/JIH)