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Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 14 of 14 for “"Secular variation"”.
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Developing Archaeomagnetic Dating for Neolithic Scotland
… material to define and better understand variations in the past geomagnetic field through the Scottish Neolithic. Six archaeological sites were extensively sampled producing 26 newly compiled archaeomagnetic directions from over 1200 samples for Neolithic Scotland. Particularly important …
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Developing archaeomagnetic dating in the British Iron Age.
… represent the prehistoric section of the British secular variation curve (SVC). These data have been incorporated into the British archaeomagnetic dataset that now comprises over 1000 magnetic directions and will be used to generate future British SVCs. The potential of the near continuous records …
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Setting the Holocene clock using varved lake sediments in Sweden
… dating, tephra isochrones and paleomagnetic secular variations were established for two sediment sequences in Värmland. These are the longest geological records with an annual resolution known to exist in Sweden. Three mid-Holocene Icelandic tephra horizons were identified within 1-cm …
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Archaeomagnetic Directional Studies Of Large Fired Structures In Britain
… methods largely confirms the previous Iron Age secular variation curve. Field observations, systematic sampling and magnetic measurement of features of various archaeological ages, as well as an experimental kiln, has shown that there are both random and systematic directional deviations which …
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A study of nitrogen isotopic systematics in lunar soils and breccias
… in order to investigate the isotopic variation in the lunar regolith and to constrain the origin of the nitrogen. The lunar soils and breccias are analysed using a high sensitivity static-vacuum mass spectrometer. capable of measuring nanogram quantities of nitrogen with a …
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Direction and intensity of Earth's magnetic field at the Permo-Triassic boundary
… of the Earth's magnetic field, no characteristic variation in palaeointensity is identified (mean value 14 µT). Such post-transitional excursions are frequently observed in younger reversal records and are explained by instabilities of the geodynamo after the reversal. However, VGPs associated …
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Pollen analysis, chronology and palaeomagnetism of three Late Weichselian sites in southern Sweden
… (GRIP) years BP, respectively. Palaeomagnetic secular variation records for the three sites are presented. Among the series of directional changes, the main characteristic, which can be found in all stratigraphies, is a broad westerly declination swing between c. 13,000 and 12,000 calendar …
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Female labour, status and marriage in late medieval York and other English towns
… and evidence presented for both regional and secular variation. The case argued is that the early emotional independence from I parents created by service, and the possibility of real economic independence outside marriage through servanthood and other employment, permitted women a degree of …
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Investigations of temporal changes in climate and the geomagnetic field via high-resolution radiocarbon dating
… geomagnetic field records also show prominent variations around 3000-2000 cal BP. In order to investigate the temporal development of past changes in climate and the geomagnetic field it is crucial to establish accurate and precise chronologies for such reconstructions. Well-constrained …
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Wavelet analysis of geomagnetic jerks
Geomagnetic jerks, or secular variation impulses, are abrupt changes in the slope of the first time derivative of the Earth's magnetic field. These changes occur on time scales of the order of a year. It has been demonstrated that the jerks might be more singular than previously supposed; their …
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Investigating the Fate of Mg-bearing Calcium Carbonates During Early Diagenesis
… abundance in geologic history also reflects the secular variation of seawater through time and is a key mineral in probing past change in climate.This study investigates whether dolomite can form from seawater in the presence of carboxylated organic matter (COM), and if the presence of COM …
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Convection and Magnetic Field Generation in Rotating Spherical Fluid Shells
… to be responsible for the generation and the variations in time of the main geomagnetic field. Questions such as linear onset and nonlinear finite-amplitude properties of rotating convection, generation and equilibration of magnetic fields in electrically conducting fluids, nonlinear feedback …
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High-resolution stratigraphy of Central and Southern Adriatic Quaternary deposits of sub-Milankovian climate change on Mediterranean circulation
… range-finding 14C AMS ages, on estimates of the secular variation of the magnetic field, on geochemical estimates of the activity depth of 210Pb short-lived radionuclide (for the core-top ages), and is in good agreement with tephrochronologic, pollen and foraminiferal data. The intra-holocenic …
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Dispersive waves in Earth's outer core
… core, following their progress as global-scale variations in the magnetic field force them to evolve both their spatial structure and propagation velocity. A growing ambient field slows them considerably, even to the point where certain rays are arrested completely and quenched by …