la Croix., AndrewSmith, Joshua W.2026-07-012026-07-012026https://hdl.handle.net/10289/18425This study was conducted to investigate the shallow stratigraphy of the Hamilton Central Business District, a city that overlies Hamilton Basin. The study focused on analysing three geotechnical cores and an exposed outcrop in Hamilton City near the Waikato River. Analysis included core logging, facies classification and paleoenvironmental interpretation, 3D structure-from-motion outcrop modelling, radiocarbon dating, as well as mineralogical assessment using X-ray diffraction. Seven unique lithofacies were identified in the cores, six of which were deposited in a braided river system; the seventh was volcanic in origin. The facies include a structureless muddy sandy gravel (F1), structureless sandy mud to muddy sand (F2), current-ripple laminated to cross-bedded muddy sand (F3), planar-bedded sandy mud to muddy sand (F4), current-ripple laminated to cross-bedded sandy mud (F5), structureless to planar bedded peat (F6A) and coal (F6B). These facies are typical of the Piako and Walton Subgroups of the Tauranga Group. The outcrop studied was a free face spanning approximately 20 metres in height and consisted of strata typical of the Hinuera Formation. One section of the outcrop showed potential evidence of liquefaction. Overall, the strata were structured or structureless, consisting of mud, sand, gravel, and organic layers. Sediments were highly pumiceous, and partially rhyolitic at times, with bed thickness ranging from sub-decimetre to metre-scale. These units, when packaged, showed several whole and partial cycles of active and abandoned river channels, indicating significant channel migration and flooding events typical of a braided-river system. The constantly migrating channels have resulted in the units encountered having laterally discontinuous physical characteristics; notably, the mineralogical composition was highly similar across samples and cores. Liquefaction susceptibility was compared with previous seismic studies, with a focus on the physical characteristics of the sediments encountered during this investigation and those of comparable sedimentary basins. The complexities of a braided river system's horizontal and vertical geometry in a geological modelling context were discussed, along with potential solutions to minimise scaling issues encountered when creating a coarse-scale 3D geological model. The vertical extent of some of the facies encountered during the investigation (F3 to F6B) was identified as the most at risk of over- or under-estimation during data upscaling. Near-well upscaling, confined by border cells, in combination with stochastic modelling, was suggested to resolve some of the scaling issues that will be encountered during model development.enAll items in Research Commons are provided for private study and research purposes and are protected by copyright with all rights reserved unless otherwise indicated.Thesis