Thesis (Ph. D.)--Oregon State University, 1997. / Typescript (photocopy). Includes bibliographical references. Also available online.

Thesis (M.S.)--Montana State University--Bozeman, 2007. / Typescript. Chairperson, Graduate Committee: Christopher S. Guy. Includes bibliographical references (leaves 66-74).

This dissertation is an analysis of the Quaternary fluvial history of central Northamptonshire. It uses new freshwater ostracod data which are interpreted using information on Quaternary and present day habitats and examines in detail associated patterns of environmental change in coarse sediments from which the ostracods were extracted. Stratigraphic, lithological and sedimentological data, supported by a study of geological maps, borehole logs and papers, are employed to produce a new hypothesis to explain the Quatemary development of the Milton River and the River Nene. The alignment of the Milton Formation Valley is established to have proceeded to the east of, but parallel with, the Nene Valley between Northampton and Higham Ferrers, where it turned to the south-east. It comprises locally derived deposits which are shown to be pre-Anglian Glaciation and, at the time of the deposition of the ostracods studied here, an interglacial environment prevailed. However, during a ‘cooling phase”, Milton Formation sediments were incised and the channel became partially infilled with fossiliferous boreal sediments. Further sedimentation continued to produce a non-fossiliferous, periglacial sand, which is typical of the Milton Formation. It is argued that this period of deposition was followed by two glacial episodes, the latter relating to the Lowestoft Formation. Stratigraphic, sedimentological and lithological evidence from the Nene valley shows vestigial terrace gravels exist between Northampton and Wellingborough. The oldest gravels of these features pre-date the Anglian age, sub-glacial tunnel valley” at Northampton, implying the Nene Valley existed prior to glaciation. Before glaciation it is suggested that the Milton River became confluent with the Nene at Northampton and, concurrently, diverted to the north-east at Higham Ferrers. This is believed to be associated with the simultaneous abandonment of the Milton Valley to the south-east of Higham Ferrers and the upstream stretch at Northampton. Evidence presented of downcutting, lateral migration, gravel reworking and changes in the ostracod assemblages in the Nene Valley confirm a history of several climatic oscillations which took place in the pre-Devensian, Devensian and Holocene. These oscillations are tentatively correlated with stages of deposition in the Nene established downstream at Peterborough. This revised fluvial history elaborates the course and age of the Milton River and establishes a pre-Devensian age for much of the Nene Valley sediment. The significance of this new understanding of the upper Nene Valley has been compared with that of the lower Nene Valley at Peterborough, Cambridgeshire. The combined evidence is used to produce a pattern of river development within the Quaternary which may be used as a model when reconstructing the palaeogeography of other rivers and their floodplains by means of their sedimentary structures and related fossils. This idea is explored to a small extent in the thesis, but is more applicable to future work. The new ostracod data throws new light on previous studies from other sites in England. Ostracod species new to the Pleistocene record are to be added to a worldwide data base

To comply with the European Union Water Framework Directive (2000), National Governments are required to achieve good chemical and ecological status of freshwater bodies. Fine sediment has been shown to be a major cause of the degradation of lakes and rivers, and as a result research in geomorphology has been directed towards the understanding of fine sediment dynamics. It was identified by a review of published literature that at present a paucity of information on sediment dynamics existed for the East Midlands, UK. The use of tracers within a sediment fingerprinting framework has recently become a heavily used technique to investigate the sources of fine sediment pressures. However, uncertainties associated with tracer behaviour have been cited as major potential limitations to sediment fingerprinting methodologies. At present few studies have quantified the uncertainties associated with tracer use, or the exact reasons why different tracers are producing different sediment provenance results. This thesis had two aims based on these gaps in published literature. First, to assess the impact of sediment sampling methodology, tracer selection, particle size corrections and organic enrichment corrections on a fine sediment fingerprinting study. Secondly, to develop a partial sediment budget for the Upper Nene river basin and its major tributaries. The results of this thesis were presented in two parts. The first part investigated Aim 1 when fingerprinting; historically deposited sediment, suspended sediment and recently deposited sediment. The second part investigated Aim 2 by constructing a fine sediment budget for the Nene river basin, consisting of; sediment yield, sediment provenance, floodplain sediment accumulation and channel bed sediment storage. A mean difference of 24.1% between the predicted contributions of sediment originating from channel banks was found when using nine different tracer groups to fingerprint the river sediment samples. When fingerprinting contributions from urban street dusts mean differences between tracer group predictions were lower, at between 8% and 11%. There was little indication that organic matter content and / or particle size caused differences between tracer group predictions. Within-source variability in tracer concentrations, and small contrasts between the tracer concentrations of the sediment source groups, were identified as probable causes of inherent uncertainty present in the fingerprinting analysis. It was determined that the ratio of the percentage difference between median tracer concentrations in the source groups and the average within-source tracer concentration coefficient of variation could indicate the likely uncertainty in model predictions prior to tracer use. When fingerprinting historically deposited sediment, a reservoir core was fingerprinted with the least uncertainty, with tracer group provenance predictions ~28% apart and with consistent down-core trends. When fingerprinting an on-line lake core and four floodplain cores, differences between tracer group predictions were as large as 100%; the down-core trends in changing sediment provenance were also different. The differences between tracer group predictions could be attributed to the organic matter content and particle size of the sediment. There was also evidence of the in-growth of bacterially derived magnetite and chemical dissolution affecting the preservation of tracer signatures. Despite the prior indications that organic matter and particle size were causing tracer non-conservatism in historical sediment cores, data corrections were found to often be ineffective at reducing the differences between tracer group predictions. The corrections were found to either have no effect on, or increase the mean differences between, tracer group predictions when fingerprinting river sediment. The sediment budget identified that the annual sediment yield of 13 - 19 t km-2 yr-1 for the Nene is low in comparison to other UK catchments. Channel banks were found to be the dominant sediment source in the Nene, typically contributing between 60% and 100% of the sediment. Rates of sediment accumulation on the Nene’s floodplain was found to be highly variable (920– 7,200 t km-2 yr-1); the presence of flood defences were likely to be a cause of this variability, and have caused a reduction in the accumulation rate since 1963. It was found that large quantities of sediment accumulated on channel beds during periods of low flows (~ 28% of the annual sediment yield), which was flushed from the bed by a series of flood events (leaving <1% of the annual sediment yield in temporary storage). An original contribution to research was made by quantifying the uncertainties associated with tracer use in a fine sediment fingerprinting investigation, as well as identifying the probable causes of the observed uncertainty. The fine sediment dynamics of the Nene basin were also investigated for the first time, and it was identified that the high contributions from channel banks in the Nene were highly a-typical for UK catchments.