Inaug.-diss.--Leipzig. / Lebenslauf. "Literatur-und Kartenverzeichnis": p. [86]-89.

Extensive fieldwork, laboratory analyses and secondary research on the glacial and coastal phenomena in Lewis and Harris have cast some light on the effects which glaciations had on the development of the coastline. Contrary to previous ideas, Harris and the major part of Lewis were probably covered by a large local ice cap, while the northern tip of Lewis and the Tolsta Head Peninsula were overridden by external ice during the last glacial phase. According to a C-14 date, this phase occurred after about 27,300 B.P. There are indications that a larger part of north Lewis was occupied by external ice during a previous glacial phase. The coastline developed in close correspondence to the pattern of glaciations. The oldest recognisable marine element is represented by a raised shore platform and cliff with an average cliff-base height of 8 m. above the modern cliff base. Because the raised shore platform is widely developed in resistant Lewisian gneiss and overlain by glacial and non-glacial sediments, the episode of abrasion at the higher level probably pre-dates the Devensian. Beach gravel which tops the raised shore platform in places is believed, on the basis of its well-rounded nature and stratigraphic position between two glacial tills, to be of Ipswichian age. The absence of the pre-Devensian rock platform and cliff and beach gravel in central Lewis, south Lewis and Harris may reflect destruction under subsequent ice advance. In this greater part of the island, differential glacial activity of generally higher intensity produced distinct coastal landforms and sediments. There is no unambiguous evidence that the sea around the island rose above its present level during the late Devensian and/or Flandrian. On the other hand, numerous Occurrences of peat below high water mark and one incidence of cemented sand below low water mark point to recent submergence. A dated peat sample form -3 m. O.D. at Holm indicates that, at around 8,800 B.P., the land/sea interface was at least 5 m. lower than at present. The indirect effects of global glaciations on eustatic sea level are considered as having been of greatest consequence to the long-term development of the coastline of Lewis and Harris since the Pleistocene.

published_or_final_version / Geography and Geology / Master / Master of Arts

This research has developed a methodology for high precision monitoring of coastal chalk sea cliffs using both terrestrial and unmanned aerial vehicle (UAV) digital photogrammetry. Two contrasting study sites of similar geology at Brighton Marina and Telscombe enabled a comparative assessment of cliff behaviour, for an engineered cliff with toe protection and cliff face stabilisation versus a natural cliff subject to active toe erosion respectively. The site at Brighton Marina was monitored between November 2014 and March 2017, during this period no rockfall was detected above the surface change threshold of 0.07 m. For the Telscombe site, monitored between August 2016 and July 2017, volumetric estimations of rockfalls populated a rockfall inventory. Frequency-magnitude analysis of the monthly inventories demonstrated negative power law scaling over seven orders of magnitude with 10,085 mass wasting events and a total volumetric flux of 3,889.35 m3. Statistically significant correlations were found, for the first time, between significant wave height (Hs) and the power law scaling coefficients, β and s with R2 values of 0.4971 and 0.5793 respectively. The model was an accurate predictor of erosion evidenced by the R2 of 0.9981 between the model predictions and observations over the data collection period. A Monte Carlo simulation of potential erosion scenarios between 2020 and 2089 was established using these relationships based on Hs probabilities and sea level forecasts derived from the UKCP09 medium emission climate model (A1B) to assess the impact of future climate change on cliff recession. For the most likely cliff recession scenario the model predicts an approximate 6% increase in recession between the current and future (UKCP09 medium emission scenario) conditions from 20.45 m to 21.76 m. The model also estimates the probability of recession breaching the A259 coastal road by 2089, this revealed an increase from 0.0778 to 0.1056 due to the influence of future climate. The photogrammetric models were also used to characterise the Newhaven Chalk cliffs and through kinematic analysis found wedge failure to be the most likely mechanism of failure, with 39.97% of mapped intersections favourable to this mode. A limit equilibrium analysis of the observed conjugate joint sets within the defended section of cliffs between Brighton Marina and Telscombe was undertaken to assess the risk of any future failure to infrastructure. This revealed that the coastal road would not be at immediate threat (breach) due to any of the modelled wedge failures occurring, however measures would need to be put in place to maintain the road in its current location were any of these failures to occur. A probabilistic recession model using current industry best practice, in the absence of a rockfall inventory, was used to predict future recession for the defended section of cliffs. Within identified ‘pinch-points' where the distance between the road and cliff edge was less than 10 m the probability of recession reaching the road over the next 100 years did not exceed 0.0014. A comparison between approaches identified the benefits of the scientific method presented in this research. The outputs of this research offer a new approach for the collection and processing of coastal monitoring data which ultimately drives the prediction of future coastal cliff recession and facilitates effective planning and mitigation.

The oceanic phenomenon of upwelling along the Oregon coast is examined. Upwelling in both the open ocean and coastal regions is discussed. An idealized model is used, envisaging the ocean off Oregon to consist of homogeneous surface and deep layers separated by a pycnocline. The equations of motion are solved to yield the vertical velocity at the base of the surface layer. A comparison is made between the model and results inferred from hydrographic data. In the open ocean region qualitative agreement is observed between the wind stress curl and the depth of the surface layer. Geostrophic meridional transports relative to the 1000 decibar surface were computed and found to be of the order of the uncertainty. In the coastal upwelling region surface layer zonal transports were computed from the meridional component of the mean wind stress and compared with values inferred from oceanographic data. Coastal upwelling along the Oregon coast is clearly associated with the northerly (longshore) component of the wind stress. / Graduation date: 1964

Thesis (Ph. D.)--University of Queensland, 2002. / Includes bibliographical references.

Thesis (M.S.)--University of Wisconsin--Madison, 1970. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Honors)--College of William and Mary, 2009. / Includes bibliographical references (leaves 45-47). Also available via the World Wide Web.

Thesis--Helsingfors. / Bibliography: p. [102]-106.

Thesis (Ph. D.)--Ohio State University, 1987. / Includes vita. Includes bibliographical references (leaves 134-141). Available online via OhioLINK's ETD Center.