M.Phil. dissertation abstracts 1998-1999
Copies of these dissertations are held in the University of Cambridge, Department of Geography Library.
Dissertation "Raised Beach Deposits of the West Sussex coastal Plain" supervised by Dr. Phil Gibbard (Cambridge). Claire gone on to the University of Cardiff working on a CASE funded PhD project entitled "Palaeooceanographic significance of Laminated Diatom-rich sediments in the Southern Ocean" with Dr. Jenny Pike (Cardiff) and Dr. Carol Pudsey (British Antarctic Survey).
Pleistocene deposits of the Sussex coastal plain
The south coast of England has been a centre of geological interest throughout the last century with debates surrounding the genesis of the different plateaux and the nature and significance of the tectonic history of the region. Many key sites are located along the Sussex Kent coasts with sites further west also contributing to our overall understanding of the Quaternary period.
Deposits of the Sussex Coastal Formation are reviewed and paleogeographic reconstruct ions are presented and critically assessed in relation to adjacent stratagraphic sequences. Examination of sedimentological characteristics is used to evaluate the depositional environments of the raised beaches and to identify similarities between different marine episodes. Mapping and stratigraphic extrapolation of BGS borehole data is used to identify paleocoastlines and possible paleogeographical evolution since deposition of the highest, Goodwood-Slindon raised beach. Additional marine deposits are identified between the currently recognised Norton and Pagham beaches. The stratigraphic relationship of these sediments is critically assessed and potential explanations of their deposition are presented.
Paleogeographic reconstruct ions are presented and discussed in light of previous evidence presented and the implications for the sea level and uplift history of the region. It is proposed here that the tectonic history is a complex one and must have been both spatially and temporally dynamic. the stratigraphy of the region provides great potential for delimiting the eustatic and tectonic inputs into relative sea level. Although the marine terraces are primarily a response to high sea level stands this project demonstrates that the tectonic complexities of this region have been underestimated and better understanding of the lowest raised beach deposits may provide stratigraphic evidence of these complexities.
The study provides a wider contextual framework for the deposits than has been presented in other literature and demonstrates the importance of regional synthesis in determining the nature of Pleistocene environments.
Sa'ad Al Omari
Dissertation "A Multi-Proxy, Palaeoecological Investigation of Holocene Peat Samples from the Voras Mountains, Northern Greece", supervised by Dr. Chronis Tzedakis (Cambridge). Sa'ad is continuing in Cambridge working with Dr. Richard Preece in the Department of Zoology.
A Multi-Proxy, Palaeoecological Investigation of Holocene Peat Samples from Voras Mountains, Northern Greece
This is a palynological investigation of the palaeoecological history of two sites in the highlands of northern Greece. The sites span the time period of approximately 6000 BP to the present. As highland sites have complexities attached to their pollen ttatched areas, palynological data have been supplemented by additional proxies in an attempt to constrain local variability. These additional techniques includes δ13C analyses, C/N ratios, and loss-on-ignition. An attempt has also been made to evaluate the utility of stable carbon isotope techniques as an aid to palynological environmental reconstruction. The results include indications of a possible climatic change (increased precipitation) from 6000 BP - 4000 BP, and evidence of intense human impact at approximately 2500 BP. Correlations with other highland sites and with the lowland site of Edessa are made to determine the local vs. regional nature of the various palaeoenvironmental signals detected.
Dissertation "A Study of the Palaeoenvironmental Changes from Pollen at Dickleburgh Moor, Norfolk",supervised by Dr. Alex Chepstow-Lusty (Cambridge). Nik has gone on to work for the Midland Electricity Board as a surveyor!
A Study of PalaeoenvironmentalChanges from Pollen at Dickleburgh Moor, Norfolk.
The aim of this project is to identify the vegetational and environmental changes that took place at Dickleburgh Moor, Norfolk, UK during the late Devensian and Holocene. This research may have implications for the understanding of past environmental changes, both on a local and regional scale. In turn, this will influence knowledge of what causes environmental and climatic changes, and how human activity can affect the environment.
The investigation was carried out by the analysis of pollen percentages and concentrations taken from several cores of lake sediment. Other sedimentary analyses were also applied in order to identify major sedimentary and environmental changes that may either support or explain changes in the pollen evidence. From analysis it was possible to interpret a vegetational history during the time of deposition of the lake sediment. The record is also compared to several other East Anglian and British sites so that local and regional patterns can be recognised.
The record extends from the lake Devensian glacial, through the following Holocene interglacial and up to Anglo-Saxon times at least. During the late-glacial, the landscape was dominated by tundra-type vegetation such as Betula, Salix, and herbaceous flora. In the early Holocene Betula formed a closed woodland as there was little competition from other flora. Other tree and shrub taxa then migrated into the area from their glacial refugia. These included Pinus sylvestris, Corylus alvellana, Qurcus and Ulmus followed later by Alnus glutinosa, Fraxinus excelsior and then Tilia. Woodland therefore dominated the landscape from the start of the Holocene. However, by 5,000 BP, changes in the landscape began to appear, mainly due to human impact. From this time the forests began to decline due to deliberate burning or felling for the purpose of agriculture. Ulmus also declined because of Dutch Elm disease. There may also have been some secondary woodland following dereliction of some clearings. The record therefore agrees with the broad regional picture, but also shows well some small local variations.
Dissertation"The Sedimentological, Taphonomic and Climatic Significance of Stratum C at Hoxne", supervised by Dr. Charles Turner (Open University). William was working as a technician in the Department of Geography and is now a tropical palynologist with a PhD in Leicester starting in October!
An investigation of the Sedimentology, Taphonomy and Climatic Significance of Stratum C at Hoxne, Suffolk.
Three-dimensional modelling of all the stratigraphic data available for the interglacial lake deposits at Hoxne, Suffolk has shown they were deposited immediately after the retreat of the Anglian ice sheet. Deposition initially from a shallow lake which formed around a block of ice within what was to become the main depression. The basin of Lake Hoxne is aligned along a north-east to south-west axis defined by the Lowestoft Till topography, the main input of water was probably from the south-west. Lake levels fluctuated widely through the interglacial and around a twelve metre thickness of sediment was deposited. During the late-temperate period, infilling of the basin and low lake levels led to the development of stream deltas, these built up thicknesses of wood-rich coarse detritus. Overlying this, brecciated clay mud contains conflicting palaeoenvironmental evidence, detailed palynological investigation of discrete clay clasts has shown this to be a product of the reworking of lower strata. This material is contained in sediments alongside deposits representative of the continued development of early glacial environments. There was substantial subsequent fluvial activity and erosion across and around the deposits in a number of discrete phases during the "Wolstonian".
Dissertation "Quaternary Volcanism in the Eastern Eifel" supervised by Dr. David Pyle (Cambridge) and Dr. Georg Waldmann (Coventry). David is continuing his research.
Quaternary volcanism in the eastern Eifel, Germany
For about the last 600,000 years the eastern Eifel on the western bank of river Rhine near Koblenz in Germany has been an area of volcanic activity. Two fossil rich volcanic tephra layers exposed in a quarry at Eppelsberg, 40K / 40Ar dated at around 223 ± 6 ka, were investigated along with strikingly similar material found in around 1860 at the Bianchi-Stollen mine about 6 km to the east. The tephras preserve imprints of herbaceous plants, deciduous trees and shrubs, and coniferous trees, along with impressions of molluscs and vertebrates. They consist of consolidated ash and air fall clasts up to 2 mm in size that were deposited by eruptions during the second major phase of volcanic activity in the eastern Eifel. Such fossil material trapped by volcanic eruptions can be used to constrain Quaternary radiometric dates, since such events could have only occurred during warmer interglacial periods.
These basaltic fossiliferous tephras and similar samples from nearby volcanic centres, up to a kilometre wide, were selected for thin sectioning and microprobe analysis. All fifteen samples have clinopyroxene phenocrysts that plot in the Diopside field and most contain amphibole, olivine and phlogopite as one or more additional mineral phases. Volcanic glass was only found in the Eppelsberg samples, which are low in MgO and so plot just outside the normal range for eastern Eifel basanites. The microprobe results support the botanical view that the Eppelsberg and Bianchi-Stollen tephras are similar and are most probably from the same series of intra-Saalian (oxygen isotope stage 7) interglacial eruptions.
Published dates for the eastern and western Eifel show that volcanic activity appears to have occurred in discrete intervals associated with the onset of interglacial periods, including the massive Laacher See eruptions during the Allerød interstadial that at one stage dammed the river Rhine. A simple flexural model shows that during glacial periods the level of the Eifel lithosphere would have dropped roughly 200 m due to the loading effects of adjacent ice sheets. Thus at higher latitudes, it would be possible for the onset of deglaciation to depressurise the mantle, generate melting and trigger a burst of inter-plate volcanism.