Reconstructing ice dynamics in the central sector of the last British-Irish Ice Sheet

The central sector (NW England and Scottish borders) of the last British-Irish Ice Sheet exhibits a palimpsest glacial geological and geomorphological signature characteristic of multi-phase ice flow and ice-marginal fluctuations. Despite its influential position at the heart of the British-Irish Ice Sheet, sourced from major ice dispersal centres of the northern Pennines, Lake District and Southern Uplands, and drained via fast-flowing outlets such as the Irish Sea Ice Stream, the region remains poorly constrained, both temporally and in terms of ice-flow dynamics. The principle goal of this thesis was therefore to reconstruct the palaeoglaciology of the central sector of the British-Irish Ice Sheet during the last glacial cycle, focusing on: (1) ice-flow dynamics with respect to palaeo-ice divides, ice-dispersal centres, flow trajectories and flow phasing; (2) the relative chronology of ice flows during advance and decay of the ice sheet; and (3) evidence for ice stream activity either within or sourced from the study area. The thesis adopted a dual approach involving both geomorphological mapping and sedimentological analysis. A 5 m resolution NEXTMap DEM was used to map over 9,000 individual landforms including subglacial lineations, hummocky terrain, moraines, meltwater channels, eskers and glaciofluvial sediment accumulations. Subglacial lineations were subdivided into discrete flow sets demarcating distinctive flow phases, and a relative chronology produced from cross-cutting relationships. Thirteen field sites, concentrated in the Solway Lowlands, supported by data collected from over 200 boreholes enabled detailed stratigraphic and sedimentological analysis to be carried out. This included stratigraphic logging, the collection of macrofabrics, particle size and geochemistry analysis on till matrixes, clast lithological counts, varve analysis and microstructural (thin sections) data. Results from this study have demonstrated that the central sector of the ice sheet was characterised by repeated ice-flow switches, initiation and termination of ice streams, drawdown into ice streams, repeated ice-marginal fluctuations (the Scottish and Blackhall Wood Re-advances) and the production of large volumes of meltwater, often impounded to form ice-dammed lakes. Six main stages of ice flow have been recognised in the region, of which stage I is thought to indicate the period of maximum ice expansion, while stages II-VI record the deglacial history. A pre-stage I event is also discussed and can be reconciled with the initial expansion of ice out of upland dispersal centres. Stage I was characterised by ice flowing eastwards across the country through major topographic lows of the Stainmore and Tyne gaps. The Tyne Gap was occupied by a topographic ice stream, which was heavily influenced by the changing dominances of both Lake District and Southern Upland ice-dispersal centres. Migration of ice divides back towards upland dispersal centres during stage II resulted in the flow of ice through the Stainmore Gap being cut-off, while the northern edge of the Tyne Gap ice stream was breached by a SE ice flow down the N Tyne Valley. Despite the maintenance of the Irish Sea Ice Stream off the western coast of Cumbria throughout stage III, the Tyne Gap and Solway Lowlands underwent widespread deglaciation. Meltwater from the Tyne Gap was routed into Glacial-Lake Wear via a major proglacial drainage network in the South Tyne Valley, while the natural basin of the Solway Lowlands also ponded-up (Glacial-Lake Blackhall Wood) as drainage became impeded by the Irish Sea Ice Stream. The overall pattern of retreat was reversed during the Blackhall Wood Re-advance (stage IV), during which ice was vigorously drawn down into the Irish Sea Ice Stream. Stage V was characterised by the continued retreat of ice out of the central sector of the British-Irish Ice Sheet; with the vast amounts of meltwater generated impounded in ice-marginal lake systems (Glacial-Lake Carlisle), or routed through meltwater channel networks or evolving glacier karst (Brampton kame belt). The landforms of the Brampton kame belt can be reconciled with ice stagnation on the reverse slope of the Tyne Gap, and is thought to have formed one component of a much larger, time-transgressive drainage network involving the Pennine escarpment and Tyne Gap meltwater channel systems. The final recognised stage in the glacial history of the region was the Scottish Re-advance, a brief incursion of ice, sourced from the Southern Uplands, onto the fringe of the Solway Lowlands. A large glacial lake is identified to have formed at the ice front, dammed against ice in the Irish Sea basin and delimited by a large deltaic complex at Holme St. Cuthbert

Waterlands

Waterlands: Prehistoric Life at Bar Pasture, Pode Hole Quarry, Peterborough recounts a decade-long archaeological investigation at Bar Pasture Farm, Pode Hole Quarry, Peterborough, and represents one of the most significant landscape excavations carried out in recent years. The 55-hectare archaeological dig was the scene of human activity on the fenland edge from the Mesolithic through to the Late Iron Age, although the majority of the evidence covered the period from the Early Neolithic through to the Middle Bronze Age. Throughout prehistory, the fen edge has represented a landscape at the margins of human habitation and exploitation. During the Early Neolithic, a substantial waterhole complex with signs of later visitation was established on the fen edge. Traces of several Beaker buildings provided elusive evidence of slightly later activity further inland, whilst during the Early Bronze Age proper, a number of impressive burial mounds were constructed within a dedicated ‘Barrow Field’. One barrow contained the nationally significant remains of an infant burial on a birch bark mat with associated grave goods. The Middle Bronze Age saw the entire re-organisation of the surrounding landscape by the creation of an extensive, rectilinear field system, served by multiple droveways and associated with a classic enclosed farmstead. The placement of later Middle Bronze Age cremation burials within the remains of earlier burial monuments bears witness to the intimate connection of this small community to their ancestors’ sacred landscape. By the 4th century BC, settlement was all but abandoned due to marine inundations, although one slightly elevated part of the landscape formed an area of refuge for an Iron Age smith and his family, who created an isolated and significant smithy

Waterlands

Waterlands: Prehistoric Life at Bar Pasture, Pode Hole Quarry, Peterborough recounts a decade-long archaeological investigation at Bar Pasture Farm, Pode Hole Quarry, Peterborough, and represents one of the most significant landscape excavations carried out in recent years. The 55-hectare archaeological dig was the scene of human activity on the fenland edge from the Mesolithic through to the Late Iron Age, although the majority of the evidence covered the period from the Early Neolithic through to the Middle Bronze Age. Throughout prehistory, the fen edge has represented a landscape at the margins of human habitation and exploitation. During the Early Neolithic, a substantial waterhole complex with signs of later visitation was established on the fen edge. Traces of several Beaker buildings provided elusive evidence of slightly later activity further inland, whilst during the Early Bronze Age proper, a number of impressive burial mounds were constructed within a dedicated ‘Barrow Field’. One barrow contained the nationally significant remains of an infant burial on a birch bark mat with associated grave goods. The Middle Bronze Age saw the entire re-organisation of the surrounding landscape by the creation of an extensive, rectilinear field system, served by multiple droveways and associated with a classic enclosed farmstead. The placement of later Middle Bronze Age cremation burials within the remains of earlier burial monuments bears witness to the intimate connection of this small community to their ancestors’ sacred landscape. By the 4th century BC, settlement was all but abandoned due to marine inundations, although one slightly elevated part of the landscape formed an area of refuge for an Iron Age smith and his family, who created an isolated and significant smithy

Space exploration challenges : characterization and enhancement of space suit mobility and planetary protection policy analysis

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics; and, (S.M. in Technology and Policy)--Massachusetts Institute of Technology, Engineering Systems Division, Technology and Policy Program, 2010.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student-submitted PDF version of thesis.Includes bibliographical references (p. 189-193).This thesis addresses two challenges associated with advanced space and planetary exploration: characterizing and improving the mobility of current and future gas pressurized space suits; and developing effective domestic Planetary Protection policies for the emerging private space industry. Gas-pressurized space suits are known to be highly resistive to astronaut movement. As NASA seeks to return to planetary exploration, there is a critical need to improve full body space suit mobility for planetary exploration. Volume effects (the torque required to displace gas due to internal volume change during movement) and structural effects (the additional torque required to bend the suit materials in their pressurized state) are cited as the primary contributors to suit rigidity. Constant volume soft joints have become the design goal of space suit engineers, and simple joints like the elbow are believed to have nearly achieved such performance. However, more complex joints like the shoulder and waist have not yet achieved comparable optimization. As a result, it is hypothesized that joints like the shoulder and waist introduce a third, and not well studied, contributor to space suit rigidity: pressure effects (the additional work required to compress gas in the closed operating volume of the suit during movement). This thesis quantifies the individual contributors to space suit rigidity through modeling and experimentation. An Extravehicular Mobility Unit (EMU) space suit arm was mounted in a -30kPa hypobaric chamber, and both volume and torque measurements were taken versus elbow angle. The arm was tested with both open and closed operating volumes to determine the contribution of pressure effects to total elbow rigidity. These tests were then repeated using a full EMU volume to determine the actual impact of elbow pressure effects on rigidity when connected to the full suit. In both cases, structural and volume effects were found to be primary contributors to elbow joint rigidity, with structural effects dominating at low flexion angles and volume effects dominating at high flexion angles; pressure effects were detected in the tests that used only the volume of the arm, but were found to be a secondary contributor to total rigidity (on average 75°) flexion angles, suggesting that the underlying mechanisms of these effects are not yet fully understood, and that current models predicting structural effects behavior do not fully represent the actual mechanisms at work. The detection of pressure effects in the well-optimized elbow joint, even if only in a limited volume, suggests that these effects may prove significant for sub-optimized, larger, multi-axis space suit joints. A novel, fast-acting pressure control system, developed in response to these findings, was found to be capable of mitigating pressure spikes due to volume change (and thus, pressure effects). Implementation of a similar system in future space suit designs could lead to improvements in overall suit mobility. A second study, which focused on the implications of the development of the US private space industry on domestic Planetary Protection policy, is also presented. As signatories of the 1967 Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space (commonly known as the Outer Space Treaty), the United States is responsible for implementing Planetary Protection procedures designed to prevent biological contamination of the Solar System, as well as contamination of the Earth by any samples returned from extra-terrestrial bodies. NASA has established policies and procedures to comply with this treaty, and has successfully policed itself independently and autonomously since the signing of the treaty. However, for the first time in the history of the American space program, private entities outside of NASA have developed the capability and interest to send objects into space and beyond Earth orbit, and no current protocol exists to guarantee these profit-minded entities comply with US Planetary Protection obligations (a costly and time-consuming process). This thesis presents a review of US Planetary Protection obligations, including NASA's procedures and infrastructure related to Planetary Protection, and based on these current protocols provides policy architecture recommendations for the emerging commercial spaceflight industry. It was determined that the most effective policy architecture for ensuring public and private compliance with Planetary Protection places NASA in control of all domestic Planetary Protection matters, and in this role NASA is charged with overseeing, supporting, and regulating the private spaceflight industry. The underlying analysis and architecture tradeoffs that led to this recommendation are presented and discussed.by Bradley Thomas Holschuh.S.M.in Technology and PolicyS.M

The Final Neolithic-Early Bronze Age transition in Phaistos, Crete: an investigation of continuity and change in ceramic manufacture

The Final Neolithic and Early Bronze Age periods in Crete are considered as times of transformation in settlement pattern, of the emergence of complex architecture and related innovative material culture, which presage the social changes of later phases. The change in ceramic repertoire has been used to argue for a technological and cultural ‘revolution’ at the beginning of the Bronze Age, perhaps even of the influx of new population. The site of Phaistos in Southern Crete offers great potential for examining the Final Neolithic-Early Bronze Age transition in Crete and to investigate the degree of continuity and change, on account of the completeness of its stratigraphy, as well as the abundance of the ceramic material. This study critically examines the production technology of ceramics during the Final Neolithic and Early Minoan I at Phaistos, addressing issues of technological change in this period of transition and discussing how the reconstruction of ceramic manufacture can be related to the changes occurring over time at the site. The investigation of technological variation within the ceramic assemblages is performed by integrating macroscopic observation and an integrated analytical programme involving thin section petrography, scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray diffractometry, in order to reconstruct technological choices on raw material choice and manipulation, surface treatment and firing practice. This is combined with the information available on forming techniques and shape. The chaîne opératoire interpretative framework is adopted as a means to reconstruct the operational sequence of pottery manufacture, and to embed such an understanding within the social context of the communities of the Mesara Plain. By examining the significance of technological choices in pottery making within the context of Phaistos, the study demonstrates a complex picture of continuity and change over the period of study, which belies recent conjecture of a single-phase transformation at the beginning of the Early Bronze Age. Furthermore, it suggests that in some of the phases considered changes in the organisation and practice of pottery production can be related to changes in consumption at this special site, which saw an array of activities before construction of the later court-centred building

Lightweighting of stiffness critical advanced high strength steel structures using fibre reinforced plastics.

In the drive for lightweighting in many industries, optimum material selection is at the forefront of research. Many solutions are being investigated, including the fabrication of multi-material components. Following a state of the art review of the literature, it has been shown that there is an opportunity to improve basic knowledge and understanding of the characteristics of hybrid steel-FRP materials for lightweight applications. This dissertation explores the potential for designing lightweight automotive steel structures through novel use of lower gauges combined with local reinforcement by fibre-reinforced plastics to achieve desired stiffness performances. The main focus of the work is to provide underpinning research to enable the further understanding of the stiffness performance of hybrid steel-FRP materials, both experimentally and in simulation. This thesis focuses on the characterisation of high strength automotive grade steel (DP600) reinforced with a fibre reinforced polyamide (PA6 GF60) laminate, however, the results are readily applicable for other combinations. The project was achieved through two main phases; each phase consisting of an iteration loop between experimentation and simulation validations. Initial characterisation was achieved using coupon samples in quasi-static three-point bend, cross-validated in simulation providing a trusted material model. Correlating experimental and simulated results showed a potential lightweighting of up to 30 % of a hybrid DP600-GFRP over a DP600 counterpart with a matched stiffness performance. Further characterisation was performed using an idealised automotive component in flexure, confirming a potential lightweighting of up to 30 %. The simulation investigation demonstrated the effect of localised hybrid reinforcements, and identified difficulties in predicting the local geometrical effects of plastic hinging. For an overall application to an automotive body-in-white, these would require further investigating. This thesis has proven that downgauging steel whilst locally reinforcing (intelligent deployment) with FRP patches provides a significant lightweight solution with a matched stiffness performance. A hybrid material model has been validated and the application to an automotive component investigated. This work provides the basic understanding for a direct application in lightweight automotive designs using computer aided engineering (CAE)

Design and Application of Surfaces with Tunable Adhesion to Liquids and Solids

Fouling affects a wide range of industries around the globe. The two main categories of fouling are the unwanted adhesion of solids, and the unwanted adsorption of liquids. The purpose of this thesis is to understand and design new mechanisms to mitigate fouling. As fouling always occurs at the interface between a surface and the foulant, the main strategy employed in this work is the fabrication of designer coatings that can be applied to any surface, such that the foulant is repelled. In the first half of this dissertation I discuss new methods for reducing the adhesion of ice to surfaces. Ice adhesion routinely hinders many industries world-wide, and to-date there have been few long-term strategies to mitigate ice adhesion. We first design elastomeric coatings exhibiting the lowest ice adhesion strengths ever reported, and formulate a predictive model for the phenomenon of interfacial slippage, such that the ice adhesion strength of any surface can be rationally designed. We then utilize fracture mechanics to design surfaces exhibiting low interfacial toughness with ice, such that the force to remove the accreted ice becomes independent of the iced area. These results contradict the last 70 years of ice-adhesion analysis. One of our new techniques for repelling ice, and solid foulants in general, is the fabrication of liquid-like, covalently grafted monolayers. We show that surfaces treated with these monolayers also exhibit extreme liquid repellency, including the first-ever reported fluorophobic surfaces (i.e. surfaces that repel extremely low surface tension, fluorinated liquids). The second half of this thesis discusses various new ways of repelling a wide variety of different fouling liquids. We fabricate optically transparent surfaces capable of repelling a wide variety of low surface tension liquids. We also design extremely mechanically robust superhydrophobic surfaces that can self-heal after physical and chemical damage. Finally, we utilize some of these water-repellent systems to effectively reduce friction drag in turbulent flow.PHDMaterials Science and EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/138592/1/kegolo_1.pd