Huge iceberg ploughmarks and associated corrugation ridges on the northern Svalbard shelf

Linear to curvilinear depressions on high-latitude continental shelves have long been regarded as the signature of the ploughing action of iceberg keels impinging on the sedimentary sea-floor (e.g. Woodworth-Lynas et al. 1991). These depressions vary in dimensions and pattern with the size of calved icebergs and their drift tracks through the polar seas. Two different sizes of iceberg appear to have affected the continental shelf north of Svalbard, producing distinctive sets of ploughmarks (Dowdeswell et al. 2010).This is the author accepted manuscript. The final version is available from the Geological Society of London via https://doi.org/10.1144/M46.

The glacier-influenced marine record on high-latitude continental margins: Synergies between modern, Quaternary and ancient evidence

Major glaciations or ‘ice ages’ are known to have affected the Earth's surface over the past three billion years. The best preserved records of these glaciations are often found in high-latitude continental margin settings where sediment has been delivered to, and then accumulated at, the edge of the ice sheet in thick glacier-influenced marine sequences. The composition and geometry of these deposits and the related assemblages of glacial landforms provide a wealth of information about the environmental setting during successive cycles of glaciation and deglaciation, including ice-dynamic and oceanographic processes. Here, we discuss modern (present day), Quaternary (last 2.6 myr) and ancient (last 1 gyr) high-latitude continental margin settings, and then contrast the methodologies used and glacier-influenced deposits and landforms most often identified for each time period. We use examples from the literature to identify synergies, as well as to note differences, between studies of glacier-influenced sediments from ancient to modern environments

Nordvestfjord: A major East Greenland fjord system

This is the author accepted manuscript. The final version is available fromGeological Society of London via https://doi.org/10.1144/M46.4

Submarine glacial-landform distribution along an Antarctic Peninsula palaeo-ice stream: A shelf-slope transect through the Marguerite Trough system (66-70° S)

The Antarctic Peninsula comprises a thin spine of mountains and islands presently covered by an ice sheet up to 500 m thick that drains eastwards and westwards via outlet glaciers (Davies et al. 2012). Recently, the Peninsula has undergone rapid warming, resulting in the collapse of fringing ice shelves and the retreat, thinning and acceleration of marine-terminating outlet glaciers (e.g. Pritchard & Vaughan 2007). At the Last Glacial Maximum (LGM), the ice sheet expanded to the continental-shelf break around the Peninsula, and was organised into a series of ice streams that drained along cross-shelf bathymetric troughs (Ó Cofaigh et al. 2014). Marguerite Bay is located on the west side of the Antarctic Peninsula, at about 66° to 70° S (Fig. 1). A 12–80 km wide and 370 km long trough extends across the bay from the northern terminus of George VI Ice Shelf to the continental shelf edge. Extensive marine-geophysical surveys of the trough reveal a suite of glacial landforms which record past flow of an ice stream, which extended to the shelf edge at, or shortly after, the LGM. Subsequent retreat of the ice stream was underway by ~14 kyr ago and proceeded rapidly to the mid-shelf, where it slowed before accelerating once again to the inner shelf at ~9 kyr (Kilfeather et al. 2011).This is the author accepted manuscript. The final version is available from the Geological Society of London via https://doi.org/10.1144/M46.18

Hacking the Catalog as an Open Access Research Tool

Part of the life cycle of scholarly communications is discovery, and one type of material often obscured by the federated results of library search interfaces is open access materials not hosted in the institutional repository but living on the open web. Selecting and cataloging such open access resources builds a focused collection of open access materials that appear in the same search results as materials that libraries lease, purchase, and host. Bringing open access materials into catalog results makes them easier to discover, use, and cite. Identifying and cataloging open access resources emphasizes the vital roles of collection development and cataloging in curating collections of open access resources for research. As with proprietary collection building, a commitment to create catalog records for the open access scholarship created by your faculty, students, and staff improves the discoverability of these resources and can bring your institutional affiliates into new scholarly citation networks. This process also offers an opportunity for modeling critical cataloging. Using local headings and affirming keywords and vocabulary to build a full catalog record improves the catalog’s affirmation of people of historically marginalized identities and asserts the critical value of ethical naming as a scholarly communications practice to support distribution and future authorship. We share here the steps for creating or a conversation for affirming and continuing this practice at your institution

Processes and patterns of glacier-influenced sedimentation and recent tidewater glacier dynamics in Darbel Bay, western Antarctic Peninsula

AbstractBathymetric data of unprecedented resolution are used to provide insights into former ice dynamics and glacial processes in a western Antarctic Peninsula embayment. An assemblage of submarine glacial landforms, which includes subglacially produced streamlined features and ice-marginal ridges, reveals the former pattern of ice flow and retreat. A group of more than 250 small (< 1–3 m high, 10–20 m wide) and relatively evenly spaced recessional moraines was identified beyond the margin of Philippa Glacier. The small recessional moraines are interpreted to have been produced during short-lived, possibly annual re-advances of a grounded ice margin during overall retreat. This is the first time that these features have been shown to be part of the assemblage of landforms produced by tidewater glaciers on the Antarctic Peninsula. Glacier-terminus changes during the last four decades, mapped from LANDSAT satellite images, were analysed to determine whether the moraines were produced during recent still-stands or re-advances of Philippa Glacier and to further investigate the short-term (annual to decadal) variability in ice-marginal position in tidewater glacier systems. The asynchronous response of individual tidewater glaciers in Darbel Bay is interpreted to be controlled mainly by local topography rather than by glacier catchment-area size.C.L. Batchelor was in receipt of a Junior Research Fellowship from Newnham College, Cambridge during this work. K.A Hogan and R.D Larter are supported by the Polar Science for Planet Earth programme funded by the Natural Environment Research Council, U.K

Sediment-rich meltwater plumes and ice-proximal fans at the margins of modern and ancient tidewater glaciers: Observations and modeling

Turbid meltwater plumes and ice-proximal fans occur where subglacial streams reach the grounded marine margins of modern and ancient tidewater glaciers. However, the spacing and temporal stability of these subglacial channels is poorly understood. This has significant implications for understanding the geometry and distribution of Quaternary and ancient ice-proximal fans that can form important aquifers and hydrocarbon reservoirs. Remote-sensing and numerical-modelling techniques are applied to the 200 km-long marine margin of a Svalbard ice cap, Austfonna, to quantify turbid meltwaterplume distribution and predict its temporal stability. Results are combined with observations from geophysical data close to the modern ice front to refine existing depositional models for ice-proximal fans. Plumes are spaced about 3 km apart and their distribution along the ice front is stable over decades. Numerical modelling also predicts the drainage pattern and meltwater discharge beneath the ice cap; modelled water-routing patterns are in reasonable agreement with satellite-mapped plume locations. However, glacial retreat of several kilometres over the past 40 years has limited build-up of significant ice-proximal fans. A single fan and moraine ridge is noted from marine-geophysical surveys. Closer to the ice front there are smaller recessional moraines and polygonal sediment lobes but no identifiable fans. Schematic models of ice-proximal deposits represent varying glacierterminus stability: (i) stable terminus where meltwater sedimentation produces an ice-proximal fan; (ii) quasi-stable terminus, where glacier readvance pushes or thrusts up ice-proximal deposits into a morainal bank; (iii) retreating terminus, with short still-stands, allowing only small sediment lobes to build up at melt-stream portals. These modern investigations are complemented with outcrop and subsurface observations and numerical modelling of an ancient, Ordovician glacial system. Thick turbidite successions and large fans in the Late Ordovician suggest either high-magnitude events or sustained high discharge, consistent with a relatively mild palaeo-glacial setting.We thank BP Algeria for sponsorship, Ed Jones and Liz Jolley of BP for supporting the project.This is the accepted manuscript. The final published version is available from Wiley at http://dx.doi.org/10.1111/sed.1219

Past water flow beneath Pine Island and Thwaites glaciers, West Antarctica

Abstract. Outburst floods from subglacial lakes beneath the Antarctic Ice Sheet modulate ice-flow velocities over periods of months to years. Although subglacial lake drainage events have been observed from satellite-altimetric data, little is known about their role in the long-term evolution of ice-sheet basal hydrology. Here, we systematically map and model past water flow through an extensive area containing over 1000 subglacial channels and 19 former lake basins exposed on over 19 000 km2 of seafloor by the retreat of Pine Island and Thwaites glaciers, West Antarctica. At 507 m wide and 43 m deep on average, the channels offshore of present-day Pine Island and Thwaites glaciers are approximately twice as deep, 3 times as wide, and cover an area over 400 times larger than the terrestrial meltwater channels comprising the Labyrinth in the Antarctic Dry Valleys. The channels incised into bedrock offshore of contemporary Pine Island and Thwaites glaciers would have been capable of accommodating discharges of up to 8.8×106 m3 s−1. We suggest that the channels were formed by episodic discharges from subglacial lakes trapped during ice-sheet advance and retreat over multiple glacial periods. Our results document the widespread influence of episodic subglacial drainage events during past glacial periods, in particular beneath large ice streams similar to those that continue to dominate contemporary ice-sheet discharge. UK Natural Environment Research Council’s iSTAR programme (grant nos. NE/J005703/1, NE/J005746/1, and NE/J005770/1). James D. Kirkham: Debenham Scholarship from the Scott Polar Research Institute, University of Cambridge, and a UK Natural Environment Research Council Ph.D. studentship awarded through the Cambridge Earth System Science Doctoral Training Partnership (grant no. NE/L002507/1

How couples with dementia experience healthcare, lifestyle, and everyday decision-making

Copyright © International Psychogeriatric Association 2018. Objectives: Recent research has demonstrated the challenges to self-identity associated with dementia, and the importance of maintaining involvement in decision-making while adjusting to changes in role and lifestyle. This study aimed to understand the lived experiences of couples living with dementia, with respect to healthcare, lifestyle, and everyday decision-making.Design: Semi-structured qualitative interviews using Interpretative Phenomenological Analysis as the methodological approach.Setting: Community and residential care settings in Australia.Participants: Twenty eight participants who self-identified as being in a close and continuing relationship (N = 13 people with dementia, N = 15 spouse partners). Nine couples were interviewed together.Results: Participants described a spectrum of decision-making approaches (independent, joint, supported, and substituted), with these approaches often intertwining in everyday life. Couples' approaches to decision-making were influenced by decisional, individual, relational, and external factors. The overarching themes of knowing and being known, maintaining and re-defining couplehood and relational decision-making, are used to interpret these experiences. The spousal relationship provided an important context for decision-making, with couples expressing a history and ongoing preference for joint decision-making, as an integral part of their experience of couplehood. However, the progressive impairments associated with dementia presented challenges to maintaining joint decision-making and mutuality in the relationship.Conclusions: This study illustrates relational perspectives on decision-making in couples with dementia. Post-diagnostic support, education resources, proactive dyadic interventions, and assistance for spouse care partners may facilitate more productive attempts at joint decision-making by couples living with dementia

Marginal Fluctuations of a Svalbard Surge-Type Tidewater Glacier, Blomstrandbreen, since the Little Ice Age: A Record of Three Surges

© 2016 Regents of the University of Colorado. Previous advances and retreats of Blomstrandbreen within the cold period known as the Little Ice Age, between approximately 1400 and 1920, are relatively well documented. The seafloor characteristics associated with these glacier fluctuations, and their importance for the identification of similar surge-type tidewater glaciers, are discussed. We use detailed multibeam-bathymetric data acquired within Nordvågen, the marine area offshore of Blomstrandbreen, to provide a new understanding of the style and pattern of deglaciation around Blomstrandhalvøya since Blomstrandbreen's neoglacial maximum. Glacial landforms on the seafloor of Nordvågen comprise overridden moraines, glacial lineations, terminal moraines, and annual recessional moraines. Crevasse-fill ridges, which are often regarded as a characteristic landform of surging tidewater glaciers, are present on only restricted areas of Nordvågen. Significantly, this study shows that large terminal surge moraines and numerous crevasse-fill ridges may not always be well developed in association with glacier surges, with implications for the identification of surges in the geological record. Using historical observations, aerial photographs, and satellite imagery of Blomstrandbreen, we have correlated former ice-marginal positions with mapped submarine landforms. Three surge events occurred during a pattern of overall retreat, with a spacing of about 50 years between active advance phases; this represents a relatively short quiescent phase for Svalbard glaciers. Average retreat rates of 10-50 m yr-1 are typical of the quiescent phase of the surge cycle, whereas surge advances vary from 200 m to over 725 m