Sensitivity of Surface Materials and Vegetation to Disturbance in the Queen Elizabeth Islands: An Approach and Commentary

Concern about potential and actual disturbance of surface materials, vegetation and wildlife of the Queen Elizabeth Islands has risen sharply in the last few years. The purpose of this paper is to outline an approach to the problem, based on terrain studies, and to offer a commentary on the recent paper by T.A. Babb and L.C. Bliss in Arctic. … For a rational assessment of the problem, information is required on: a) surface materials - ice content, texture, engineering properties; b) topography and landforms; c) geomorphic processes; d) drainage - seasonal change and single events; e) vegetation - percentage cover and composition by species; f) summer temperatures, and moisture balance in soil; g) wildlife. … Surface materials are very significant elements of the terrain, especially when potential for disturbance is being considered. Hence, surface materials are used by the present writers as a nucleus around which other elements of the terrain are grouped. … Two of the present writers undertook in 1972 an exercise in the mapping of sensitivity at a scale of 1:500,000 of the Queen Elizabeth Islands, based primarily on bedrock maps and extensive personal communications, but found it unsatisfactory because the degree of detail was insufficient to reflect the variability in the sensitivity of the terrain. … [In evaluating the paper by Babb and Bliss, the present authors conclude that]: The overall objective of these authors in emphasizing the "susceptibility of the soils and vegetation to surface disturbance" is good. However the methods used to achieve this objective are inconsistent, and in several cases the results are inaccurate. A serious deficiency is that the criteria for determining categories of "susceptibility" are obscure. … The "Polar Desert" category is described as an area with 10% or less plant cover, low susceptibility to disturbance and low ground ice content. One interpretation of this seems to be that poorly-vegetated areas are less susceptible to disturbance of vegetation than are more densely vegetated areas. Only in so far as a low plant density lessens the probability of direct impact of vehicles on plants is this interpretation obviously true. A sparsely vegetated area may be an important, or even critical, range for ungulates; therefore the effect of disturbance of it could be great. The type of vegetation - such as willow, sedge, saxifrage, grass or bryophyte - is a vital consideration. An alternative interpretation is that unvegetated areas (90% of the Polar Desert category, classed as "soils") have a low sensitivity to surface disturbance. This is not true for some major areas of both eastern Melville Island and Western Ellesmere Island where highly sensitive surfaces, almost devoid of vegetation, are subject to extensive slope failure or thermokarst development, even without disturbance. Where the authors have left their major field of expertise and have commented on geology and geomorphology, weaknesses are evident. They appear to draw a direct relationship between active-layer soil moisture and "susceptibility". For overland travel this is generally true, but if excavation penetrates the shallow active layer and the frost table, then the relationship certainly no longer holds. Furthermore, the implication of a relationship between susceptibility, ice content and vegetation cover is simplistic and can be misleading. The assertion that "10% or more vegetation cover indicates the existence of sufficient moisture for the segregation of horizontal ice layers" is without basis. The present writers have drilled over 300 shallow (1-6 m) holes in eastern Melville Island and western Ellesmere Island to evaluate ice content and have found the relationship between vegetation, ground ice and materials to be complex. &hellip

Microstructures and mechanical properties of as cast Mg‐Zr‐Ca alloys for biomedical applications

The microstructures and mechanical properties of as cast Mg-Zr-Ca alloys were investigated for potential use in biomedical applications. The Mg-Zr-Ca alloys were fabricated by commercial pure Mg (99.9 mass-%), Ca (99.9 mass-%) and master Mg-33 mass-%Zr alloy. The microstructures of the alloys were examined by X-ray diffraction analysis and optical microscopy, and the mechanical properties were determined from tensile tests. The experimental results indicate that the Mg-Zr-Ca alloys with 1 mass-%Ca are composed of one single a phase; these alloys with 2 mass-%Ca consist of both Mg 2Ca and α phase, and all the alloys exhibit typical coarse microstructures. An increase in Zr increases the strength of Mg-Zr-Ca alloys with 1 mass-%Ca, and the formation of Mg2Ca decreases the strength of the alloys. Mg-1Zr-1Ca alloy (mass-%) has the highest strength and best ductility among all the studied alloys

The heterogeneous crustal architecture of the Falkland Plateau Basin

Continental break-up can be oftentimes associated with intracontinental wrenching that can lead to the generation of transform margins and transform marginal plateaus. The wrenching phase can be accompanied by complicated processes, which result in heterogeneous structural and crustal architectures. This makes understanding the evolution of such tectonic settings challenging. The Falkland Plateau is an example of a transform marginal plateau where regional wrenching accompanied the incipient stages of Gondwanan continental break-up to result in a mosaic of crustal types underlying its largest basin: the Falkland Plateau Basin (FPB). The uncertainties in crustal boundaries have led to several models for the evolution of the plateau, which hinder the development of a reliable plate reconstruction of Southern Gondwana. We integrate seismic reflection, gravity and magnetic data to propose an updated crustal architecture of the FPB. The results show that extended continental crust underlies the basin in the west and north. The eastern and central parts consist of a juxtaposition of intruded and underplated continental crust which transitions southwards to a thick oceanic domain. The basin is crosscut by three main NE–SW trending shear zones which facilitated the development of the contrasting crustal and structural domains interpreted across the plateau. This integrated reassessment of the FPB provides new insights into the tectonic evolution of the plateau, the deformation associated with wrenching and transform margin formation and our understanding of the tectono-stratigraphic evolution of such areas

Landscape evolution during Holocene transgression of a mid‐latitude low‐relief coastal plain: The southern North Sea

Low-relief coastal landscapes are at major risk of rising sea levels, as vertical changes in relative sea level have far-reaching lateral effects. Integration of a dense 2D grid of seismic reflection data with sedimentological and geotechnical data obtained in two offshore wind farm zones allows detailed documentation of postglacial landforms and environmental change over a 1,021 km2 area in the western sector of the southern North Sea. Following the retreat of Last Glacial Maximum ice sheets from the southern North Sea, the resulting postglacial terrestrial landscape provided a surface for peatland formation as climate started to warm and the water table rose in response to relative sea-level rise. Southward-draining fluvial networks formed contemporaneously with the peatlands, and remnants of this terrestrial wetland landscape are buried beneath Holocene marine sediments. Distinctive isolated incisional features and discrete widening of fluvial channels that cut through the peats are interpreted as either tidal ponds or relict tidal channels. These features record the evolution of this landscape through the Early Holocene as marine transgression inundated a low-relief coastal plain. The erosion of the peatlands observed in the cores, the patchy preservation of the organic wetland landscape, and the lack of preserved barrier systems recorded by the seismic reflection data suggest that the rate of relative sea-level rise outpaced sediment supply during the Late Postglacial and Early Holocene in this area of the southern North Sea. In a regional context, the southward draining river channels contrast to northward fluvial drainage to the North Sea, pointing to a subtle drainage divide in the palaeolandscape and the presence of a low-relief land bridge separating the North Sea and the English-Channel/La Manche during the Early Holocene. The documented scenario of rising sea levels combined with decreasing sediment supply in a low-relief setting is a situation faced by many global deltas and coastlines, which makes the southern North Sea a crucial archive of coastal landscape change

Collapse of the last Eurasian Ice Sheet in the North Sea modulated by combined processes of ice flow, surface melt, and marine ice sheet instabilities

The record of the confluence and collapse of the British‐Irish Ice Sheet and the Fennoscandian Ice Sheet is obscured by the North Sea, hindering reconstructions of the glacial dynamics of this sector of the Eurasian Ice Sheet complex during the last glacial cycle. Previous numerical simulations of the deglaciation of the North Sea have also struggled to capture the confluence and separation of the British‐Irish and Fennoscandian Ice Sheets. We ran an ensemble of 70 experiments simulating the deglaciation of the North Sea between 23 and 18 ka BP using the BISICLES ice sheet model. A novel suite of quantitative model‐data comparison tools was used to identify plausible simulations of deglaciation that match empirical data for ice flow, margin position, and retreat ages, allowing comparisons to large amounts of empirical data. In ensemble members that best match the empirical data, the North Sea deglaciates through the collapse of the marine‐based Norwegian Channel Ice Stream, unzipping the confluence between the British‐Irish Ice Sheet and the Fennoscandian Ice Sheet. Thinning of the Norwegian Channel Ice Stream causes surface temperature feedbacks, rapid grounding line retreat, and ice stream acceleration, further driving separation of the British‐Irish and the Fennoscandian Ice Sheets. These simulations of the North Sea deglaciation conform with the majority of empirical evidence, and therefore provide physically plausible insights that are consistent with reconstructions based on the empirical evidence, and permit a quantitative comparison between model and data

The Origin and 3D Architecture of a Km-Scale Deep-Water Scour-Fill: Example From the Skoorsteenberg Fm, Karoo Basin, South Africa

Scours, and scour fields, are common features on the modern seafloor of deep-marine systems, particularly downstream of submarine channels, and in channel-lobe-transition-zones. High-resolution images of the seafloor have improved the documentation of the large scale, coalescence, and distribution of these scours in deep-marine systems. However, their scale and high aspect ratio mean they can be challenging to identify in outcrop. Here, we document a large-scale, composite erosion surface from the exhumed deep-marine stratigraphy of Unit 5 from the Permian Karoo Basin succession in South Africa, which is interpreted to be present at the end of a submarine channel. This study utilizes 24 sedimentary logs, 2 cored boreholes, and extensive palaeocurrent and thickness data across a 126 km2 study area. Sedimentary facies analysis, thickness variations and correlation panels allowed identification of a lower heterolithic-dominated part (up to 70 m thick) and an upper sandstone-dominated part (10–40 m thick) separated by an extensive erosion surface. The lower part comprises heterolithics with abundant current and sinusoidal ripples, which due to palaeocurrents, thickness trends and adjacent depositional environments is interpreted as the aggradational lobe complex fringes. The base of the upper part comprises 2-3 medium-bedded sandstone beds interpreted as precursor lobes cut by a 3–4 km wide, 1–2 km long, and up to 28 m deep, high aspect ratio (1:100) composite scour surface. The abrupt change from heterolithics to thick-bedded sandstones marks the establishment of a new sediment delivery system, which may have been triggered by an updip channel avulsion. The composite scour and subsequent sandstone fill support a change from erosion- and bypass-dominated flows to depositional flows, which might reflect increasingly sand-rich flows as a new sediment route matured. This study provides a unique outcrop example with 3D stratigraphic control of the record of a new sediment conduit, and development and fill of a large-scale composite scour surface at a channel mouth transition zone, providing a rare insight into how scours imaged on seafloor data can be filled and preserved in the rock record

Sedimentary architecture and landforms of the late Saalian (MIS 6) ice sheet margin offshore of the Netherlands

Reconstructing the growth and decay of palaeo-ice sheets is critical to understanding the relationships between global climate and sea-level change and to testing numerical ice sheet models. In this study, we integrate recently acquired high-resolution 2D seismic reflection and borehole datasets from two wind-farm sites offshore of the Netherlands to investigate the sedimentary, geomorphological, and glaciotectonic records left by the Saalian Drenthe substage glaciation, when Scandinavian land ice reached its southernmost extent in the southern North Sea (ca. 160 ka, Marine Isotope Stage 6). A complex assemblage of glaciogenic sediments and glaciotectonic structures is buried in the shallow subsurface. The northern wind-farm site revealed a set of NE–SW-oriented subglacial meltwater channels filled with till and glaciofluvial sediments and an E–W-trending composite ridge with local evidence of intense glaciotectonic deformation that denotes the maximum limit reached by the ice. Based on the identified glacial geomorphology, we refine the mapping of the maximum ice sheet extent offshore, revealing that the ice margin morphology is more complex than previously envisaged and displaying a lobate shape. Ice retreat left an unusual paraglacial landscape characterised by the progressive infilling of topographic depressions carved by ice-driven erosion and a diffuse drainage network of outwash channels. The net direction of outwash was to the west and southwest into a nearby glacial basin. We demonstrate the utility of offshore wind-farm data as records of process–form relationships preserved in buried landscapes, which can be utilised in refining palaeo-ice sheet margins and informing longer-term drivers of change in low-relief settings

Marine ice sheet instability and ice shelf buttressing of the Minch ice stream, Northwest Scotland

Uncertainties in future sea level projections are dominated by our limited understanding of the dynamical processes that control instabilities of marine ice sheets. A valuable case to examine these processes is the last deglaciation of the British-Irish Ice Sheet. The Minch Ice Stream, which drained a large proportion of ice from the northwest sector of the British-Irish Ice Sheet during the last deglaciation, is well constrained, with abundant empirical data which could be used to inform, validate and analyse numerical ice sheet simulations. We use BISICLES, a higher-order ice sheet model, to examine the dynamical processes that controlled the retreat of the Minch Ice Stream. We simulate retreat from the shelf edge under constant "warm" surface mass balance and subshelf melt, to isolate the role of internal ice dynamics from external forcings. The model simulates a slowdown of retreat as the ice stream becomes laterally confined at a "pinning-point" between mainland Scotland and the Isle of Lewis. At this stage, the presence of ice shelves became a major control on deglaciation, providing buttressing to upstream ice. Subsequently, the presence of a reverse slope inside the Minch Strait produces an acceleration in retreat, leading to a "collapsed" state, even when the climate returns to the initial "cold" conditions. Our simulations demonstrate the importance of the Marine Ice Sheet Instability and ice shelf buttressing during the deglaciation of parts of the British-Irish Ice Sheet. Thus, geological data could be used to constrain these processes in ice sheet models used for projecting the future of our contemporary ice sheets

The Particle-Vibration Coupling Form Factor

peer reviewe

eCute: Difference is good

This paper provides an overview of ongoing research on cultural and emotional learning, thereby utilizing engaging roleplay with synthetic characters. The paper explains the underlying learning objectives and provides an overview of how we intend to achieve them. This includes a technical framework integrating affective AI characters and innovative interaction technologies. The framework will be used to realize a virtual learning environment hosting the synthetic characters. Finally a brief description of an evaluation approach for the anticipated learning objectives is given