A review of topographic controls on moraine distribution

Ice-marginal moraines are often used to reconstruct the dimensions of former ice masses, which are then used as proxies for palaeoclimate. This approach relies on the assumption that the distribution of moraines in the modern landscape is an accurate reflection of former ice margin positions during climatically controlled periods of ice margin stability. However, the validity of this assumption is open to question, as a number of additional, nonclimatic factors are known to influence moraine distribution. This review considers the role played by topography in this process, with specific focus on moraine formation, preservation, and ease of identification (topoclimatic controls are not considered). Published literature indicates that the importance of topography in regulating moraine distribution varies spatially, temporally, and as a function of the ice mass type responsible for moraine deposition. In particular, in the case of ice sheets and ice caps ( > 1000 km2), one potentially important topographic control on where in a landscape moraines are deposited is erosional feedback, whereby subglacial erosion causes ice masses to become less extensive over successive glacial cycles. For the marine-terminating outlets of such ice masses, fjord geometry also exerts a strong control on where moraines are deposited, promoting their deposition in proximity to valley narrowings, bends, bifurcations, where basins are shallow, and/or in the vicinity of topographic bumps. Moraines formed at the margins of ice sheets and ice caps are likely to be large and readily identifiable in the modern landscape. In the case of icefields and valley glaciers (10–1000 km2), erosional feedback may well play some role in regulating where moraines are deposited, but other factors, including variations in accumulation area topography and the propensity for moraines to form at topographic pinning points, are also likely to be important. This is particularly relevant where land-terminating glaciers extend into piedmont zones (unconfined plains, adjacent to mountain ranges) where large and readily identifiable moraines can be deposited. In the case of cirque glaciers (< 10 km2), erosional feedback is less important, but factors such as topographic controls on the accumulation of redistributed snow and ice and the availability of surface debris, regulate glacier dimensions and thereby determine where moraines are deposited. In such cases, moraines are likely to be small and particularly susceptible to post-depositional modification, sometimes making them difficult to identify in the modern landscape. Based on this review, we suggest that, despite often being difficult to identify, quantify, and mitigate, topographic controls on moraine distribution should be explicitly considered when reconstructing the dimensions of palaeoglaciers and that moraines should be judiciously chosen before being used as indirect proxies for palaeoclimate (i.e., palaeoclimatic inferences should only be drawn from moraines when topographic controls on moraine distribution are considered insignificant).

Late Quaternary glaciations in Far NE Russia; combining moraines, topography and chronology to assess regional and global glaciation synchrony

During various periods of Late Quaternary glaciation, small ice-sheets, -caps, -fields and valley glaciers, occupied the mountains and uplands of Far NE Russia (including the Verkhoyansk, Suntar-Khayata, and Chersky Mountains; the KolymaeAnyuy and Koryak Highlands; and much of the Kamchatka and Chukchi
Peninsulas). Here, the margins of former glaciers across this region are constrained through the comprehensive mapping of moraines from remote sensing data (Landsat 7 ETM+ satellite images; ASTER Global Digital Elevation Model (GDEM2); and Viewfinder Panorama DEM data). A total of 8414 moraines
are mapped, and this record is integrated with a series of published age-estimates (n = 25), considered to chronologically-constrain former ice-margin positions. Geomorphological and chronological data are compiled in a Geographic Information System (GIS) to produce ‘best estimate’ reconstructions of ice extent during the global Last Glacial Maximum (gLGM) and, to a lesser degree, during earlier phases of glaciation. The data reveal that much of Far NE Russia (~1,092,427 km2) preserves a glaciated landscape (i.e. is bounded by moraines), but there is no evidence of former ice masses having extended more than 270 km beyond mountain centres (suggesting that, during the Late Quaternary, the region has not been occupied by extensive ice sheets). During the gLGM, specifically, glaciers occupied ~253,000 km2, and rarely extended more than 50 km in length. During earlier (pre-gLGM) periods, glaciers were more extensive, though the timing of former glaciation, and the maximum Quaternary extent, appears to have been asynchronous across the region, and out-of-phase with ice-extent maxima elsewhere in the Northern Hemisphere. This glacial history is partly explained through consideration of climatic-forcing
(particularly moisture-availability, solar insolation and albedo), though topographic-controls upon the former extent and dynamics of glaciers are also considered, as are topographic-controls upon moraine deposition and preservation. Ultimately, our ability to understand the glacial and climatic history of this region is restricted when the geomorphological-record alone is considered, particularly as directly-dated glacial deposits are few, and topographic and climatic controls upon the moraine record are difficult to
distinguish.

An updated moraine map of Far NE Russia

Barr and Clark published a series of maps depicting the distribution of end moraines across Far NE Russia. These
moraines outlined the former distribution and dimensions of glaciers, and were identified through the analysis of
Landsat ETM+ satellite images (15- and 30-m resolution). Now, a number of freely available digital elevation
model (DEM) datasets are available, which cover the entire 4 million km2 of Far NE Russia. These include
the 30-m resolution ASTER GDEM and the 90-m resolution Viewfinder Panorama DEM. Here we use these
datasets, in conjunction with Landsat ETM+ images, to complete the process of systematically and
comprehensively mapping end moraines. With the aid of the DEMs described above, here we present a total
dataset of 8414 moraines, which almost quadruples the inventory of Barr and Clark. This increase in the
number of moraines is considered to reflect the utility of the DEMs for mapping glacial landforms. In terms of
moraine distribution, the Barr and Clark map and the one presented here are comparable, with moraines found
to cluster in highland regions and upon adjacent lowlands, attesting to the former occupation of the region by
mountain-centred ice masses. This record is considered to reflect palaeoclimatic and topographic controls upon
the extent and dynamics of palaeoglaciers, as well as spatial variability in moraine preservation.

Mapping of risk and susceptibility of shallow-landslide in the city of Sao Paulo, Brazil

In the city of Sao Paulo, where about 11 million people live, landslides and flooding occur frequently, especially during the summer. These landslides cause the destruction of houses and urban equipment, economic damage, and the loss of lives. The number of areas threatened by landslides has been increasing each year. The objective of this article is to analyze the probability of risk and susceptibility to shallow landslides in the Limoeiro River basin, which is located at the head of the Aricanduva River basin, one of the main hydrographic basins in the city of Sao Paulo. To map areas of risk, we created a cadastral survey form to evaluate landslide risk in the field. Risk was categorized into four levels based on natural and anthropogenic factors: R1 (low risk), R2 (average risk), R3 (high risk), and R4 (very high risk). To analyze susceptibility to shallow landslides, we used the SHALSTAB (Shallow Landsliding Stability) mathematical model and calculated the Distribution Frequency (DF) of the susceptibility classes for the entire basin. Finally, we performed a joint analysis of the average Risk Concentration (RC) and Risk Potential (RP). We mapped 14 risk sectors containing approximately 685 at-risk homes, more than half of which presented a high (R3) or very high (R4) probability of risk to the population. In the susceptibility map, 41% of the area was classified as stable and 20% as unconditionally unstable. Although the latter category accounted a smaller proportion of the total area, it contained a concentration (RC) of 41% of the mapped risk areas with a risk potential (RP) of 12%. We found that the locations of areas predicted to be unstable by the model coincided with the risk areas mapped in the field. This combination of methods can be applied to evaluate the risk of shallow landslides in densely populated areas and can assist public managers in defining areas that are unstable and inappropriate for occupation. (C) 2012 Elsevier B.V. All rights reserved.

Identification of erosional mechanisms during past glaciations based on a bedrock surface model of the central European Alps

The bedrock topography beneath the Quaternary cover provides an important archive for the identification of erosional processes during past glaciations. Here, we combined stratigraphic investigations of more than 40,000 boreholes with published data to generate a bedrock topography model for the entire plateau north of the Swiss Alps including the valleys within the mountain belt. We compared the bedrock map with data about the pattern of the erosional resistance of Alpine rocks to identify the controls of the lithologic architecture on the location of overdeepenings. We additionally used the bedrock topography map as a basis to calculate the erosional potential of the Alpine glaciers, which was related to the thickness of the LGM ice. We used these calculations to interpret how glaciers, with support by subglacial meltwater under pressure, might have shaped the bedrock topography of the Alps. We found that the erosional resistance of the bedrock lithology mainly explains where overdeepenings in the Alpine valleys and the plateau occur. In particular, in the Alpine valleys, the locations of overdeepenings largely overlap with areas where the underlying bedrock has a low erosional resistance, or where it was shattered by faults. We also found that the assignment of two end-member scenarios of erosion, related to glacial abrasion/plucking in the Alpine valleys, and dissection by subglacial meltwater in the plateau, may be adequate to explain the pattern of overdeepenings in the Alpine realm. This most likely points to the topographic controls on glacial scouring. In the Alps, the flow of LGM and previous glaciers were constrained by valley flanks, while ice flow was mostly divergent on the plateau where valley borders are absent. We suggest that these differences in landscape conditioning might have contributed to the contrasts in the formation of overdeepenings in the Alpine valleys and the plateau.

Topographic and meteorological influences on spatial scaling of heavy convective rainfall in mountainous regions

Characterizing the spatial scaling and dynamics of convective precipitation in mountainous terrain and the development of downscaling methods to transfer precipitation fields from one scale to another is the overall motivation for this research. Substantial progress has been made on characterizing the space-time organization of Midwestern convective systems and tropical rainfall, which has led to the development of statistical/dynamical downscaling models. Space-time analysis and downscaling of orographic precipitation has received less attention due to the complexities of topographic influences. This study uses multiscale statistical analysis to investigate the spatial scaling of organized thunderstorms that produce heavy rainfall and flooding in mountainous regions. Focus is placed on the eastern and western slopes of the Appalachian region and the Front Range of the Rocky Mountains. Parameter estimates are analyzed over time and attention is given to linking changes in the multiscale parameters with meteorological forcings and orographic influences on the rainfall. Influences of geographic regions and predominant orographic controls on trends in multiscale properties of precipitation are investigated. Spatial resolutions from 1 km to 50 km are considered. This range of spatial scales is needed to bridge typical scale gaps between distributed hydrologic models and numerical weather prediction (NWP) forecasts and attempts to address the open research problem of scaling organized thunderstorms and convection in mountainous terrain down to 1-4 km scales.

Topographic sleep EEG changes in the acute and chronic stage of hemispheric stroke.

After stroke, the injured brain undergoes extensive reorganization and reconnection. Sleep may play a role in synaptic plasticity underlying stroke recovery. To test this hypothesis, we investigated topographic sleep electroencephalographic characteristics, as a measure of brain reorganization, in the acute and chronic stages after hemispheric stroke. We studied eight patients with unilateral stroke in the supply territory of the middle cerebral artery and eight matched controls. All subjects underwent a detailed clinical examination including assessment of stroke severity, sleep habits and disturbances, anxiety and depression, and high-density electroencephalogram examination with 128 electrodes during sleep. The recordings were performed within 10 days after stroke in all patients, and in six patients also 3 months later. During sleep, we found higher slow-wave and theta activity over the affected hemisphere in the infarct area in the acute and chronic stage of stroke. Slow-wave, theta activity and spindle frequency range power over the affected hemisphere were lower in comparison to the non-affected side in a peri-infarct area in the patients' group, which persisted over time. Conversely, in wakefulness, only an increase of delta, theta activity and a slowing of alpha activity over the infarct area were found. Sleep slow-wave activity correlated with stroke severity and outcome. Stroke might have differential effects on the generation of delta activity in wakefulness and sleep slow waves (1-8 Hz). Sleep electroencephalogram changes over both the affected and non-affected hemispheres reflect the acute dysfunction caused by stroke and the plastic changes underlying its recovery. Moreover, these changes correlate with stroke severity and outcome.

Patterns of landscape form in the upper Rhône basin, Central Swiss Alps, predominantly show lithologic controls despite multiple glaciations and variations in rock uplift rates

The development of topography depends mainly on the interplay between uplift and erosion. These processes are controlled by various factors including climate, glaciers, lithology, seismic activity and short-term variables, such as anthropogenic impact. Many studies in orogens all over the world have shown how these controlling variables may affect the landscape's topography. In particular, it has been hypothesized that lithology exerts a dominant control on erosion rates and landscape morphology. However, clear demonstrations of this influence are rare and difficult to disentangle from the overprint of other signals such as climate or tectonics. In this study we focus on the upper Rhône Basin situated in the Central Swiss Alps in order to explore the relation between topography, possible controlling variables and lithology in particular. The Rhône Basin has been affected by spatially variable uplift, high orographically driven rainfalls and multiple glaciations. Furthermore, lithology and erodibility vary substantially within the basin. Thanks to high-resolution geological, climatic and topographic data, the Rhône Basin is a suitable laboratory to explore these complexities. Elevation, relief, slope and hypsometric data as well as river profile information from digital elevation models are used to characterize the landscape's topography of around 50 tributary basins. Additionally, uplift over different timescales, glacial inheritance, precipitation patterns and erodibility of the underlying bedrock are quantified for each basin. Results show that the chosen topographic and controlling variables vary remarkably between different tributary basins. We investigate the link between observed topographic differences and the possible controlling variables through statistical analyses. Variations of elevation, slope and relief seem to be linked to differences in long-term uplift rate, whereas elevation distributions (hypsometry) and river profile shapes may be related to glacial imprint. This confirms that the landscape of the Rhône Basin has been highly preconditioned by (past) uplift and glaciation. Linear discriminant analyses (LDAs), however, suggest a stronger link between observed topographic variations and differences in erodibility. We therefore conclude that despite evident glacial and tectonic conditioning, a lithologic control is still preserved and measurable in the landscape of the Rhône tributary basins.

Head and eye movements and lane keeping in drivers with hemianopia and quadrantanopia compared to controls

Purpose: To compare the eye and head movements and lane-keeping of drivers with hemianopia and quadrantanopia with that of age-matched controls when driving under real world conditions. Methods: Participants included 22 hemianopes and 8 quadrantanopes (M age 53 yrs) and 30 persons with normal visual fields (M age 52 yrs) who were ≥ 6 months from the brain injury date and either a current driver or aiming to resume driving. All participants drove an instrumented dual-brake vehicle along a 14-mile route in traffic that included non-interstate city driving and interstate driving. Driving performance was scored using a standardised assessment system by two “backseat” raters and the Vigil Vanguard system which provides objective measures of speed, braking and acceleration, cornering, and video-based footage from which eye and head movements and lane-keeping can be derived. Results: As compared to drivers with normal visual fields, drivers with hemianopia or quadrantanopia on average were significantly more likely to drive slower, to exhibit less excessive cornering forces or acceleration, and to execute more shoulder movements off the seat. Those hemianopic and quadrantanopic drivers rated as safe to drive by the backseat evaluator made significantly more excursive eye movements, exhibited more stable lane positioning, less sudden braking events and drove at higher speeds than those rated as unsafe, while there was no difference between safe and unsafe drivers in head movements. Conclusions: Persons with hemianopic and quadrantanopic field defects rated as safe to drive have different driving characteristics compared to those rated as unsafe when assessed using objective measures of driving performance.

Artful determination : "state of the art" and PCME Ltd v. Goyen COntrols Co. UK Ltd

In a recent decision by Mr Justice Laddie, a patent was held anticipated by, inter alia, prior use of a device which fell within the claims of the patent in suit, even though its circuitry was enclosed in resin. The anticipating invention had been "made available to the public" within the terms of section 2 (2) of the Patents Act 1977 because its essential integers would have been revealed by an interesting character, the "skilled forensic engineer".

Controls on soil respiration in semiarid soils

Soil respiration in semiarid ecosystems responds positively to temperature, but temperature is just one of many factors controlling soil respiration. Soil moisture can have an overriding influence, particularly during the dry/warm portions of the year. The purpose of this project was to evaluate the influence of soil moisture on the relationship between temperature and soil respiration. Soil samples collected from a range of sites arrayed across a climatic gradient were incubated under varying temperature and moisture conditions. Additionally, we evaluated the impact of substrate quality on short-term soil respiration responses by carrying out substrate-induced respiration assessments for each soil at nine different temperatures. Within all soil moisture regimes, respiration rates always increased with increase in temperature. For a given temperature, soil respiration increased by half (on average) across moisture regimes; Q(10) values declined with soil moisture from 3.2 (at -0.03 MPa) to 2.1 (-1.5 MPa). In summary, soil respiration was generally directly related to temperature, but responses were ameliorated with decrease in soil moisture. (C) 2004 Elsevier Ltd. All rights reserved.