Multiple remnant glaciers preserved in Beacon Valley, Antarctica
Cite as: Glacial Geology and Geomorphology, rp02, 2005
http://boris.qub.ac.uk/ggg/papers/full/2005/rp022005/rp02.html
Please note that, although the following is a full list of GGG papers, those from 2002 are currently unavailable. The site is being upgraded and we hope to re-launch in April.
[2005 rp02] A. M. Lorrey
Multiple remnant glaciers preserved in Beacon Valley, Antarctica
Cite as: Glacial Geology and Geomorphology, rp02, 2005
http://boris.qub.ac.uk/ggg/papers/full/2005/rp022005/rp02.html
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[2005 rp01] H. Schröder,
A. Kokarev,
S. Harrison
Rock glaciers in the northern Tien Shan, Kazakhstan: new data on movement rates and distribution
Cite as: Glacial Geology and Geomorphology, rp01, 2005
http://boris.qub.ac.uk/ggg/papers/full/2005/rp012005/rp01.html
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This paper describes the distribution and movement rates of rock glaciers in the Zailijskij Alatau mountains of the northern Tien Shan in Kazakhstan. In this region, the distribution and density of the rock glaciers are closely related to topoclimatic factors. Environmental controls on the development of rock glaciers in the Osörna valley in the central part of Sailijskij Alatau are briefly discussed. Velocity measurements on the surface of the Gordezkij rock glacier from 1923 to 1985 show that the surface of the rock glacier has moved downslope at an average velocity of 0.18 to 1.1 m per year. On the basis of the length:surface velocity ratio we estimate that the rock glacier is some 5300 years old. Since the development of rock glaciers in this region is probably associated with high rates of debris accumulation during phases of glacier retreat, they may be seen as partly paraglacial in origin.
[2001
rp02] W. A. Mitchell and Taylor, P. J.
Rock Glaciers in the Northwestern Indian Himalaya
Cite as: Glacial Geology and
Geomorphology, rp02, 2001
http://boris.qub.ac.uk/ggg/papers/full/2001/rp022001/rp02.html
Rock glaciers form an important element of the coarse debris supply system in high mountains. In the northwest Indian Himalaya they are widely distributed north of latitude 32°, where the influence of the southwest summer monsoon becomes attenuated leading to a high desert environment with an annual precipitation of c. 250mma-1. Both talus-derived and moraine-derived forms can be observed at altitudes above 3200m. Many are currently active, although some appear to have lower stable sections where there is no exposure of fine material and the clasts have a well-developed rock varnish. Moraine-derived types are clearly
[2001
rp01] Harrison, S. and
Anderson, E.A
Late Devensian rock glacier in the
Nantlle Valley, North Wales.
Cite
as: Glacial Geology and Geomorphology,
rp01, 2001
http://boris.qub.ac.uk/ggg/papers/full/2001/rp012001/rp01.html
In this paper we describe a relict rock glacier on the south-facing flank of the Nantlle Valley, North Wales. The landform is composed of debris of both glacial and talus origin. Macrofabric analyses undertaken on debris above the steep frontal slope demonstrate clast fabrics formed by the compressive shearing of debris and these are considered to reflect the thrusting of material over the slower moving frontal margin. The absence of surface collapse structures suggests that the rock glacier did not contain a large body of ice, which further implies that the ice which facilitated movement was periglacial in origin. At present, the absolute age of the rock glacier is not known, but it is considered more likely that it formed during the final stages of the Dimlington Stadial of the Devensian glaciation (Late Glacial Maximum), than during the Younger Dryas.
[2000 rp01] Dornbusch,
U.
Cite as: Glacial Geology
and Geomorphology, rp01, 2000
http://boris.qub.ac.uk/ggg/papers/full/2000/rp012000/rp01.html
Pleistocene
glaciation of the dry western Cordillera in southern Peru (14°25' - 15°30'
South)
Evidence of Pleistocene glaciations can be
found at many locations in the western Cordillera of southern Peru in an
area that has so far been neglected by field research (Fig. 1). Two
locations are presented in this paper, ranging in size from small cirque
glaciations to large ice caps. The examples provide the westernmost
evidence for glacial action with more locations further to the Northeast
that have to be taken into account when estimating the ages of the
glaciations. Glacial sediments reach as low as 3650m in the area of Pampa
Galeras and well developed glacial moraines can be found as close as 60km
from the coast at only 4240m. From the two locations in this paper and the
additional locations in the hinterland four glacial stades can be
distinguished. Correlation with data in the literature make it possible to
assign age estimates to the four glacial stades. The oldest glaciation is
older than 24ka and had snow lines ranging from ~4000m in the northwest
(plateau glaciation at Pampa Galeras) to ~4300m in the Southeast. The
second oldest is younger than 24ka with snow lines ranging from ~4200m in
the Northwest to ~4450m in the Southeast. These snow line altitudes are
several hundred metres lower than snow line altitudes published in the
literature (e.g. Broecker and Denton 1990 or Heine 1977). The snow line
depression from the present value for the lowest glaciation is ~900m. The
rise of the snowline towards the Southeast is similar to the rise of the
present-day snow line in the Cordillera Ampato (Dornbusch 1998),
indicating similar patterns of the regional circulation and location of
climatic belts.
References:
Broecker, W.S. and Denton, G.H. 1990 The role of
ocean-atmosphere reorganisation in glacial cycles. Quaternary Science
Reviews, 9, 305-341
Dornbusch, U. 1998 Current large scale climatic conditions in
southern Peru and their influence on snowline altitudes. Erdkunde, 52,
41-54
Heine, K. 1977 Beobachtungen und Überlegungen zur
eiszeitlichen Depression von Schneegrenze und Strukturbodengrenze in den
Tropen und Subtropen. Erdkunde, 31(3), 161-178
[1999 rp10] Hodson,A.
Glacio-fluvial sediment and solute transfer in high Arctic basins: examples from Svalbard.
An analysis of temporal variability in proglacial
suspended sediment and solute time series is undertaken using multiple
regression models and data collected from three west Spitsbergen glacier
basins. The regression models assess the significance of a range of
independent variables designed to supplement discharge and to represent
sediment and solute supply variability at diurnal, medium-term and
seasonal time scales. The glacier basins studied include a largely cold
based glacier (Austre Brøggerbreen), a largely warm based glacier
(Finsterwalderbreen) and an intermediate polythermal glacier
(Erdmannbreen). In each basin it is found that several of the supply
variables are significant, but major differences are found in the
coefficients and significance of the seasonal supply predictors. At
shorter time scales differences between the different glacier basins are
less apparent, although diurnal supply variability is most significant at
Austre Brøggerbreen. It is suggested that an important cause of the
differences in the regression models is the effect of the variable glacier
thermal regimes upon sediment availability and meltwater pathways,
particularly at the glacier bed. However, differences in the size of the
glacier basins as well as the experimental designs adopted in each study
may also contribute to the model characteristics. It is therefore
suggested that more standardised and integrated studies should be
conducted in order to fully understand the controls upon high Arctic
glacio-fluvial sediment/solute transfer.
[1999 rp09] Jones, H and Arnold, N.
Modelling the entrainment and transport of suspended sediment in subglacial hydrological systems
Research in subglacial hydrology has traditionally focused on examining proglacial sediment budgets as pointers to subglacial physical processes and changes in the configuration of subglacial hydrology. Recent work has incorporated information from borehole investigations, dye-tracing and direct observations, in an attempt to understand subglacial networks. Ongoing work at Haut Glacier d'Arolla, Switzerland has provided insight into the diurnal and seasonal variations in its hydrology, supporting the concept of a largely distributed system which evolves seasonally into a mainly channelised system of expanding or contracting conduits. A physically-based, distributed model of glacier hydrology has been created and applied to Haut Glacier d'Arolla, which calculates surface melt and water routing through an evolving glacier hydrological system during the course of a melt season. As yet, no model exists which mathematically represents small-scale sediment processes at the base of the glacier. This work couples a largely physically-based sediment model to the hydrology model for Haut Glacier d'Arolla. Empirical equations calculate sediment erosion and deposition within the two-dimensional conduit network at the base of the glacier. Using a continuity equation, the model routes this sediment through the inferred drainage system and calculates total output of suspended sediment into the proglacial stream. Results show that changes in calculated sediment concentrations vary over the melt season in some agreement with measured field data, having reasonable diurnal and seasonal patterns of flux. Early season overprediction is caused by the limitations of the hydrology model, which at present only allows for a conduit system along the length of the glacier for the whole season. Consequently, the best match between model and field data is seen during late-season, when fully-developed conduits are believed drain most subglacial water.
[1999 rp08] Richards, A.E. and McCaffrey, K.J.
W.
Component facies and architecture of glaciodeltaic foreset sequences are often studied in order to reconstruct the behaviour of the feeder system, or changes in the sediment sink. This paper describes large exposures of glaciodeltaic foreset facies from the Salpausselkä I delta-moraine in southern Finland and examines whether the scale-invariant depositional events there reflect underlying non-linear dynamical processes in the sedimentary system. Consequently, the extent to which the Quaternary scientist can infer temporal and spatial variability in the glaciofluvial depocentre from glaciodeltaic foreset sequences is discussed.
[1999 rp07] Hambrey, M. J., Bennett, M.R.,
Glasser, N. F., Huddart, D. and Crawford, K.
Facies and landforms associated with ice deformation in a tidewater glacier, Svalbard
Numerous tidewater glaciers in Svalbard, now in recession, have produced an assemblage of landforms linked to facies derived from both marine and terrestrial settings. Of these landforms, the most prominent are moraine-mound ("hummocky moraine") complexes that are the product of thrusting within and in front of the glacier terminus. This paper reviews a comprehensive glaciological, sedimentological and geomorphological dataset obtained from the Kongsvegen/Kronebreen glacier complex in Kongsfjorden (79°N), and outlines the development of an extensive end-moraine system comprising a variety of landforms. Studies of contemporary ice-contact features show that many of these landforms can be linked to ice structures: (i) thrusting of basal and subglacial sediments into the ice body to form moraine-mound complexes, (ii) the folding of supraglacial debris layers into the ice to form linear spreads of angular debris, and (iii) the development of "foliation-parallel ridges" comprising basal debris (sometimes mistaken as flutes). Of these, thrusting is the most important landform-producing process, and is the principal mode whereby a wide variety of facies are transferred from the fjord floor onto adjacent land areas. Analysis of the role of glacier structures in debris transfer and the sedimentology and geomorphology of high-Arctic moraine systems can provide much useful information, not only about glacier dynamics, but also the manner in which Pleistocene moraine systems could have been formed.
[1999 rp06] Howell, D., Siegert,M.J. and
Dowdeswell, J.A.
The extent of the Late Weichselian Eurasian High Arctic Ice Sheet was established from glacial-geological evidence relating to the former ice margin. This Late Weichselian ice-sheet margin was then used as a boundary condition for a numerical ice-sheet modelling experiment. An inverse approach to modelling was employed, where the ice-sheet extent was forced to match that derived from geological data. The model used environmental inputs representative of Late Weichselian conditions. Thus, a plausible scenario for the Late Weichselian glaciation of the Eurasian High Arctic was established. The model was then subjected to a series of sensitivity tests to examine the response of the ice sheet to variation in environmental inputs. The model predicts that the maximum ice thickness was 2 000 m within the Barents Sea and 3 000 m over Scandinavia. Large cross-shelf bathymetric troughs were occupied by ice streams which acted to drain ice from the central Barents Sea toward the continental margin where iceberg calving occurred. In this reconstruction, Northern Siberia, the eastern Taymyr Peninsula and the Laptev Sea remained free of ice at the last glacial maximum. Variations in environmental inputs to ± 10% of standard values did not affect model results significantly.
[1999 rp05] Knight, P.G. and Knight, D.A.
Theoretical models have suggested that subglacial water can enter basal ice along crystal boundaries. This has previously been proposed as a mechanism for entraining debris into the base of ice sheets without entraining layers of frozen meltwater. We describe two sets of laboratory experiments designed to establish whether the hypothesis that sediment entrainment into polycrystalline ice could occur along crystal boundaries is mechanically realistic. One set of experiments explores the response of basal sediment to the vertical passage of thermal fronts. A second set explores the response of basal sediment to the imposition of different pressure gradients through the ice.
The experiments demonstrate that debris particles of 30-70m can be entrained upwards from subglacial sediment into the vein network of polycrystalline ice in response to both thermal and pressure gradients. The calibre of the sediment entrained is controlled by vein diameter, and the disposition of sediment within the ice is controlled by the geometry of the vein network. The entrainment process may be sensitive not only to absolute temperature and pressure values but to the strength of thermal and pressure gradients. At the resolution of the experiments so far carried out, no alteration of the ice is evident other than at crystal boundaries.
Component facies and architecture of glaciodeltaic foreset sequences are often studied in order to reconstruct the behaviour of the feeder system, or changes in the sediment sink. This paper describes large exposures of glaciodeltaic foreset facies from the Salpausselkä I delta-moraine in southern Finland and examines whether the scale-invariant depositional events there reflect underlying non-linear dynamical processes in the sedimentary system. Consequently, the extent to which the Quaternary scientist can infer temporal and spatial variability in the glaciofluvial depocentre from glaciodeltaic foreset sequences is discussed.
[1999 rp04] Huddart, D.
Supraglacial trough fills, southern Scotland: origins and implications for deglacial processes.
The origin of glaciofluvial ridges (kames) in Nithsdale, southern Scotland as supraglacial trough fills associated with the decay of ice-cored ridges in a marginal environment has been suggested. A range of types has been recognised: a) ridges formed in supraglacial troughs with both ice-walls and floors, in which the sediment fill has been subject to both syn- and post-depositional deformation of the glaciofluvial gravels; b) ridges formed in ice-walled troughs, in which there has been glaciofluvial erosion into subglacial till or bedrock and the sediments show minimal syn- and post-depositional deformation, except at the landform margins and c) glaciolacustrine trough fills where the sediment has accumulated in ice-walled troughs which indicate fills that are relatively undisturbed. The glacier associated with these marginal supraglacial trough fills was not stagnant and drainage from this ice margin was associated with a terminal ice margin in the Dumfries area and as a proglacial sandur to the south and south-east. The term kame has no genetic significance and, if used at all, should refer only to an ice-contact, glaciofluvial deposit in a ridge or mound form.
[1999 rp03] Glasser, N.F., Bennett, M.R.,
Hambrey, M.J. and Huddart, D.
The morphology, composition and origin of medial moraines on polythermal glaciers in Svalbard
Medial moraines are an important feature of high-level sediment transport within valley glaciers but to date they have only been described from temperate glaciers, whilst their formation has rarely been described from a structural glaciology perspective. In this paper evidence is presented from polythermal valley glaciers in Svalbard which suggests that ice-deformational processes, such as the folding of stratification and the development of longitudinal foliation, are capable of organising debris into medial moraines. Exposure of these medial moraines by ablation near the glacier snout produces a series of wedge-shaped debris ridges at the glacier surface. Where folding of primary stratification produces these moraines, they are dominated by passively transported material including angular clasts. More intense folding is represented by the development of longitudinal foliation. Debris in this foliation is more diverse in its nature. Basal debris is present where material has been folded from the bed and glaciofluvial sediment is present where englacial streams are elevated along fold hinges. Further research is required to test the applicability of this folded stratification model to temperate glaciers, to larger ice masses and to quantify its role in the development of Pleistocene landforms.
[1999 rp02] Waller, Richard I. and Hart, Jane
K.
Mechanisms
and Patterns of Motion Associated with the Basal Zone of the Russell
Glacier, South-West Greenland
Field investigation at the Russell Glacier, Greenland attempted to measure the rates and patterns of motion associated with the basal zone of an Arctic glacier. Movement data was collected by surveying the displacement of a series of markers to which reflectors were attached. The resulting data suggest that during the period of study, the majority of the motion was associated with basal sliding. In contrast, relatively little movement was accommodated by creep within the debris-rich basal ice layer present. This finding has potentially wide-ranging implications for our understanding of the dynamic processes and behaviour associated with polythermal glaciers.
[1999 rp01] Sailer, R., Kerschner, H. and
Heller, A.
Three-dimensional reconstruction of Younger Dryas glaciers with a raster-based GIS
Glacier surfaces and equilibrium line altitudes (ELA) are reconstructed from Younger Dryas moraines (Egesen Stadial) in the Ferwall group (western Austria). Traditional manual reconstruction and a raster-based Geographical Information System (GIS) are used. The interactive GIS-based reconstruction uses the theoretical profile of a glacier tongue for the glacier tongue and a constant shear stress model for the cirque areas. A Digital Terrain Model with 20 m grid mesh width provides the geometrical basis to the GIS. Moraines and other ice marginal features are used as input data. The results of the manual and computer based reconstruction agree surprisingly well. Therefore, the calculated shear stress values and ELAs should be reliable. Shear stresses range between 1.23 bars for the Egesen maximum (early Younger Dryas) and 0.39 bars for the Egesen III advance (late Younger Dryas). Equilibrium line depressions relative to the mid-19th century maximum range between -290 m and -120 m respectively. In total, the GIS-supported models based on simple glaciological theory seem to be reliable tools for the reconstruction of former glacier surfaces.
[1998 rp04] Evans, D.J.A ., Rea, B.R. and Benn, D.I.
Subglacial deformation and bedrock plucking in areas of hard bedrock
Evidence is presented from Loch Quoich, Scotland, Sogn-og-Fjordane, Norway and St Jonsfjorden, Svalbard relating to subglacial sediment deformation sequences and associated bedrock plucking processes. It is suggested that bedrock quarrying at the base of thin deforming tills may play an important role in bedrock erosion.
 |
| | Citation |
[1998 rp03] Payne, D.
Climatic implications of rock glaciers in the arid Western Cordillera of the Central Andes
Active rock glaciers are present between 4525-4810 m in the field area because aridity precludes the formation of glacier ice. The lowest altitude of rock glacier activity corresponds closely to the 0°C isotherm. Inactive rock glaciers probably mark the position of a former 0°C isotherm.
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[1998 rp02] Harrison, S and Davenport, J.
The grounding of icebergs calved from the tidewater San Rafael glacier in Chilean Patagonia along boulder beaches of the Laguna San Rafael has resulted in the development of a number of grounding features including scour pits, troughs, wallow depressions, ice-pushed ridges and boulder pavements. Site One , experiencing contemporary scouring by icebergs exhibits three grounding features whilst at Site Two, unaffected by iceberg grounding since the 1920s, only two types of grounding features have survived. Site One is relatively impoverished biologically.
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[1998 rp01] Klein, Andrew G. and Isacks, Bryan L.
Alpine Glacial Geomorphological Studies In The Central Andes Using Landsat Thematic Mapper Images.
A mosaic of Landsat Thematic Mapper images was constructed to enable the extent of late Pleistocene glaciation in the central Andes between 15 and 22 S° latitude to be mapped. From the mapping, the number, area, and volume of the late Pleistocene glaciers were calculated and the magnitude and pattern of late Pleistocene snowline depression was estimated.
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[1997 rp01] Breckenridge, R. M., Sprenke, K. F.
An overdeepened glaciated basin, Lake Pend Oreille, northern Idaho.
At Lake Pend Oreille, located near the southernmost extent of late Pleistocene Cordilleran glaciation in Idaho and immediately downstream of the Pleistocene Lake Missoula ice dams, seismic reflection surveys show that the bedrock surface has been glacially overdeepened to a depth more than 200 m below present-day sea level. The seismic sections show evidence of subglacial erosion, Missoula Flood deposition, and a post-flood glacial readvance.
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[1996 rp02] Jacobsen, F.M.
A highly reliable mono-pulse radio echo-sounding system for use on temperate valley glaciers.
The construction of a mono-pulse radio echo-sounding system is described. The system is designed for measuring ice thickness on temperate valley glaciers, and is suitably ruggedized and weatherproofed for this task. Two versions, with slightly differing specifications, are described. Both are easily portable and can be linked to portable computer systems for data storage. The system has been used successfully on Austre Okstindbreen, a temperate valley glacier in north Norway.
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[1996 rp01] Hart, J.K.
Subglacial deformation associated with a rigid bed environment, Aberdaron, North Wales.
At Aberdaron, North Wales, a complex sequence of homogeneous tills and fluvial sediments overlies a hard rock base. The lower diamicton association at the bottom of the sequence consists of deformed tills and lenses of stratified sediments. It is suggested that these represent deforming bed tills and subglacial fluvial units which have been deformed together by subglacial excavational deformation.
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[1999 tn01] Mooers, H.
Comparison of loss on ignition and coulometric titration for determining carbonate content of till.
Sixty-one till samples collected from surface exposures and bore holes were analyzed for total inorganic carbon by loss on ignition (LOI) and coulometric titration. Results indicate no difference in the analyses and LOI provides accurate, rapid and inexpensive determination of total carbonate content of till.
| [1997 tn01] | Benn, D.I., and Gemmell, A.M.D, |
Equilibrium-line altitudes (ELAs) of former glaciers are commonly reconstructed using the accumulation-area ratio method, based on the assumption that the accumulation area of the glacier occupies some fixed proportion of the total glacier area. However, this method takes no account of glacier hypsometry, and is therefore subject to large errors in regions where glaciers exhibit a wide range of shapes and sizes. A more rigorous balance ratio method was introduced by Furbish and Andrews (1984) based on idealized mass-balance curves and glacier hypsometry, but is laborious and time-consuming to apply. We introduce a spreadsheet program which will rapidly calculate glacier ELAs using the balance ratio method, and which allows hypsometric variations to be accounted for in ELA reconstructions.
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| [1996, tn01] | Rea, B.R. |
A note on the experimental production of a mechanically polished surface within striations
Experimental striations have been produced using a
modified, soil direct-shear box. For high normal loads (1040 and 1840 N) a
mechanically polished surface was developed at the base of some
striations. The polished surface represents a shear plane developed
through the comminution debris at the trailing edge of the clast-bed
contact.
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This section will make available a forum to which Field Reports and similar informal (i.e. non-refereed) submissions may be made. This will allow rapid dissemination of interesting observations, with a view to encouraging increased informal debate on a range of topics.
[br07] Martini, I. Peter
(Editor). Late Glacial and
Postglacial Environmental Changes: Quaternary, Carboniferous-Permian,
and Proterozoic
Oxford University Press, New York, 1997
ISBN 0-19-508541-8, £49.50 343pp
[br06] J. K. Hart and Martinez, K. Glacial
Analysis: An Interactive Introduction. CD-ROM
Routledge, London, 1997
ISBN 0-415-16978-X. £39.99
[br05] Lowe, J.J. and Walker, M.J.C.
Reconstructing Quaternary
Environments (2nd Edition)
Longman, London, 1997
ISBN 0 5821 101662 (HB) 1-85728-004-0 PB £ 24.95, 446pp
[br04] Hambrey, Michael J.
Glacial Environments
U.C.L. Press, London, 1994
ISBN 1-85728-005-9 (hbk) 1-85728-004-0 (pbk) £ 17.95, 296pp
[br03] Barsch, D.
Rock Glaciers. Indicators for
the Present and Former Geoecology in High Mountain Environments
Springer (Series in the Physical Environment, No. 16), Berlin, 1996
ISBN 3-540-60742-0 (hbk), £105.00, 331pp
[br02] Ehlers, J.
Quaternary and Glacial
Geology
John Wiley Sons, Chichester, 1996
ISBN 0 471 95576 0, £75.00, 547pp
[br01] J. Menzies (ed.) Modern
Glacial Environments: Processes, Dynamics and Sediments
Glacial Environments: Volume 1,
Butterworth-Heineman, Oxford, 1995,
ISBN 0 7506 2351 9 (pbk), £40.00, 621 pp
© 1996, 1997, 1998, 1999 BGRG