D. E Sugden - Profile on Academia.edu (original) (raw)
Papers by D. E Sugden
Past and present stability of the Weddell Sea sector of the Antarctic Ice Sheet
Modelling the post-glacial evolution of the Foundation Ice Stream, Weddell Sea embayment, Antarctica
The version presented here may differ from the published version. If citing, you are advised to c... more The version presented here may differ from the published version. If citing, you are advised to consult the published version for pagination, volume/issue and date of publication 1 A community-based geological reconstruction of Antarctic Ice Sheet deglaciation since the Last Glacial Maximum The RAISED* Consortium
Transactions of the Institute of British Geographers, 1968
ABSTRACT This paper attempts to reinterpret the scenery of the Cairngorm mountains; in particular... more ABSTRACT This paper attempts to reinterpret the scenery of the Cairngorm mountains; in particular, it suggests that there is little evidence for the view that the mountains escaped a cover of ice during the Pleistocene. Following discussion of the problems of interpretation, the two major elements in the landscape of the mountains are examined in turn. The first, comprising the subdued, rolling slopes with associated fluvial forms, conformable pseudobedding, tors and rotted granite exposures, is held to reflect the detailed form of the massif in pre-glacial times. Precipitous valleys and ice-moulded forms form the second major element of the landscape and, with the exception of forms of local glaciation, reflect the passage north-eastward across the mountains of a major Scottish ice sheet. Using examples from East Greenland, it is suggested that watershed breaching occurred beneath such an ice sheet rather than as a result of valley-glacier action. The distribution of the landforms of glacial erosion can be related to a large extent to the pre-glacial topography. Troughs appear to have been excavated along the lines of pre-glacial river valleys suitably orientated for the discharge of Scottish ice, while pre-glacial valleys at right angles to the main direction of ice flow have frequently retained their original fluvial form. Apparently, new troughs, such as the Lairig Ghru, have been created where no suitable pre-glacial valley existed. The clarity of the junction between the two associations of landforms and the survival since pre-glacial times of such relatively fragile forms as tors is a remarkable tribute to the selectivity with which the overriding ice sheet eroded.
A Journey Through the Pindus Mountains in 1963
The Geographical Journal, 1964
Earth and Planetary Science Letters, 2005
In situ produced cosmogenic 3 He analyses provide independent support for the model of a stable, ... more In situ produced cosmogenic 3 He analyses provide independent support for the model of a stable, hyper-arid polar climate persisting in East Antarctica since the mid-Miocene and provide quantitative constraints on long-term rates of erosion within the Dry Valleys. In the Coombs Hills area, a series of cobble-size boulders form mega-ripples with wavelengths of approximately 50 m. Their topographic position and association with features characteristic of scabland, such as stripped, corrugated bedrock surfaces, indicate the boulders were deposited by subglacial floodwaters. Such outburst flooding could only have occurred during overriding of the northern Dry Valleys by a greatly expanded East Antarctic ice sheet. Timing of the overriding episode has been previously assigned to 14.8 to 13.6 Ma by correlation with volcanic ash deposits dated by 40 Ar/ 39 Ar in the Asgard Range of the Dry Valleys. Cosmogenic 3 He concentrations in clinopyroxene from Ferrar dolerite boulders are consistent with 8.6 to 10.4 Ma exposure, calculated using scaling factors appropriate for Antarctica and assuming zero erosion. These are among the oldest surface exposure dates yet measured on Earth, but are not however consistent with the 40 Ar/ 39 Ar chronology used to define the age of the landscape due to unconstrained levels of erosion. Erosion rates of 0.03-0.06 m Ma À1 are necessary to have produced the measured boulder exposure age if they were deposited at 14.8 Ma. These are less than half the steady-state erosion rate derived from cosmogenic 3 He in the nearby bedrock surfaces (0.17 m MaÀ1) and testify to the extreme stability of the landscape.
Report of the Oxford University expedition to East Greenland, 1962
Journal of Glaciology, 1979
Understanding the relationship between the morphology of former ice-sheet beds and glaciological ... more Understanding the relationship between the morphology of former ice-sheet beds and glaciological processes is handicapped by the difficulty of establishing which stage of a cycle of ice-sheet growth and decay is responsible for most erosion. Discussions at this conference and in the literature display a variety of opinions, some favouring periods of ice-sheet build up, others periods of fluctuations, and still others steady-state maximum conditions. Here it is suggested that there is geomorphological evidence which points to the dominance of maximum conditions. Along the eastern margins of the Laurentide and Greenland ice sheets there is a sharp discontinuity between Alpine relief which stood above the ice-sheet surface at the maximum and plateau scenery which was covered by the ice sheet. Often the two types of relief are adjacent and yet separated by an altitudinal difference of only 100–200 m. The existence of an abrupt rather than gradual transition from one relief type to the o...
Earth Surface Dynamics, 2016
Multi-temporal and fine-resolution topographic data products are increasingly used to quantify su... more Multi-temporal and fine-resolution topographic data products are increasingly used to quantify surface elevation change in glacial environments. In this study, we employ 3-D digital elevation model (DEM) differencing to quantify the topographic evolution of a blue-ice moraine complex in front of Patriot Hills, Heritage Range, Antarctica. Terrestrial laser scanning (TLS) was used to acquire multiple topographic datasets of the moraine surface at the beginning and end of the austral summer season in 2012/2013 and during a resurvey field campaign in 2014. A complementary topographic dataset was acquired at the end of season 1 through the application of structure from motion with multi-view stereo (SfM-MVS) photogrammetry to a set of aerial photographs acquired from an unmanned aerial vehicle (UAV). Three-dimensional cloud-to-cloud differencing was undertaken using the Multiscale Model to Model Cloud Comparison (M3C2) algorithm. DEM differencing revealed net uplift and lateral movement of the moraine crests within season 1 (mean uplift ∼ 0.10 m) and surface lowering of a similar magnitude in some inter-moraine depressions and close to the current ice margin, although we are unable to validate the latter. Our results indicate net uplift across the site between seasons 1 and 2 (mean 0.07 m). This research demonstrates that it is possible to detect dynamic surface topographical change across glacial moraines over short (annual to intra-annual) timescales through the acquisition and differencing of fine-resolution topographic datasets. Such data offer new opportunities to understand the process linkages between surface ablation, ice flow and debris supply within moraine ice.
Post-glacial thinning history of the Foundation Ice Stream, Weddell Sea embayment, Antarctica
Interglacial or Early Wisconsin Shell Fragments in Till on the Flanks of Sondre Stromfjord, West Greenland
Arctic and Alpine Research, 1976
Geology, 1976
ABSTRACT The hypothesis of deep erosion of shields by continental ice sheets put forward by W. A.... more ABSTRACT The hypothesis of deep erosion of shields by continental ice sheets put forward by W. A. White is being used by neighboring disciplines. Although valuable as a speculative hypothesis, there is field evidence to contradict it. After discussion of the evidence, it is concluded that Pleistocene glacial erosion has removed no more than a few tens of metres of material from the shield areas of the Northern Hemisphere.
Nature Communications
Ice can sculpt extraordinary landscapes, yet the efficacy of, and controls governing, glacial ero... more Ice can sculpt extraordinary landscapes, yet the efficacy of, and controls governing, glacial erosion on geological timescales remain poorly understood and contended, particularly across Polar continental shields. Here, we assimilate geophysical data with modelling of the Eurasian Ice Sheet — the third largest Quaternary ice mass that spanned 49°N to 82°N — to decipher its erosional footprint during the entire last ~100 ka glacial cycle. Our results demonstrate extreme spatial and temporal heterogeneity in subglacial erosion, with rates ranging from 0 to 5 mm a−1 and a net volume equating to ~130,000 km3 of bedrock excavated to depths of ~190 m. A hierarchy of environmental controls ostensibly underpins this complex signature: lithology, topography and climate, though it is basal thermodynamics that ultimately regulates erosion, which can be variously protective, pervasive, or, highly selective. Our analysis highlights the remarkable yet fickle nature of glacial erosion — critically...
The Morphology of Kaldalon, a Recently Deglaciated Valley in Iceland
Geografiska Annaler, 1962
(1962). The Morphology of Kaldalon, A Recently Deglaciated Valley in Iceland. Geografiska Annaler... more (1962). The Morphology of Kaldalon, A Recently Deglaciated Valley in Iceland. Geografiska Annaler: Vol. 44, No. 3-4, pp. 347-365.
IEEE Transactions on Geoscience and Remote Sensing, 1989
coefficients of percent liquid water content U, in Table on p. 305 are too large in magnitude by ... more coefficients of percent liquid water content U, in Table on p. 305 are too large in magnitude by a factor of 10 (i.e., -0.990 should be -0.0990, etc.). In the paper entitled "Surface Snow Properties Effects on Millirneter-Wave Backscatter," by L. D. Williams er al., which ap-
Continental Morphology and East Antarctic ice sheet sensitivity
Quaternary Science Reviews, 2007
Ice-free areas Antarctica reveal a multi-million year history of landscape evolution, but most at... more Ice-free areas Antarctica reveal a multi-million year history of landscape evolution, but most attention up to now has focused on the Transantarctic Mountains. The Amery Oasis in the northern Prince Charles Mountains borders the Lambert Glacier-Amery Ice Shelf System that drains 1 million km 2 of the East Antarctic Ice Sheet, and therefore provides a record of fluctuations of both local and regional ice since the ice sheet first formed in early Oligocene time. This glacial record has been deciphered by (i) geomorphological mapping from aerial photographs and on the ground, (ii) documenting the relationship between thick well-dated, uplifted glaciomarine strata and the underlying palaeolandscape, (iii) examining surficial sediment facies, and (iv) surface-exposure dating using 10 Be and 26 Al. The SE Amery Oasis records at least 10 million years of landscape evolution beginning with a prelate Miocene phase of glacial erosion, followed by deposition of glaciomarine strata of the Battye Glacier Formation (Pagodroma Group) in late Miocene time. A wet-based ice sheet next expanded over the SE Amery Oasis, following which deposition of the glaciomarine Pliocene Bardin Bluffs Formation (Pagodroma Group) took place. Both formations were uplifted; by at least 500 and 200 m, respectively. Their tops are characterised by geomorphological surfaces upon which intensive periglacial activity took place. Higher-level bedrock areas were subjected to deep weathering and torformation. Early Pleistocene time was characterised by expansion of a cold-based ice sheet across the whole area, but it left little more than patches of sandy gravel and erratic blocks. Late Pleistocene expansion of local ice (the Battye Glacier) saw deposition of moraine-mound complexes on low ground around Radok Lake and ice-dammed lake phenomena. Subglacial drainage of the lake escaped to the east exhuming the sediment-filled gorges. Holocene landscape modification has been relatively superficial. Overall, the landscape of the Amery Oasis evolved primarily under the influence of wet-based (probably polythermal) glaciers in Miocene and Pliocene times, whereas the Quaternary Period was characterised mainly by cold-based glaciers that had comparatively little impact on the landscape.
Scottish Journal of Geology, May 1, 1973
Geomorphology, Education and Relevance
Lichenometry: Dedicated to the Memory of the Late Roland E. Beschel || Polar Geomorphologyby A. J. Price; D. E. Sugden
Past and present stability of the Weddell Sea sector of the Antarctic Ice Sheet
Modelling the post-glacial evolution of the Foundation Ice Stream, Weddell Sea embayment, Antarctica
The version presented here may differ from the published version. If citing, you are advised to c... more The version presented here may differ from the published version. If citing, you are advised to consult the published version for pagination, volume/issue and date of publication 1 A community-based geological reconstruction of Antarctic Ice Sheet deglaciation since the Last Glacial Maximum The RAISED* Consortium
Transactions of the Institute of British Geographers, 1968
ABSTRACT This paper attempts to reinterpret the scenery of the Cairngorm mountains; in particular... more ABSTRACT This paper attempts to reinterpret the scenery of the Cairngorm mountains; in particular, it suggests that there is little evidence for the view that the mountains escaped a cover of ice during the Pleistocene. Following discussion of the problems of interpretation, the two major elements in the landscape of the mountains are examined in turn. The first, comprising the subdued, rolling slopes with associated fluvial forms, conformable pseudobedding, tors and rotted granite exposures, is held to reflect the detailed form of the massif in pre-glacial times. Precipitous valleys and ice-moulded forms form the second major element of the landscape and, with the exception of forms of local glaciation, reflect the passage north-eastward across the mountains of a major Scottish ice sheet. Using examples from East Greenland, it is suggested that watershed breaching occurred beneath such an ice sheet rather than as a result of valley-glacier action. The distribution of the landforms of glacial erosion can be related to a large extent to the pre-glacial topography. Troughs appear to have been excavated along the lines of pre-glacial river valleys suitably orientated for the discharge of Scottish ice, while pre-glacial valleys at right angles to the main direction of ice flow have frequently retained their original fluvial form. Apparently, new troughs, such as the Lairig Ghru, have been created where no suitable pre-glacial valley existed. The clarity of the junction between the two associations of landforms and the survival since pre-glacial times of such relatively fragile forms as tors is a remarkable tribute to the selectivity with which the overriding ice sheet eroded.
A Journey Through the Pindus Mountains in 1963
The Geographical Journal, 1964
Earth and Planetary Science Letters, 2005
In situ produced cosmogenic 3 He analyses provide independent support for the model of a stable, ... more In situ produced cosmogenic 3 He analyses provide independent support for the model of a stable, hyper-arid polar climate persisting in East Antarctica since the mid-Miocene and provide quantitative constraints on long-term rates of erosion within the Dry Valleys. In the Coombs Hills area, a series of cobble-size boulders form mega-ripples with wavelengths of approximately 50 m. Their topographic position and association with features characteristic of scabland, such as stripped, corrugated bedrock surfaces, indicate the boulders were deposited by subglacial floodwaters. Such outburst flooding could only have occurred during overriding of the northern Dry Valleys by a greatly expanded East Antarctic ice sheet. Timing of the overriding episode has been previously assigned to 14.8 to 13.6 Ma by correlation with volcanic ash deposits dated by 40 Ar/ 39 Ar in the Asgard Range of the Dry Valleys. Cosmogenic 3 He concentrations in clinopyroxene from Ferrar dolerite boulders are consistent with 8.6 to 10.4 Ma exposure, calculated using scaling factors appropriate for Antarctica and assuming zero erosion. These are among the oldest surface exposure dates yet measured on Earth, but are not however consistent with the 40 Ar/ 39 Ar chronology used to define the age of the landscape due to unconstrained levels of erosion. Erosion rates of 0.03-0.06 m Ma À1 are necessary to have produced the measured boulder exposure age if they were deposited at 14.8 Ma. These are less than half the steady-state erosion rate derived from cosmogenic 3 He in the nearby bedrock surfaces (0.17 m MaÀ1) and testify to the extreme stability of the landscape.
Report of the Oxford University expedition to East Greenland, 1962
Journal of Glaciology, 1979
Understanding the relationship between the morphology of former ice-sheet beds and glaciological ... more Understanding the relationship between the morphology of former ice-sheet beds and glaciological processes is handicapped by the difficulty of establishing which stage of a cycle of ice-sheet growth and decay is responsible for most erosion. Discussions at this conference and in the literature display a variety of opinions, some favouring periods of ice-sheet build up, others periods of fluctuations, and still others steady-state maximum conditions. Here it is suggested that there is geomorphological evidence which points to the dominance of maximum conditions. Along the eastern margins of the Laurentide and Greenland ice sheets there is a sharp discontinuity between Alpine relief which stood above the ice-sheet surface at the maximum and plateau scenery which was covered by the ice sheet. Often the two types of relief are adjacent and yet separated by an altitudinal difference of only 100–200 m. The existence of an abrupt rather than gradual transition from one relief type to the o...
Earth Surface Dynamics, 2016
Multi-temporal and fine-resolution topographic data products are increasingly used to quantify su... more Multi-temporal and fine-resolution topographic data products are increasingly used to quantify surface elevation change in glacial environments. In this study, we employ 3-D digital elevation model (DEM) differencing to quantify the topographic evolution of a blue-ice moraine complex in front of Patriot Hills, Heritage Range, Antarctica. Terrestrial laser scanning (TLS) was used to acquire multiple topographic datasets of the moraine surface at the beginning and end of the austral summer season in 2012/2013 and during a resurvey field campaign in 2014. A complementary topographic dataset was acquired at the end of season 1 through the application of structure from motion with multi-view stereo (SfM-MVS) photogrammetry to a set of aerial photographs acquired from an unmanned aerial vehicle (UAV). Three-dimensional cloud-to-cloud differencing was undertaken using the Multiscale Model to Model Cloud Comparison (M3C2) algorithm. DEM differencing revealed net uplift and lateral movement of the moraine crests within season 1 (mean uplift ∼ 0.10 m) and surface lowering of a similar magnitude in some inter-moraine depressions and close to the current ice margin, although we are unable to validate the latter. Our results indicate net uplift across the site between seasons 1 and 2 (mean 0.07 m). This research demonstrates that it is possible to detect dynamic surface topographical change across glacial moraines over short (annual to intra-annual) timescales through the acquisition and differencing of fine-resolution topographic datasets. Such data offer new opportunities to understand the process linkages between surface ablation, ice flow and debris supply within moraine ice.
Post-glacial thinning history of the Foundation Ice Stream, Weddell Sea embayment, Antarctica
Interglacial or Early Wisconsin Shell Fragments in Till on the Flanks of Sondre Stromfjord, West Greenland
Arctic and Alpine Research, 1976
Geology, 1976
ABSTRACT The hypothesis of deep erosion of shields by continental ice sheets put forward by W. A.... more ABSTRACT The hypothesis of deep erosion of shields by continental ice sheets put forward by W. A. White is being used by neighboring disciplines. Although valuable as a speculative hypothesis, there is field evidence to contradict it. After discussion of the evidence, it is concluded that Pleistocene glacial erosion has removed no more than a few tens of metres of material from the shield areas of the Northern Hemisphere.
Nature Communications
Ice can sculpt extraordinary landscapes, yet the efficacy of, and controls governing, glacial ero... more Ice can sculpt extraordinary landscapes, yet the efficacy of, and controls governing, glacial erosion on geological timescales remain poorly understood and contended, particularly across Polar continental shields. Here, we assimilate geophysical data with modelling of the Eurasian Ice Sheet — the third largest Quaternary ice mass that spanned 49°N to 82°N — to decipher its erosional footprint during the entire last ~100 ka glacial cycle. Our results demonstrate extreme spatial and temporal heterogeneity in subglacial erosion, with rates ranging from 0 to 5 mm a−1 and a net volume equating to ~130,000 km3 of bedrock excavated to depths of ~190 m. A hierarchy of environmental controls ostensibly underpins this complex signature: lithology, topography and climate, though it is basal thermodynamics that ultimately regulates erosion, which can be variously protective, pervasive, or, highly selective. Our analysis highlights the remarkable yet fickle nature of glacial erosion — critically...
The Morphology of Kaldalon, a Recently Deglaciated Valley in Iceland
Geografiska Annaler, 1962
(1962). The Morphology of Kaldalon, A Recently Deglaciated Valley in Iceland. Geografiska Annaler... more (1962). The Morphology of Kaldalon, A Recently Deglaciated Valley in Iceland. Geografiska Annaler: Vol. 44, No. 3-4, pp. 347-365.
IEEE Transactions on Geoscience and Remote Sensing, 1989
coefficients of percent liquid water content U, in Table on p. 305 are too large in magnitude by ... more coefficients of percent liquid water content U, in Table on p. 305 are too large in magnitude by a factor of 10 (i.e., -0.990 should be -0.0990, etc.). In the paper entitled "Surface Snow Properties Effects on Millirneter-Wave Backscatter," by L. D. Williams er al., which ap-
Continental Morphology and East Antarctic ice sheet sensitivity
Quaternary Science Reviews, 2007
Ice-free areas Antarctica reveal a multi-million year history of landscape evolution, but most at... more Ice-free areas Antarctica reveal a multi-million year history of landscape evolution, but most attention up to now has focused on the Transantarctic Mountains. The Amery Oasis in the northern Prince Charles Mountains borders the Lambert Glacier-Amery Ice Shelf System that drains 1 million km 2 of the East Antarctic Ice Sheet, and therefore provides a record of fluctuations of both local and regional ice since the ice sheet first formed in early Oligocene time. This glacial record has been deciphered by (i) geomorphological mapping from aerial photographs and on the ground, (ii) documenting the relationship between thick well-dated, uplifted glaciomarine strata and the underlying palaeolandscape, (iii) examining surficial sediment facies, and (iv) surface-exposure dating using 10 Be and 26 Al. The SE Amery Oasis records at least 10 million years of landscape evolution beginning with a prelate Miocene phase of glacial erosion, followed by deposition of glaciomarine strata of the Battye Glacier Formation (Pagodroma Group) in late Miocene time. A wet-based ice sheet next expanded over the SE Amery Oasis, following which deposition of the glaciomarine Pliocene Bardin Bluffs Formation (Pagodroma Group) took place. Both formations were uplifted; by at least 500 and 200 m, respectively. Their tops are characterised by geomorphological surfaces upon which intensive periglacial activity took place. Higher-level bedrock areas were subjected to deep weathering and torformation. Early Pleistocene time was characterised by expansion of a cold-based ice sheet across the whole area, but it left little more than patches of sandy gravel and erratic blocks. Late Pleistocene expansion of local ice (the Battye Glacier) saw deposition of moraine-mound complexes on low ground around Radok Lake and ice-dammed lake phenomena. Subglacial drainage of the lake escaped to the east exhuming the sediment-filled gorges. Holocene landscape modification has been relatively superficial. Overall, the landscape of the Amery Oasis evolved primarily under the influence of wet-based (probably polythermal) glaciers in Miocene and Pliocene times, whereas the Quaternary Period was characterised mainly by cold-based glaciers that had comparatively little impact on the landscape.
Scottish Journal of Geology, May 1, 1973
Geomorphology, Education and Relevance
Lichenometry: Dedicated to the Memory of the Late Roland E. Beschel || Polar Geomorphologyby A. J. Price; D. E. Sugden