scholarly journals Victoria Lower Glacier and Ross Sea Glaciation, Dry Valleys Area, South Victoria Land, Antarctica

1987 ◽  
Vol 33 (115) ◽  
pp. 293-299
Author(s):  
T.J.H. Chinn
Keyword(s):  
Shear Zone ◽  
Ross Sea ◽  
Complex Structure ◽  
Radiocarbon Date ◽  
Dry Valleys ◽  
Radiocarbon Age ◽  
The North ◽  
Victoria Land ◽  
Radio Echo Sounding ◽  
Echo Sounding

AbstractVictoria Lower Glacier is a complex structure of ice from two distinct sources (Schultz Glacier to the north and a local névé of Victoria Lower Glacier) that join at a broad median shear zone. Evidence from the margins suggest that both are currently retreating. Algae in a block of frozen stratified sediment from within the ice of the terminal margin has a radiocarbon age of 20 200 ± 2400 year BP (NZ 6531 A), indicating that the glacier has advanced since that time. Superposition of ice levels of Ross Sea I glaciation on a radio echo–sounding profile of bedrock beneath the glacier indicates that it is unlikely that Ross Sea I ice entered the valley. The radiocarbon date supports this finding.

scholarly journals Victoria Lower Glacier and Ross Sea Glaciation, Dry Valleys Area, South Victoria Land, Antarctica

1987 ◽  
Vol 33 (115) ◽  
pp. 293-299 ◽  
Author(s):  
T.J.H. Chinn
Keyword(s):  
Shear Zone ◽  
Ross Sea ◽  
Complex Structure ◽  
Radiocarbon Date ◽  
Dry Valleys ◽  
Radiocarbon Age ◽  
The North ◽  
Victoria Land ◽  
Radio Echo Sounding ◽  
Echo Sounding

AbstractVictoria Lower Glacier is a complex structure of ice from two distinct sources (Schultz Glacier to the north and a localnévéof Victoria Lower Glacier) that join at a broad median shear zone. Evidence from the margins suggest that both are currently retreating. Algae in a block of frozen stratified sediment from within the ice of the terminal margin has a radiocarbon age of 20 200 ± 2400 year BP (NZ 6531 A), indicating that the glacier has advanced since that time. Superposition of ice levels of Ross Sea I glaciation on a radio echo–sounding profile of bedrock beneath the glacier indicates that it is unlikely that Ross Sea I ice entered the valley. The radiocarbon date supports this finding.

scholarly journals Comparison of Electromagnetic and Seismic-Gravity Ice Thickness Measurements in East Antarctica

1975 ◽  
Vol 15 (73) ◽  
pp. 137-150 ◽  
Author(s):  
David J. Drewry
Keyword(s):  
Seismic Reflection ◽  
East Antarctica ◽  
Ice Thickness ◽  
South Pole ◽  
Victoria Land ◽  
Radio Echo Sounding ◽  
Mean Differences ◽  
Thickness Measurements ◽  
Better Than ◽  
Echo Sounding

AbstractThe errors involved in ice thickness determinations in Antarctica by seismic reflection shooting, gravity observations and radio-echo sounding are briefly discussed. Relative accuracies of 3%, 7-10% and 1.5% have been suggested. Double checks of ice depths from radar sounding in east Antarctica indicate an internal consistency of measurement for this technique of <1%. Comparison of carefully executed seismic shooting and routine radio-echo sounding results against absolute ice thickness values from two deep core drilling sites show no significant differences between these two remote methods (i.e. both are better than 1.5%).Over 60 comparisons are examined between radar ice thicknesses and over-snow measurements obtained on eight independent traverses in east Antarctica. Three traverses exhibit consistently unacceptable results-U.S. Victoria Land Traverse II (southern leg), Commonwealth Transanlarctic Expedition and the U.S.S.R. Vostok to South Pole Traverse—which probably result from misinterpretation of “noisy” seismograms. The remaining comparisons indicate mean differences, including some navigational uncertainty, of ≈3%, <8% and 5% between radio-echo and (1) seismic, (2) gravity, and (3) gravity tied to seismic determinations, respectively.

scholarly journals Ice-Sheet flow in the Vicinity of Southern Victoria Land, Antarctica: Implications for Glacial Chronology

1979 ◽  
Vol 24 (90) ◽  
pp. 483
Author(s):  
David J. Drewry
Keyword(s):  
Ice Sheet ◽  
East Antarctica ◽  
Small Surface ◽  
The North ◽  
Ice Surface ◽  
Glacial Chronology ◽  
Victoria Land ◽  
Dry Valley ◽  
Radio Echo Sounding ◽  
Taylor Glacier

Abstract Systematic radio echo-sounding during three seasons since 1971–72 has produced data on the configuration of the ice sheet in East Antarctica. In the sector extending inland from southern Victoria Land, the ice sheet exhibits a large ridge which drives ice towards David Glacier in the north and Mulock and Byrd Glaciers to the south. Within 100 km of the McMurdo dry-valley region soundings along ten sub-parallel lines (c. 10 km apart) provides detail on ice surface and flow patterns at the ridge tip. A small surface dome lies just inland of Taylor Glacier. The surface drops by 100 m or more before rising to join the major ridge in East Antarctica.

scholarly journals Genetic diversity among populations of Antarctic springtails (Collembola) within the Mackay Glacier ecotone

Genome ◽  
2016 ◽  
Vol 59 (9) ◽  
pp. 762-770 ◽  
Author(s):  
Clare R. Beet ◽  
Ian D. Hogg ◽  
Gemma E. Collins ◽  
Don A. Cowan ◽  
Diana H. Wall ◽  
...  
Keyword(s):  
Climate Changes ◽  
Ross Sea ◽  
Sequence Divergence ◽  
Running Waters ◽  
The North ◽  
Victoria Land ◽  
The Reformation ◽  
Springtail Species ◽  
Biogeographic Regions ◽  
Coi Sequences

Climate changes are likely to have major influences on the distribution and abundance of Antarctic terrestrial biota. To assess arthropod distribution and diversity within the Ross Sea region, we examined mitochondrial DNA (COI) sequences for three currently recognized species of springtail (Collembola) collected from sites in the vicinity, and to the north of, the Mackay Glacier (77°S). This area acts as a transition between two biogeographic regions (northern and southern Victoria Land). We found populations of highly divergent individuals (5%–11.3% intraspecific sequence divergence) for each of the three putative springtail species, suggesting the possibility of cryptic diversity. Based on molecular clock estimates, these divergent lineages are likely to have been isolated for 3–5 million years. It was during this time that the Western Antarctic Ice Sheet (WAIS) was likely to have completely collapsed, potentially facilitating springtail dispersal via rafting on running waters and open seaways. The reformation of the WAIS would have isolated newly established populations, with subsequent dispersal restricted by glaciers and ice-covered areas. Given the currently limited distributions for these genetically divergent populations, any future changes in species’ distributions can be easily tracked through the DNA barcoding of springtails from within the Mackay Glacier ecotone.

Evidence for regional climate change in the recent evolution of a high latitude pro-glacial lake

1996 ◽  
Vol 8 (1) ◽  
pp. 49-59 ◽  
Author(s):  
Jenny Webster ◽  
Ian Hawes ◽  
Malcolm Downes ◽  
Michael Timperley ◽  
Clive Howard-Williams
Keyword(s):  
Mixed Layer ◽  
Lake Level ◽  
Regional Climate ◽  
Regional Climate Change ◽  
Physical Structure ◽  
Mcmurdo Dry Valleys ◽  
Dry Valleys ◽  
The North ◽  
Victoria Land ◽  
Upper Mixed Layer

Lake Wilson, a perennially ice-capped, deep (>100 m) lake at 80°S in southern Victoria Land was investigated in January 1993. Water chemistry and physical structure showed three distinct layers; an upper c. 35 m mixed layer of low salinity, moderately turbid water; a less turbid mid layer, 20 m thick of slightly higher salinity and supersaturated with oxygen; and a deep 20 m brackish layer (conductivity c. 4000 μS cm−1) with anoxic conditions in the lower 5 m. Extreme supersaturation of N2O (up to 400 times air saturation) together with high nitrate concentration (4000 mg m−3) was recorded in the deep layer. Phytoplankton biomass and photosynthetic activity was confined to the upper mixed layer and the band of supersaturated dissolved oxygen located at 40–55 m appears to represent a relict layer from when the lake level was lower. The evidence from a comparison of profiles between 1975 and 1993 suggests that Lake Wilson has risen 25 m since 1975, synchronous with a period of lake level rise in the McMurdo Dry Valleys lakes to the north at 77°S. Geochemical diffusion models indicate that Lake Wilson had evaporated to a smaller brine lake about 1000 yrs BP, which also fits the pattern shown by the McMurdo Dry Valleys lakes. Climate changes influencing lake levels have thus covered a wide area of southern Victoria Land.

scholarly journals Technical procedures for aeromagnetic surveys in Antarctica during the Italian expeditions (1988-1992)

1994 ◽  
Vol 37 (5 Sup.) ◽  
Author(s):  
E. Bozzo ◽  
A. Colla ◽  
G. Caneva ◽  
A. Meloni ◽  
A. Caramelli ◽  
...  
Keyword(s):  
Ross Sea ◽  
Base Stations ◽  
Aeromagnetic Survey ◽  
The North ◽  
Terra Nova Bay ◽  
Victoria Land ◽  
Range Type ◽  
Line Spacing ◽  
Tie Lines ◽  
Shelf Region

For most of Antarctica, the geophysical data now available are those of aeromagnetic surveys performed there from 1950 to 1960. Until 1984, the inaccurate positioning and insufficient monitoring of geomagnetic time variations allowed the investigation of the geomagnetic residual field only along profiles. The Ganovex IV aeromagnetic survey, performed by BGR-USGS over the Ross Sea and the Northern Victoria Land, and the geophysical investigations of BAS on the Southern Antarctic peninsula and the Ronne ice shelf region corresponds to the recent advancement of these techniques in Antarctica. The first experiments of aeromagnetic measurements, during the Italian expeditions in Antarctica were made during the 1988-1989 field season. Some geomagnetic helicopter borne profiles were accomplished with a Proton Precession Magnetometer (PPM) in the Terra Nova Bay-Gerlache Inlet area. In the 1989-1990 ItaliAntartide expedition some profiles were flown over the suture between the Wilson and Bower terranes, in Northern Victoria Land. During the 1991-1992 expedition, in cooperation with researchers of BGR (Bundesanstalt fur Geowissenschaften und Rohstoffe) of Hannover, the GITARA I (German ITalian Aeromagnetic Rescarch Antarctica) program, as part of the LIRA (Litospheric Investigation in the Ross Sea Area) project, was carried out. The investigated area lies between the latitudes 74°18' S and 75°18' S and the longitudes 160°30' E and 164°30'E and it corresponds to a portion of the North Victoria Land, located between the Eisenhower Range and the, DrygaIski Ice Tongue. The survey was made with a Cesium vapour magnetometer. The positioning system was of the “Range-Range” type, it consisted of three transmitters (beacons), installed inside the investigated area and located with GPS measurements. The line spacing was 4.4 km, with tie lines every 22 km. The survey covered an area of 6500 km2 . Four PPM base stations for the determination of the time variation corrections were installed. The aeromagnetic anomalies wilI allow the comparison with the ground geomagnetic surveys performed during the previous Antarctic expeditions, also in connection with the aeromagnetic maps of Ganovex IV, located at the northern and eastern boundaries of the GITARA area.

scholarly journals Ice dynamics and basal properties of Sofiyskiy glacier, Altai mountains, Russia, based on DGPS and radio-echo sounding surveys

2003 ◽  
Vol 37 ◽  
pp. 286-292 ◽  
Author(s):  
Frank Pattyn ◽  
Bert De Smedt ◽  
Sang De Brabander ◽  
Wim Van Huele ◽  
Anna Agatova ◽  
...  
Keyword(s):  
Force Balance ◽  
Surface Velocity ◽  
Seasonal Temperature ◽  
Altai Mountains ◽  
Ice Dynamics ◽  
The North ◽  
Basal Sliding ◽  
Radio Echo Sounding ◽  
Different Response ◽  
Echo Sounding

AbstractCentral Asian glaciers, compared to other glaciers in the world, should exhibit a different response to changing climate owing to (i) the extreme continentality that gives rise to aridity and large seasonal temperature variations, and (ii) the coincidence of accumulation and ablation seasons in summer. A detailed 4year field survey has been carried out on Sofiyskiy glacier in the south Chuya range(Altai mountains), Russia. Field observations reveal that this glacier retreated steadily during the 20th century at a rate of 18.3 m a–1, considerably faster than Maliy Aktru glacier, 30km to the north. Based on radio-echo sounding (RES), the subglacial topography of Sofiyskiy glacier has been reconstructed, and stake and snow-pit measurements enable the determination of surface velocity and mass balance. Basal sliding plays an important role in Sofiyskiyglacier’s behaviour, as is shown by a force-balance analysis. An analysis of RES measurements yields the bed reflection power (BRP). Using the three-layer reflectivity model of Born and Wolf (1986), the BRP is compared with the theoretical bed reflectivity for two contrasting layers of varying porosity and thickness. Results indicate that Sofiyskiy glacier possibly exhibits a polythermal regime.

Ice-Sheet flow in the Vicinity of Southern Victoria Land, Antarctica: Implications for Glacial Chronology

1979 ◽  
Vol 24 (90) ◽  
pp. 483-483
Author(s):  
David J. Drewry
Keyword(s):  
Ice Sheet ◽  
East Antarctica ◽  
Small Surface ◽  
The North ◽  
Ice Surface ◽  
Glacial Chronology ◽  
Victoria Land ◽  
Dry Valley ◽  
Radio Echo Sounding ◽  
Taylor Glacier

AbstractSystematic radio echo-sounding during three seasons since 1971–72 has produced data on the configuration of the ice sheet in East Antarctica. In the sector extending inland from southern Victoria Land, the ice sheet exhibits a large ridge which drives ice towards David Glacier in the north and Mulock and Byrd Glaciers to the south. Within 100 km of the McMurdo dry-valley region soundings along ten sub-parallel lines (c. 10 km apart) provides detail on ice surface and flow patterns at the ridge tip. A small surface dome lies just inland of Taylor Glacier. The surface drops by 100 m or more before rising to join the major ridge in East Antarctica.

Two unpublished accounts of the British Antarctic Expedition, 1839–43

Polar Record ◽  
1961 ◽  
Vol 10 (69) ◽  
pp. 587-604
Keyword(s):  
Ross Sea ◽  
Terrestrial Magnetism ◽  
The North ◽  
Prince Edward Islands ◽  
Victoria Land ◽  
Antarctic Expedition ◽  
North Magnetic Pole ◽  
Antarctic Continent ◽  
James Ross Island ◽  
Set Up

[The British Antarctic Expedition, 1839–43, consisted of two Naval vessels, H.M.S. Erebus and Terror, with Sir James Clark Ross as leader and Captain F. R. M. Crozier as second-in-command. The objects of the expedition were mainly concerned with terrestrial magnetism, a subject of particular interest to Ross who had discovered the North Magnetic Pole in 1831. The expedition circumnavigated the Antarctic continent and made a number of important geographical discoveries. It twice penetrated the pack ice.of the Ross Sea; it discovered, and roughly charted, 500 miles of new coastline in Victoria Land; it discovered Ross Island and the Ross Ice Front, also the James Ross Island group; it visited Prince Edward Islands, les Crozet and les Kerguelen; and it sighted Joinville Island and the Balleny Islands. Observations of terrestrial magnetism were made from stations, either permanent or temporary, set up during the voyage.

Comparison of Electromagnetic and Seismic-Gravity Ice Thickness Measurements in East Antarctica

1975 ◽  
Vol 15 (73) ◽  
pp. 137-150 ◽  
Author(s):  
David J. Drewry
Keyword(s):  
Seismic Reflection ◽  
East Antarctica ◽  
Ice Thickness ◽  
South Pole ◽  
Victoria Land ◽  
Radio Echo Sounding ◽  
Mean Differences ◽  
Thickness Measurements ◽  
Better Than ◽  
Echo Sounding

AbstractThe errors involved in ice thickness determinations in Antarctica by seismic reflection shooting, gravity observations and radio-echo sounding are briefly discussed. Relative accuracies of 3%, 7-10% and 1.5% have been suggested. Double checks of ice depths from radar sounding in east Antarctica indicate an internal consistency of measurement for this technique of &lt;1%. Comparison of carefully executed seismic shooting and routine radio-echo sounding results against absolute ice thickness values from two deep core drilling sites show no significant differences between these two remote methods (i.e. both are better than 1.5%).Over 60 comparisons are examined between radar ice thicknesses and over-snow measurements obtained on eight independent traverses in east Antarctica. Three traverses exhibit consistently unacceptable results-U.S. Victoria Land Traverse II (southern leg), Commonwealth Transanlarctic Expedition and the U.S.S.R. Vostok to South Pole Traverse—which probably result from misinterpretation of “noisy” seismograms. The remaining comparisons indicate mean differences, including some navigational uncertainty, of ≈3%, &lt;8% and 5% between radio-echo and (1) seismic, (2) gravity, and (3) gravity tied to seismic determinations, respectively.

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