Showing papers on "Antarctic sea ice published in 1972"
TL;DR: The Camp Century, Greenland, deep ice core reveals seasonal variations in the isotopic composition of the ice back to 8,300 years BP as discussed by the authors. But the complexity of the glaciological regime at Byrd Station precludes a rational choice of a time scale.
Abstract: The Camp Century, Greenland, deep ice core reveals seasonal variations in the isotopic composition of the ice back to 8,300 years BP. This is not the case for the Byrd Station, Antarctica, deep ice core. Both cores show long-term perturbations in isotopic composition reflecting climatic changes from before the beginning of the last glaciation. But the complexity of the glaciological regime at Byrd Station precludes a rational choice of a time scale. Pole-to-pole correlations of the palaeoclimatic data therefore become speculative except for the more pronounced features and general trends.
522 citations
TL;DR: In this article, it is suggested that existing models for the interpretation of ancient tills and the sequences in which they lie are often too simple and lead to erroneous stratigraphic and palaeogeographic conclusions.
Abstract: Sedimentary sequences currently forming at the margins of Spitsbergen glaciers are identical in thickness and detail to many Pleistocene and pre-Pleistocene glacigenic sequences. The transport of considerable volumes of englacial debris leads directly to the predominance of supraglacial till deposition, giving hummocky till surfaces and till plains. The association of supraglacial outwash with flow till produces tripartite till/outwash/till sequences, and multitill sequences, which are the result of a single glacier retreat phase. Complex tectonic structures, often with systematic regional trends are described, which are not the result of ice pushing but of downslope flow and collapse of supraglacial sequences above melting ice. New classifications are suggested for ice-contact stratified deposits and till, both of which depend upon position of deposition, supraglacial, englacial or subglacial It is suggested that existing models for the interpretation of ancient tills and the sequences in which they lie are often too simple and lead to erroneous stratigraphic and palaeogeographic conclusions. Till is too often interpreted solely as lodgement till, and it is suggested that many Pleistocene and earlier sequences, currently thought of as products of repeated glacier advance and readvance, may be perfectly normal products of a single retreat phase by a glacier with a thick englacial debris load. Ways of reconstructing the structural character of ancient ice margins are presented and it is also suggested that the thermal regimes of past ice sheets can be reconstructed from the nature of their deposits. The last Pleistocene ice sheet in Britain is thought to have been composed, at its maximum extent, of cold ice in the marginal zone and temperate ice in the internal zone.
267 citations
TL;DR: In this paper, the authors examined the role of glaciation in the formation of relic offshore permafrost in relatively shallow Arctic coastal areas, and the evidence suggests that offs...
Abstract: Underground ice is restricted to permafrost areas where its distribution is sporadic and often unpredictable. A knowledge of the distribution and abundance of underground ice is essential to northern development, because a variety of man induced disturbances can cause underground ice to thaw, often with serious consequences. The criteria for a classification of the principal types of underground ice are the source of the water prior to freezing and the processes which transfer water to the freezing plane. The origin of massive icy bodies in the Western Arctic of North America is explained by a water expulsion theory. The excess water now found in the icy bodies is attributed to water expelled from coarse textured sediments by the downward growth of permafrost. The suggested mechanism is illustrated by three pingos which have grown since 1950. The role of glaciation in the formation of relic offshore permafrost in relatively shallow Arctic coastal areas is examined. The evidence suggests that offs...
198 citations
TL;DR: The history of the Laurentide and Innuitian ice sheets is reviewed to help decide which model (or whether a combination of the two) is more appropriate at different times.
Abstract: Estimates are made of the volumes of the Laurentide ice sheet and the Innuitian ice sheet (covering the Canadian Arctic Islands north of latitude 74°N) from 18,000 to 6000 B.P. Relevant parts of the existing theory of flow in an ice sheet are first reviewed. Two limiting models are considered: a steady-state ice sheet, the dimensions of which do not change with time, and a stagnant ice sheet that thins at the same rate everywhere. Formulas relating ice thickness to radius and volume to area are given. The relation between area and volume of six existing ice sheets is examined to guide the choice of numerical parameters. The history of the Laurentide and Innuitian ice sheets is reviewed to help decide which model (or whether a combination of the two) is more appropriate at different times. Their volumes and thicknesses are then calculated from areas measured on a recent map of ‘speculative’ positions of the ice margins. Volume estimates for the Laurentide ice sheet are 26.5 × 106 km³ at maximum, 17.5 × 106 km³ at 11,800 B.P., and 6 × 106 km³ at 8500 B.P. The sea entered Hudson Bay shortly before 8000 B.P. and Foxe Basin a few hundred years thereafter. This divided the ice sheet into separate Keewatin, Labrador, and Foxe-Baffin ice sheets, which had an estimated total volume of 106 km³ at 7500 B.P. The Keewatin and Labrador sectors had disappeared by about 6000 B.P. The volume of the Innuitian ice sheet at maximum is estimated at 106 km³. It had decreased to its present-day value of 5 × 104 km³ by about 8000 B.P. Maximum errors in these figures are estimated at between. ±16% and ±20% at different times, plus an unknown amount for inaccuracies in the map of the ice margins. From maximum until about 12,000 B.P. the volume of the Laurentide ice sheet decreased much more rapidly than its thickness. If, at the ice sheet maximum, bedrock below its center in Hudson Bay was in isostatic equilibrium, between 150 and 390 meters of uplift must have occurred between 9000 and 8000 B.P. Melting of ice in the Laurentide and Innuitian ice sheets between 15,000 and 6000 B.P. can account for a rise in sea level of between 56 and 76 meters.
148 citations
TL;DR: In this article, a microscopic examination of autoradiographs suggests that heterotrophic metabolism by the algae was negligible and that assimilation of the added substrate was almost exclusively by bacteria.
Abstract: Complex algal populations in the bottom few centimeters of arctic sea ice are accompanied by bacteria, protozoans, and other organisms. Community uptake of dissolved organic substances, assayed with 14C-glycine, 14C-glucose, and 3H-acetate, was slow. Microscopic examination of autoradiographs suggests that heterotrophic metabolism by the algae was negligible and that assimilation of the added substrate was almost exclusively by bacteria.
112 citations
TL;DR: In this article, it was shown that erosion by continental ice sheets removed stratigraphic cover to exhume some of the world's largest areas of exposed Precambrian crystalline rock.
Abstract: The following observations suggest that erosion by continental ice sheets removed stratigraphic cover to exhume some of the world9s largest areas of exposed Precambrian crystalline rock. 1. Of the world9s large areas of exposed Precambrian rock, two were centrally located beneath great Pleistocene continental ice sheets that no longer exist, are proportionate to those ice sheets in size and similar in shape, and are great lowlands holding central seas. Most of the others are in areas that were covered by Paleozoic ice sheets and are presently overlain only by stratigraphic cover that is younger than those ice sheets. 2. Around Laurentian and Fennoscandian shields, arcs of exhumation control major topography and drainage. These are arcuate lowlands of continental scope encircling the shields at the Precambrian-Paleozoic contact where glaciation skinned Paleozoic rocks off crystalline basement. They are geometrically similar and are proportional in size to the ice sheets that excavated them. They form the St. Lawrence and upper MacKenzie valleys, including America9s greatest lake basins—Great Bear, Great Slave, Athabaska, Reindeer, Winnipeg, Winnipegosis, Lake of the Woods, Rainy Lakes, Great Lakes, and St. Lawrence Trough. European counterparts are Skagerrak, Baltic, Gulf of Finland, Lakes Ladoga and Onega, Onega Bay, Gulf of Dvinsk, and White Sea. 3. Peripheral parts of shields that were inundated by Pleistocene ice sheets show exhumed pre-Paleozoic terrain with a regional slope that is radially outward, down-glacier. Central parts are flat-floored basins that slope radially inward up-glacier and have no monad-nocks because glacial erosion cut deeply into pre-Paleozoic basement. 4. Erosion by the Laurentide and Fenno-scandian ice sheets has carved great hierarchies of ellipsoidal basins. In North America, the master basin holds Hudson Bay; the lesser radiating basins, farther down-glacier, hold the Great Lakes. A similar but lesser hierarchy has eastern Lake Ontario as its master basin and the Finger Lakes of New York as its lesser radiating basins.
91 citations
TL;DR: In this paper, a 4-week period after the initiation of river flow into the ice-covered ocean was observed along the Beaufort Sea coast of Alaska in 1970 during a 4 week period, during which the fast ice was inundated by fresh water overflow for as far as 10 km from shore.
Abstract: Reconnaissance observations were made along the Beaufort Sea coast of Alaska in 1970 during a 4-week period after initiation of river flow into the ice-covered ocean. During the first few days following river breakup, the fast ice was inundated by fresh-water overflow for as far as 10 km from shore. The water drained through widely distributed drain holes (strudel) in the ice creating scour depressions in the sea bottom. Later the rivers flowed directly into growing open-water areas surrounding distributary mouths and thence seaward below the fast ice. The presence of the sea ice during river flood greatly restricts the cross-sectional area available for the seaward flow out to at least the 2-m contour, where the bottom slope suddenly steepens. At the Colville Delta, the 2-m bench extends 5 to 8 km from shore and presumably represents an area of sediment bypassing. It appears that only insignificant amounts of sediment are rafted away from arctic Alaska9s deltas during the final breakup of the sea ice.
70 citations
TL;DR: Stable isotope analysis has been used successfully to distinguish between several different ice types in an ice tongue floating on sea water in Antarctica as discussed by the authors, and at one critical location this technique has provided the only means of discriminating unambiguously between glacial ice and fresh-water ice formed from desalinated sea water.
Abstract: Stable isotope analysis has been used successfully to distinguish between several different ice types in an ice tongue floating on sea water in Antarctica. At one critical location this technique has provided the only means of discriminating unambiguously between glacial ice and fresh-water ice formed from desalinated sea water. This part of the ice tongue is now underlain by a layer of desalted sea water thick enough to prevent any further accretion of sea ice at this location.
65 citations
TL;DR: In this paper, the bottom roughness reflects the action of grounded ice on the bottom of the Beaufort Sea shelf, and the likelihood is that an area of ice gouging on the inner shelf contains younger gouges than a similar area on the outer shelf.
42 citations
Book•
01 Jan 1972
TL;DR: In this paper, the positions of the continental ice sheet were determined in the light of the evidence provided by various end moraines, notably so-called De Geer morainees.
Abstract: The purpose of this study was to analyze the stages of deglaciation in southern and western Finland as well as in the Gulf of Bothnia. The positions of the continental ice sheet were determined in the light of the evidence provided by various end moraines, notably so‑called De Geer moraines. The findings were based on the interpretation of aerial photographs and topographic maps as well as on first‑hand investigations in the field. The earlier view of the deglaciation in the region covered proved to be correct, in the main, but revisions had to be made in certain details. The most important of the results involving changes were the following: 1) The continental ice sheet receded between the coast of the Gulf of Finland and the SalpausseIka systems toward the northwest maintaining a straight front. No bend corresponding to the great bend in Salpausselka I existed in the ice margin during this stage. The bend in the ice margin formed as it re‑advanced later to Salpausselka 1. 2) No long and narrow glacial bay existed in the region of Lake Paijanne. 3) Hameenkangas, the Nasijarvi formation and the Jyvaskyla esker developed at the edge of the glacier synchronously, forming a bipartite end‑moraine are. 4) In the region of Etela-Pohjamnaa (South Bothnia) and in the Quarken (Merenkurkku), the ice sheet retreated in a northwesterly direction. The ice margin did not cross the Quarken in a northwest‑southeast line. 5) In the great open stretch of the Gulf of Bothnia (= Bothnian Sea), there never existed a big glacial estuary – instead there was a great ice lobe. Normal 0 21 false false false FI X-NONE X-NONE /* Style Definitions */
table.MsoNormalTable
{mso-style-name:"Table Normal";
mso-tstyle-rowband-size:0;
mso-tstyle-colband-size:0;
mso-style-noshow:yes;
mso-style-priority:99;
mso-style-parent:"";
mso-padding-alt:0cm 5.4pt 0cm 5.4pt;
mso-para-margin-top:0cm;
mso-para-margin-right:0cm;
mso-para-margin-bottom:10.0pt;
mso-para-margin-left:0cm;
line-height:115%;
mso-pagination:widow-orphan;
font-size:11.0pt;
font-family:"Calibri","sans-serif";
mso-ascii-font-family:Calibri;
mso-ascii-theme-font:minor-latin;
mso-hansi-font-family:Calibri;
mso-hansi-theme-font:minor-latin;}
30 citations
TL;DR: In this article, it appears that millenial and longer variations in cloud-level temperature on the polar ice sheets have been caused by changing atmospheric turbidity over the past 105 yr.
Abstract: DATA relevant to the causation of climatic change, particularly changes in mean annual temperature at the surface over intervals of from 10 to 105 yr, have been accumulating gradually in various laboratories engaged in studying the two long ice cores from Camp Century, Greenland, and “New” Byrd Station, Antarctica This note consolidates these and other data and interprets them in the framework of existing theory It appears that millenial and longer variations in cloud-level temperature on the polar ice sheets have been caused by changing atmospheric turbidity over the past 105 yr
TL;DR: In this article, three groups of landforms of deglaciation are analyzed, namely those associated with the disappearance of Inland ice (main Greenland ice sheet), the withdrawal of local Sukkertoppen ice, and the changing of relative sea level.
Abstract: Three groups of landforms of deglaciation are analyzed, namely those associated with (1) the disappearance of Inland ice (main Greenland ice sheet), (2) the withdrawal of local Sukkertoppen ice, and (3) the changing of relative sea level. Consideration of their interrelationships in space and time allows a reconstruction of the process of deglaciation. There was an overall westerly movement of Inland ice across the area and this persisted during the early stages of deglaciation. Later stages of deglaciation reflect progressive downwasting with ice persisting in the troughs while adjacent plateau areas became free of ice. The highest marine limit is at 123 m and this incursion of the sea took place ca. 8,800 to 9,000 radiocarbon years BP. Local Sukkertoppen ice appears to have played an insignificant role during this main phase of deglaciation. Subsequently several Sukkertoppen outlet glaciers have advanced over marine deposits. The paper concludes with consideration of some wider implications. The importance of downwasting and meltwater activity during deglaciation is stressed. Also it is noted that isostatic recovery follows the Greenlandic pattern with high initial rates of uplift, apparently ceasing ca. 3,000 to 5,000 years BP. Unlike arctic Canada and Scandinavia where uplift has continued to the present day, the continued existence of a major ice sheet in Greenland is probably responsible for this recent stabilization. Finally, it is suggested that the last Inland ice sheet accomplished little erosion in the area compared to earlier ice sheets.
TL;DR: Satellite photographs for 2 years (March-September) have been used to study ice cover in the polynia called "North Water", and to determine whether reliable ice maps could be made from satellite data without computer analysis.
Abstract: Satellite photographs for 2 years (March-September) have been used to study ice cover in the polynia called "North Water," and to determine whether reliable ice maps could be made from satellite data without computer analysis After early July the clouds became opaque and distinction between cloud and ice is impossible It was concluded that ice distribution for short periods could best be obtained by careful photograph interpretation The most persistent open water is found at the northern edge, at about 78° N The southern ice edge is diffuse The changes in ice cover in the North are mainly caused by freezing and melting, whereas ice transport is important in the southern area
TL;DR: In this paper, the Laurentide and Scandinavian ice sheets would have large effects on global climate, and the authors suggest rapid growth of continental sheets with the development of thin ice cover over a large area.
TL;DR: In this paper, the authors described two localities with sub-till sediments from a Weichselian interstadial in the Gudbrandsdal (Bergersen & Garnes 1971).
Abstract: The authors have previously described two localities with sub-till sediments from a Weichselian interstadial in the Gudbrandsdal (Bergersen & Garnes 1971). Based on studies of striae and tills, the last glaciation is preliminarily divided into four phases. Most of the till in the investigated area is believed to have been deposited during the two first phases, A and B. During phase A the glaciers advanced from high mountain areas. Entering the valleys, the ice gave rise to ice-dammed lakes, the deposits of which are found as sub-till sediments. Phase B was the main phase of the inland ice with an ice divide northwest of the Gudbrandsdal. Later, during phase C, the ice divide was situated above the central part of the Gudbrandsdal. Consequently, the glacio-geological processes in the investigated area were modest during both phase C and the deglaciation period, phase D. During the latter, a gradual transition from active to stagnant to dynamically dead ice took place. Simultaneously the meltwater drainage ...
TL;DR: Open channels in sea ice may be acting as sources of atmospheric ions, as well as acting as Sources of Atmospheric ions, in response to changes in the temperature and direction of flow.
Abstract: Open channels in sea ice may be acting as sources of atmospheric ions.
01 Jan 1972
TL;DR: In this article, the authors discuss ice conditions in the Davis Strait and Baffin Bay and the effect of ocean currents on ice formation, and the authors also discuss the effects of wind currents on the formation of ice.
Abstract: : The report discusses ice conditions in the Davis Strait and Baffin Bay and the effect of ocean currents on ice formation.
01 Aug 1972
TL;DR: The AIDJEX Scientific Plan as mentioned in this paper proposes to conduct measurements from an array of drifting stations in the Arctic Ocean to understand the forces acting on the ice and the resulting motion and deformation of the ice pack.
Abstract: Bulletin No. 15 is devoted exclusively to the AIDJEX Scientific Plan. An operations and logistics plan for the main experiment will appear in a later Bulletin. An understanding of the large-scale response of sea ice to its environment is needed for solving many important theoretical and practical problems, ranging from the interaction between ice cover and global circulation to the passage of ships in ice-covered seas. It is proposed to conduct measurements from an array of drifting stations in the Arctic Ocean. The measurement programs at the stations will define all the forces acting on the ice and the resulting motion and deformation of the ice pack. The data from the proposed experiment should yield new results on the rheology of sea ice and on the interactions between the Arctic Ocean, the sea ice, and the atmosphere. A series of pilot studies is now in progress. The main experiment is scheduled to begin in the spring of 1975, and to last for about one year.
01 Feb 1972
TL;DR: In this article, the authors examined the relationship between water motion and ice motion on shorter time and space scales by a more detailed examination of the hydrographic and current structure in the Beaufort Sea gyre.
Abstract: : The relationship between water motion and ice motion is not so well understood. Over very large time and space scales in the Beaufort Sea gyre, the ice and water motions are obviously correlated; both perform a large clockwise rotation, and both are in geostrophic balance. The objective of this experiment was to examine this interrelationship on shorter time and space scales by a more detailed examination of the hydrographic and current structure.
TL;DR: In this paper, the sea ice pressure experienced by the icebreaker Louis S. St Laurent while escorting the tanker Manhattan in the Baffin Bay area in April-May 1970 were observed along with certain wind, ice and ship performance data.
Abstract: Sea-ice pressures encountered by the icebreaker Louis S. St. Laurent while escorting the tanker Manhattan in the Baffin Bay area in April-May 1970 were observed along with certain wind, ice and ship performance data. Pressure severity was estimated qualitatively. Most pressure episodes occurred during periods of onshore winds; and frequency of occurrence increased with higher wind speeds as did pressure severity. Pressure episodes were of short duration, but the overall inhibiting effect on vessel performance was substantial.
Dissertation•
01 Jan 1972
TL;DR: The results of a comprehensive three-year study of the Harr Ice Piedmont, Anvers Island, Antarctica are presented in this article, where the mass balance of a representative part of the piedmont is considered to be in equilibrium or possibly, slightly positive.
Abstract: The results of a comprehensive three-year study of the Harr Ice Piedmont, Anvers Island, Antarctica are presented. The piedmont stands on a low coastal platform ranging from slightly below sea level to 200 m. a.s.l. Ice thickness ranges from 60 to 80 m. at the coastal cliffs to more than 600 m. inland. Annual accumulation is high. There is a strong relationship between elevation and accumulation rates and a marked variation of accumulation rates from year to year. Surface ice velocities range from 14 m/year to 218 m/year and there is considerable ice streaming as a result of the subglacial topography. The mass balance of a representative part of the piedmont is considered to be in equilibrium or possibly, slightly positive. A study of a peripheral ramp shows annual fluctuations of balance and it is hypothesised that there may be a long-term tendency towards a positive regime. Ice core studies indicate that there is no dry snow facies but all other facies are identified. The saturation line lies at approximately 600 m. a.s.l. and the equilibrium line ranges from 60 to 120 m. a.s.l. Englacial ten-metre temperatures range from -0.8 oC near the coast to -4.9 oC inland. Deformation velocities have been calculated and basal sliding velocities inferred. It is hypothesised that basal conditions are not everywhere the same and that parts of the piedmont are frozen to bedrock. It is suggested that basal sliding and erosion are related and that the piedmont is selectively eroding its bed and accentuating the subglacial topography. Evidence of erosion, debris-rich ice, exists in the piedmont but is below sea level at the coastal cliff. The piedmont is not a "Strandflat Glacier" which is cutting a planed surface at a level controlled by the sea.
01 May 1972
TL;DR: In this paper, an impulse radar system was developed to perform shallow subsurface investigations, which is known as Electromagnetic Subsurface Profiling (ESP) and is the electrical analog of the seismic sub-bottom profiling method used in marine geology.
Abstract: : An impulse radar system was developed to perform shallow subsurface investigations. The technique is known as Electromagnetic Subsurface Profiling (ESP) and is the electrical analog of the seismic sub-bottom profiling method used in marine geology. The radar system operates by detecting the interface between two materials having different electrical properties. For sea ice and lake ice, an electromagnetic pulse is generated near the ice surface and the reflections from the surface and the ice/water interface are displayed on a continuous strip-chart recorder. Large masses of ground ice in perma-frost have been located with the system. Theoretical considerations indicate that the system also should be able to determine the approximate volume of interstitial ice in frozen soils. (Modified author abstract)
TL;DR: For the three Antarctic ice shelf stations considered (Norway Station, Maudheim, and Halley Bay) it was shown that from spring to autumn a systematic diurnal variation of the mean vector wind at the surface exists as mentioned in this paper.
Abstract: For the three Antarctic ice shelf stations considered (Norway Station, Maudheim, and Halley Bay) it is shown that from spring to autumn a systematic diurnal variation of the mean vector wind at the surface exists. Different factors that may be responsible for this variation are discussed. The results seem to agree well with the assumption that in areas far from the ice front (the seaward edge of the ice shelf) the main cause is the larger net gain of momentum in the lowest layers during the middle of the day, while closer to the ice front there is an additional effect of the varying contrast between the air temperature over the sea and over the ice shelf.
26 Oct 1972
TL;DR: In this article, the authors used 15 locations on the USSR Arctic coast to construct theoretical ice growth curves based on mean monthly and mean daily maximum and minimum temperatures, respectively, for 15 locations.
Abstract: : Frost-degree data for 15 locations on the USSR Arctic coast are used to construct theoretical ice growth curves. The frost degree data are based on mean monthly and mean daily maximum and minimum temperatures. Zubov's ice growth equations converts frost degree day accumulations into ice thickness. (Author)