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The ASTIS database cites the following 58 publication(s) by Gerald Holdsworth. Publications are listed from newest to oldest. Please tell us about publications that are not yet cited in ASTIS.


Discovery of mid-third-millennium B.P. wood at Ogilvie Pass in the St. Elias Mountains of Canada   /   Holdsworth, G.   Lacourse, T.
(Alaska journal of anthropology, v. 12, no. 2, 2014, p. 92-94)
References.
Correction of mean temperature supplied by author, 13° C should read -13° C.
ASTIS record 82124.
Languages: English
Web: https://www.alaskaanthropology.org/wp-content/uploads/2015/11/Research-Notes-AJA-v122.pdf
Libraries: ACU

On 11 May 2005, a site was being prepared for an automatic weather station (AWS) on the end of a rock ridge. This ridge descended from a mountain summit on the west side of Ogilvie Glacier, which descends 1,300 m in 12 km to merge into Logan Glacier flowing west along the north side of Mount Logan. The west end of the West Ridge of Mt. Logan terminates on the other side of Ogilvie Glacier opposite the AWS site (GPS coordinates 60° 37' 07", 140° 47' 00"; 2,930 m asl). To the south, there is a dropoff into Quintino Sella Glacier, which flows southwest into Alaska. Thus the ridge and the surrounding snow-covered glacier ice form a pass between two snow sheds. About 5 m west of the AWS site, located in a slight depression in the ridge, two stick-sized pieces of wood were seen protruding 10 to 12 cm through a patch of gravel exposed after some large boulders had been removed for stabilizing the AWS tripod. On a later visit a third stick 1.32 m long was discovered partly protruding from a surface layer of clear ice. All sticks were lying flat and parallel to the long axis of the ridge within approximately a 1 m² area. The site has a mean annual temperature of [-13 °C] with severe winter winds and there are no signs of moss or lichens on any of the rocks, which are sedimentary-metamorphic and highly fractured. There is no possibility that the wood ever grew there or was transported there by ice. Furthermore the thick end of the 1.32 m stick was splintered, as typically results from screwing a branch off a tree by hand or, in this case, likely screwing a stem out of the ground. The evidence strongly suggested the wood was placed there by human hands. On 10 June 2007, after clearing the site of snow and ice, much more than existed in 2005, a sample of the loosened stick (then protected by rocks) was obtained by the author for dating purposes. A 14C AMS radiocarbon age of 2430 ± 20 yrs BP was obtained in 2010 (ULA-1912/UCIAMS-84618). This places it in the mid-Neo-Glacial interval of the Holocene. ... (Au)

F, G, H, U
Archaeology; Exploration; Glacier ice; Glaciers; Radiocarbon dating; Weather stations; Willows; Wood fuel

G0811
Logan, Mount, Yukon; St. Elias Mountains, Alaska/British Columbia/Yukon


Colin Bruce Bradley Bull (1928-2010)   /   Holdsworth, G.
(Arctic, v. 63, no. 4, Dec. 2010, p. 483-484, portrait)
References.
ASTIS record 72131.
Languages: English
Web: http://pubs.aina.ucalgary.ca/arctic/Arctic63-4-483.pdf
Web: doi:10.14430/arctic3344
Libraries: ACU

Colin Bruce Bradley Bull was born on 13 June 1928 in Birmingham, United Kingdom. The family moved to Herefordshire, where Colin completed his early schooling. In 1945, he enrolled at the University of Birmingham and earned a Bachelor of Science in physics with first-class honours. A following master's degree quickly led to a doctorate in solid-state physics in 1952. While writing his thesis, which related to the properties of fluorescent coatings on radar screens, Bull was introduced to rock climbing in Great Britain. And in the summer of 1951, as if to apply what he had learned, he traveled with a group of hardy, geologically minded graduate student friends to Spitsbergen, where they figured out the geological structure and history of a selected area of the island. He wrote a highly readable book about this venture called Innocents in the Arctic (Bull, 2005). The experience must have made a lasting impression upon him because after only a short time in the Physics Department of Cambridge University, he joined the British North Greenland Expedition (1952-54) as a geophysicist-glaciologist and meteorologist. He used a Worden gravity meter to determine the thickness of the Greenland ice cap and also did gravity traverses over proglacial lake ice to determine lake depth. The Greenland expedition marked his departure from experimental physics into a life of exploration and glaciology, with a gravity meter as his "stock research instrument." In 1955, he joined the Cambridge (UK) expedition to the Norwegian glacier Austerdalsbrae, where again he employed a gravity meter to determine glacier thicknesses. This was the first time that the method had been applied to a valley glacier (Bull and Hardy, 1956). In 1956, he married Diana Gillian Garrett. Soon after, they emigrated to New Zealand, where Colin accepted a senior lectureship in the Department of Physics at Victoria University of Wellington (VUW). His polar experience was immediately put to use when he assumed the leadership of the 1958-59 VUW Antarctic Expedition to the Dry Valleys region. He returned to Antarctica as a member of the 1960-61 VUW Antarctic Expedition party. On both expeditions, he used a gravity meter in the Wright Valley and the Koettlitz Glacier region both to delineate geological structure (a rock fault) and to determine glacier thicknesses. At a 40th anniversary celebration, Colin was commissioned to write a book about the 1958-59 VUW Antarctic Expedition, which was published in 2009 as Innocents in the Dry Valleys, using the now familiar Twainian title twist. In 1961, Colin accepted an invitation by Richard P. Goldthwait, Professor of Geology at the Ohio State University (OSU), to relocate to Columbus, Ohio. There he taught geophysics (specializing in glaciology) and helped to establish the Institute of Polar Studies, later called the Byrd Polar Research Center (BPRC). The next summer he and four others journeyed to Southwest Greenland to begin a reconnaissance of the Sukkertoppen ice cap. On the expedition was Fritz Löwe, the legendary German meteorologist who was a member of the 1930-31 Alfred Wegener expedition to the Greenland ice cap. Together with Henry Brecher, now a BPRC icon, Colin and Löwe established a line across the ice cap, along which gravity measurements were made to determine ice thicknesses. By now, Colin was known for his expedition cooking. In February 1964, I attended Ohio State University to study glaciology under Professor Bull and glacial geology under Professor Goldthwait. That summer, after spring course work, Colin persuaded me to join him and two of his other grad students and Henry (from the Geodetic Sciences Department, OSU) at the Arctic Institute of North America's research station at Kluane Lake, Yukon. We were all flown up to "Divide Camp" on the Kaskawulsh Glacier. Henry and I opted to do our master's theses on the north arm of the glacier, I measuring crevasse geometries and dynamics and Henry measuring short-term vari a tions in ice flow rate. Without my being aware of any "arrangement," Colin turned up one day with the OSU Worden gravity meter! He did the gravity measurements I needed along one of our surveyed lines, as well as the reduction of the data. In spring 1965, we received the first of three annual grants from the National Science Foundation for studying processes within a glacier that was frozen to its bed Colin had determined, on the basis of observations he made during the VUW Antarctic Expeditions, that one of the Wright Valley (Antarctica) glaciers would be suitable. By late November 1965, I was starting my PhD fieldwork on the Meserve Glacier, which I had selected. He had judged that with my engineering and mountaineering background, I could figure things out. ... I was about third in his succession of 14 graduate students from six countries in the 1960s and 1970s. Two of his distinguished glaciology students remained at OSU: the late Professor Ian Whillans and Professor Lonnie (‘Iceman’) Thompson. Thompson and his wife, Professor Ellen Mosely-Thompson, expertly maintain a busy ice-core processing laboratory and teach courses in glaciology/climatology. The contributions of Colin's students are just one of his many legacies. Colin was a member of the Board of Governors of the Arctic Institute of North America (1967-72), director of the Institute of Polar Studies (1965-69), Chairman of the Department of Geology (1969-72), and Dean of the College of Mathematical and Physical Sciences (1972-86). In that capacity, he strived to keep the growing Byrd Polar Research Center well supported. In 1986, he and Gillian moved to Bainbridge Island near Seattle. Colin maintained a large polar library and later began writing his own expedition books. He still found time to provide his glaciological expertise to a Chilean mining company. Here is a man who was specially built for polar exploration, who received the Polar Medal from Queen Elizabeth II and the Antarctica Service Med al from the U.S. government for participating in more than 25 action-packed polar expeditions during his distinguished career. He was largely self-trained in "on the job" expeditionary matters, and, as typical of the adventurous British, he was a skillful improviser. His death came unexpectedly while he and Gillian were cruising the Alaska Marine Highway. For me this is not an obituary, but a tribute: his image and memory live on. ... (Au)

F, V
Biographies; Bull, Colin Bruce Bradley, 1928-2010; Crevasses; Expeditions; Glacier variations; Glaciers; Gravity measurement; Instruments; Measurement; Publishing; Thickness

G0811, G15, G10
Antarctic regions; Kaskawulsh Glacier, Yukon; Nordgrønland


A GCM-based analysis of circulation controls on delta 18O in the southwest Yukon, Canada : implications for climate reconstructions in the region   /   Field, R.D.   Moore, G.W.K.   Holdsworth, G.   Schmidt, G.A.
(Geophysical research letters, v. 37, L05706, 2010, 5 p., ill., maps)
References.
ASTIS record 69958.
Languages: English
Web: doi:10.1029/2009GL041408
Libraries: ACU

To improve our understanding of paleoclimatic records in the southwest Yukon, we examined controls on precipitation delta 18O using an isotopically-equipped atmospheric general circulation model (GCM). Our results show that, particularly during the cool-season, elevated delta 18O is associated with a deeper Aleutian Low and stronger southerly moisture flow, while lower delta 18O is associated with the opposite meteorological conditions. These results suggest that the large mid-19th century shift towards lower delta 18O values seen in paleoclimate records from the region was associated with a shift towards a weaker Aleutian Low. While in disagreement with a previous interpretation of this shift, it is consistent with records of glacial advance and tree-ring growth during the same period, and observational studies of Aleutian Low controls on temperature and precipitation in the region. (Au)

F, A, E, B, D
Atmosphere; Atmospheric temperature; Bottom sediments; Boundary layers; Cores; Dendrochronology; Glaciers; Isotopes; Mathematical models; Measurement; Meteorological instruments; Mountains; Ocean-atmosphere interaction; Oxygen-18; Palaeoclimatology; Precipitation (Meteorology); Seasonal variations; Snow; Spatial distribution; Synoptic climatology; Temporal variations; Water vapour; Winds

G0811, G061, G05, G0812, G06
Alaska, Gulf of; Barrow, Alaska; Bethel, Alaska; Jellybean Lake, Yukon; Logan, Mount, Yukon; North Pacific Ocean; Whitehorse, Yukon; Yellowknife, N.W.T.; Yukon


Interpreting H2O isotope variations in high-altitude ice cores using a cyclone model   /   Holdsworth, G.
(Journal of geophysical research, v.113, no. D8, D08103, Apr. 2008, 11 p., ill.)
References.
ASTIS record 63924.
Languages: English
Web: doi:10.1029/2007JD008639
Libraries: ACU

Vertical profiles of isotope (delta 18O or deltaD) values versus altitude (z) from sea level to high altitude provide a link to cyclones, which impact most ice core sites. Cyclonic structure variations cause anomalous variations in ice core delta time series which may obscure the basic temperature signal. Only one site (Mount Logan, Yukon) provides a complete delta versus z profile generated solely from data. At other sites, such a profile has to be constructed by supplementing field data. This requires using the so-called isotopic or delta thermometer which relates delta to a reference temperature (T). The construction of gapped sections of delta versus z curves requires assuming a typical atmospheric lapse rate (dT/dz), where T is air temperature, and using the slope (d delta/dT) of a site-derived delta thermometer to calculate d delta/dz. Using a three-layer model of a cyclone, examples are given to show geometrically how changes in the thickness of the middle, mixed layer leads to the appearance of anomalous delta values in time series (producing decalibration of the delta thermometer there). The results indicate that restrictions apply to the use of the delta thermometer in ice core paleothermometry, according to site altitude, regional meteorology, and climate state. (Au)

F, E, B, A, D
Atmospheric chemistry; Atmospheric circulation; Atmospheric humidity; Atmospheric temperature; Boundary layers; Climatology; Clouds; Coasts; Cores; Deuterium; Glacial epoch; Glaciers; Ice caps; Ice sheets; Isotopes; Mathematical models; Measurement; Meteorological instruments; Ocean-atmosphere interaction; Oxygen-18; Palaeoclimatology; Precipitation (Meteorology); Recent epoch; Satellite photography; Sea water; Seasonal variations; Snow; Spatial distribution; Storms; Surface properties; Synoptic climatology; Temperature; Temporal variations; Topography; Velocity; Water vapour; Winds

G0811, G15, G10, G11
Alps, Europe; Antarctic regions; Donjek Glacier, Yukon; Greenland; Himalaya Mountains; Logan, Mount, Yukon; North Atlantic Ocean; Rocky Mountains, Alberta; Summit, Greenland


A composite isotopic thermometer for snow   /   Holdsworth, G.
(Journal of geophysical research, v.113, no. D8, D08102, Apr. 2008, 13 p., ill.)
Appendix.
References.
ASTIS record 63923.
Languages: English
Web: doi:10.1029/2007JD008634
Libraries: ACU

The isotopic delta thermometer for snow is an equation that relates the isotopic delta value (derived from 18O/16O or D/H values) to some prescribed reference temperature. In contrast to the usual linear least squares fit of mean annual isotopic versus site mean annual surface temperature , a cubic equation is fitted to a composite, global, spatial (, ) data set. A ± 4‰ local variance along the curve indicates that delta values are influenced by factors other than the temperature signal, but in the long-scale smoothing process these factors are filtered out. As data over the complete range of raw temperatures are inhomogeneous, because of the existence of strong temperature inversions in the cold half, a transformation scheme is applied to homogenize the data. This produces a new series, . These values are more likely to be near the mean condensation temperature () of the snow. The slope, d /d, as a quadratic function of , best fits many published spatial and temporal slope determinations. The results have obvious application to the theory of isotopic processes not covered here. However, in an important practical application, the new equation can be utilized in the construction of diagrams of delta versus altitude where a delta value needs to be obtained from a known or calculated air temperature and where field data are gapped, especially at high altitude. Such diagrams can be used to demonstrate cases where site-specific delta thermometers may become invalid because of atmospheric structural changes, as shown in an associated paper that will be briefly outlined. (Au)

F, E
Atmospheric circulation; Atmospheric humidity; Atmospheric temperature; Boreholes; Climatology; Cores; Glaciers; Ice sheets; Isotopes; Mathematical models; Measurement; Meteorological instruments; Oxygen-18; Precipitation (Meteorology); Slopes; Snow; Spatial distribution; Surface properties; Temperature; Velocity; Winds

G15, G0811, G10, G13
Antarctic regions; Greenland; Logan, Mount, Yukon; Spitsbergen, Svalbard


Variability in the climate of the Pacific Ocean and North America as expressed in the Mount Logan ice core   /   Moore, G.W.K.   Alverson, K.   Holdsworth, G.
(Papers from the International Symposium on Ice Cores and Climate, held in Kangerlussuaq, Greenland, 19-23 August 2001 / Edited by E.W. Wolf et al.. Annals of glaciology, v. 35, 2002, p. 423-429, ill., maps)
References.
ASTIS record 54886.
Languages: English
Web: doi:10.3189/172756402781817185
Libraries: ACU

In this paper, we explore the climate signal contained in the annual snow-accumulation time series from a high-altitude ice core drilled on Mount Logan in the Saint Elias mountain range of western Canada. With the global meteorological fields from the U.S. National Centers for Environmental Prediction re-analysis, we construct composites of the atmospheric circulation and temperature patterns associated with anomalous snow accumulation at the Mount Logan site over the period 1948-87. These results confirm, with an independent method, previous work that identified the existence of a coherent upper-tropospheric circulation anomaly extending over much of the North Pacific Ocean and North America that is associated with snow accumulation at the site. This anomaly has a similar structure to that associated with the extratropical response to the El Nino-Southern Oscillation. Coherent structures consistent with this circulation pattern also exist in both air- and land-temperature fields. In particular, heavy (light) snow accumulation at the site is associated with warmer (colder) air and surface temperatures over the North Pacific Ocean and North America. Over the North Pacific, the sea-surface temperature anomaly associated with heavy snow accumulation at the site has a "horseshoe" pattern that is similar to that associated with the Pacific Decadal Oscillation. (Au)

E, F, D, J
Accumulation; Atmospheric circulation; Atmospheric temperature; Climate change; Climatology; Cores; Glaciers; Heat transmission; Mathematical models; Ocean temperature; Satellites; Snowfall; Temporal variations

G0811, G06, G05
Japan; Logan, Mount, Yukon; North America; North Pacific Ocean; Yukon


Quantitative measurements of Tweedsmuir Glacier and Lowell Glacier imagery   /   Holdsworth, G.   Howarth, P.J.   Ommanney, C.S.L.
(Glaciers of North America / Edited by Richard S. Williams and Jane G. Ferrigno. U.S. Geological Survey professional paper, 1386-J-1, 2002, p.J312-J326, ill., 1 map)
References.
ASTIS record 53253.
Languages: English
Libraries: ACU

Tweedsmuir and Lowell Glaciers ... are located in the St. Elias Mountains in the watershed of the Alsek River, a river that they both have dammed in the recent past. The terminal regions of both glaciers exhibit prominent surface features typical of surging glaciers .... It is likely that their surges are, at least in part, thermally controlled .... One of the most distinctive aspects of their surface features is the folded structure seen in the exposed ice in the lower part of each glacier. The folds are defined by medial moraines and by different ice types, which may appear white, blue, or gray depending on the content of air bubbles and fine-grained sediment. ... For the features to be seen on visible-band satellite images, the lower (ablation) region of the glacier, where the fold fields are found, needs to be totally free of seasonal snow cover. Because of this, and because of a high incidence of cloud cover in the region, the best period to obtain imagery to study moraine movement is normally in August or September, when also, the low Sun angle provides optimum scene contrast and relief detail. ... Significant information has been obtained about the dynamics of two large surging glaciers that occupy segments of a major Yukon-British Columbia-Alaska river system (the Alsek). This information has come from analysis of suitably selected Landsat imagery, supplemented by minimal ground-based observations. ... (Au)

F, A, E
Aerial photography; Clouds; Drainage; Flow; Glacial melt waters; Glacier lake outbursts; Glacier lakes; Glacier surges; Glaciers; Hydrology; Maps; Mass balance; Measurement; Moraines; Optical properties; Remote sensing; River discharges; Rivers; Satellite photography; Strain; Thickness; Topography; Velocity

G0811, G06
Alsek River region, Alaska/British Columbia/Yukon; Alsek River, Alaska/British Columbia/Yukon; Grand Pacific Glacier, Alaska/British Columbia; Hubbard Glacier, Alaska/Yukon; Lowell Glacier, Yukon; Melbern Glacier, British Columbia; Seward Glacier, Alaska/Yukon; St. Elias Mountains, Alaska/British Columbia/Yukon; Tweedsmuir Glacier, British Columbia/Yukon


Glaciers of the St. Elias Mountains   /   Clarke, G.K.C.   Holdsworth, G.
(Glaciers of North America / Edited by Richard S. Williams and Jane G. Ferrigno. U.S. Geological Survey professional paper, 1386-J-1, 2002, p.J301-J312, ill., 1 map)
References.
With a section on Quantitative Measurements of Tweedsmuir Glacier and Lowell Glacier Imagery by Gerald Holdsworth, Philip J. Howarth, and C. Simon L. Ommanney, ASTIS record 53253.
ASTIS record 53252.
Languages: English
Libraries: ACU

The St. Elias Mountains region of Canada is made up of a series of mountain ranges that contain a particularly wide variety of glacier types, defined both morphologically and thermally. This variety is a result of the extreme topography, which has a maximum relief of 4,200 meters within a few kilometers, coupled with the large gradients recorded in precipitation and temperature throughout the ranges. Glacier types seen here are valley glaciers, high-elevation plateau glaciers, ice fields and associated outlet glaciers, and piedmont glaciers of different shapes and sizes. Glacier lengths range from about a kilometer to more than 70 kilometers (Hubbard Glacier, which ends in Alaska, has a length of 72 kilometers in Canada and a total length of 112 kilometers); their areas range from a few square kilometers to more than 1,200 square kilometers for Seward Glacier. Temperate glaciers are common at low elevations, particularly on the Pacific Ocean side of the axis (drainage divide). Subpolar glaciers are present on the north (continental) side of the axis even at low elevations. Cold glaciers, at "polar" temperatures, exist on high-elevation plateaus such as on Mount Logan (5,956 meters). The presence of a large concentration of generally subpolar surging glaciers in the region is particularly noteworthy. This topic receives the most attention here because features diagnostic of surges are easily detected on satellite images, from which time-series measurements, related to the dynamics of the glacier, may be made, as shown for Tweedsmuir Glacier and Lowell Glacier. (Au)

F, A
Aerial photography; Arctic Institute of North America. Icefield Ranges Research Project; Drainage; Glacial melt waters; Glacier lake outbursts; Glacier lakes; Glacier surges; Glaciers; Hydrology; Mountains; Remote sensing; Research; River discharges; Rivers; Satellite photography; Valleys

G0811, G0821, G06
Alsek River region, Alaska/British Columbia/Yukon; Chitina River region, Alaska; Donjek River region, Yukon; Lowell Glacier, Yukon; Slims River region, Yukon; St. Elias Mountains, Alaska/British Columbia/Yukon; Tweedsmuir Glacier, British Columbia/Yukon; White River region, Alaska/Yukon


Glaciers of the Coast Mountains   /   Clarke, G.K.C.   Holdsworth, G.
(Glaciers of North America / Edited by Richard S. Williams and Jane G. Ferrigno. U.S. Geological Survey professional paper, 1386-J-1, 2002, p.J291-J300, ill., 1 map)
References.
ASTIS record 53251.
Languages: English
Libraries: ACU

The Coast Mountains follow the Pacific coast of Canada and extend from southwestern British Columbia to southwestern Yukon Territory. The predominantly granitic bedrock forms elevated blocks that have been deeply dissected by erosion, yielding a distinctive pattern of disjointed highland ice fields that are drained by radiating outlet glaciers. Popular interest in the glaciers of the Coast Mountains centers on the hazards and problems that they engender and on their attractions as a recreational resource. Scientific interest has largely focused on their status as climate indicators. We touch on these various themes by discussing the glacier-associated problems of the Granduc mining operation near Leduc Glacier in northwestern British Columbia, the outburst floods of glacier-dammed Flood Lake, and the recreational and scientific roles of small glaciers in Garibaldi Provincial Park near Vancouver, British Columbia. (Au)

F, P, L, S, E
Climate change; Drainage; Effects of climate on ice; Environmental impacts; Glacier lake outbursts; Glacier lakes; Glaciers; Glaciology; Location; Mapping; Mass balance; Measurement; Mining; Ores; Outdoor recreation; Parks; Remote sensing; Research; SAR; Satellite photography; Tunnels

G0811, G0821
British Columbia; Leduc Glacier, British Columbia; Yukon


Barnes Ice Cap : geomorphology and thermodynamics   /   Holdsworth, G.
(Glaciers of North America / Edited by Richard S. Williams and Jane G. Ferrigno. U.S. Geological Survey professional paper, 1386-J-1, 2002, p.J178-J184, ill., maps)
References.
ASTIS record 53249.
Languages: English
Libraries: ACU

... Holdsworth discusses information from satellite images that is relevant to an understanding of the geomorphology of the Barnes Ice Cap and the events that define its morphology. (ASTIS)

F, E, A
Aerial photography; Calving (Ice); Drainage; Geomorphology; Glacier lakes; Glaciers; Glaciology; Ice caps; Mass balance; Moraines; Remote sensing; Satellite photography; Spatial distribution; Thermal regimes; Thermodynamics; Topography

G0813
Barnes Ice Cap, Nunavut; Generator Lake, Nunavut


Altitudinal variation of the stable isotopes of snow in regions of high relief   /   Holdsworth, G.   Krouse, H.R.
(Journal of glaciology, v. 48, no.160, 2002, p. 31-41, ill., maps)
Appendices.
References.
ASTIS record 51949.
Languages: English
Web: doi:10.3189/172756502781831638
Libraries: ACU

A major discontinuity in the variation of delta 18O (delta D) with altitude in high mountains was first seen in data from Mount Logan, Yukon Territory, Canada (Holdsworth and others, 1991). The profile of delta vs altitude revealed three well-defined regions: (1) a lower, monotonic, fractionation sequence below ~3 km; (2) a middle layer, typically 1-2 km thick, within which delta values are nearly constant or stepped with altitude, and (3) part of another fractionation sequence in the "quasi-geostrophic flow region" above ~5.3 km. The middle region was inferred to be a "mixed layer", combining moisture from regions (1) and (3). This type of structure is now seen to occur on other high-altitude mountains, including Cerro Aconcagua, Argentina, where observations reach almost 7 km. The new observations confirm the general occurrence of a multi-layered atmosphere during precipitation at high-altitude glacier sites. This structure is linked to synoptic-scale polar cyclones, where the middle layer is identified as being the signature of the warm-front zone. These results have implications for the common practice of using a specific, spatially derived, isotopic thermometer in the time domain for the paleoclimatic interpretation of high-altitude ice-core delta records. (Au)

F, A, E, B
Atmosphere; Boundary layers; Cores; Glaciers; Isotopes; Mathematical models; Measurement; Meteorological instruments; Mountains; Oxygen-18; Palaeoclimatology; Snow; Snow stratigraphy; Snowstorms; Spatial distribution; Synoptic climatology; Temporal variations; Winds

G0811, G06, G05, G0813
Alaska; Logan, Mount, Yukon; North Pacific Ocean; St. Elias Mountains, Alaska/British Columbia/Yukon; Whitehorse, Yukon; Yukon


Climate change in the North Pacific region over the past three centuries   /   Moore, G.W.K.   Holdsworth, G.   Alverson, K.
(Nature, v.420, no.6914, 28 Nov. 2002, p. 401-403, ill., maps)
References.
ASTIS record 50476.
Languages: English
Web: doi:10.1038/nature01229
Libraries: ACU

The relatively short length of most instrumental climate records restricts the study of climate variability, and it is therefore essential to extend the record into the past with the help of proxy data. Only since the late 1940s have atmospheric data been available that are sufficient in quality and spatial resolution to identify the dominant patterns of climate variability, such as the Pacific North America pattern and the Pacific Decadal Oscillation. Here we present a 301-year snow accumulation record from an ice core at a height of 5,340 m above sea level - from Mount Logan, in northwestern North America. This record shows features that are closely linked with the Pacific North America pattern for the period of instrumental data availability. Our record extends back in time to cover the period from the closing stages of the Little Ice Age to the warmest decade in the past millennium. We find a positive, accelerating trend in snow accumulation after the middle of the nineteenth century. This trend is paralleled by a warming over northwestern North America which has been associated with secular changes in both the Pacific North America pattern and the Pacific Decadal Oscillation. (Au)

E, F, D, V
Accumulation; Atmospheric circulation; Atmospheric humidity; Atmospheric pressure; Atmospheric temperature; Climate change; Climatology; Cores; Glaciers; History; Hydrology; Ocean-atmosphere interaction; Snow; Trenching

G05, G0811
Logan, Mount, Yukon; North America; North Pacific Ocean; St. Elias Mountains, Alaska/British Columbia/Yukon


Atmospheric teleconnection between Japan and the Saint Elias Mountains, Yukon   /   Holdsworth, G.
(Memoirs of National Institute of Polar Research (Japan). Special issue, no. 54, 2001, p. 161-168, ill., 1 map)
References.
ASTIS record 45854.
Languages: English
Libraries: ACU

Cross correlation between time series of (1) total precipitation for a combined four-station network in northern Japan and of (2) the net snow accumulation determined from an ice core obtained from Mount Logan (60.5°N, 5340 m) situated in the Saint Elias Mountains, Yukon, reveals high, statistically significant, cross correlation coefficients of +0.38 for annual data increasing up to +0.71 for seven point smoothing of the two 89 year series. The distance between sites is about 7000 km spanning the complete Pacific Ocean between latitudes of about 40°N and 60°N. A review of the extensive literature of oceanology and climatology for the North Pacific Ocean region indicates that a strong coupling exists between the ocean and the atmosphere especially up to and associated with the Polar Front Zone along which major cyclogenesis occurs during most months of the year. Cyclones track generally from west to east with a strong northerly component especially in the eastern (Gulf of Alaska) sector. Examination of these cyclones on GOES satellite images shows that weather systems can transport moisture from mid latitude ocean sources (<40°N) to high on Mount Logan over the top of the warm front zone and high above intervening coastal topography. Thus, the positive correlation between the two time series can be physically justified and qualifies the link as a genuine teleconnection. (Au)

E, F, D
Accumulation; Atmospheric circulation; Atmospheric humidity; Atmospheric pressure; Atmospheric temperature; Climatology; Cores; Glaciers; Meteorology; Ocean currents; Ocean temperature; Ocean-atmosphere interaction; Oceanography; Precipitation (Meteorology); Satellite photography; Snow; Storms; Weather stations; Winds

G05, G0811, G061
Alaska, Gulf of; British Columbian waters; Japan; Logan, Mount, Yukon; North Pacific Ocean; St. Elias Mountains, Alaska/British Columbia/Yukon


Extra-tropical response to ENSO as expressed in an ice core from the Saint Elias Mountain Range   /   Moore, G.W.K.   Holdsworth, G.   Alverson, K.
(Geophysical research letters, v. 28, no. 18, Sept. 15, 2001, p.3457-3460, ill., maps)
References.
ASTIS record 20190.
Languages: English
Web: doi:10.1029/2000GL012397
Libraries: ACU

The El-Niño Southern Oscillation (ENSO) is the dominant mode of inter-annual variability of the atmosphere-ocean system in the tropical Pacific and exerts its influence in the extra-tropics through persistent large-scale wave-like patterns in the atmosphere known as teleconnections. Although the physics of ENSO in the tropics is relatively well understood, our knowledge of its extra-tropical response is based on teleconnection patterns that are statistical in origin and derived from relatively short time series. In this paper we analyze the ENSO signal in an annually resolved record of snow accumulation covering the period 1736-1985 from an ice core obtained in the Saint Elias Mountains of the Yukon. This region is located in the center of an area with one of the most significant teleconnection signatures associated with ENSO. The high elevation of the site where the ice core was obtained allows it to sample the mid and upper-tropospheric flow where the extra-tropical response to ENSO has its largest amplitude. As we show, these characteristics of the site result in a significant ENSO signal in the snow accumulation time series. (Au)

E, F, D
Accumulation; Atmospheric circulation; Atmospheric humidity; Climate change; Climatology; Cores; Forecasting; Glaciers; Instruments; Measurement; Meteorology; Ocean currents; Ocean temperature; Ocean-atmosphere interaction; Oceanography; Oxygen-18; Precipitation (Meteorology); Snow; Sulphates; Tritium; Volcanism; Winds

G05, G0811
Logan, Mount, Yukon; North Pacific Ocean; South Pacific Ocean; St. Elias Mountains, Alaska/British Columbia/Yukon


Calibration changes in the isotopic thermometer for snow according to different climatic states   /   Holdsworth, G.
(Geophysical research letters, v. 28, no. 13, July 1, 2001, p.2625-2628, ill.)
References.
ASTIS record 14249.
Languages: English
Web: doi:10.1029/2000GL011999
Libraries: ACU

Bore hole thermometry indicates that the estimated temperature shift at Summit (Greenland) from the Last Glacial to Holocene times was ~50% higher than the value obtained using the traditional isotopic delta (T) thermometer calibrated with today's data. A mechanism offered by Boyle (1977) to explain the anomalous ice core delta shift is examined. The mechanism, called the Boyle Effect, is theoretically possible but if it operated at Summit, it appears to be only capable of accounting for slightly more than half of the Summit delta 18O anomaly of ~4.3‰. A new semi-quantitative mechanism is proposed that could account for the remaining part of the anomaly. Other mechanisms have been advanced but they are not so amenable to quantitative application and testing. (Au)

F, A, E
Atmospheric circulation; Atmospheric humidity; Atmospheric temperature; Boreholes; Climatology; Cores; Ice sheets; Instruments; Mathematical models; Measurement; Ocean temperature; Oxygen-18; Pleistocene epoch; Precipitation (Meteorology); Recent epoch; Storms; Temperature; Velocity; Winds

G10, G11, G0811
Logan, Mount, Yukon; North Atlantic Ocean; Summit, Greenland


Mount Logan on CD-ROM : the top of Canada   /   Holdsworth, G.
Calgary, Alta. : Arctic Institute of North America, 1999.
1 CD-ROM : col. ill., maps (some col.).
ISBN 0-919034-95-0
References are highlighted in green, clicking on them opens a pop-up window with the full citation.
Words in the glossary are highlighted in blue, clicking on them opens a pop-up window containing the definition.
This CD-ROM is volume 1. Volume 2 is in progress.
ASTIS record 50377.
Languages: English
Libraries: ACU

Minimum system requirements: Windows 95, 98 or NT: Pentium 166 MHz, 32 MB memory, 20 MB disk space, 16 bit color, 16 bit sound, and 8X speed CD-ROM. Macintosh: PowerPC, 32 MB memory, 20 MB diskspace, System 7.1 or later, 16 bit color, and 8X speed CD-ROM. After installation, double-clicking on Logan.exe starts the program and a window opens with numerous options including Intro and Chapters. Intro presents a slide show of Mount Logan set to music and "On the Greatness of a Mountain" by Lama Anagarika Govinda. Chapter 1, "The Discovery of Majestic Mountain: prehistory - 1982", is the main introduction and contains information on the first recorded sightings of Mount Logan (called Majestic Mountain until 1890). Chapter 2, "Interlude", is a biography of Sir William E. Logan who was the founder and first director of the Geological Survey of Canada. American explorer/geologist I.C. Russell sighted Majestic Mountain in 1890 and named it Mount Logan. Chapter 3, "The Alaska Boundary Politics, Surveys, and Exploration: 1892 to 1945" discusses the Alaska Boundary Survey and the International Boundary Commission's work on defining and surveying the Alaska/Yukon/B.C. border. Included is information on the first altitude survey, first ascent, and first aerial photographs of Mount Logan. Chapter 4, "Exploration and Ascents: 1950 to Present", describes the subsequent ascents and climbing history of Mount Logan. Chapter 5, "Topographic and Geodetic Surveys of Mount Logan: 1948 - Present", contains background information on geodesy and geomatics, a history of surveying mountains in Alaska and Yukon, and information on the Arctic Institute of North America's Project Snow Cornice (1948-49) which provided the first opportunity to survey Mount Logan at close range from the south. Included with the Chapters is "Panorama", a 360° photographic view from the summit of Mount Logan. (ASTIS)

B, A, F, V, W
Aerial photography; Arctic Institute of North America. Project Snow Cornice; Biographies; Boundaries; CD-ROMs; Exploration; Explorers; Geographical positioning systems; Geography; Geological Survey of Canada; Geological Survey of Canada Yukon Expedition, 1887-1901; Geologists; Gravity measurement; History; Klondike Gold Rush, 1898; Mountaineering; Mountains; Natural history; Pictorial works; Recent epoch; Size; Surveying; Topography

G0811, G0821, G06, G061, G05
Alaska, Gulf of; Alaska, Gulf of, region; British Columbian waters; Icy Bay, Alaska; Logan, Mount, Yukon; St. Elias Mountains, Alaska/British Columbia/Yukon; Yakutat Bay, Alaska


An assessment of the regional distribution of the oxygen-isotope ratio in northeastern Canada   /   Giovinetto, M.B.   Holdsworth, G.   Fisher, D.A.   Waters, N.M.   Zwally, H.J.
(Papers from the International Symposium on Representation of the Cryosphere in Climate and Hydrological Models, held at Victoria, British Columbia, Canada, 12-15 August 1996 / Edited by J.E. Walsh. Annals of glaciology, v. 25, 1997, p. 214-219, ill., 1 map)
References.
ASTIS record 52412.
Languages: English
Libraries: ACU

A compilation of mean values of the oxygen-isotope ratio relative to standard mean ocean water (delta 18O, in‰;) for 22 sites representative of conditions in north-eastern Canada is complemented with data on mean annual surface temperature, latitude, surface elevation, and mean annual shortest distance to open ocean denoted by the 10% sea-ice concentration boundary. Stepwise regression analysis is used to develop a multivariate model suitable to infer the distribution of delta 18O in an area of complex topography and possibly mixed sourcing of advected water vapor. The best model is produced by a run in the backward mode at the 95% confidence level in which only temperature, latitude and distance to the open ocean remain in the model (the correlation coefficient is 0.915, and adjusted coefficient of determination is 0.809, the root mean square residual is 1.62). This model is similar to the best delta 18O predictive model derived elsewhere for Greenland, suggesting a common principal source of advected moisture. (Au)

F, E
Atmospheric temperature; Databases; Firn; Ice caps; Isotopes; Mathematical models; Oxygen; Spatial distribution; Topography; Water vapour

G0813, G10
Agassiz Ice Cap, Nunavut; Axel Heiberg Island, Nunavut; Baffin Island, Nunavut; Barnes Ice Cap, Nunavut; Devon Ice Cap, Nunavut; Ellesmere Island, Nunavut; Meighen Ice Cap, Nunavut; Penny Ice Cap, Nunavut; Steensby Land, Greenland; Ward Hunt Ice Shelf, Nunavut


Historical biomass burning : late 19th century pioneer agriculture revolution in Northern Hemisphere ice core data and its atmospheric interpretation   /   Holdsworth, G.   Higuchi, K.   Zielinski, G.A.   Mayewski, P.A.   Wahlen, M.   Deck, B.   Chylek, P.   Johnson, B.   Damiano, P.
(Journal of geophysical research, v.101, no. D18, Oct. 27, 1996, p.23,317-23,334)
References.
ASTIS record 40019.
Languages: English
Web: doi:10.1029/96JD01158
Libraries: ACU

Ice core data from Yukon and Greenland spanning from ~1750 to 1950 indicate that between ~1850 and <=1910 a clear atmospheric signal exists of an episodic biomass burning event that is referred to as the Pioneer Agriculture Revolution. This is best seen in NH4 ions and particulate concentrations but also in some limited black carbon concentration data, where for all three quantities maximum levels reach about 3 times the prerevolution background concentrations. Tree cellulose delta 13C data and some early, controversial, French, air CO2 data, occurring within the same time interval, are interpreted as providing other independent evidence for the same, mainly North American, late 19th century biomass burning event. Some hitherto problematic northern hemisphere ice core derived CO2 concentration data may now be interpreted as containing a biomass burn signal, and these data are compared, especially as to the time of occurrence, with all the other results. A global carbon cycle model simulation of atmospheric CO2 mixing ratios using a maximum input of 3Gt(C)/yr at northern midlatitudes produces "anomalous" CO2 levels close to some of the ice core carbon dioxide values. However, other values in this data set do not reasonably represent fully mixed atmospheric values. This suggests that these values might be transients but still "tracers" for biomass burning. Nevertheless, it appears possible that interhemispheric CO2 gradients of similar magnitude to the present one could have existed briefly late last century. (Au)

B, F, N
Agriculture; Atmospheric chemistry; Biomass; Carbon dioxide; Cores; Fires; Glacier ice

G0811, G10
Greenland; Yukon


An ice-core-based record of biomass burning in the Arctic and Subarctic, 1750-1980   /   Whitlow, S.   Mayewski, P.   Dibb, J.   Holdsworth, G.   Twickler, M.
(Tellus, no.46B, no. 3, July 1994, p. 234-242, ill., map)
References.
ASTIS record 73708.
Languages: English
Web: doi:10.1034/j.1600-0889.1994.t01-2-00006.x
Libraries: ACU

Ammonium records from 3 ice cores, 20D and GISP2 (Greenland) and Mt. Logan (Yukon), covering the period from 1750 to the 1980s are analyzed. For each data set, samples with NH4+ concentrations greater than one standard deviation above the mean value also tend to be enriched in NO3- and K+, similar to the chemical composition of aerosols from aged biomass burning plumes. We believe the NH4+ spikes originate from biomass burning events. There is not a one to one correspondence between documented large fires and NH4+ spikes, nor are specific annual layers with elevated NH4+ concentrations often found in more than one core. However, frequency of NH4+ spikes increase during periods of more extensive and intensive biomass burning in the NH4+ source areas for the ice core sites. The 20D and GISP2 records are characterized by increased spike frequency from 1790 to 1810 and from 1830 to 1910. This latter time coincides with a period of increased biomass burning documented in the historical fire records for northern North America. In contrast to both Greenland ice core records, the Mt. Logan NH4+ record shows periods of increased spike frequency from 1770-1790, 1810-1830, 1850-1870 and 1930-1980. The poor agreement between the Mt. Logan record and the records from Greenland suggests that another source area, perhaps Siberia, may be the dominant summertime source area for NH4+ spikes in Mt. Logan snow. (Au)

F, E, J, B
Aerosols; Air pollution; Ammonium; Atmosphere; Atmospheric circulation; Biomass; Calcium; Chlorine; Cores; Fires; Geological time; Glaciers; Isotopes; Magnesium; Nitrogen; Nitrogen oxides; Oxygen; Potassium; Recent epoch; Seasonal variations; Snow; Sodium; Spatial distribution; Sulphates; Temporal variations

G0811, G10, G08, G14
Canada; Greenland; Logan, Mount, Yukon; Sibir', Russian Federation


Ice-core sulfate from three northern hemisphere sites : source and temperature forcing implications   /   Mayewski, P.A.   Holdsworth, G.   Spencer, M.J.   Whitlow, S.   Twickler, M.   Morrison, M.C.   Ferland, K.K.   Meeker, L.D.
(Arctic air, snow and ice chemistry / Edited by C. Davidson and R. Schnell. Atmospheric environment, v. 27, no. 17-18, Dec. 1993, p.2915-2919, ill.)
References.
ASTIS record 73705.
Languages: English
Web: doi:10.1016/0960-1686(93)90323-Q
Libraries: ACU

Comparison of ice-core nss sulfate records (two sites in Greenland and one in the North Pacific) with temperature change records for the regions including these core sites provides further confirmation that change in the concentration of anthropogenic sulfate has had a significant effect on regional temperature during at least the period ~AD1940-1970 over at least the Atlantic portion of the Arctic. Using the AD1880-1985 portion of our ice-core records as an analog, we provide a test of the potential temperature depression caused by non-seasalt (nss) sulfate aerosols over Greenland during the period ~AD700-1900 concluding that the anthropogenic era is unique by comparison. Statistical examination of this record allows a determination of the relative contributions of volcanic vs biogenic source nss sulfate during this period plus a characterization of the variability in these two sources. (Au)

F, E, J, B
Aerosols; Air pollution; Atmospheric circulation; Atmospheric temperature; Climate change; Cores; Glaciers; Recent epoch; Solar radiation; Spatial distribution; Sulphates; Sulphur dioxide; Temporal variations; Volcanism

G0811, G10
Greenland; Logan, Mount, Yukon


Northern Hemisphere concentrations of methane and nitrous oxide since 1800 : results from the Mt. Logan and 20D ice cores   /   Dibb, J.E.   Rasmussen, R.A.   Mayewski, P.A.   Holdsworth, G.
(Chemosphere (Oxford), v. 27, no. 12, Dec. 1993, p.2413-2423, ill.)
References.
ASTIS record 73662.
Languages: English
Web: doi:10.1016/0045-6535(93)90263-5
Libraries: ACU

Concentrations of CH4 and N2O have been determined in bubbles extracted from the Mt. Logan (Yukon) and 20D (south Greenland) ice cores. The enclosure dates of the trapped gas samples range from 1802 to 1960; thus these data help to document the anthropogenic increases of these two greenhouse gases in the Northern Hemisphere atmosphere. In general, the new data are in accord with previous ice core studies showing accelerating increases in concentration of both gases since 1900. The Mt. Logan records appear to be the first for any trace gases from alpine glacial ice. The present data set is too sparse to be conclusive, but suggests generally higher CH4 concentrations over south Greenland than Mt. Logan, particularly the 1850-1900 period. (Au)

F, E
Atmospheric chemistry; Cores; Firn; Gases in ice; Glacier ice; Isotopes; Mathematical models; Measurement; Methane; Nitrogen oxides; Temporal variations

G0811, G10
Greenland; Logan, Mount, Yukon


Can the solar cycle and climate synchronize the snowshoe hare cycle in Canada? Evidence from tree rings and ice cores   /   Sinclair, A.R.E.   Gosline, J.M.   Holdsworth, G.   Krebs, C.J.   Boutin, S.   Smith, J.N.M.   Boonstra, R.   Dale, M.
(American naturalist, v.141, no. 2, Feb. 1993, p. 173-198, ill.)
(Kluane Boreal Forest Ecosystem Project contribution, no. 24)
References.
ASTIS record 53366.
Languages: English
Libraries: ACU

Dark marks in the rings of white spruce less than 50 yr old in Yukon, Canada, are correlated with the number of stems browsed by snowshoe hares. The frequency of these marks is positively correlated with the density of hares in the same region. The frequency of marks in trees germinating between 1751 and 1983 is positively correlated with the hare fur records of the Hudson Bay Company. Both tree marks and hare numbers are correlated with sunspot numbers, and there is a 10-yr periodicity in the correlograms. Phase analysis shows that tree marks and sunspot numbers have periods of nearly constant phase difference during the years 1751-1787, 1838-1870, and 1948 to the present, and these periods coincide with those of high sunspot maxima. The nearly constant phase relations between the annual net snow accumulation on Mount Logan and (1) tree mark ratios, (2) hare fur records before about 1895, and (3) sunspot number during periods of high amplitude in the cycles suggest there is a solar cycle-climate-hare population and tree mark link. We suggest four ways of testing this hypothesis. (Au)

J, I, E, H, V, F
Accumulation; Animal food; Animal live-capture; Animal population; Biological clocks; Climate change; Cores; Dendrochronology; Effects monitoring; Fur trade; Glaciers; Grazing; Hares; History; Hudson's Bay Company; Meteorology; Predation; Snow; Solar radiation; Taiga ecology; Temporal variations; Testing; Trophic levels; Weather stations; White spruces; Winter ecology

G0811
Kluane Lake region, Yukon; Logan, Mount, Yukon


Mount Logan map, research and reference folio   /   Holdsworth, G.   Sawyer, B.
Calgary, Alta. : Arctic Institute of North America, 1993.
2 sheets : ill. (1 col.), 2 maps (1 col.) ; 50 x 66 cm.
ISBN 0-919034-75-6
Scale 1:100,000.
References.
ASTIS record 35044.
Languages: English
Libraries: ACU

[This folio consists of two sheets. The first one] ... contains spectacular views of Mt. Logan by two of North America's premier aerial photographers of glaciated mountain scenery, a brief historical sketch of Sir William E. Logan (at the beginning of this text) and an introduction, acknowledgments and ordering details. On the reverse side there is a map at scale 1:75,000 which is a part of the original map at that scale. It was derived from the original compilations for the 1:50,000 scale map series published by the Department of Energy & Resources in 1987 and shows the principal exploration routes and research sites on the mountain. The numbers seen beside each route line correspond with the publication reference numbers given on the second sheet. The second sheet shows an impressive view of Mount Logan's southern aspects in which three major ridges are visible as well as a geological fault. There are some accompanying notes on the geology and geodesy relevant to the mountain. On the reverse side (p.4) is a map at scale 1:100,000, which is a 33% reduced version of the 1:75,000 scale manuscript minus a small northern strip. ... (Au)

A, B, F, Y, V
Aerial photography; Expeditions; Geological Survey of Canada; Geology; Geophysics; Glaciology; History; Maps; Mountaineering; Mountains; Research; Research stations

G0811
Logan, Mount, Yukon


Ice core climate signals from Mount Logan, Yukon, A.D. 1700-1897   /   Holdsworth, G.   Krouse, H.R.   Nosal, M.
In: Climate since A.D. 1500 / Edited by R.S. Bradley and P.D. Jones. - London ; New York : Routledge, 1992, p. 483-504, ill., maps
References.
ASTIS record 32098.
Languages: English

In this chapter, two climate time series for the Mt. Logan ice core are presented and analyzed. The data sources used in this analysis are described, as are the calibration and verification procedures. These findings are then analyzed in the context of findings from other studies, including a comparison with a tree ring series derived from northern Yukon tree line cores, oceanographic data, historical and early instrumental data. (ASTIS)

F, E
Climate change; Cores; Glaciers; Palaeoclimatology

G0811
Logan, Mount, Yukon


Variation of the stable isotopes of water with altitude in the Saint Elias Mountains of Canada   /   Holdsworth, G.   Fogarasi, S.   Krouse, H.R.
(Journal of geophysical research, v. 96, no. D 4, Apr. 20, 1991, p.7483-7494, ill., maps)
References.
ASTIS record 73702.
Languages: English
Web: doi:10.1029/91JD00048
Libraries: ACU

The stable isotopes of water, measured in melt samples taken from snow pits and cores at locations between 1750- and 5930-m altitude on Mount Logan (5951 m) and between 2900 and 4900 m on Mount Steele (5079 m), in the Saint Elias Mountains, Yukon, show a distinctive altitudinal distribution. Several delta 18O and delta D versus altitude profiles indicate the general persistence of a nearly iso-delta step, or staircase structure, separating a lower region of altitude dependent isotopic fractionation between 1750 and 3350 m from another apparent fractionation sequence appearing above about 5300 m. Both of these sequences, but especially the lower one, indicate orderly processes. On the one hand, postdepositional changes to isotope ratios in snow at different altitudes may cause distortions to an otherwise nearly monotonic isotope fractionation sequence, but the main anomaly appears to be far too large to be explained in this way. On the other hand, an explanation linked to processes occurring in the lower and midtroposphere is based on established meteorological principles as well as on upper air data. This hypothesis is proposed as the primary one to explain the gross features of the observed isotope profiles. It is compatible with the concept of secondary-source moisture arriving via the upper troposphere, and it does not exclude the effects of postdepositional stratigraphic and stable isotope ratio changes. Over interannual time scales, any vertical modulation of the observed isotope-altitude structure, from, for example, changes in wind regime, would give rise to an additional signal in any ice core delta time series. These findings identify a potential difficulty in the interpretation of stable isotope records obtained from high mountain ice core sites. It is possible that the results may have application to atmospheric circulation modeling, where the effects of extreme topography are being studied. (Au)

F, E, D
Atmosphere; Atmospheric humidity; Atmospheric pressure; Atmospheric temperature; Balloons; Boundary layers; Cores; Deuterium; Isotopes; Mountains; Ocean temperature; Ocean-atmosphere interaction; Oxygen; Oxygen-18; Precipitation (Meteorology); Seasonal variations; Snow; Snow stratigraphy; Spatial distribution; Temporal variations; Topography; Velocity; Winds

G0811, G061
Alaska, Gulf of; Logan, Mount, Yukon; St. Elias Mountains, Alaska/British Columbia/Yukon; Steele, Mount, Yukon


The origin of non-sea-salt sulphate in the Mount Logan ice core   /   Monaghan, M.C.   Holdsworth, G.
(Nature, v.343, no.6255, 18 Jan. 1990, p. 245-248, ill., map)
References.
ASTIS record 29964.
Languages: English
Web: doi:10.1038/343245a0
Libraries: ACU

It has been suggested that oxidized sulphur compounds might play an important part in influencing climate, as they serve as cloud condensation nuclei and thus could affect the radiative properties of clouds. Schwartz, however, finds no evidence for a climate response arising from the increased concentrations of oxidized sulphur compounds resulting from the burning of fossil fuels. He contends that such a response should be detectable if these compounds are indeed important, as they are distributed widely in the atmosphere. Measurements of sulphate concentrations in an ice core from Mount Logan (5,951 m), in northwestern Canada, indicate that the background concentration of non-sea-salt sulphate in snow deposited on the ice cap during the past century has remained nearly constant. Here we report 210Pb/137Cs ratios measured in the ice core and in soil cores collected at nearby low-altitude sites. ... (Au)

F, E, V
Aerosols; Climate change; Clouds; Cores; History; Ice caps; Soils; Sulphates

G0811
Logan, Mount, Yukon


Analysis of a 290-year net accumulation time series from Mt. Logan, Yukon   /   Holdsworth, G.   Krouse, H.R.   Nosal, M.   Spencer, M.J.   Mayewski, P.A.
In: Snow cover and glacier variations : proceedings of an international symposium held during the Third Scientific Assembly of International Association of Hydrological Sciences at Baltimore, Maryland, USA, 10-19 May 1989 / Edited by S.C. Colbeck
(IAHS-AISH publication, no. 183, 1989, p. 71-79, ill.)
References.
ASTIS record 66429.
Languages: English
Libraries: ACU

A 102.5-m mechanically continuous firn and ice core sequence retrieved from the Northwest Col of Mt. Logan (latitude 60°30'N; longitude 140°35'W; site location 5340 m a.s.l.) in the Yukon Territory, Canada, has been analyzed continuously for stable isotopes, pH and liquid electrolytic conductivity. Specific sections of the core have been analyzed for total ß-activity (0-22 m) and trace ion concentrations (across major volcanic events) in order to date the core. In the lower half of the core, nitrate and some other ionic species are used to identify annual increments except between AD 1693 and AD 1720 and between AD 1729 and AD 1735 where only average annual increments are given. Annual increments were converted to water equivalents, then corrected for ice flow thinning as well as for origin, since a significant net accumulation gradient exists across the borehole site. The time series was subjected to cross correlation analysis, using instrumental data for the last 80 years, and to spectral analyses, using a 250-year sequence. (Au)

F
Accumulation; Chemical properties; Cores; Electrical properties; Firn; Glaciers; Isotopes; Mathematical models; Measurement; Oxygen-18; Seasonal variations; Snow water equivalent; Temporal variations; Volcanism; Water pH

G0811
Logan, Mount, Yukon


John Hainsworth Mercer, 1922-1987   /   Holdsworth, G.   Blake, W.
(Arctic, v. 41, no. 2, June 1988, p. 164-165, ill.)
References.
ASTIS record 49688.
Languages: English
Web: http://pubs.aina.ucalgary.ca/arctic/Arctic41-2-164.pdf
Web: doi:10.14430/arctic1712
Libraries: ACU

From 1951 until 1954, Mercer studied at McGill University. His Ph.D. thesis, ... was based on field work carried out in the vicinity of the Grinnell and Terra Nivea ice caps on southern Baffin Island. ... Mercer was highly motivated by field work and literally thrived on it. Typically, and often to the chagrin of at least one of his contemporaries, Mercer did not unnecessarily burden himself (or others) with loads of data. Many of his papers seemed to be largely based on his unusual synthesizing and perceptive powers, supported, where necessary, by a few, but key, radioisotope dates. Mercer was not a compulsive lecturer - in fact, he shunned such "duties" - but for those of us at the institute as graduate students (of which G.H. was one) Mercer was frequently a source of both private inspiration and considerable amusement. An important paper in 1968 set in motion his and others' ideas on the dynamics of "marine ice sheets" (Mercer, 1968). ... His realistic thinking through the ice sheet dynamics scenarios and the associated sea level changes inspired the numerical modellers to dedicate their paper to him. ... The results of his field work are of great importance in synthesizing the spatial variations of global climate change, which was one of the underlying themes of Mercer's research. ... His stimulating presence will be widely missed, especially by those at the Byrd Polar Research Center in Columbus, Ohio. (Au)

F, E
Biographies; Climate change; Glaciology; Ice caps; Ice sheets; Mathematical models; Mercer, John Hainsworth, 1922-1987; Scientists

G01, G0813
Baffin Island, Nunavut; Grinnell Glacier, Nunavut; Polar regions; Terra Nivea Ice Cap, Nunavut


An investigation of low-stress ice rheology on the Ward-Hunt Ice Shelf   /   MacAyeal, D.R.   Holdsworth, G.
(Journal of geophysical research, v. 91, no. B 6, May 10, 1986, p.6347-6358, ill., 1 map)
References.
ASTIS record 40979.
Languages: English
Web: doi:10.1029/JB091iB06p06347
Libraries: ACU

Deformation of the Ward-Hunt Ice Shelf, Northwest Territories, Canada, can be used to study the rheology of ice in the low-stress, low-strain rate regime (10**-12/s). Finite element simulations are separately displayed to demonstrate what the effects of ice salinity, ice temperature, and sea-ice back pressure have on the spreading rates of this ice shelf. We conclude that in general these effects tend to obscure any differences between the commonly used non-Newtonian flow law and the Newtonian flow law recently reinterpreted from field measurements. The numerical simulations indicate that there are specific locations where useful field measurements could be carried out on the ice shelf. (Au)

F
Creep; Deformation; Flow; Ice shelves; Mathematical models; Physical properties; Salinity; Strain; Stress; Surface properties; Temperature; Thermal properties; Thermal regimes

G0813
Ward Hunt Ice Shelf, Nunavut


Evidence for a link between atmospheric thermonuclear detonations and nitric acid   /   Holdsworth, G.
(Nature, v.324, no.6097, 11 Dec. 1986, p. 551-553, ill.)
References.
ASTIS record 21270.
Languages: English
Web: doi:10.1038/324551a0
Libraries: ACU

Suitably located glacier cores, obtained from high-altitude, low-temperature sites, can reveal detailed information about atmospheric air chemistry at sub-annual resolution. Such data may provide input to climate-change models, the study of acid precipitation patterns and many other phenomena. Here I present data from an ice core which show that during the era of intense atmospheric thermonuclear weapons testing (ATWT) a significant part of the nitrate content in the snow was modulated by the intensity of the nuclear detonations. The fixation of nitrogen by nuclear fireballs leads to NOx gases in the atmosphere and ultimately to nitric acid in precipitation. At certain concentrations, these gases and the associated aerosols may perturb the climate. (Au)

E, F
Acid rain; Aerosols; Atmospheric chemistry; Chemical properties; Climate change; Cores; Glaciers; Nitrogen oxides; Snowfall

G0811
Logan, Mount, Yukon


Ice shelf creep rates and the flow law of ice   /   Holdsworth, G.
(Nature, v.319, no.6056, 27 Feb. 1986, p. 727)
References.
ASTIS record 20191.
Languages: English
Web: doi:10.1038/319727a0
Libraries: ACU

A suggestion that creep measurements made on the Ward Hunt Ice Shelf, Canada, should provide needed information relevant to defining the flow law for ice, exposed the fact that such measurements had already been carried out. Attempts to improve our knowledge of the flow law for ice have been under way for the past 30 years and the latest attempt seems unlikely to be the last. This communication is intended to point out that the data referred to in ref. 2 cannot easily be interpreted to provide information relevant to investigations of the flow law for ice. I will attempt here to summarize the major difficulties surrounding this problem. ... (Au)

F
Creep; Flow; Ice shelves

G0813
Ward Hunt Ice Shelf, Nunavut


Acid content of snow from a mid-troposphere sampling site on Mount Logan, Yukon Territory, Canada   /   Holdsworth, G.   Peake, E.
(Proceedings of the Symposium on Snow and Ice Chemistry and the Atmosphere, held in Peterborough, Ontario, Canada, 19-24 August 1984 / Edited by W.P. Adams. Annals of glaciology, v. 7, 1985, p. 153-160)
References.
ASTIS record 19951.
Languages: English
Libraries: ACU

An ice core 103 m long was extracted in 1980 from an altitude of 5340 m on the icefield plateau of Mount Logan, Yukon Territory (lat 60 35 N, long 140 30 W). The firn-ice transition occurs at a depth of 65 m, corresponding to about the year 1880. The chemistry of this upper 65 m is apparently dominated by acid-ion species, the peaks in which are provisionally identified with several documented volcanic events. Although the analyses cover only selected discontinuous intervals, it appears that there is no significant long-term trend in the background acidity level of the precipitation at this location over the past century, in contrast to the results from the North American Arctic and Greenland. Nitrate ion concentration shows pseudo-seasonal variations, which may be associated with stratospheric-tropospheric interactions, although other seasonally linked mechanisms are possible. This result has also been reported for ice-core sequences from Greenland. Other nitrate pulses are tentatively associated with local volcanic events and a possible meteorite event (the entry of Tunguska in 1908). One of the largest short-term sources of sulfate ions is probably from volcanically-quiet nitrate and sulfate ion concentrations are compared with similar Greenland data in an attempt to throw further light on the origin of the acids. ... (Au)

F, G
Chemical properties; Cores; Electrical properties; Glaciers; Impurities; Snow

G0811
Logan, Mount, Yukon


Oscillation of a floating glacier tongue   /   Vinogradov, O.G.   Holdsworth, G.
(Cold regions science and technology, v. 10, no. 3, Apr. 1985, p. 263-271, ill.)
References.
ASTIS record 19693.
Languages: English
Web: doi:10.1016/0165-232X(85)90037-0
Libraries: ACU

A simplified glacier tongue, modelled as a beam interacting with water waves, is analyzed in order to understand better the possible mechanism of iceberg calving. The analysis and results are mainly numerical, although some analytical results valid for a limited range of frequencies are also given. For this model it is apparent that there is no critical beam length exhibiting a particular vulnerability to calving, since the mode of beam oscillation varies not only with the shape of the sea swell spectrum but also with the changing beam length, and so points of maximum stress shift continuously. The possibility of fatigue failure must be considered if an ice tongue is subjected to waves of a certain frequency for a sufficiently long time. (Au)

G, D, F
Calving (Ice); Glaciers; Icebergs; Models; Ocean waves; Stress

G16


Iceberg   /   Holdsworth, G.
In: The Canadian encyclopedia. - Edmonton, Alta. : Hurtig Publishers, 1985, v. 2, p. 859-860, col. ill., map
ASTIS record 18494.
Languages: English
Libraries: ACU

This concise presentation on icebergs includes calving mechanisms of parent glaciers responsible for the formation of icebergs, the physical appearance of icebergs, their occurrence globally and dimensions, and iceberg dynamics and stability. More briefly described are possible applications of icebergs (research platform; fresh-water supply) and iceberg hazards in the northern hemisphere, especially the threat they pose to offshore oil and gas production and marine transportation. (ASTIS)

G, F
Calving (Ice); Glaciers; Iceberg stability; Icebergs; Movement; Physical properties

G09, G11, G081, G01
Canadian Arctic waters; Labrador Sea; North Atlantic Ocean; Polar regions


Pollen, oxygen isotope content and seasonality in an ice core from the Penny Ice Cap, Baffin Island   /   Short, S.K.   Holdsworth, G.
(Arctic, v. 38, no. 3, Sept. 1985, p. 214-218, ill., map)
References.
ASTIS record 17466.
Languages: English
Web: http://pubs.aina.ucalgary.ca/arctic/Arctic38-3-214.pdf
Web: doi:10.14430/arctic2136
Libraries: ACU

The results of pollen analyses of 12 ice core samples, covering an eight-year period from 1972 through 1979 from the divide of the Penny Ice Cap, Baffin Island, are reported. The pollen spectra are dominated by long distance transported pollen, especially the conifers Picea and Pinus. Alnus pollen is generally rare. In contrast, pollen spectra from both modern polsters and fossil peat sections in the same area are both characterized by local pollen types. Pollen influx values range from 2 to 8 grains/cm²/yr. Where the sampling intervals happened to coincide with established seasonal intervals (as interpreted from later oxygen isotope studies) the pollen spectra showed seasonal characteristics. This occurred in five out of the twelve samples. Comparison of these data is made with data from Devon Island Ice Cap. Such information may be useful in reconstructing paleoclimates. (Au)

F, H, E
Cores; Ice caps; Oxygen-18; Palaeoclimatology; Palynology

G0813
Penny Ice Cap, Nunavut


Radioactivity levels in a firn core from the Yukon Territory, Canada   /   Holdsworth, G.   Pourchet, M.   Prantl, F.A.   Meyerhof, D.P.
(Atmospheric environment, v. 18, no. 2, 1984, p. 461-466, ill.)
References.
ASTIS record 69960.
Languages: English
Web: doi:10.1016/0004-6981(84)90123-9
Libraries: ACU

Gross ß-activity and tritium concentration measurements made on a 26.8m length of consolidated snow (firn) core retrieved from an altitude of 5340 m on Mt. Logan (Yukon Territory, Canada) have revealed a detailed chronology of natural and anthropogenic radioactivity levels extending from about 1943 to 1980. Oxygen isotope measurements were used to assist in the dating of the core and a reliable time scale spanning 1950-1980 has been established with an accuracy of at least ±0.5 y, and in some cases ±0.25 y. An immediate result is the establishment of mean annual accumulation rates, which are, for the years 1963-1980: 0.36m/y and for 1951-1980: 0.39 m/y water equivalent. Another result is the estimation of the ‘stratospheric residence time’ for the fission fallout products (mainly 90Sr and 137Cs). A value of the stratospheric residence time of about 1 y is derived from data spanning 1963-1967. Reference to the history of atmospheric thermonuclear device testing shows that individual or specific groups of tests by different countries can be identified. Comparison of the gross ß-activity data with a similar set from Station Centrale (Greenland) shows that although the same trends exist in the two data sets, the amplitude of most corresponding major peaks in the Greenland data is significantly lower. Since the accumulation rates at the two sites are almost identical and since the deposition of radioactive aerosols in any case is expected to be dominated by dry fall-out, the differences are assumed to be related to the trajectory path and to the diffusion rates of the radionuclide clouds. (Au)

F, E, R
Accumulation; Aerosols; Air pollution; Chemical properties; Cores; Density; Firn; Glaciers; Isotopes; Measurement; Military operations; Oxygen; Precipitation (Meteorology); Radionuclides; Snow; Temporal variations; Tritium

G0811, G10, G06
Greenland; Kodiak, Alaska; Logan, Mount, Yukon; Whitehorse, Yukon


Ice drilling technology : proceedings of the Second International Workshop/Symposium on Ice Drilling Technology, Calgary, Alberta, Canada, 30-31 August, 1982   /   Holdsworth, G.   Kuivinen, K.C.   Rand, J.H.
Hanover, N.H. : Cold Regions Research and Engineering Laboratory, 1984.
vi, 142 p. : ill. ; 28 cm.
(Special report - U.S. Army Cold Regions Research and Engineering Laboratory, 84- 34)
Appendix.
References.
ASTIS record 16420.
Languages: English
Libraries: ACU NFSMO

... Until quite recently, most of the ice drilling activities were in support of research, such as glacier physics studies, climatic change investigations and special hydrological studies. Now, with the northward and ultimately the southward extension of exploration for fossil hydrocarbons, it has been necessary for exploration companies to drill and core through multi-year sea ice, pressure ridges, ice islands and even through shelf ice. These undertakings are required in order to determine the material properties of floating ice for embedding instrumentation and for determining the magnitudes of the possible thrusts that might be exerted by moving ice on engineering structures. ... In Greenland ice core, it is possible to recognize most, if not all, of the major volcanic eruptions throughout recorded history, to detect some that were not recorded, and to extend the log of volcanic events beyond the dawn of written records. Such time series have an important bearing on modelling volcanism, which ranks in importance with earthquake modelling. Such time series also have an important input to climatic research. ... In terms of ice depth, activities in the Arctic, related to resource exploration, demand a continuous development of drills and corers to meet special conditions and new requirements. The same may be true for the coastal Antarctic areas, as geophysical exploration is carried out there and recovery operations develop. (Au)

F, G
Cores; Drilling; Equipment and supplies; Glaciers; Ice islands; Ice shelves; Pressure ridges; Sea ice

G01
Polar regions


Glaciological reconnaissance of an ice core drilling site, Penny Ice Cap, Baffin Island   /   Holdsworth, G.
(Journal of glaciology, v. 30, no.104, 1984, p. 3-15, figures, tables)
Appendices.
References.
ASTIS record 15012.
Languages: English
Libraries: ACU NFSMO

A site situated close to the main divide of the Penny Ice Cap, Baffin Island was occupied in 1979 for the purpose of determining the suitability of this ice cap for providing proxy climatic data and other environmental time series for a span of 100,000 a. A 20 m core was extracted and analyzed for stable oxygen isotopes, tritium concentration, pH, electrolytic conductivity, major ion concentrations, and particulate concentration. An adjacent dedicated shallow core was analysed for pollen content to determine if a significant seasonal variation in the pollen rain existed. From these measurements, and from the observations made on the stratigraphic character of the core, the mean net accumulation rate over the approximately 30 year period covered by the core is found to be about 0.43 m water equivalent per year. This is in agreement with a single value determined 26 years earlier at a nearby site (Ward and Baird, 1954). The mean annual temperature in the bore hole was found to be close to -14.4°C, possibly some 2-5° warmer than the expected mean annual surface air temperature at the site. The difference is due to the expulsion of latent heat upon freezing of melt water at depth in the snow-pack which gives rise to the many ice layers observed in the core. The percentage thickness of ice layers per year may be correlated with summer temperatures. Total ice depths were measured using a 620 MHz radar echo-sounder. In the vicinity of the divide, over an area of 1 km², the ice depths vary from about 460 to 515 m. These values compare favourably with values determined from an airborne radar depth-sounding flight carried out over the ice cap by a joint U.S.-Danish mission operating out of Sondre Stromfjord, Greenland. The data suggest that the ice-cap divide would be a worthwhile location to deep core drill with an expected useful coverage of at least the Holocene period. (Au)

F, B
Cores; Drilling; Glaciers; Ice caps; Ice divides; Isotopes; Palaeoclimatology; Recent epoch; Tritium

G0813
Penny Ice Cap, Nunavut


Measuring and mapping Canada's highest mountain   /   Holdsworth, G.
In: High Altitude Physiology Study - collected papers / Edited by C.S. Houston. - Arlington, Va. ; Calgary, Alta. : Arctic Institute of North America, [1981?], p. 111-116, map
The High Altitude Physiology Study camp at Logan High has been used by other groups for other purposes. This is one of two projects not related to physiology that were done at Logan High and included in this "collected papers" volume.
ASTIS record 63810.
Languages: English
Libraries: ACU

... The first recorded sighting of Mount Logan, in the summer of 1890, was made by Professor I.C. Russell .... Russell was credited in official Canadian publications as the source of a surprisingly accurate estimate of Mount Logan's height, 19,539 ft (5955.5 m). No documents have been found that reveal the computations involved in obtaining this value. ... The early surveying of Logan is so obscure that now it is almost impossible to determine the exact sources of some of the height values .... some expeditions into the Mount Logan region that had only a casual interest in surveying turned in surprisingly accurate values. The first organization to report officially on the measuring of Mount Logan was the United States Coast & Geodetic Survey. ... calculating its height at 19,512 ft (5,947.3 m). In 1898, three new elevations appeared in the literature. ... Inside the back cover of this book [The Yukon Territory published by F.M. Trimmer] is a map described as "Rugg's new map of the Klondike Goldfields". Mount Logan is shown with a height of 19,590 ft (5,97l m). No data source is given. The second 1898 publication is William Ogilvie's Official Guide to the Klondike, which gives ... a value of 19,539 ft (5,955.5m). ... Ogilvie gives no information on the source. The third height for Mount Logan, 19,500 ft (5,943.6 m), appeared in Russell's paper Glaciers of North America, published in the December 1898 issue of The Geographical Journal. In 1901 the first edition of James White's Altitudes in Canada gave Ogilvie's value of 19,539 ft (5,955.5 m) for Mount Logan's height. The second edition of Altitudes, published in 1903, attributes the value of 19,539 ft (5,955.5 m) to Russell. This attribution continued until the 1961 edition .... In 1906 the United States Geological Survey published its Professional Paper No. 45 which included a map, compiled in 1903, showing Mount Logan with a height of 19,540 ft. (5,955.8 m). This may have been a rounding of White's value of 19,539 ft (5,955.5 m). The 1910 Encyclopaedia Britannica (Cambridge Edition) quotes without reference the 19,540 ft (5,955.8 m) value, whereas the compilers of Pears' Cyclopaedia prefer 19,510 ft (5,946.6 m). The International Boundary Commission (IBC) published in 1981 its report on the Alaska-Canada boundary survey, which was based on field work done up to 1913. This report contains a new height of 19,850 ft (6,050.4 m). The value was obtained by taking measurements from photographs of the peak taken from survey stations east of the international boundary. ... the IBC value was adopted and has been used to the present day on the topographic maps of the area. The first suggestion that this last value might be too high and that the earlier values were closer to the correct height, resulted from a survey of the Seward Glacier region during the Arctic Institute of North America's Project Snow Cornice in 1948-49. ... Dr. [Walter] Wood was able to recalculate the height of the summit of Mount Logan as 19,543 ft (5,957 m). This result was not published until 1974 .... My paper in the same report gives the results of a survey done in 1968 from the North Peak of Mount Logan. I concluded that the altitude of the summit cannot be substantially greater than about 19,500 ft (5,943.6 m). Dr. Wood, using results of both investigations, proposed a new value for the summit of 19,586 ft (5,970 m). As a result of the 1974 survey, which will be described shortly, a value of 19,520 ft ±10 ft (5,950 m ±3 m) is now proposed. ... (Au)

A, V, E
Atmospheric temperature; Equipment and supplies; Exploration; History; Logistics; Measurement; Microwave radiation; Mountaineering; Mountains; Photography; Size; Surveying; Velocity; Visibility

G0811
Logan, Mount, Yukon


Glaciology : Mt Logan style   /   Holdsworth, G.
(Canadian alpine journal, v. 64, 1981, p. 60-61, ill.)
References.
Text on p. 60; three photos on p. 61.
ASTIS record 63861.
Languages: English
Libraries: ACU

We reported earlier that ice core drilling on the north-west col of Mt Logan was feasible, both from a logistic standpoint and from a palaeoclimaticians point of view. In practical terms this meant, firstly that suitably designed drilling equipment could be flown by fixed wing aircraft to the north-west col site (5300 m) on Mt Logan and, secondly that a core, once retrieved, would yield a sufficiently interesting and useful climate record to justify the expense of obtaining it. The first of these conjectures has now been established and the second awaits the complete analysis of the 103 m ice core which we have just obtained during the 1980 summer. On 23 May the newly constructed electro-mechanical ice core drill was flown by Heliocourier (with a little help from an Alouette III helicopter) to the divide at the head of Kaskawulsh Glacier (2600 m), and on 24 and 25 May it was given a trial which proved satisfactory. Next the party of four was flown across to near the base of the east ridge of Mt Logan in preparation for the acclimatization phase that was to precede work on Logan. This ascent was intended to be a non-oedemic one as we quite expected to have to remain on the north-west col for the best part of two months. ... By 29 May we had moved into camp 1 at about 2650 m on the ridge after ferrying the last of the loads from the glacier camp. ... Camp 2 (3110 m) was occupied on 31 May. ... By 2 June we had established and occupied camp 3 (3475 m). ... by 4 June we occupied camp 4 (3930 m?). ... Camp 5 at 4270 m was a truck stop since we had already deposited loads at close to 4880 m .... Camp 6 was at the top of the "snow dome" and camp 7 at about 5330 m on the slope rising up the east peak. This camp is at about the same level as the north-west col. ... We chose to ignore the east peak and traversed across to the col between it and the main peak, possibly the first time it has been done. A cache was established on the col and camp 8 placed further on, only one hour below the main peak (5951 m). The summit was climbed by all members in the "after hours" on 14 and 15 June. A final downhill run on the 17th put us on the north-west col .... It only remained for us to establish camp ... and wait for "positive" weather and our equipment. Flights began on 23 June but it was not until 2 July that we had the drill operating and had extracted our first 20 m of ice core. On the 8th, with the drill down at 62 m it jammed, but was recovered .... After this scare the rig was transplanted and a 30 m hole quickly drilled in one day to replenish cores which had melted in improper storage in Whitehorse. The drilling rig was moved once more to the centre of the north-west col where a 46 m hole was drilled but terminated due to excessively low advance rates and to the build up of chips. A final carefully "engineered" hole was then advanced to 103 m before the whole operation was terminated on 25 July due to slow drilling rates, poor core, and lateness of the season. On the basis of the ice thickness' (120 ±5 m), accumulation rate (0.41 m, ie water equivalent, per year), and vertical velocity (0.9 m per year), we estimate that the time span covered by this core is in the order of 500 years. The cores, except the lower 60 m of the deep core, were flown out to Whitehorse for storage. The remainder were sealed in a snow cave dug for that purpose. Most of the drill rig was cached at 5300 m as by this time the weather had turned and was typified by prolonged snow falls. ... The borehole was logged for temperature (seemingly everywhere colder than -28°C below the level of mean annual temperature), diameter, inclination and vertical strain, before being plugged. Finally on the 11th we cached all remaining equipment and plunged off down the "Trench route" (of low repute), as we had been warned of further impending bad weather. ... The following day both Heliocouriers flew in to the 3300 m site in the trench - thus ending our 79 day contact with the mountain. ... (Au)

F, Y, K, E
Acclimatization; Accumulation; Boreholes; Cores; Coring; Equipment and supplies; Flow; Gastrointestinal disorders; Glaciers; Glaciology; Logistics; Mountain sickness; Mountaineering; Snow; Strain; Temperature; Testing; Thickness; Winds

G0811
Logan, Mount, Yukon


A mechanism for the formation of large icebergs   /   Holdsworth, G.   Glynn, J.E.
(Journal of geophysical research, v. 86, no. C 4, Apr. 20, 1981, p.3210-3222, ill.)
Appendices.
References.
ASTIS record 6742.
Languages: English
Web: doi:10.1029/JC086iC04p03210
Libraries: ACU NFSMO

The calving of floating glaciers to form icebergs is a major form of ice loss from the Antarctic ice sheet. Disintegration of massive, unconfined, seaward extending ice shelves or glacier tongues gives rise to the largest type of iceberg, some of which have horizontal dimensions exceeding 100 km. Several ice tongues are known to exhibit a quasi-cyclic pattern of calving and subsequent regrowth. A mechanism that would seem to explain this type of calving behavior is based on the vibrational characteristics of the system of a buoyant ice plate floating in shallow water. ... For relatively high modes of oscillation, low level, but sustained cyclic bending stresses may lead to crack propagation and subsequent fatigue failure in the ice. The contribution of other mechanisms which induce tensile stresses in the ice are considered to be very important in an overall view of the calving problem, and some of these mechanisms are discussed in relation to the vibration mechanism. It is possible to view the proposed vibration mechanisms as a trigger which raises the resultant stresses in the ice to the point where fracture will occur. (Au)

G
Calving (Ice); Glacier variations; Glaciers; Icebergs; Mathematical models; Stress; Vibration

G15
Antarctic regions


Glaciological studies on Mt Logan, 1978   /   Holdsworth, G.   Jones, D.P.
(Canadian alpine journal, v. 62, 1979, p. 67, ill.)
References.
ASTIS record 63860.
Languages: English
Libraries: ACU

In July 1977, J Wyss and party erected a 10'6" diameter, 8' high dome shelter on the north-west col of Mt Logan at an elevation of 5360 m (17,590 ft). This work was done under contract for Environment Canada which is funding an ice core drilling program on the north-west col through 1979, when the main core extraction will begin - already a year behind schedule. In July 1978, a group of five people occupied the shelter from where glaciological work on and to the east of the col was carried out. We used the King Trench route for the ascent which took 15 days. Earlier measurements of snow accumulation, ice movement and strain in the ice were begun in 1975. These data, together with a single ice thickness profile obtained in 1976 by airborne radar had provided us with a tentative basis for deciding where to core drill for optimum information retrieval. The further measurements made in 1978 were intended to improve or extend existing data so that a reliable basis would exist for selecting the final drill site(s). Since the drill construction had been delayed one year, this seemed a worthwhile activity. The measurements that were made are as follows: 1. The horizontal and vertical position of each pole in the five pole strain net on the col was determined, enabling movement and rate of strain of the ice to be computed. 2. The snow accumulation at the five poles was found. 3. Ice depths to bedrock were measured with two separate radar systems: one a 620 MHz pulsed unit and the other a 1-5 MHz "monopulse" radar. The former instrument samples a much smaller bedrock area than the latter but allowing for this the depth values obtained by the two methods where they were operated at the same point were reconcilable with one another. Spot depths at 35 points on a 100 m grid indicated the existence of a trench-like feature trending south-east from the col with a local maximum depth of about 360 m. 4. At a site 300 m east from the col a hand augered core hole was extended to 18.6 m from the surface. The cores were flown off the plateau for analyses which are not all completed yet. A similar but slightly shallower core hole was drilled in 1975 on the crest of the col and it was felt that an independent set of preliminary data nearer the proposed deep (250 m) hole would be desirable. 5. The ice temperature down to 18.5 m was determined and the "10 m temperature" found to be -28.7°C with transient temperatures as cold as -29.3°C, figures in essential agreement with previous values. Due to adverse weather the final flight to bring people out of the Trench back to Kluane Lake was 28 July. (Au)

F
Accumulation; Boreholes; Cores; Coring; Flow; Glaciers; Glaciology; Location; Radar; Snow; Strain; Temperature; Thickness

G0811
Logan, Mount, Yukon


Mount Logan (Yukon Territory) field report 1978   /   Holdsworth, G.   Canada. Glaciology Division   Dansgaard, W.   Johnsen, S.   Prantl, F.   Johnston, L.
Ottawa : Dept. of the Environment, Glaciology Division, 1979.
67 p. : ill., map (folded in pocket) ; 28 cm.
References.
Appendices: 1. Tritium profiles. - 2. Pollen analysis of snow. - 3. Palaeoclimatic "proxy" data.
Imperfect copy: lacks map in pocket.
ASTIS record 13829.
Languages: English
Libraries: ACU

In July, 1978, glaciological fieldwork was carried out in the vicinity of the North West Col on Mt. Logan .... This work was a continuation and extension of previous studies made at that location .... The fieldwork was also a substitute for the electromechanical core drilling originally planned for 1978 but which had to be postponed due to delays in drill manufacture. ... The present studies are intended to enable proper evaluation and planning for the projected medium-depth ice core drilling scheduled for 1980. ... A detailed climatic record covering approximately the last 1,000 years is being aimed for on the basis of a computed depth-age relationship and the design capabilities of the drill. A major time control horizon for the core will be identification of the White River Eruption events (c.a. 1,250 years B.P.) .... This may be a visual identification (ash) or an identification made on the basis of conductivity measurements of the melted drill chips. ... A significant development accruing from this work should be the construction of a time-depth model where compactible firn occupies a large percentage of the total ice column, and for the case of varying accumulation rate and ice thickness along the flow line, since the latter is not negligible as may be the case for the large ice sheets. ... The principal analyses made on the ice core will be the oxygen isotope ratio (delta 18O), chemical species, particulates, conductivity (also pH and possibly sulphates) and density. In addition to the above core measurements, certain measurements will be made in the hole. These will be temperature, hole closure and tilt. A special notch reamer has been designed to ream a groove in the borehole wall at specified intervals so that, by successively logging borehole diameter, the vertical strain rate may be determined from the change in notch separation. ... records span up to 100,000 years .... (Au)

F
Chemical properties; Cores; Density; Drilling; Glaciers; Isotopes

G0811
Logan, Mount, Yukon


Installation of a dome shelter on Mount Logan, Yukon Territory   /   Holdsworth, G.
(Arctic, v. 32, no. 1, Mar. 1979, p. 33-41, ill., figures)
References.
ASTIS record 2165.
Languages: English
Web: http://pubs.aina.ucalgary.ca/arctic/Arctic32-1-33.pdf
Web: doi:10.14430/arctic2603
Libraries: ACU

Describes the design and installation of a type of geodesic dome shelter to be used as living quarters for researchers on Mt. Logan, Yukon Territory. Information on the selection and description of the canopy, the foundations, installation, and performance of the structure is included. (ASTIS)

M
Research stations; Shelters; Tents

G0811
Logan, Mount, Yukon


Iceberg calving from floating glaciers by a vibrating mechanism   /   Holdsworth, G.   Glynn, J.E.
(Nature, v.274, no.5670, 3 Aug. 1978, p. 464-466, ill.)
References.
ASTIS record 16190.
Languages: English
Web: doi:10.1038/274464a0
Libraries: ACU NFSMO

Observations of Antarctic super tabular icebergs, which can exceed 100 km on a side, have shown that their origin can frequently be traced to previously existing super ice tongues, which are a class of massive seawards-extending ice shelves. ... Because the calvings do not generally occur along a line coincident with the grounding line, where, under normal tidal flexure the stresses are greatest, and because multiple fracturing is observed we have sought a nontidal theory for ice-tongue fracture. A mechanism for generating significant bending stresses at locations along an ice tongue far from the grounding zone is by vibration of the glacier in a mode higher than the fundamental. In this report, we outline an approximate analysis of the modes of free vibration of a buoyant, elastic, tapering ice tongue floating in shallow water of variable depth. ... (Au)

F, G, D
Calving (Ice); Elastic plates; Ice shelves; Icebergs; Ocean waves; Vibration

G15, G01
Antarctic regions; Polar regions


Some mechanisms for the calving of icebergs   /   Holdsworth, G.
In: Iceberg utilization : proceedings of the First International Conference and Workshops on Iceberg Utilization for Fresh Water Production, Weather Modification and Other Applications, held at Iowa State University, Ames, Iowa, USA, October 2-6, 1977 / Edited by A.A. Husseiny. - New York ; Toronto : Pergamon, 1978, p. 160-175, ill.
References.
ASTIS record 16181.
Languages: English
Libraries: ACU NFSMO

This paper reviews several mechanisms whereby calving of icebergs may occur. An ice-shelf or ice-tongue may fracture in a number of locations, evidently in all cases, primarily as a result of the induction of a bending moment superimposed on the normal expansive creep of the floating slab. The bending may occur (a) at the hinge-line; (b) at the seaward margin; or (c) at some intermediate location. Hinge-line calving may be caused by the geometry of the bedrock in the hinge (flotation) zone, or by the action of the tides, or a combination of these two effects. Marginal calving can be explained by a process of continuous downwarping of the frontal ice-cliff, due to the imbalance there between the "hydrostatic" stress in the ice and the sea water pressure. Icebergs thus produced will be strongly prismatic and generally tilted. Calving at intermediate distances might be explained by the action of alternating bending stresses set up as the slab vibrates in a particular mode due to ocean wave excitation. Because these stresses are cyclic and because crevasses occur in floating glaciers, the magnitude of the stresses needed for failure may be quite small. (Au)

G, F
Calving (Ice); Elasticity; Ice shelves; Icebergs; Mathematical models; Mechanical properties; Models

G15
Antarctic regions


Expedition reports : Mount Logan, Centennial Ridge   /   Holdsworth, G.
(American alpine journal, v. 21, no. 1, 1977, p. 196-197)
ASTIS record 71534.
Languages: English
Libraries: ACU

On July 5 K. Blackwood, David P. Jones, J. (Kobi) Wyss and I were flown in from Kluane Lake by helicopter to a site at 8300 feet on a cirque level with the base of "Independence Ridge” (Blomberg's route) but close to the flanks of the large ridge which meets with “Independence Ridge” at 15,000 feet. (Blackwood had to be evacuated on the 9th because of injury.) We propose the name “Centennial Ridge” in honour of the U.S. Bicentennial and the less recent Canadian Centennial. T. Kawakami referred to this ridge in A.A.J., 1966, page 150, indicating that they had intended to climb it in 1965 but instead did “Independence Ridge.” We occupied our camps as follows: I at 10,000 feet on July 8, II at 13,300 feet on July 12, III at 12,100 feet on July 23, IV at 13,700 feet on July 17, V at 16,100 feet on July 19, VI (the main scientific camp) at 17,400 feet on July 20. On July 30 a further camp (VII) was established beside the rocks near the summit of the West Peak at 19,410 feet, where a topographic survey was carried out. On July 31 Wyss reached the main summit (5951 meters or 19,524 feet). Jones, Wyss and I climbed the Northeast Peak (17,999 feet) on July 20 and Wyss and I reached the West Peak (19,410 feet) on July 29 and 30. We fixed 4250 feet of rope in the 9700 vertical feet between Base Camp and the Northeast Peak. The descent on snowshoes into the King Trench pick-up point at 10,800 feet was made on August 1. The aim of this expedition was to carry out scientific work; the visits to the higher peaks were necessary to carry out a topographic survey. A fuller account of the expedition will appear in the Canadian Alpine Journal, 1977. (Au)

A, F, Y
Acclimatization; Geographical names; Glaciers; Glaciology; Mapping; Mountaineering; Mountains; Snow; Surveying; Topography

G0811
Logan, Mount, Yukon


Glaciological studies on Mt Logan   /   Holdsworth, G.
(Canadian alpine journal, v. 60, 1977, p. 56-58, map)
References.
Text on p. 57-58; map on p. 56.
ASTIS record 63859.
Languages: English
Libraries: ACU

We reported earlier, work on the plateau of Mt Logan which was intended to support a Department of the Environment decision regarding the viability of extracting an ice core from the North-west Col area (5300 to 5400 m altitude). Information obtained from such an ice core is expected to provide a good basis for reconstructing palaeoclimatic changes over the last few centuries, for this part of the continent. ... According to Houston, in order to suppress the possibility of oedema occurring, ascent rates as slow as 150 m/day above about 3000 m should be adhered to. Thus, an ascent involving an altitude gain of 7400 ft (2260 m) between 10,800 ft (3300 m) and 18,200 ft (5550 m) should take about two weeks to be on the safe side. ... This year we decided to adhere as close as possible to Houston's guidelines by taking a route which by itself would impose a limit on our rate of ascent. The altitude gain involved here was about 9700 ft (2960 m) to the summit of the North-East Peak and thus the "Houston time" would work out at about 17 to 18 days. The ascent actually look 15 days, because towards the end impatience was beginning to set in and we waived some of the rules. This resulted in no ill effects, and on 22 July, when the weather on the plateau had improved sufficiently, we began setting up our operation. Equipment had already been flown up in the Arctic Institute's Helio Courier. Our 1976 program included: 1. Taking ice depth soundings on the North-West Col. ... 2. The accumulation and movement pole array on the Col was resurveyed. Average snow accumulation there for 1975-76 was 1.2 m (at density 0.35 Mg/m³). Measured strains there corroborated an ice depth of at least 100 m. 3. Two 2-metre deep snow pits were dug on the Col and at the Arctic Institute camp site and in the base of both a 6 m core hole was drilled to provide further samples for oxygen isotope analyses as well as particulate and pollen counts. Temperatures were also measured in these holes. At the same depth below the surface, it is about 1°C warmer this year at the camp site compared with that at the North-West Col (-28.9°C) some 700 m away and 40 m higher. 4. Further surveying was carried out to improve the 1:10,000 scale map coverage of the area .... It now looks promising for mounting a drilling operation on the plateau using a portable Swiss designed electro-mechanical drill capable of coring to 150 m in a few days. We plan on drilling in 1978. After essential analyses are performed on the ice core in 1979 it should be possible to make a contribution to climatic change studies covering the last few centuries in the north-west part of the continent. (Au)

F, A, Y
Acclimatization; Accumulation; Boreholes; Cores; Coring; Flow; Glaciers; Glaciology; Isotopes; Mapping; Mountaineering; Oxygen-18; Radar; Snow; Strain; Surveying; Temperature; Thickness

G0811
Logan, Mount, Yukon


Mt. Logan field report   /   Holdsworth, G.
[Ottawa?] : Dept. of the Environment, Glaciology Division, 1976- .
v. : ill., graphs ; 28cm.
References.
Contents: - 1975. - 1978.
ASTIS record 1107.
Languages: English
Libraries: ACU

The purpose of this research is to determine if it is logistically feasible and scientifically justified to extract an ice core of approximate length 100 m from the high altitude plateau on Mt. Logan. Suitable analyses performed on samples of the ice core should provide information on climatic change in this part of the continent. ... (Au)

F
Cores; Density; Glaciers; Isotopes; Snow; Thickness

G0811
Logan, Mount, Yukon


Another round on Mt Logan   /   Holdsworth, G.
(Canadian alpine journal, v. 59, 1976, p. 68-69, map)
References.
Text on p. 68; map on p. 69.
ASTIS record 63857.
Languages: English
Libraries: ACU

Because of its altitude above sea level (causing hypoxia effects and logistics constraints), because of its fickle and often tedious weather conditions, and because of the rather narrow time/temperature window in which one might successfully accomplish scientific work-other than the tent bound variety, any rather extensive program of research that is to be carried out on Mt Logan's summit plateau (5300 m) usually must be done by increments over a number of years. ... through the good offices of Dr Walter Wood of the American Geographic Society, the original survey notes and computations made by the surveyors of the US Coast and Geodetic Survey, pertaining to observations made on Mt Logan in 1892, have been located in Washington, DC. Multiple intersecting rays onto the high peak produced the following results: phi = 60°34'00".7 N; lambda = 140°23'49".0 W, z = 5949 m (1892). This compares well with our own results of phi = 60°34'03".1 N; lambda= 140°24'14".7 W, z = 5951 m (1974). Considering therefore that the surveys were made from different datums and were fundamentally different in structure, the probability is that the error in the new altitude does not exceed about ±5 m, although prior estimates of the probable error ran as high as to be within 25 m (±12.5 m) based on suspected weaknesses in the vertical control existing in some of the Yukon peaks. We have, of course, assumed that the geometry of the summit of the high peak has not changed substantially in 82 years. ... Our survey results have been verified by the Canadian Geodetic Survey who recommends the use of the value of 5951 m (19,524 ft) for the altitude of the high peak, and therefore this figure will appear on subsequent maps. ... As in previous years the ascent was made via the King Trench Route. Climbing time was about one week. In order to study the deformation of the ice in the area of the proposed drill site, two stations were set up on rock outcrops occurring on either side of the North West Col. An array of poles was set out and sunk in the snow for the purpose of measuring the horizontal strain rates there. A 2 m deep snow pit was dug near the central pole and a 13.8 m core was extracted from the base of this using a SIPRE corer. From this corer and from the pit walls, samples were taken for tritium and O18/O16 analysis. When available, these results will enable past accumulation rates to be determined. Current values are 1.3-1.5 m (snow) per year. A radio echo-sounder was operated at the AINA Camp and an ice depth of about 120 m is tentatively deduced. These and other considerations will be used to determine if it is worth drilling for a 100 m core. We previously reported a 10 m temperature of -24.5°C made at the AINA camp site in 1968. Our 1975 measurements yielded a 10 m temperature of -28.9°C at the North West Col. The depth-density curves at the two sites are almost identical, whereas the accumulation rate on the Col is about 2/3 of that at the AINA camp which suggests that the difference is real. However, the reason for this large temperature difference has not yet been accounted for. ... (Au)

F, A
Accumulation; Boreholes; Cores; Coring; Deformation; Flow; Glaciers; Glaciology; Isotopes; Mapping; Oxygen; Radar; Snow; Strain; Surveying; Temperature; Topography; Tritium

G0811
Logan, Mount, Yukon


Taking the measure of Mount Logan   /   Holdsworth, G.
(Canadian geographical journal, v. 90, no. 3, Mar. 1975, p. 28-33, ill., 1 map)
ASTIS record 57889.
Languages: English
Libraries: ACU

This article presents an account of the discovery of Mount Logan and history of surveying attempts to determine its height. (ASTIS)

A, V
Exploration; History; Measurement; Mountaineering; Mountains; Size; Surveying

G0811
Logan, Mount, Yukon


Resurvey of Mt Logan   /   Holdsworth, G.
(Canadian alpine journal, v. 58, 1975, p. 16-20, ill., maps)
References.
ASTIS record 45520.
Languages: English
Libraries: ACU

In 1968 the author was involved in a survey to determine the altitude of a research installation on the plateau of Mt Logan. Although this work was incomplete it was possible to show that, if the altitudes of Mt Steele, Mt Lucania and two International Boundary Commission (IBC) stations were reliable, then the altitude of the main summit of Mt Logan could not be substantially greater than about 19,500 ft (5945 m). To show this I first obtained an altitude for the North Peak (then determined to be 5560 m p/m 5 m) the position of which was determined by resection. Using a set of vertical angles onto the West Peak combined with a scaled map distance (with a p/m 100 m error) from the North Peak, an elevation difference between the two points was established. Unfortunately, there was no time then to make any further observations but some measurements by A. Carpe proved very useful. Carpe participated in the first ascent of the summit in 1925 and took a clinometer reading from the High Peak to the West Peak. From this angle and from the scaled distance off the Centennial Map Sheet it is possible to show that the elevation difference between these points is close to 100 ft. Since my West Peak altitude came to about 19,400 ft (5913 m) this meant that the altitude of the High Peak could not be much more than about 19,500 ft (p/m 50 ft, 5945 p/m 15 m). On their own these values and the method of attainment appear fairly rough, but it pointed, at least, to the possibility of there being a significant error (300 ft or 100 m) in the then accepted altitude of Mt Logan (19,850 ft). When Dr Walter Wood of the American Geographic Society was informed of these observations he referred to the results of a survey he did in 1948-49 on the Seward Glacier. From a number of stations, forming a semi-rigid network, he resected to all major peaks, including the High and East Peaks of Mt Logan, Mt St Elias and other International Boundary Survey Peaks. ... Wood then calculated from the then accepted altitudes of his six stations, a new altitude for the High Peak (5957 m = 19,543 ft) which is about 100 m lower than the value appearing on current maps. This result was not reported then, because, as one might imagine, a certain degree of difficulty would have arisen if an American expedition had reported a substantially lower altitude for Canada's highest peak, which was believed to have been surveyed by the "surveying élite" of the IBC. So the data lay dormant for 25 years. Now, the value of 19,850 ft originates with the 1918 IBC Report where, on page 163, appears the coordinates and altitudes of two peaks: Mt Logan, East Dome (17,876 ft) and Mt Logan, Middle Dome (18,523 ft) both observed in 1913. ... there is a footnote which reads: "No trigonometric determination was made of the position and elevation of the highest point of Mt Logan. A photographic determination of its elevation (altitude) gives 19,850 ft". In a recent effort to locate the original photographic plates and the marked prints, I regret to have to report that they are missing and it is presumed that they were borrowed and either lost or destroyed. Thus we have no way of repeating and checking the calculation that was made. ... (Au)

A, V, Y, B, E
Atmospheric temperature; Geology; History; Logistics; Mountaineering; Storms; Surveying; Topography

G0811
Logan, Mount, Yukon


Deformation and flow of Barnes Ice Cap, Baffin Island   /   Holdsworth, G.
Ottawa : Inland Waters Directorate, 1975.
vii, 19 p. : ill. ; 28 cm.
(Scientific series - Inland Waters Directorate, no. 52)
References.
ASTIS record 45280.
Languages: English
Libraries: ACU

Measurements taken in 1970 and 1971 of the positions of 43 surface stations along a transect (10.4 km long) from the divide to the northeast margin of the south dome of Barnes Ice Cap, have enabled surface velocities and strain rates to be computed along surface "flow lines" generated from the velocity distribution. Using a variation of a method developed by Budd (1969), the parameters nu = 4.2 ± 0.1 and Beta = 11.9 (±1.0). MN/m² s**(1/4.2) in the flow law are determined for the stress range 0.05 < tau <0.1 MN/m² where tau is the effective stress. From the measured vertical velocities of the ice and the buildup of superimposed ice over the period 1970-73, it appears that this part of the ice-cap surface is rising. This is not necessarily the case elsewhere or when averaging is done over longer periods of time. More data are required before it is known whether the divide is stable or is still migrating, as the result of a surge. (Au)

F
Deformation; Flow; Ice caps

G0813
Barnes Ice Cap, Nunavut


Mt. Logan survey, 1968   /   Holdsworth, G.
(Icefield Ranges Research Project, scientific results, v. 4, 1974, p. 273-275, map)
References.
ASTIS record 66488.
Languages: English
Libraries: ACU

A value for the height of the north peak of Mt. Logan is given. Survey data indicate that the currently accepted values for the heights of the principal peaks of Mt. Logan may be too high by about 100 m. (Au)

A
Logistics; Mountains; Quality assurance; Surveying; Topography

G0811
Logan, Mount, Yukon; Lucania, Mount, Yukon; Steele, Mount, Yukon; Walsh, Mount, Yukon


Iceberg studies in the Glaciology Division, Environment Canada   /   Loken, O.H.   Ommanney, C.S.L.   Holdsworth, G.
(Sea ice : proceedings of an international conference sponsored by the National Research Council of Iceland [and] the Bauer Scientific Trust, Reykjavik, Iceland, May 10-13, 1971 / Edited by T. Karlsson. R.r. - National Research Council, Reykjavik, '72- 4, p. 146-151, ill., map)
References.
ASTIS record 16380.
Languages: English
Libraries: ACU NFSMO

... The Glaciology Division ... has started a project to determine the geographical distribution of Canadian tidewater glaciers and to assess the rate of calving from selected typical glaciers. ... This paper briefly reviews the current studies. ... Our study can be divided into 3 phases .... The first phase is an inventory of all tidewater glaciers, the second a study of the mechanics of the calving process itself and the third a study of the rate of ice discharge from various glaciers and of the distribution of icebergs in selected areas. (Au)

F, G, R
Calving (Ice); Canada. Glaciology Division; Glaciers; Icebergs; Spatial distribution

G10, G0813, G09, G11
Baffin Bay-Davis Strait; Ellesmere Island, Nunavut; Greenland; Labrador Sea; North Atlantic Ocean


Iceberg studies in the glaciology subdivision   /   Loken, O.H.   Ommanney, C.S.L.   Holdsworth, G.   Arnold, U.C.
In: Proceedings of the Canadian Seminar on Icebergs held at the Canadian Forces Maritime Warfare School, CFB Halifax, Halifax, Nova Scotia, Canada, December 6-7, 1971. - [Halifax, N.S. : Maritime Command Headquarters, 1971?], p. 128-134
References.
ASTIS record 16274.
Languages: English
Libraries: ACU NFSMO

... [The studies of the Glaciology subdivision] can be divided into four parts. The first is an inventory of all tidewater glaciers, the second a study of the mechanics of the calving process itself, the third a study of the rate of iceberg discharge from various glaciers and the fourth is a study of the distribution of icebergs in selected areas. ... (Au)

G, F
Calving (Ice); Glaciers; Icebergs; Spatial distribution

G081
Canadian Arctic waters


An examination and analysis of the formation of transverse crevasses, Kaskawulsh Glacier   /   Holdsworth, G.
(Icefield Ranges Research Project, scientific results, v. 1, 1969, p. 109-125, ill., maps)
Appendices.
References.
This article is a modified version of G. Holdsworth's Institute of Polar Studies report described by ASTIS record 70009.
ASTIS record 66461.
Languages: English
Libraries: ACU

The main purpose of this investigation was (1) to examine the applicability of Nye's theoretical expression for the longitudinal strain rate on the surface of a valley glacier; namely to test whether: Epsilon-dot(x) = (m(Vb)/(m(Vb)+us)) (a/h + (us)k(cot(alpha)) - (1/h)(delta h/delta t) - Epsilon-dot(y) + (½h)(V-bar)(dk/dx)) and (2) to investigate the mechanics and mode of formation of transverse crevasses. In an area at the head of a valley glacier, a regional strain rate field was derived from velocity and strain net measurements. The result of a comparison between measured and computed strain rates is inconclusive because the assumptions on which the theoretical equation is dependent are not valid except in one short section, where an approximate agreement is found. A value of regional longitudinal extending strain rate of about 3.5 × 10**-5/day is associated with the occurrence of the first transverse crevasse in previously unfractured firn. The strain rate gradient and hence the rate of stress development associated with this critical strain rate is considered to be important. Localized strain rates and stresses of at least an order of magnitude greater than regional values are deduced to be responsible for fracturing of ice. Regional values of strain rate do not give a theoretical depth of crevasses close to the observed values. Strain rates of at least an order of magnitude greater are required to produce a rough agreement. Crevasse spacings average 2.8 × mean crevasse depth, which is about 26 m. Some methods of computing crevasse spacings are given. Nielsen's formula gives a spacing close to the mean of the measured spacings. A concept of the formation of transverse crevasses is discussed. This follows closely the hypothesis of Meier. The crevasses appear to be forming at the margins of the ice stream and to be propagating quietly towards the center; a plastic rather than an elastic behavior is thus suggested. Suitably placed seismograph stations could be used to locate initial points of failure within the ice. (Au)

F
Ablation; Accumulation; Crevasses; Deformation; Elasticity; Flow; Formation; Fracturing; Glaciers; Glaciology; Mechanical properties; Plasticity; Spatial distribution; Strain; Stress; Velocity; Viscosity

G0811
Kaskawulsh Glacier, Yukon


An examination and analysis of the formation of transverse crevasses, Kaskawulsh Glacier, Yukon Territory, Canada   /   Holdsworth, G.
Columbus, Ohio : The Ohio State University, 1965.
x, 90 p. : ill., maps ; 28 cm.
(Report - Ohio State University. Institute of Polar Studies, no. 16)
Appendices.
References.
Report date: June 1965 (on title page), and August 1965 (on cover).
ASTIS record 66461 describes a modified and shortened version of this report.
ASTIS record 70009.
Languages: English
Libraries: ACU

The main purpose of this investigation was (1) to examine the applicability of Nye's theoretical expression for the longitudinal strain rate on the surface of a valley glacier; namely to test whether: Epsilon-dot(x) = (m(Vb)/(m(Vb)+us)) (a/h + (us)k(cot(alpha)) - (1/h)(delta h/delta t) - Epsilon-dot(y) + (½h)(V-bar)(dk/dx)) and (2) to investigate the mechanics and mode of formation of transverse crevasses. In an area at the head of a valley glacier a regional strain rate field was derived from velocity and strain net measurements. The result of a comparison between measured and computed strain rates is inconclusive because the assumptions on which the theoretical equation is dependent are not valid except in one short section, where an approximate agreement is found. A value of regional longitudinal extending strain rate of about 3.5 × 10**-5/day is associated with the occurrence of the first transverse crevasse in previously unfractured firn. The strain rate gradient and hence the rate of stress development associated with this critical strain rate is considered to be important. Localized strain rates and stresses of at least an order of magnitude greater than regional values are deduced to be responsible for fracturing of ice. Regional values of strain rate do not give a theoretical depth of crevasses close to the observed values. Strain rates of at least an order of magnitude greater are required to produce a rough agreement. Crevasse spacings average 2.8 × mean crevasse depth, which is about 26 m. Some methods of computing crevasse spacings are given. Nielsen's formula gives a spacing close to the mean of the measured spacings. A concept of the formation of transverse crevasses is discussed. This follows closely the hypothesis of Meier. The crevasses appear to be forming at the margins of the ice stream and to be propagating quietly towards the center; a plastic rather than an elastic behavior is thus suggested. Suitably placed seismograph stations could be used to locate initial points of failure within the ice. (Au)

F, A
Ablation; Accumulation; Crevasses; Deformation; Elasticity; Flow; Formation; Fracturing; Glaciers; Glaciology; Gravity measurement; Mechanical properties; Plasticity; Snow stratigraphy; Spatial distribution; Strain; Strength; Stress; Surveying; Thickness; Velocity; Viscosity

G0811
Kaskawulsh Glacier, Yukon


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