bluuebunny/crossref_metadata_2025_split huggingface dataset:
Internal Deformation and Thermal Anomalies in Lower Blue Glacier, Mount Olympus, Washington, U.S.A.
Authors: Shreve R.L. , Sharp R.P. 
Published: September 2017

AbstractIn 1957 through 1962 six deep holes were drilled by means of specially developed electrically powered hotpoints, 4 cm diameter aluminum pipes were placed in them, and annual inclinometer surveys were made to investigate the deformation field and flow law of the ice at depth. Although a strongly maritime climate with moderate temperatures implies that lower Blue Glacier should be temperate, freezing at depths as great as 200 m, sometimes even in summer, seriously hindered inclinometer surveys. This freezing cannot be due solely to chilling by winter cold and to leakage into initially dry pipes, but may also be due to wintertime changes of water Table in the glacier and to contamination of the ice by antifreeze. Another possibility, residual subfreezing zones carried down from the ice fall, seems unlikely.Because the relatively inextensible pipe slips lengthwise in the deforming hole, observations of pipe motion at best give only the two components of ice velocity perpendicular to the hole. Thus, a single hole gives two independent equations connecting the nine unknown derivatives of the velocity components; two holes give four equations: and three or more give at most six. Incompressibility of the ice, when applicable gives another. The remaining unknowns must be either neglected or estimated from assumptions about the flow field. At the Blue Glacier holes the longitudinal strain-rate is less than about 0.01 per year, becoming more extensional down-glacier and more compressional at depth, because the holes were moving through a reach in which the surface steepens and the bed becomes more steep-sided and flat-bottomed. Although the effective strain-rates are only about 0.01 to 0.1 per year, so that errors are relatively large, they are in reasonable agreement with flow laws deduced from laboratory experiments by Glen, from tunnel contraction by Nye, and from deformation of Athabasca Glacier bore holes by Paterson and Savage, except that in the range of strain-rates covered the viscosities found for Blue Glacier are about half those derived from the other studies.
Excess Pressure Observed in a Water-filled Cavity in Athabasca Glacier, Canada
Authors: Paterson W.S.B. , Savage J.C. 
Published: September 2017

AbstractDuring drilling in the Athabasca Glacier in April 1968, a cavity containing water was punctured at a depth of 9.2 m below the ice surface. Upon removing the drill, water gushed from the bore hole for about 55 s indicating an excess pressure of at least 0.25 bar within the cavity. The surrounding ice was slightly below the pressure melting point, and the excess pressure was apparently generated by the reduction in volume of the cavity caused by freezing of some of the water within it.
Interpretation of the Orientation of Ice Dendrites Growing from Supercooled Water
Authors: Levi Laura 
Published: September 2017

AbstractAn interpretation is proposed of the phenomenon of splitting of ice dendrites growing from supercooled water and of their orientation at an angle α to the basal plane. Both phenomena are related to the instabilities which develop on the dendritic cap when the ratio Vc/Va of the growth velocities in the direction of the c- and a-axes exceeds a certain limit. The different interface supercoolings, (δTi)a and (δTi)c at the tip and at the sides of the dendrite cap are considered. Although Vc/Va increases with the bath supercooling ΔT it is found that Vc ≪ Va for (δTi)c = (δTi)a through the whole range investigated (o < ΔT ≤ 18 deg). The increase of α with the concentration of solutes is also qualitatively explained. Considering the kinetic theory of the molecular growth mechanism, the results obtained for Vc as a function of (δTi)c would indicate that most of the studied interval must correspond to the transitional regime of growth.
Late Weichselian Potholes Near Wolverhampton, England
Authors: Morgan Alan V. 
Published: September 2017

AbstractThree potholes and a narrow channel cut into bedrock in a side-hill position were observed beneath an Irish Sea till west of Wolverhampton, England. The potholes and the channel are believed to have been cut by subglacial or latero-glacial streams flowing beneath or immediately beside the Irish Sea ice sheet. They were later choked by sand and gravel from this ice sheet and capped by till which ended the glaciofluvial deposition. Deposits below and above the till have been 14C dated at 30 655 and 13 490 years B.P. at localities between 13 and 27 km north of the trench section described.
The Early History of Glacial Theory in British Geology
Authors: Hansen Bert 
Published: September 2017

AbstractMuch of the history of British geological thought in the second quarter of the nineteenth century centered on problems which are now explained by reference to the events of the Ice Age. This paper reviews the data and theories then current among British geologists as the background of the British response to Louis Agassiz’s “modern” theory of a glacial epoch. Today, as we read Agassiz’s amazing speculation, our own sympathy for the striking accuracy of his ideas masks from us the difficulty they faced in gaining acceptance. By first examining the context into which the glacial theory was introduced, we can then appreciate the novelty of Agassiz's efforts and understand the long delay in their achieving prominence. The present examination suggests that this delay was due to the unfortunate merger of Agassiz’s new ideas with the older drift theory of Charles Lyell.
A Possible Relation Between Grain Size, Density, and Light Attenuation in Natural Snow Cover
Authors: Bergen James D. 
Published: September 2017

AbstractThe extinction coefficient for the transmission of light through snow cover is related to the grain size and density of the snow cover. The connection is made by means of an empirical relation between the latter parameters and the air permeability and by the Carmen–Kozney relation between the air permeability and specific surface of a porous medium. The results are compared with a set of measurements found in the literature with fair agreement between the predicted and measured values of the extinction coefficient.
Effects of a Debris Slide on “Sioux Glacier”, South-Central Alaska
Authors: Reid John R. 
Published: September 2017

AbstractThe lower one-third of “Sioux Glacier” in south-central Alaska was buried beneath a debris slide during the 27 March 1964 earthquake. Investigations to determine the effect of this cover on the regimen of the glacier revealed that it has increased in thickness by as much as 28 m, primarily as a result of the insulating effect of this debris cover. In areas where debris has continuously veneered the surface, at least since 1938, the ice is also thicker. A longitudinal profile reveals that the area near the upper extent of the slide debris has become intensely crevassed and has been lowered as much as 8 m between 1965 and 1966, while the terminal area is up to 5 m higher and is characterized by thrusting. It is concluded that a kinematic wave passed through this glacier sometime between 1965 and 1966.The upper zone of debris-veneered ice is moving at 175 m/year while the terminal area is flowing at only 21 m/year. The rate of down-glacier decrease in velocity is about 0.06 m/year per meter of horizontal distance except for an area approximately 1 km from the terminus. Here, the rate of decrease in velocity is 0.1 m/year per meter. The change in rate is presumed to be related to topographic control caused by the recent thinning of the ice here.
The Mechanical Properties of Single Crystals of Pure Ice
Authors: Jones S. J. , Glen J. W. 
Published: September 2017

AbstractResults obtained from tensile and compressive tests on pure ice single crystals at various temperatures down to −90°C are reported. At −50°C tensile creep tests give a continually increasing creep rate until fracture, as observed at higher temperatures. The stress dependence of the strain-rate is discussed. Fracture stress increases with decreasing temperature. Results from constant strain-rate compressive tests are compared with theoretical curves computed from Johnston’s (1962) theory of dislocation multiplication. A dislocation velocity of the order of 0.5×10−8 m s−1 is deduced for ice at −50°C.
Glaciar Yanasinga (Central Peru): 24 Years of Measurements
Authors: Petersen U. , Sassarini L. , Plenge R. 
Published: September 2017

AbstractGlaciar Yanasinga (lat. 11° 36′ S., long. 76° 12′ W., 4850 m a.s.l.) is probably one of the few glaciers in the equatorial region on which measurements have been performed during the last 24 years. These were carried out in the years 1944, 1945, 1946, 1947, 1948, 1949, 1957, 1963 and 1968. The results of these surveys are presented on a map and references are given for those interested in obtaining more detailed information.
I.G.Y. Glaciological Work at Wilkes Station, Antarctica
Authors: Hollin J. T. , Cameron R. L. 
Published: September 2017

AbstractThe Wilkes Station area comprises 75 km.2 of rock which form one of the most extensive exposures on this part of the East Antarctic coast. During 1957 and 1958 the continental ice sheet south-east of Wilkes Station was explored to a distance of 100 km. inland, and its form and behaviour studied by means of topographic, movement and gravity surveys. Surface stake measurements inland showed a net accumulation equivalent to 13.7 cm. of water in 1958. Sub-surface measurements of wetness, hardness, density, grain size, crystal size, shape and fabric and electrical conductivity were made at 60 locations and to depths which reached 62 m. at an auxiliary inland station. Meteorological observations were made and englacial temperatures measured. In summary, the ice sheet in this area provides a typical section of a polar glacier. The evidence for glacial fluctuations and the possibility of establishing a chronology for these are discussed.
The Response of Fjord Glaciers to Changes in the Firn Limit
Authors: Mercer J. H. 
Published: September 2017

AbstractGlaciers in fjords almost always reach standstill positions at the fjord mouths or at changes in their width. Between such positions the terminus is usually advancing or retreating: the advance may be anomalous compared to glaciers on dry land in the vicinity, and the retreat may be catastrophically rapid. These peculiarities of fjord glaciers can be at least partly explained by considering conditions to be expected in an ideal fjord of constant width: the glacier cannot reach equilibrium by changing the extent of its ablation area or its calving terminus, and these cannot change their altitude with respect to sea-level in response to a rise or fall in the firn limit.
Measurement of Firn Motion by a Magnetic Prospecting Method
Authors: Lliboutry L. 
Published: September 2017

AbstractThe compaction and flow within névé can be studied by means of magnetized steel tubes buried in vertical pits. The locations of the tubes, their distances from the surface, down to a depth of 10 m., and their angles with the vertical can be determined from measurements made with a B.M.Z. magnetometer.
A Tentative Theory of Ogive Formation
Authors: King C. A. M. , Lewis W. V. 
Published: September 2017

AbstractThe dark and light bands on glaciers known as ogives are only found beneath ice falls and avalanche fans. They are not to be confused with sedimentary layering, which may appear similar. Vareschi’s pollen studies are considered in relation to the present theory; his evidence is re-interpreted and shown to support the theory put forward.The Norwegian glacier Austerdalsbreen has a fine double set of ogives, one set on ice from Odinsbreen and the other on ice from Thorsbreen. These ogives are continuous from near the feet of these ice falls down to the end of the main glacier. The ice from the collecting ground of Jostedalsbreen which moves slowly towards the head of these ice falls is normally stratified as seen in the deep crevasses immediately above the ice falls. The high velocity of flow, 2,000 m. per year in the upper part of Odinsbre ice fall, causes the ice to stretch into a thin and heavily crevassed layer which exposes a very high proportion of surface per unit volume to the sun, the rain and the snow. In summer this leads to:(1) crystal changes, primarily of enlargement, (2) an infusion of dirt which blows on to the glacier from the neighbouring snow-free and vegetation-free land surfaces, and (3) water filling the bottom of some of the deeper crevasses, which may later freeze. On the other hand, the ice which passes down the ice falls in winter is largely protected by a mantle of snow; crystal changes then are slow, little dust collects, and less water pours into the crevasses which, instead, are filled with new snow. So the ice reaching the lower part of the ice falls and moving on to form the main glacier, Austerdalsbreen, has been subjected throughout its mass to seasonal differences. These differences seem to be more systematic in the deeper ice, and only when the chaotic surface layers are melted away, do they appear on the surface of Austerdalsbreen as well defined ogives. The greater proportion of blue, bubble-free ice with large crystals in the “summer” ice, is alone sufficient to distinguish it from the lighter-coloured “winter” ice with its more frequent bands of white bubbly ice having very small crystals. But as ablation continues, more and more dust is brought to the surface and this still further darkens the “summer” ice. In addition the darker ice melts more readily and tends to form troughs in the glacier surface which retard stream flow, hold the lingering snows, and trap further dust and dirt. The cracks between large crystals also hold dirt better than the smooth hard white surfaces which occur more frequently in the “winter” ice. Hence the ogives remain distinct throughout their journey down Austerdalsbreen. Near the snout the medial moraine is very abundant along the darker bands deriving from Thorsbreen, and this further supports our view that this darker ice was in the ice fall in summer when most debris falls from the rock walls on to the ice fall.
New Zealand Glaciations and the Duration of The Pleistocene
Authors: Gage Maxwell 
Published: September 2017

AbstractRecent work has resulted in recognition of an additional glaciation preceding the Waimaunga Glaciation in the late Pleistocene. This followed the mid-Pleistocene climax of earth movements responsible for most of the present mountainous relief of New Zealand, but only after an interval of time long enough for the construction and subsequent deep dissection of Banks Peninsula shield volcano. It is inferred from this and other geological evidence that the earliest late Pleistocene glaciation was separated from the early Pleistocene Ross Glaciation by several hundred thousand years, and that the Pleistocene Period altogether covers at least one million years.
Theory of Performance of Isothermal Solid-Nose Hotpoints Boring in Temperate Ice
Authors: Shreve R. L. 
Published: September 2017

AbstractThe performance of a thermal ice-drill having a smooth, solid, impervious frontal surface, termed a “solid-nose hotpoint”, is determined by the velocities, pressures, and temperatures in the thin layer of warm melt water between the hotpoint and the ice. The efficiency, the speed of penetration, the temperature of the frontal surface, and the distribution of pressure on it can be calculated from the equations of non-turbulent fluid flow. For hotpoints whose frontal surfaces are isothermal and axially symmetric, these quantities are functions of the total input of power Q of the weight W on the hotpoint, of the radius a and “shape factor” S of the frontal surface, and of the pertinent physical properties of water and ice. The calculation shows that with increasing “performance number” the efficiency E decreases and the surface temperature θ0 increases. Thus, for example, E = 1·00 and θ0 = 0°C. when N = 0.0 E = 0·76 and θ0 = 48°C when N = 1.4; and E = 0·60 and θ0 = 103°C. when N = 3.0. The coefficient Λ is a constant equal to . The shape factor S is a dimensionless number between 0 and 1 that varies according to the shape of the frontal surface, greater values of S being associated with blunter profiles (thus S = 1.0 for a plane frontal surface perpendicular to the axis). For coring hotpoints the same numerical results are obtained, but the performance number is given bywhere 2ϖia is the inside diameter of the hotpoint.
Investigation of Shear Zones in the Ice Sheet Margin, Thule Area, Greenland
Authors: Swinzow George K. 
Published: September 2017

AbstractThe structure of silty ice bands and the formation of their resulting shear moraines are investigated in the light of new evidence provided by two ice tunnels and additional surface investigation in the general Thule area. Previous investigations are examined and discussed; a new interpretation of the phenomena is presented.
Mass Balance Studies in Kebnekajse
Authors: Schytt Valter 
Published: September 2017

AbstractThe mass balance of Storglaciären in Kebnekajse, Swedish Lappland, has been studied in some detail sine 1946. Out of sixteen budget years, fourteen have given a deficit, one a surplus and one has been balanced. It is emphasized that more attention should be paid to the accuracy needed for significant mass balance studies. At present the density of the observation network on Storglaciären is 120 observations per km.2 for accumulation and 13 observations per km.2 for ablation measurements. The net loss during the sixteen years of observation amounts to nearly 10 per cent of the total glacier volume, and it is suggested that the principal cause of this loss is the increase in the mean summer temperature.
A New Advance of the Jan Mayen Glaciers and a Remarkable Increase of Precipitation
Authors: Lamb H. H. , Probert-Jones J. R. , Sheard J. W. 
Published: September 2017

AbstractA new advance since about 1954 of the glaciers descending on all sides of the great volcanic mountain Beerenberg (2,277 m.) on the island of Jan Mayen (lat. 71° N., long. 8° W.) has been reported. Annual precipitation in the area appears to have risen fairly steadily and in the 1950’s had almost doubled as compared with the 1920’s. Other places around the Greenland Sea show substantial increases of precipitation after 1920 as compared with the 1910–20 rate, but mostly attained a maximum in the 1930’s or around 1940. Periodicities are briefly discussed as well as secular change. Temperatures at Jan Mayen have fallen somewhat since the 1930’s but they have not altered much since the 1940’s. The likely causes in terms of changes of the atmospheric circulation and other circumstances, including lag in the glaciers’ response, are briefly discussed. The increase of precipitation seems to be the main, almost the sole, causative factor in the glacial advance.
Orientation Fabrics in Lake Ice
Authors: Lyons J. B. , Stoiber R. E. 
Published: September 2017

AbstractLaboratory experiments and field observations permit an explanation of the varying crystallographic orientations observed in lake ice in terms of four factors: (1) coincidence of the plane of most rapid growth in ice (the basal plane) with the vector of thermal flux, (2) mechanical fragmentation of early-formed dendrites and plates by winds above a critical velocity (approximately 2.7 m./sec.), (3) the presence of a sufficiently thick layer of supercooled water to permit vertical crystal growth, and (4) the operation of geometric factors, first pointed out by Perey and Pounder, which result in the gradual elimination of the flatter plates of growing ice by the steeper ones.
Heat Conduction in Thinning Ice Sheets
Authors: Jenssen D. , Radok U. 
Published: September 2017

AbstractA numerical treatment of the heat conduction in ice sheets subject to vertical shrinking, geothermal and frictional heating from below, and surface accumulation or ablation, is outlined and illustrated with results computed for an arbitrary ice thickness profile. The movement of the ice is found to increase its basal temperature when the ice is thick, and to decrease it in the fringe zone where the ice becomes thin. The treatment seems capable of extension to cover both the thermal and dynamic aspects of ice motion.
Glaciological Observations on the Ross Ice Shelf Near Scott Base, Antarctica
Authors: Stuart A. W. , Bull C. 
Published: September 2017

AbstractOn the Ross Ice Shelf near Scott Base the annual surface snow accumulation is about 18 g.cm.−2. The increase of firn density with depth is greater than normal, due to horizontal compaction. Where the bottom of the ice shelf has a density less than 0.8 g.cm.−3 the shelf becomes brine-soaked by vertical infiltration. The bottom of the shelf is melting, at about 44 g.cm.−2 yr.−1 where the bottom is impermeable ice and 73 g.cm.−2 yr.−1 where the bottom is permeable firn. Surface velocities at 40 points within 30 km. of Scott Base vary between 4 and 840 m.yr.−1. From the pattern of velocities, ice thicknesses and surface features, a transition zone is delineated, separating the Ross Ice Shelf from the “McMurdo Ice Shelf”.
The Glaciers of Jan Mayen
Authors: Kinsman D. J. J. , Sheard J. W. 
Published: September 2017

AbstractA descriptive account of the glaciers of Jan Mayen is given, based on the results of two recent University of London expeditions. The positions of most of the glacier snouts are compared with previous records and a general advance of the ice margin is reported. The discovery of massive tillite deposits low down in the volcanic sequence is thought to confirm the post-Pleistocene origin of the present Beerenberg mountain. An outline of the geological and topographical evolution of the mountain is related to the history of its glaciation. Three major advances of the ice margin are described, the most recent having taken place within the last 350 years. The transient nature of high-altitude rime structures is demonstrated.
Glaciations of the Pindar River Valley, Southern Himalayas
Authors: Ahmad N. , Saxena H. B. 
Published: September 2017

AbstractThe Pindari Glacier is situated in the heart of the Kumaon Hills in lat. 30° 17′ N. and long. 80° 0′ E. This glacier was visited by the authors in October 1959 when morphological and other observations were made. On the basis of these observations, it appears that during the last hundred years the rate of retreat of this glacier has been phenomenal, and it may be as much as 132 ft. (40.2 m.)/yr. There is also evidence that in the past the Pindari valley suffered at least two glacial advances.
Two Tunnels in Cold ice at 4,000 m. on the Breithorn
Authors: Fisher Joel E. 
Published: September 2017

AbstractA description is given of two tunnels, each 60–70 m. long, one directly above the other, at 4,000 and 4,020 m, a.s.l. excavated through cold firn and ice of the Breithorn in the Alps. The temperature rose from −5.5° C. at the portal to −0.5° C. at the rock interface 70 m, from the portal in the upper tunnel, and from −5.5° C. to 0° C. at a water reservoir 60 m. from the portal in the lower tunnel. In both cases cracks or minute sealed crevasses, cut by the tunnel, operated to cool the ice locally below the temperature to be expected from a smooth curve. Possible. origins of the water reservoir are discussed.Small amounts of air at a moderate pressure, enclosed in small, sealed cracks and hollows, were punctured between 60 and 70 m. from the portal in the upper tunnel. The pungent odor of the air thus released was identified as ozone (a) by its characteristic odor, (b) by its reaction on rubber, and (c) by potassium iodide starch paper tests. The source of such ozone is suspected to be minute electric sparks resulting from static electric charges built up in cold ice when it is subjected under pressure to cracking or deformation; Photographs taken with exposures of 8 hr. in the upper tunnel at night apparently show such sparks.A description is given of the appearance of cold ice, frozen to the bedrock, being forcibly tortured into streamers and bands by the movement of the entire ice body at 0.6 m./yr.