ALBERT

Description: In the Foreword to the first issue of Polar Record the editor wrote: ‘In the first place an attempt will be made merely to record the chief polar events of the preceding six months; but it is hoped that the scope of the journal will gradually be extended. The main body of The Polar Record, therefore, is a resume of polar news extracted from the best available sources’. This was a formidable task even in 1931, and a cursory glance at the latest volume indicates the tremendous growth and advances that have taken place since then. It is an impressive record and to mark the journal's 50th anniversary I shall use this information to make a general comparison of British polar activities, and the driving force behind them, in the pre- and post-war periods.

Description: A standard heavy ion nuclear structure facility has been used to detect several long-lived radioisotopes by counting the accelerated ions. The problem of eliminating strong isobaric background beams has been solved by combining the energy loss dispersion through a uniform Al foil stack with the high momentum resolution of an Enge split-pole magnetic spectrograph. Radioisotope concentrations in the following ranges have been measured: 14C/12C = 10–12 to 10–13, 26Al/27Al = 10–10 to 10–12, 32Si/Si = 10–8 to 10–14, 36Cl/Cl = 10–8 to 10–11.

Description: A variety of organic contaminants can potentially have impact on aquatic birds by their affecting surface tension. Avian plumage constitutes a porous barrier to water and the air trapped between the feathers serves as thermal insulation. When the air is displaced, the birds expend extra energy to maintain a normal body temperature, but this response cannot be sustained for long, especially at low environmental temperatures. When energy stores are depleted, hypothermia and death ensue. Surface tension is the force that resists infiltration of water into the plumage. The critical surface tension for feather wetting is conservatively estimated to be in the range 38–50 mN m-1. The hypothesis that surface-active organic contaminants can have significant detrimental effects on aquatic birds was evaluated. New data obtained in a study of water penetration pressures in Lesser Scaup contour feathers show that the 'wettability safety factor' is reduced by about half during moult. That is, the critical surface tension was raised to approximately 49–58 mN m-1 in moulting Lesser Scaup. The energetic and behavioural effects of oil contamination are reviewed, and it is concluded that even small quantities of organic material may confer significant physiological cost. The available data generally support the hypothesis that waterfowl face a potential risk associated with chronic or periodic mild depression of water surface tension due to organic pollutants, including oils and detergents. However, much of the evidence is indirect and further research, especially long-term assessment of surface tension in marine, estuarine and freshwater habitats, is needed to determine whether a real environmental problem exists.

Description: Milk yield was determined by the weigh-suckle-weigh method over 2 years (1983 and 1984 calvings), for a total of 305 purebred Hereford (H×H) and first-cross Brahman×Hereford (B×H), Simmental×Hereford (S×H) and Friesian×Hereford (F×H) cows grazing three pasture systems at Grafton, New South Wales, Australia. The age of the cows ranged from 6 to 11 years. The data were used to evaluate different estimates of milk yield and to examine the effects of milk yield on growth of calves up to weaning.Of all the cow traits studied, average lactation milk yield (average of early, mid and late-lactation milk yields) had the highest correlation coefficient with calf 210-day weight (r=0·73) and pre-weaning average daily gain (ADGtotal, r=0·73), and explained 〉50% of the variation in the calf traits. However, milk yield was also moderately correlated with other cow traits (liveweight and body condition score). Thus, to predict calf performance, milk yield data may not be required if detailed data on other cow traits are available. This is supported by the finding that differences in the coefficients of determination (R2) between models for calf 210-day weight and ADGtotal which included average lactation milk yield and other cow traits (highest R2=69%) and models which included other cow traits but no milk yield estimate (highest R2=57%) were

Description: The collision of India and Asia can be defined as a process that started with the closing of the Tethyan ocean that, during Mesozoic and early Tertiary times, separated the two continental plates. Following initial contact of Indian and Asian continental crust, the Indian plate continued its northward drift into Asia, a process which continues to this day. In the Ladakh–Zanskar Himalaya the youngest marine sediments, both in the Indus suture zone and along the northern continental margin of India, are lowermost Eocene Nummulitic limestones dated at ∼54 Ma. Along the north Indian shelf margin, southwest-facing folded Palaeocene–Lower Eocene shallow-marine limestones unconformably overlie highly deformed Mesozoic shelf carbonates and allochthonous Upper Cretaceous shales, indicating an initial deformation event during the latest Cretaceous–early Palaeocene, corresponding with the timing of obduction of the Spontang ophiolite onto the Indian margin. It is suggested here that all the ophiolites from Oman, along western Pakistan (Bela, Muslim Bagh, Zhob and Waziristan) to the Spontang and Amlang-la ophiolites in the Himalaya were obducted during the late Cretaceous and earliest Palaeocene, prior to the closing of Tethys.The major phase of crustal shortening followed the India–Asia collision producing spectacular folds and thrusts across the Zanskar range. A new structural profile across the Indian continental margin along the Zanskar River gorge is presented here. Four main units are separated by major detachments including both normal faults (e.g. Zanskar, Karsha Detachments), southwest-directed thrusts reactivated as northeast-directed normal faults (e.g. Zangla Detachment), breakback thrusts (e.g. Photoksar Thrust) and late Tertiary backthrusts (e.g. Zanskar Backthrust). The normal faults place younger rocks onto older and separate two units, both showing compressional tectonics, but have no net crustal extension across them. Rather, they are related to rapid exhumation of the structurally lower, middle and deep crustal metamorphic rocks of the High Himalaya along the footwall of the Zanskar Detachment. The backthrusting affects the northern margin of the Zanskar shelf and the entire Indus suture zone, including the mid-Eocene–Miocene post-collisional fluvial and lacustrine molasse sediments (Indus Group), and therefore must be Pliocene–Pleistocene in age. Minimum amounts of crustal shortening across the Indian continental margin are 150–170 km although extreme ductile folding makes any balancing exercise questionable.

Description: The grounding-line region of Rutford Ice Stream was surveyed from the ground during 1978–79 and 1979–80, and from the air in 1980–81. Maps of surface elevation and ice thickness of an area of 1 000 km2allow the grounding line to be delineated and show that the ice stream consists of several distinct fingers of thick ice trending parallel to the flow. In one area, the floating ice is more than 2 000 m thick. Hydrostatic tiltmeters were used to pinpoint the grounding line. Repeated survey of a network of stakes gave velocity and strain-rates for both longitudinal and transverse profiles. Radio echo-fading pattern studies showed the ice to be completely sliding near the grounding line. Modelling of the ice stream, using steady-state theory, shows that the bottom melting rate is around 1.8 m a−1. The small surface and bottom gradients imply that the position of the grounding line may be sensitive to small changes in ice thickness.

Description: The grounding-line region of Rutford Ice Stream was surveyed from the ground during 1978–79 and 1979–80, and from the air in 1980–81. Maps of surface elevation and ice thickness of an area of 1 000 km2 allow the grounding line to be delineated and show that the ice stream consists of several distinct fingers of thick ice trending parallel to the flow. In one area, the floating ice is more than 2 000 m thick. Hydrostatic tiltmeters were used to pinpoint the grounding line. Repeated survey of a network of stakes gave velocity and strain-rates for both longitudinal and transverse profiles. Radio echo-fading pattern studies showed the ice to be completely sliding near the grounding line. Modelling of the ice stream, using steady-state theory, shows that the bottom melting rate is around 1.8 m a−1. The small surface and bottom gradients imply that the position of the grounding line may be sensitive to small changes in ice thickness.

Description: Two methods were used to locate the grounding line on the Rutford Ice Stream. The first method determined where the glacier was floating in hydrostatic equilibrium, while the second method measured the flexing close to the grounding line due to ocean tides. The ratio of surface elevation to ice thickness of the glacier goes through the hydrostatic equilibrium value 1 to 2 km downstream of where tidal flexing was recorded. This behaviour can be explained if the upward pressure of the sea at the base of the ice is augmented by a vertical shear-stress gradient within the glacier to overcome its weight. Simple el as tie-beam theory matches the flexure profile data if a modified elastic modulus and effective thickness are used. Tiltmeters can he used to monitor the position of the grounding line if the geometry of the flexing region can be defined.