Glaciers in the Southern Patagonia Icefield (SPI) have been shrinking in recent decades, but due to a lack of field observations, understanding of the drivers of ablation is limited. We present a distributed surface energy balance model, forced with meteorological observations from a west–east transect located in the north of the SPI. Between October 2015 and June 2016, humid and warm on-glacier conditions prevailed on the western side compared to dry and cold conditions on the eastern side. Controls of ablation differ along the transect, although at glacier-wide scale sensible heat (mean of 72 W m−2 to the west and 51 W m−2 to the east) and net shortwave radiation (mean of 54 W m−2 to the west and 52 W m−2 to the east) provided the main energy sources. Net longwave radiation was an energy sink, while latent heat was the most spatially variable flux, being an energy sink in the east (−4 W m−2) and a source in the west (20 W m−2). Ablation was high, but at comparable elevations, it was greater to the west. These results provide new insights into the spatial variability of energy-balance fluxes and their control over the ablation of Patagonian glaciers.

An outline is given of the Quaternary geology and geomorphology of Court Hill Col in Failand Ridge near Clevedon, Avon County, from observations made during the construction of the M5 Motorway.

A glacial col-gully about 100 m wide and approximately 25 m deep is described. The col-gully, eroded through the Carboniferous Limestone, opens and deepens northward. Associated with the Col and the col-gully is a complex sequence of Quaternary deposits. Uppermost in the sequence is a layer of red sandy silt (cover sand) approximately 0.5 m thick, of periglacial origin, probably of Devensian (Weichselian) age. Largely confined to the col-gully are unstratified tills, stratified ice-contact deposits and glacio-lacustrine deltaic deposits. The glaciogenic deposits are up to 25 m thick. Boulders of about 8 Mg in weight have been observed.

The geomorphology of the col-gully, and the stratification and composition of the glaciogenic deposits, demonstrate that an ice sheet at least 85 m thick had impinged against the south flank of Failand Ridge and was discharging immense quantities of water and sediment down an ice-contact slope through the Col into a small ice-marginal lake north of the col-gully. The ice sheet is regarded as being Wolstonian, or Anglian, in age.

The precise origins of the col-gully and the interpretation of the glacial sequence are not yet completely clear. However, it is believed that the balance of evidence indicates that both the col-gully itself and the glaciogenic deposits represent a complex sub-, en- and pro-glacial sequence associated with the downwasting and division of an ice mass into two parts by the "emergence" of Failand Ridge. The possible extent and geomorphological implications of ice-sheet penetration into the Bristol area are briefly discussed.

An unusual humped formation of floating ice, about 10 m. high, 100 m. wide and 1,200 m. long. was observed on the Ottawa River, Canada. Some characteristics of this formation are described. The cause of the humps was found to be frazil ice deposited in a trench about 90 m. wide, 90 m. deep and 1,200 m. long. The frazil ice was formed in rapids up-stream from the humps.

Although it is known that cirque glaciers once existed in the Falkland Islands, it has remained in doubt whether or not the islands were ever covered by ice caps or an ice sheet during the Cainozoic. This paper scrutinizes geomorphological evigernce on the south-eastern flank of a high massif in West Falkland. It is suggested that, at the time of their maximum extent in the Cainozoic, the largest glaciers were no more than 2.7 km long.

Steady-state creep-rates of polycrystalline ice were investigated as a function of temperature, grain-size, and inclusion concentration through uniaxial compression in the laboratory. Samples were run at a constant load with the temperature systematically varied between about —5°C and —40°C. The presence of inclusions inhibits dynamic recrystallization and grain growth; the average crystal size produced by recrystallization is inversely proportional to the inclusion concentration. At temperatures above —8°C, creep-rate is enhanced by about a factor of two. This appears to be the result of the combined effects of recrystallization with accompanying grain growth and grain-boundary sliding. Over the temperature range —10°C to —40°C, the apparent activation energy for creep increases with increasing volume fraction of inclusions. This is apparently due to a thermally activated process which is modified by internal stresses created by the inclusions.

Jökulhlaups, also known as outburst floods, have occurred every 1 to 5 years from Strandline Lake, one of the largest glacier-dammed lakes in North America. The development of a distinct calving embayment in the lobe of Triumvirate Glacier which dams the lake, as well as the filling of a number of supraglacier pools, appear to be reliable precursors to a jökulhlaup. Analysis of contour maps made from photographs taken immediately before and after the jökulhlaup of 17 September 1982 indicate that over 95% of the lake drains, a volume of approximately 7 × 108 m3 of water. The glacier lobe which dams the lake fractures and subsides during a jökulhlaup, indicating that the release mechanism is hydrostatic lifting of the ice off of a sub-glacial spillway. Evidence from the ice-free margins of the glacier suggests that the spillway may be controlled by bedrock. Large variation in the refilling period of Strandline Lake indicates that the subglacial drainage tunnels can remain open for as much as a few years after a jökulhlaup, before they become sealed by sediments and/or glacier ice.

Measurements of ice temperature to depths of 30–40 m. are given for a number of points on the ice sheet in MacRobertson Land. Variations of mean surface temperature with elevation and with latitude, and the temperature gradients below a depth of 15 m. are compared with results from other parts of Antarctica and from Greenland. Explanations of negative temperature gradients near the surface of ice sheets are reviewed, and an equation derived by Robin is checked against the measurements following its recent justification from conduction theory. Surface ice velocities necessary for development of the observed temperature gradients are computed, and these values are then compared with ice velocities estimated independently from flow measurements at the coast and continuity considerations. It is found that, if negative gradients are attributed solely to the Robin effect, improbably high ice velocities are called for, and so climatic change is reconsidered. Some evidence of secular warming in Antarctica is mentioned and a recent numerical solution of the conduction equation for the surface-warming case is described. It is concluded that the measured temperature profiles can be explained reasonably by climatic amelioration.

The climate-modeling problems associated with global change underline the importance of understanding paleoclimates. The available evidence, which suggests that the Earth has never been fully glaciated, poses an especially serious problem for the early Earth when the Sun was about 20–30% fainter than today. In conventional explanations of this “faint young Sun paradox”, presumed very high levels of atmospheric greenhouse gases are required to prevent runaway glaciation of the Earth. Here we explore other possible explanations of this paradox. As an extension of our previous work on this subject, we illustrate how-dynamical beat-flux feed backs may have prevented the early Earth from freezing. Our simulations are carried out using a two-dimensional, seasonal-climate model with physically based parameterizations for atmospheric meridional-heat transport and sea ice. It ís found that dynamical heat-flux feed backs alone may have protected the Archean Earth against a runaway glaciation to a considerable degree.

The quality and utility of the records of oxygen-isotopic abundances, dust concentrations and anionic concentrations preserved in the ice at Siple Station (75°55′ S, 84° 15′ W) are assessed from four shallow (20 m) cores. The combination of high accumulation (0.56 m a−1 w.e.) and low mean annual temperature (—24°C) preserves the prominent seasonal variations in δ18Ο which are very spatially coherent. Sulfate concentrations vary seasonally and, in conjunction with δ18Ο, will allow accurate dating of deeper cores from Siple Station. The concentrations of insoluble dust are the lowest measured in Antarctica, making Siple Station an excellent location to examine large increases in atmospheric tubidity.

The seasonal variations and annual fluxes of the anions are examined for the last two decades (AD 1966–85) with regard to probable sources. An unusually high sulfate flux in 1976 may reflect the February 1975 eruption of Mount Ngauruhoe, New Zealand. No annual signal in nitrate concentration is confirmed and no unusually high nitrate fluxes support the suggestion of nitrate production by large solar flares. However, nitrate flux is higher for the latter half of the 1970s and early 1980s, possibly reflecting the recent loss of stratospheric ozone.

Finally, comparison of the δ18O record with available surface-temperature data (AD 1957–85) reveals that multi-year trends along the western coast of the Antarctic Peninsula are recorded at Siple. More importantly, comparison with areally weighted temperature reconstructions suggests that the δ18Ο record may reflect larger-scale, persistent trends in the high southern latitudes. The strong spatial coherence of the preserved records, the potential for accurate dating, and possible relevance to larger-scale processes make Siple Station an excellent site for paleoenvironmental reconstruction from ice cores.

Stresses and velocities at depth are calculated across Jutulstraumen, an ice stream in Dronning Maud Land, draining about 1% of the Antarctic ice sheet. The force-balance study is based on data from kinematic GPS measurements on three strain nets, each consisting of 3 × 3 stakes. The maximum measured velocity is 443 m a−1 and the velocity variation over short distances is large compared with studied ice streams in West Antarctica. The surface topography together with the measured velocities across the profile indicate that the bottom topography has a great influence on the flow direction, even where the ice thickness is more than 2000 m. The basal shear stresses are calculated as 180, 227 and 146 kPa in the three Strain nets, while the corresponding driving stresses are 180, 122 and 111 kPa (±5%). The heat produced by sliding and internal deformation is sufficient to keep the base at the pressure-melting point. The annual basal melting is estimated to be about 60 mm. Investigations on the effect of temperature softening show that the flow parameter’s influence on the effective strain rate is more important than the flow parameter’s direct softening in the flow low alone. The mass flow calculated by the force-balance method is between 87 and 96% of pure plug flow and total discharge is calculated to be 13.3 ± 10 km3a-1.

This is the first paper in a two-part series which gerscribes the gersign, operation, and testing of a successful 5 MHz radio-echo soungerr for temperate glaciers. This part gerals with the electromagnetic characteristics of temperate glaciers at radio freequencies. Earlier workers' problems in sounding through temperate ice are explained in terms of electromagnetic scattering by water-filled voids. The freequency gerpengernce of the scattering indicates that returns freom scatterers diminish rapidly at freequencies below about 10 MHz. A system with the following characteristics is recommengerd: a transmitted pulse with a center freequency of about 5 MHz, duration of about 1 cycle, and a receiver which is untuned and which measures field intensity rather than power. Spectral methods for studying the size distribution of scatterers are presented. An actual instrument and field trials will be gerscribed in a forthcoming publication by R. S. Vickers and R. Bollen.

Calving has been studied for glaciers ranging from slow polar glaciers that calve on dry land, such as on Deception Island (63.0° S, 60.6° W) in Antarctica, through temperate Alaskan tide-water glaciers, to fast outlet glaciers that float in fiords and calve in deep water, such as Jakobshavns Isbræ (69.2° N, 49.9° W) in Greenland. Calving from grounded ice walls and floating ice shelves is the main ablation mechanism for the Antarctic and Greenland ice sheets, as it was along marine and lacustrine margins of former Pleistocene ice sheets, and is for tide-water and polar glaciers. Yet, the theory of ice calving is underdeveloped because of inherent dangers in obtaining field data to test and constrain calving models. An attempt is made to develop a calving theory for ice walls grounded in water of variable depth, and to relate slab calving from ice walls to tabular calving from ice shelves. A calving law is derived in which calving rates from ice walls are controled by bending creep behind the ice wall, and depend on wall height h, forward bending angle θ crevasse distance c behind the ice wall and depth d of water in front of the ice wall. Reasonable agreement with calving rates reported by Brown and others (1982) for Alaskan tide-water glaciers is obtained when c depends on wall height, wall height above water and water depth. More data are needed to determine which of these dependencies is correct. A calving ratio c/h is introduced to understand the transition from slab calving to tabular calving as water deepens and the calving glacier becomes afloat.

A reconnaissance was made of one of two small ice caps near the Robeson Channel coast of northern Ellesmere Island. It is shown that, after a period of net wastage, this ice cap is now thickening slightly and extending its margins. The present regime of the ice cap is a direct result of generally cooler summers in the last decade.

The rate of ice growth and heat transfer during a stationary wet-growth icing was studied, based on wind-tunnel experiments of Reynolds numbers of I04 to 105, and air temperatures of 0°C to –13°C. The convective heat-transfer coefficient, a quantity of primary importance entering the heat-balance equation of a freezing surface, was found to depend strongly on the liquid water content in the air (or rather, on the impinging water flow on the surface). The convective heat-transfer coefficient was considered theoretically and the dependence is thought to be caused by an increase in the surface roughness and, especially, by an effect of the impinging water droplets on viscous sub-layers and on turbulent heat transfer near the icing boundary. The above evaluation allows us to calculate an accretion efficiency for each icing condition.

The earliest airborne geophysical campaigns over Antarctica and Greenland in the 1960s and 1970s collected ice penetrating radar data on 35 mm optical film. Early subglacial topographic and englacial stratigraphic analyses of these data were foundational to the field of radioglaciology. Recent efforts to digitize and release these data have resulted in geometric and ice-thickness analysis that constrain subsurface change over multiple decades but stop short of radiometric interpretation. The primary challenge for radiometric analysis is the poorly-characterized compression applied to Z-scope records and the sparse sampling of A-scope records. Here, we demonstrate the information richness and radiometric interpretability of Z-scope records. Z-scope pixels have uncalibrated fast-time, slow-time, and intensity scales. We develop approaches for mapping each of these scales to physical units (microseconds, seconds, and signal to noise ratio). We then demonstrate the application of this calibration and analysis approach to a flight in the interior of East Antarctica with subglacial lakes and to a reflight of an East Antarctic ice shelf that was observed by both archival and modern radar. These results demonstrate the potential use of Z-scope signals to extend the baseline of radiometric observations of the subsurface by decades.

The paper considers one-dimensional freezing and thawing of ice–water systems for the conditions first examined by Stefan. An order-of-magnitude analysis applied to the governing equations and boundary conditions quantifies the error resulting from the neglect of various factors. Principal among these are density difference, initial superheat and variable properties.

Asymptotic solutions for the temperature distribution and interface history are developed for a wide range of boundary conditions: prescribed temperature or heat flux, prescribed convection and prescribed radiation. Comparison with known results reveals the general adequacy of the asymptotic solutions and an estimate of the error incurred.