The Vaughan Lewis Glacier is one of the more striking glaciers in the Juneau Icefield Of Alaska. It lies in lat. 58° 50’ N., long. 134° 17’ W., at the head of a great canyon extending 30 miles (48 km.) inland from the northern end of Alaska's “inside passage”, about 36 miles (58 km.) north-north-east of the town of Juneau (Fig. 1 ); the glacier trends generally north westward for approximately 3·5 mil es (5.6 km.) to a nice fall where it joins the Gilkey Glacier.

Laboratory studies of the supercooling and freezing of baths of sea-water are described and compared with features of natural sea ice. By using dyes the convection cells in the sea-water test baths could be studied. and the growth of crystals relative to this cell structure could be observed. Brine expelled by the separation of ice from the system commonly followed the pre-existing convection channels. Sections of sea ice are interpreted in the light of these observations, and sea ice is shown to inherit drainage channels and banding features from the characteristics of the parent liquid system.

In this paper a study of lake ice at Peters Lake with respect to crystallographic nature and impurity in crystal grain boundaries is described. The appearance of the ice structure in 1962 was quite uniform over the whole area of the lake; it showed predominantly horizontal c-axes. Another type of ice with predominantly vertical c-axes could not be found even in the surface layer of the ice. The cause of these two types of ice is explained as being due to wind action. A correlation between the grain-size and the depth of ice is expressed in exponential form down to a depth of 100 cm. A linear relationship between the thickness of ice and the depth of snow cover was obtained. Impurity in grain boundaries measured as specific electrical conductivity was hard to detect in such a pure ice as that at the lake whose purity was about 1 micromho/cm. Supplementary data from Lake Nukabira, Hokkaido, are summarized and compared with the data from Peters Lake.

The nature of candle ice, stratified ice and ice of radial structure observable on ice island t-3 was investigated. Cores were drilled through the ice island at two sites. Crystallographic examination, and visco-clastic and chlorinity measurements, were made all along the cores. Results indicate that the ice body of t-3 is composed of three strata; the stratum above a heavy dirt layer is composed of iced firn which shows a granular nature with crystalline facets; that below the dirt layer is “basement ice”; and at the bottom is a sea-ice layer 1.8 m. thick. The basement ice is subdivided into four strata. Petrographic studies of dirt samples obtained from the surface and from the ice cores were carried out by an X-ray diffraction method; from the results, the dirt is thought to be dust of Precambrian granite or gneiss, which are the prevailing rocks in Ellesmere Island. The structure of t-3 was inferred from assumptions based on the data obtained from the core drillings at the two sites.

The Burroughs Glacier, south-east Alaska, is a slow-moving remnant (14×3km.) of a much more extensive glacier. It is now entirely below the firn line; ablation has revealed ice structures and fabric once 300 m. or more below the glacier surface.

At the present glacier surface three kinds of ice are identified—foliated ice, coarse-grained border ice and very coarse-grained basal ice.

Two systems of fine-grained foliation are present. Differential movement in the glacier has caused recrystallization along closely spaced planes. At the glacier surface this produces a steeply dipping longitudinal foliation. A gently dipping foliation, having a regional trough-like structure, may be associated with former stratification planes or with former spoon-shaped shear surfaces.

The optic orientation of crystals in the coarser layers of the foliated ice shows three weak maxima, and in the finer layers a single weak maximum, corresponding to one of the coarse layer maxima, and normal to the gently dipping foliation plane. The other maxima in the coarse layers are orientated close to the poles of principal fracture planes.

In the coarse ice the fabric shows a pattern with three maxima similar to that obtained in torsion shear experiments. In the glacier the pattern may be formed by shear near the glacier bottom or along gently dipping foliation planes. Grain-size increases towards the glacier terminus, especially in the stagnant ice zone.

Structural evidence suggests that in the early stages of the Little Ice Age the ice flow was from west to east. Later it was to east and west from an ice crest in the upper Burroughs Glacier. Structures produced by present movement have been superimposed on older structures.

Specimens of polar snow from the South Pole, Antarctica, were tested to investigate air permeability K (cm.sec.−1), ultimate compressive strength σc (g.cm.−2) and dynamic Young’s modulus E (g.cm.−2) as a function of density. Anisotropy in a single layer of snow (snow between two summer crusts) was found in all three properties. Comparison with data for snow from Site 2, Greenland showed an empirical relation for both areas:

Air permeabilities are different at the two sites because of time and meteorological effects.

Temperature, inclination, and closure have been measured in a 309 m. deep drill hole at Byrd Station, Antarctica. The results of five series of measurements taken yearly since February 1958 show that temperatures below 70 m. have remained constant since December 1958, that the closure rate has accelerated, and that the hole has undergone negligible inclination from the vertical. Anomalous temperatures in the upper levels of the drill hole are attributed to the steel casing that was permanently emplaced to a depth of 36 m. during drilling in 1957–58. A positive temperature gradient was observed in the casing, but negative gradients exist below the casing and a constant gradient profile is developed below 170 m. Both ice motion and climatic changes at Byrd Station are thought to have contributed to the formation of the observed negative temperature gradients. Insignificant bending of the drill hole would imply negligible differential motion in the upper 300 m. of the 2,400 m. thick ice sheet at Byrd Station. The rate of hole closure has accelerated throughout the 4 yr. period of observations, except at the bottom of the drill hole, where the most recent measurements (February 1962) show that some constraint is now developing. Deformation rates throughout the drill hole are not proportional to some constant power of the stress; instead the value of the power has been found to increase with both increasing stress and time of application of stress. This behavior is attributed to some process of continuous deformational recrystallization of ice in the walls of the drill hole. A recoring of the deformed drill hole to investigate such effects is advocated.

The annual layers in an ice sheet become thinner by plastic deformation, and measurements of annual accumulation by the examination of cores therefore need correction. A simple correction factor is derived.

Compared with freshwater ice, whose physical properties are well known, sea iceis a relatively complex substance whose transition to a completely solid mixtureof pure ice and solid salts is completed only at extremely low temperaturesrarely encountered in nature. The physical properties of sea ice are thusstrongly dependent on salinity, temperature and time. Many of these propertiesare still not fully understood or accurately known, particularly those importantfor the understanding of a natural ice cover. The specific heat for example isan important term in the calculation of the heat energy content of a cover.However, Malmgren (1927), whose calculatedvalues of the specific heat of sea ice are in general use, neglected the directcontribution of the brine present in inclusions. Re-examination of thequestion of specific and latent heats of sea ice has led to distinguishingbetween the freezing and melting points and enabled significant observations inthis range. Similarly, because the thermal conductivity is a necessary parameterin the description of the thermal behaviour of ice. the sea-ice modelsuggested by Anderson (1958) has beenmodified and extended in the present work to the case of saline ice containingair bubbles. This enabled the completion of calculations of density andconductivity. In order to illustrate the theoretically calculated values.measurements were made on sea-ice samples to determine the specific heat,density and thermal conductivity.

In August 1961 an aluminum pipe (3.5 cm. internal diameter, 4.2 cm. external diameter) having 92 specially modified socket couplings (5.0 cm. external diameter) sealed with a quick-polymerizing synthetic rubber was sunk 226 m. in a vertical water-filled bore hole in Blue Glacier, Washington. U.S.A. The geometry of threads and mating surfaces of pipe and coupling was designed to cause increasing external water pressure to tighten the seal. One joint at a depth of 66 m. immediately developed an extremely slow leak (probably because of faulty cleaning), but the other 91 joints apparently were sound, as the pipe was free of water to a depth of at least 157 m. when resurveyed after one year.

Gravity studies indicate that the Sukkertoppen ice cap is about 400 m. thick. The annual snow accumulation increases westwards from about 13 g. cm.−2 near the eastern edge of the ice cap to about 34 g. cm. −2 near Mount Atter, in the south-west. Probably all of the ice cap is “temperate”.