Glacial geological studies on the Windmill Islands and along the Budd Coast at the margin of the Law Dome, East Antarctica, indicate that the glacial extent of Law Dome has fluctuated during the Holocene. The morphology and structural geology of the present ice margin and Løken Moraines indicate that Law Dome has readvanced over part of the Windmill Islands since the culmination of the post-glacial retreat. Sedimentological and geochemical analyses show that Løken Moraines comprise reworked proglacial and coastal marine sediments and ice, which supports the morphological and structural evidence for a readvance. A chronology for the readvance is produced from relative lichenometry of Løken Moraines and coastal nunataks in conjunction with 14C radiocarbon dates from the proglacial and coastal zones. The combined glaciological and geological evidence suggests that the readvance occurred after c. 4000 yr BP in response to a positive mass balance on Law Dome during the Holocene.

A regional chemical boundary termed the ‘salt line’, in the Vestfold Hills of East Antarctica, has been investigated using X-ray diffraction and electron probe analyses of surficial salts, and conductivity of surficial sediments. West of the salt line, halite and thenardite are abundant. These salts are derived from dispersal of marine aerosols, saturation of sediment by seawater during postglacial marine transgression, and glacial dispersal of salt-saturated fjord bottom sediments. East of the salt line, subglacial calcium carbonates and salts formed by chemical weathering of their substrates occur. Chemically and morphologically diverse minerals form the weathering products. They include two minerals not found previously in Antarctica, dypingite and hydromagnesite, and the first confirmed occurrence of brushite.

At Mount Charity, north-eastern Palmer Land, Rb–Sr whole-rock dating has identified three successive phases of granitoid emplacement in Triassic (232 ± 4 Ma), Jurassic (168 ± 1 Ma), and Cretaceous (120 ± 4 Ma) times. The Triassic suite comprises tonalites, granodiorites (including one two-mica granodiorite), monzogranite and a granite having either I-type or S-like mineralogies. The Jurassic suite includes only S-like granites, and the Cretaceous biotite tonalites and biotite granodiorite are all I-type. The three suites have negative ∈Nd and positive ∈Sr, and have subtly different Nd and Sr isotope characteristics: Suite A, ∈Srt =+30 to +53 and ∈Ndt =−0.9 to −3.1, Suite B, ∈Srt =+43 to +64 and ∈Ndt =−2 to −5.3, Suite C, ∈Srt =+22 to +23 and ∈Ndt =−2.5 to −2.6. Mineralogical and compositional differences between the three suites suggest that different sources were tapped. All the granitoids are isotopically intermediate in composition between Palmer Land crust and depleted asthenosphere. We suggest that the I-type granitoids were produced by melting of meta-igneous crust; by contrast, the S-like granitoids represent partial melts of garnet-bearing sedimentary crust. Syn-magmatic structures in Suite A are compared with known structural events in western Palmer Land and suggest that extension controlled Triassic pluton emplacement. The Jurassic magmas were also emplaced during an episode of arc extension, and intrusion of the Cretaceous magmas was probably controlled by regional extension and dextral transtension. Successive phases of magmatism focussed at Mount Charity are consistent with reactivated faults acting as magma conduits.

Fisher Massif consists of Mesoproterozoic (c. 1300 Ma) lower amphibolite-facies metavolcanic rocks and associated metasediments, intruded by a variety of subvolcanic and plutonic bodies (gabbro to granite). It differs in both composition and metamorphic grade from the rest of the northern Prince Charles Mountains, which were metamorphosed to granulite facies about 1000 m.y. ago. The metavolcanic rocks consist mainly of basalt, but basaltic andesite, andesite, and more felsic rocks (dacite, rhyodacite, and rhyolite) are also common. Most of the basaltic rocks have compositions similar to low-K island arc tholeiites, but some are relatively Nb-rich and more akin to P-MORB. Intermediate to felsic medium to high-K volcanic rocks, which appear to postdate the basaltic succession, have calc-alkaline affinities and probably include a significant crustal component. On the present data, an active continental margin with associated island arc was the most likely tectonic setting for generation of the Fisher Massif volcanic rocks.

Cape Dubouzet is mainly composed of a volcanic-subvolcanic complex of extrusive rhyolitic breccias, a banded rhyolite and a semi-annular body of dacite porphyry rich in xenoliths of metamorphic rocks. Major and REE geochemistry indicate that the volcanic rocks are calc-alkaline and that they are genetically related by fractional crystallization of a plagioclase-bearing assemblage from a common magma. Rb-Sr data suggest that the rhyolitic complex is of Middle-to-Late Jurassic age, and that it is intruded by Late Cretaceous stocks of banded diorite and gabbro. All these rocks are partially covered by moraines whose clasts are of local provenance. Xenoliths in the dacite porphyry suggest that the northern tip of the Antarctic Peninsula is underlain by a metamorphic complex composed of amphibolites, meta-tonalites and pelitic gneiss containing garnet, sillimanite, cordierite, hercynite, and andalucite. Such rocks are not known in the Scotia metamorphic complex, nor in the Trinity Peninsula Group and its low grade metamorphic derivatives, which also occur as rare xenoliths in the dacite. Previous dating of xenoliths collected from the moraines suggested a late Carboniferous age for this amphibolite-grade metamorphism. Both the Jurassic-Cenozoic magmatic arc of the Antarctic Peninsula and the accretionary complex rocks of the Trinity Peninsula Group were thus developed, at least in part, over pre-existing continental crust.

The Bunger Hills Oasis (66°15'S; 100°45'E), a large ice-free expanse on the coast of East Antarctica, contains many lakes, only a few of which maintain an ice cover all year. To understand the environmental conditions that allow for persistent ice cover we established an automatic meteorological station on White Smoke Lake, a perennially ice-covered lake in contact with the Apfel Glacier. The data were collected from January 1992–July 1993. The mean annual solar flux during this period was 115 W m−2, the mean wind speed 4.6 m S−1, and the mean air temperature −11.2°C. Summer degree-days above freezing (71 °C-days) are similar to regions of the Antarctic (the McMurdo Dry Valleys - 78°45'S; 163°00'E) with thick perennial lake ice but the winter freezing degree days (3987 °C-Days) are much smaller and are closer to regions with seasonal ice covers (e.g. the high Arctic). The Bunger Hills Oasis seems to be in a marginal climatic region for the persistence of thick lake ice. Therefore, the extent of glacier ice contact becomes the controlling factor in maintaining an ice cover all year. We propose that this is either through the heat sink the glacier offers, and/or the positive feedback for ice growth provided by the high albedo of the adjacent glacier.

The seasonal and spatial variation of downward longwave radiation (L↓) at the surface of the Antarctic ice sheet is studied using data from four stations. L↓ is found to depend on the fourth power of the surface temperature but on the sixth power of the temperature at the top of the surface inversion layer. The former result is shown to be a consequence of the dominance of longwave radiation in the surface energy balance while the latter raises some questions concerning the radiative properties of Antarctic clouds. Simple parametrizations of L↓ as a function of temperature are suggested; these may find application in validating General Circulation Model radiation calculations over Antarctica.

Total electron content (TEC) measurements obtained at two Antarctic stations over nine months beginning early in 1994 have been analysed as a first step to performing ionospheric tomography. Two receiving systems were deployed at the Faraday and Halley research stations operated by the British Antarctic Survey to monitor signals from a random selection of passes of satellites in the Navy Navigational Satellite System. The resultant measurements of total electron content have been inverted and combined with ionosonde measurements of true height and foF2 to yield two-dimensional contour maps of ionospheric electron density. In spite of the poor geometry of the observations, some 130 satellite passes were found to be suitable for reconstruction using the techniques developed for ionospheric tomography. The contour maps of plasma density have been compared with independent observations of the vertical electron density profile measured by the dynasonde ionospheric sounder located at Halley. An example is presented of a deep trough investigated by the technique, illustrating the potential of the tomographic method for study of an extended spatial region of the ionosphere over inhospitable terrain.

Atmospheric surface pressures on the East Antarctic ice sheet are examined as a contribution to a new regional climatology based on automatic weather stations (AWS). Monthly mean pressures along two meridional AWS lines show near the coast a semi-annual oscillation with equinoctial minima, which become submerged inland under a larger annual oscillation, asymmetrically shaped around a summer solstice peak. Such a peak could arise when air surrounding the ice sheet is heated and enabled to spread out over the ice. This concept has provided a classical prediction of the ice sheet's mean elevation; in this paper the theory is expressed in a more modern form. After the summer “flood” the vertical tropospheric circulation driving the progressive katabatic surface layer drainage from the ice sheet should create relatively higher pressures below the convergence region over the ice sheet center and lower pressures near the coast. In fact the observed mean monthly surface pressures decrease with elevation more slowly than follows from substituting the observed mean temperature-elevation gradients (“topographical lapse rates”) in the hydrostatic equation. However, below the surface inversion along the sloping ice sheet surface the hydrostatic balance is shown to be governed by temperatures higher than observed at the surface. Hydrostatic pressures are calculated with climatic estimates of the inversion strength. Their differences from the observed monthly mean surface pressures represent non-hydrostatic residuals which can be added to pressures at the coast to form elevation-free (“sea level”) pressure profiles. These show both the expected coastal troughs and high pressure over an ice sheet summit (Dome C).

The surface pressure of an Antarctic station displays two minima, one in spring, the other in autumn. It is believed that these minima are caused by radiative forcing, as the gradient of the extra-terrestrial radiation is largest during the two equinoxes. The best correlation (r = 0.85) was obtained when the pressure lagged the radiation gradient by ten days.