Two types of experiments were performed near Upstream B Camp on Ice Stream B2 using a high-resolution ground-penetrating radar system. In the first type of experiment, tracking a metal drill tip through the upper 85 m of the ice column indicated an approximately linear decrease of wave speed with depth down to 50 m, with a constant speed of 170 ± 4 m µs−1 below. We believe the (unexpected) linearity may have been caused by one or more buried crevasses. In the second experiment, a survey of a 250 km2 grid showed a population of buried crevasses at about 30 m depth that have an estimated burial age of 210 ± 25 years, which is taken to indicate that this ice has been exhibiting streaming behavior for at least that length of time. One 3 km segment along the edge of the survey area nearest the center of the stream showed virtually flat, undisrupted stratigraphy down to the maximum depth of our measurements. The fact that this ice was accelerated from near-zero speed to its present 440 m a−1 without cracking or folding suggests that this ice may have been incorporated into the ice stream as a solid block.

An accurate knowledge of the thermal properties of firn and ice within a glacier is essential for any reliable mathematical model of heat transfer. This paper considers the problem of determining the thermal properties of firn at Dome C, Antarctica, for use in such a model.

First, the difficulties in accurately determining thermal properties are discussed. Then a physical experiment which can be performed under field conditions, but which will yield a well-posed mathematical problem for determining the unknown properties, is presented. Next, two different numerical techniques for solving the mathematical problem are discussed. Finally, some numerical approximations and error estimates are presented for the results of applying our numerical procedure to data from Dome C. Although insufficient data were obtained to test our methods fully, we have established a measurement procedure and a method of analysis which appear to be promising.

Bed topography is a critical parameter for determining the modern-day and future dynamics of ice sheets and their outlet glaciers. This is because the topography controls the state of stress for glaciers. At glacier termini, topography can influence the timing of terminus retreat by controlling access to warm ocean waters and/or by influencing the ability of a glacier terminus to retreat over bed bumps (moraines). Inland from the terminus, the topography can also influence where glacier retreat and thinning can stabilize. In part, this is because of knickpoints in bed topography created through glacial erosion that may influence the extent to which thinning can diffuse inland for an individual glacier and thus, the timing and magnitude of long-term mass loss. Here we provide a review of the current literature on these topics. While much of the reviewed literature assumes that topography is stable on relevant timescales to humans, new research suggests that topography may change much faster than previously thought and this further complicates our ability to project future outlet glacier change.