The first physical evidence of subglacial volcanism under the West Antarctic Ice Sheet.

The West Antarctic ice sheet (WAIS) is highly vulnerable to collapsing because of increased ocean and surface temperatures. New evidence from ice core tephra shows that subglacial volcanism can breach the surface of the ice sheet and may pose a great threat to WAIS stability. Micro-CT analyses on englacial ice core tephra along with detailed shard morphology characterization and geochemical analysis suggest that two tephra layers were derived from subglacial to emergent volcanism that erupted through the WAIS.

Making EBSD on water ice routine.

Electron backscatter diffraction (EBSD) on ice is a decade old. We have built upon previous work to select and develop methods of sample preparation and analysis that give >90% success rate in obtaining high-quality EBSD maps, for the whole surface area (potentially) of low porosity (<15%) water ice samples, including very fine-grained (<10 μm) and very large (up to 70 mm by 30 mm) samples. We present and explain two new methods of removing frost and providing a damage-free surface for EBSD: pressure cycle sublimation and 'ironing'.

SEM/EDS comparison of polar and seasonal temperate ice.

We have developed a method employing a scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy for examining uncoated ice specimens. By permitting the ice to sublimate in the SEM at temperatures between -115 degrees and -60 degrees C, enough ions are produced to prevent specimen charging. The absence of a conductive coating permits both the acquisition of uncompromised X-ray spectra, and a dynamic view of impurities as the ice sublimates.