Horizon near sunset at Siple Dome.
An intensely crevassed region of the Ross Ice Shelf called "Steershead" (because of its shape in satellite imagery), as seen from the Twin Otter on the way back to McMurdo (looking south). The crevassing is due to the fact that this region of the ice shelf is "grounded", while ice all around it is afloat and moving at much faster speeds. The region that curves off to the left of the photo makes one of the steer's "horns".
Another view of Steershead.
A very large crevasse, or "rift", on the Ross Ice Shelf (looking East, towards West Antartica). When these large rifts approach the seaward edge of the ice shelf, they often result in calving of the very large "tabular" ice bergs (for example, the iceberg B-15 that has been in the news recently).