Two Greenpeace crew members walk along a huge iceberg rising 36 meters from the waters of Kane Basin. It is likely that this unusual feature started life as an englacial channel within the Humboldt glacier that it has calved from. Englacial channels carry melt-water from the surface of the glacier down to the bed-rock underneath. Because icebergs turn in the water the feature may also have been part of a moulin -a vertical channel draining into the glacier. Glaciologists sometimes refer to these holes within glaciers as "Rothlisburger channels". Rothlisburger proposed a theory of how an equilibrium develops between the external forces of the enclosing glacial structure and the internal pressure, (flow and frictional melt rate) of the water inside. Some of these properties appear to be evident in this iceberg, though the channel may have since been widened and enlarged by the subsequent tidal and surface melting and erosion. This berg was observed to drift to and fro across Kane Basin for some weeks, at different times, grounding on the sea bed, on both the North and South sides.