August 12, 2015: Turn, Turn again

New IceEvening of 11 August, after a science talk on physical oceanography of the region we all discussed the possible effects of long-term warming on Petermann Fjord. Some doubts about how long the shelf will last in the future.  Uncertain. We are trying to avoid idle speculation.

Seismic reflection operations (Danish team with American mammal observer ready to curtail the sound source if needed) crossed to Canada from Petermann ice front).  We are attempting to get good data across a narrow bathymetric high we have tentatively named “The Fin”, ranging from about 300 m to 800 m below sealevel, to discover its construction.  From old maps we were not sure if this was a real feature or a glitch in the data.  We crossed at an oblique angle.  It is real! Of uncertain origin, it appears to have steeply dipping rock beds.  We can view Cape Baird on Judge Daly Peninsula, Ellesmere Island, and there too we see steeply dipping beds. This is different from Greenland where bedding around Petermann Fjord is nearly horizontal. There may be a fault between these regions, most likely extending from along the NE Coast of Ellesmere Island, through The Fin, to the northwestern edge of Hall Land near Newman Bugt. These features form a straight line, sculpted by the ice.

Our attempts to reach Canadian Coast were thwarted by multi-year sea ice flowing southward out of Robeson Channel. We can’t get to Canada. We turn back to the southeast across Hall Basin to Bessel’s Fjord, then across outer Petermann Sill looking for evidence of a past ice-shelf grounding line, then back north for another look at the Fin.  Ice diverted our line again, so we pulled in the airgun and tested sound sources with a hydrophone.  Now returning to a coring site; bumping across scattered ice floes.  One helicopter just left with the beach team and another flew to assist the boulder team.  1030 UTC — Southern Robeson Channel off Hall Land: Old sea ice drifting south. New sea ice freezing; a thin skin on glassy waters under blue skies.

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