West Antarctic Ice Sheet Stability:
Glacial Record from the Ohio Range of
the Horlick Mountains in the Bottleneck
Hal Borns*, Aaron Putnam, UMaine
Robert Ackert, Sujoy Mukhopadhyay, Harvard.
December 15, 2004 to February 15, 2005
January 8, 2005

click on a photo
to see full size

Asymmetric gouges suggesting an eastward flow direction preserved in the granite surface.

Sample from summit of Tuning Nunatak, looking east.

Looking down on the terrace series along the northern flank of Tuning Nunatak.





The Tuning Nunatak, pt. 2

Today was a gorgeous one – a bit different than the last few. There was no semblance of a breeze, and temperatures were soaring just over freezing! However, the beautiful weather hadn’t fully arrived until midday, when we had already ruled out the Bennett Nunataks. Instead, we went back to the Tuning Nunatak, which again proved itself to be an amazing place to spend such a day, and yielded some interesting discoveries.

The bedrock surfaces were similar to what we saw on the Discovery Ridge, with beautifully abraded surfaces and plucked faces. Chattermarks and lunate gouges appeared preserved in the granite surface with profile symmetry suggestive again of eastward-flowing ice… Here was another outcrop with an ancient glacial surface showing ice-flow heading the opposite direction (and wet-based, which is not characteristic of the Antarctic Ice Sheets today or in recent ice ages).

We found a series of bedrock terraces on the north side of the mountain, all of which appeared to be related to this old glaciation. The nature of the terraces was interesting in that they had perched erratics all the way up, and seemed to represent periods of stability when a portion of the terrace would fracture off and be conveyed away. This may have created the step-like system of terraces, however it may be related to a much older glaciation than the erratics we sampled on the surface. Our exposure ages will hopefully shed some light on these structures.

We sampled a transect of erratics up the system of terraces, using the altimeter calibrated to the Trimble at the top to record elevations. We then called it a day, and I got to ride the sled and view the monstrous Darling Ridge the whole way home. Unfortunately, a slight breeze had perked up coming from the west (180 degrees from the prevailing wind direction), and it seemed to be going the same velocity as the ski-doo towing me. Therefore, I ended up a bit nauseous from the exhaust I was breathing the whole way back. But the day was still to die for, and the weather still has not changed. I took some pictures which I hope will capture even a fraction of the beauty of this escarpment, and truly enjoyed scrambling around on Tuning Nunatak. I even cinematically captured Peter ‘trundling’ a rock over the edge of the cliff onto the snow-slope and down to the ice – certainly a moment of comical mischief!

Previous | Return to Bottleneck Home | Next