91B0FBB4-04A9-D5D7-16F0F3976AA697ED
C9A22247-E776-B892-2D807E7555171534
Friday 1/4/02
63 40 S
56 22 W
1 pm
Just above freezing, no wind, developing sea fog

We are back in  Erebus and Terror Gulf after spending the past two days in the area of the Swift Glacier on James Ross Island.

The Swift Glacier area not only provided spectacular scenery,  but the high influx of sediment into the water column provided numerous sites to collect water samples with the CTDT as well as sediment grabs and cores. The SCUD underwater video system provided great views of sea floor bed forms such as current generated ripples in the soft sediments.

Although slightly overcast, the second day in the area was very mild with temperatures around 9 C. After additional station work we moved along the coast examining the various bays and inlets that dot this part of James Ross Island. Near the end of the Howarth Glacier a sediment plume was visible from the ship. Tidal flats along the edge of a small hill looked promising for a landing site and around three in the afternoon zodiacs were put in the water and we headed for shore. Boot sucking mudflats greeted us on shore, but once past these and up a hill, a barren rock landscape unfolded.



(Click image for larger version.) Photo caption: Kate, Emily and Anna brace themselves against the strong winds coming down off the glacier. Resistant volcanic flows cap peaks in the background forming a landscape reminiscent of the southwestern U.S.

Cresting the hill cold, density driven winds coming off the high plateau and funneled down the glacier created a well below freezing wind chill. Wind polished rocks could occasionally be found as we traversed this area. Periglacial features such as stone polygons and frost wedging could also be found. Ahead of us lay the Howarth Glacier.


(Click image for larger version.) Photo caption: Dr. Bob Gilbert heads off across weathered volcanics. The irregular topography of a moraine can be seen in the middle distance with the glacier behind.

The glacier appears to have developed into two active areas with a stagnant ice area defined by the large morainal ridge and associated dead ice features. This is the area where we concentrated our studies. The moraine is ice cored, covered with debris but is no longer being supplied by sediment laden ice. It is probably a remnant section of a large terminal moraine formed when the ice (to the right of the moraine in the image) was much thicker and extended further out. A smaller terminal moraine associated with an active portion of the glacier can be seen as a "U" shaped feature just to the upper left of the end of the marked morainal ridge. This is the irregular surface seen in the middle distance of the photo with Dr. Gilbert.

Warm temperatures, melting last winter's snow, produced large volumes of water running on the surface, in channels and within the ice itself. As this water travels over and through the ice, sediment trapped in the ice, melts out and is picked up by the swiftly flowing water. Increasing volume and speed of the meltwater allows more sediment to be entrained. As the stream enters the ocean the rapid drop in velocity results in sediment coming out of suspension and depositing a delta of sediment at the meltwater stream's mouth. Fine silts and clays remain in suspension further from shore, resulting in the visible sediment plume seen from the ship.


(Click image for larger version.) Photo caption: View looking down a surface meltwater stream towards the ocean. Note the volume of water, the sediment on the exposed ice surface and the discoloration at the mouth of the stream as it enters the ocean. Discoloration is a brownish tinge to the water in front of the line of icebergs, compared to the greenish-blue color at the far right of the photo.


In one small area, all the major features of glacial and fluvial transport systems were visible.


(Click image for larger version.) Caption: Large boulder of subglacially erupted volcanic rock sits atop a snow pillar. The rock rolled to this position when snow covered the entire surface. The rock somewhat compressed the snow under it, and protected the snow from the direct sun. Snow not protected by the rock melted away leaving the rock balanced on it's snow pillar.



(Click image for larger version.) Caption: This view shows ice just to the west of the northern tip of the moraine marked on the LANDSAT image. This area of stagnant debris covered ice provides a tremendous source of sediment for the meltwater streams to transport to the ocean.



(Click image for larger version.)

Caption: NBP Captain Joe Borkowski and Dr. Eugene Domack enjoy the sunshine on the deck behind the bridge.

Work is now in progress to collect the samples in Erebus and Terror Gulf that we could not collect due to high winds a couple of days ago. The calm conditions that existed when I started writing this have changed. Seas remain calm, winds are around 26 knots and wind chill is -14 C. Sunshine makes it quite comfortable on deck when you are out of the wind.

Cheers,

Dave

Photo caption (for first image) : A false color composite LANDSAT image of a portion of  the southeastern coast of James Ross Island. The false color represents ice and snow in shades of white and blue, barren rock in reds and water as black. The width of the image covers approximately 16 miles.

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