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Week 2

2/23/05
04:13 GMT
65 15 S
61 21 W
-3 C
heavy snow
12 knot winds
mix of open water and ice

A long day of sampling and deployment of instruments ended with the deployment of a sediment trap in a building snowstorm and dropping temperatures. The clouds lowered progressively during the day, and, by sunset, snow began to fall. Luckily, plans for tonight involve transiting to another section of the area via a course designed to fill in additional sea floor topography details. Transit will take over 10 hours at the slow speeds needed in the poor visibility conditions we currently have.

1:30 a.m. View from the starboard bridge wing as the Gould travels through heavy snow towards Exasperation Inlet.

Under these conditions, the mate on the bridge has two additional seamen on watch with him to avoid any potential problems. As you can see from the image, forward-looking spotlights cut through the blowing snow and illuminate the waters in front of the ship. Additionally, two collision-avoidance radar screens provide a view of what is further ahead.

Today's Jumbo Piston Core operation went very smoothly. This was the first deployment of the JPC on the Gould.  The JPC is a system designed for deep penetration into the sea floor. As configured, we recovered 20 feet of sediment today. Unlike the Kasten cores, these cores are capped and sealed on the ship, placed in a refrigerated van in the hold, and shipped back to the Department of Geosciences core storage facility at Hamilton College for analysis at a later date. The sheer mass & size of the JPC makes for a very long deployment operation. The large mass visible above the white flange weighs 4000 lbs.

Marine Projects Coordinator Steve Ager (left) and Marine Science Tech T.J. Hurlburt prepare the Jumbo Piston Core for lowering on its first deployment on the Laurence M. Gould. The large "bomb" at the top of the core weighs 4000 lbs, and 30 feet of steel pipe with PVC liners hang below.

2/24/2005
21:43 GMT
65 21.025 S
61 41.941 W
-1.2 C
1.7 knot winds
gray low clouds 1/2 way down the mountains on shore
smooth water with occasional icebergs & bergy bits

We have not moved much over the past 2 days; currently working to define a complex set of structures on the bottom and periodically doing some sampling of the sediments.

The complex sea floor topography requires multiple passes from various directions to work out the orientation of a series of deep troughs that extend seaward from the valley glaciers. Prior to these valley glaciers merging into and feeding the Larsen B ice shelf, they originally carved individual valleys in the sea floor. Mapping these valleys, now partially filled with sediments, is one major part of our work here. The character and thickness of the sediments gives us a hint of the history of the area over the past 10,000 years or so.

Unlike the multibeam system on the Palmer, the Gould is equipped with a single transducer for mapping the sea floor. This means that we can only see what is directly below the ship and therefore need to make multiple passes from various directions to define the shape and trend of various structures. Using a commercial software package connected to the ship's transducer system, we are collecting the raw depth data as hourly files. The software provides a simple color-coded display of depth that we use to plan our track.

Using the Smith McIntyre grab sampler, we are able to relatively quickly get a sample of the bottom sediments before moving on with our survey. The grab sampler scoops up approximately 12 x 8 x 6 inch deep sample of the sea floor. Back on deck, the sediment in the grab is photographed, quickly evaluated as  an indicator for the suitability for a kasten core, and sub samples are collected for physical properties, foram and diatom studies. The remaining sediment is sieved for larger objects such as drop stones, or biological specimens.

The Smith McIntyre grab as it returns to the surface. The jaws are cocked open when it is deployed and heavy springs snap the jaws shut when the trigger feet touch the bottom. Note the large rock caught in the jaws. Although not a common occurrence, this results in a loss of some or all of the sediment sample as the grab is returned to the surface. In this case the sediment was cohesive enough that only some washed out on the return trip. The rock was transported from the land by the valley glaciers and incorporated into the ice shelf. At some point, it melted out of the ice and dropped to the sea floor below.

Heather Schrum (left), Veronica Willmott and Ashley Hatfield collect samples from the Smith McIntyre grab. Dressed for work on the back deck, they are wearing required float coats & hard hats along with neck warmers and gloves to stay warm in the cold wind blowing off the nearby glaciated mountains.

We have been "camped" in about the same place for the past couple of days as we work out some sticky problems with sea floor topography we are having trouble visualizing.

Luckily the scenery on shore is spectacular. We have been as close as 1/10 of a mile from shore and in places the rocks plunge directly into the water. Many of the glacial valleys have fjord like structure with massive vertical cliffs coming right out of the water. Less than a quarter mile from shore we were in 600 meters of water. The captain was pretty cautious. He likes to look at the topography on the land and visualize the same topography under his ship. What he saw on land was that we could go from 600 meter water depth to essentially zero in virtually no time. Because ships neither stop or turn on a dime we proceed very slowly in these areas (which have never been charted as we are the first to visit them) with one eye always fixed on the bottom depth recorder.

We have not had a clear day since we have been in this area. The clouds tend to sit just on or below the tops of the rocky headlands. I cannot imaging how spectacular this would be on a clear blue sky day. The low clouds give the area it's on sort of majestic look.

We are planning on heading south from here towards 65 42' before starting our track back to the north. Weather is holding well, not too cold and the wind is not too bad away from the mountains. Ice conditions have been good and not causing us too many problems.

-commentary provided by Dave Tewksbury, geology technician at Hamilton College

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