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23 November, 2004

Ghostly Graveyard

Temperature: 5 *F with light snow

Location: Lake Hoare

It amazes me how subtle changes in the environment can have a profound impact in

the feeling it conveys. We had a light snow throughout the day today which blanketed the surrounding hills with a dusting of snow. The whiteness put a soft, almost tender, touch to the starkness of the mountains.

The lake also revealed some subtle changes today. One of my tasks was to collect water samples from just above the mat at four different depths: 52 , 39, 26, and 16 feet. To collect the samples, I took four empty core tubes with me and stoppers for each end. I positioned myself at the respective depths, and then carefully gathered water from just above the matt. I then stoppered both ends and moved to the next depth.

The shallow water sample required that I swim to an area that was just beneath the ice. Due to the recent warm weather, there has been a fair amount of run off entering the lake. This has created a milky layer, almost like fog, just below the ice. The layer has been getting thicker over the last two days.

In order to understand the subtle change the lake showed, one must understand some basics about the mat. The bacteria that Ian is studying photosynthesize and in the process release oxygen into the lake. Sometimes the oxygen bubbles get trapped underneath the mat, which eventually causes the mat to bulge and ultimately lift off. The mat then gets trapped beneath the ice until it gets absorbed into the ice.

Today, while collecting my shallow water sample, I swam into a region of the lake where there has been considerable lift off. Immense pieces of mat were dangling from the bottom of the ice into the fog layer. It looked like a ghostly graveyard. It was beautiful.

1) A "short core." The very thin layer on the top is the current mat.

2) Kay places an oxygen sensor into the water sample I just retrieved from the lake.

3) Measuring the ph of the lake water sample.

4) Cross section of a mat sample.

5) Cross section through a pinnacle area.

6) Our helmets drying by the heater!

7) My triple hood design to cope with the broken face seal!

8) Me, happy again with my fixed hood!

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