Dive Photos Posted: 01OCT'97
|Near McMurdo Station, an underwater observation tube was inserted below the 1.5 m sea ice to provide a view of the bottom surface of the ice, for non-divers. The center photo shows me cleaning the ice off the windows of the OB-tube. The two other shots were taken by Donal inside the tube looking out.|
|At a site called Arrival Heights, I am collecting starfish for our experimental work.|
|At the tip of Cape Evans, we dove a site where there was a gentle current, which turned out to ba a good habitat for several species of soft corals, sponges, and a pink encrusting algae.|
|Rob Robbins cruises by a large sponge at the Cape Evans site.|
|Rob is photographing a brine channel.....|
|A brine channel is a frozen tube of ice. Here's how it is formed: 1. as seawater freezes salts get trapped in the ice crystal lattice; 2. As the sea ice ages, the ice crystal structure becomes more organized and pushes out (excludes) the salt ions; 3. These salt ions collect in liquid pools and make a dense brine solution; 4. With air temps below 0 F, the brine pools become super-cooled (chilled below the freezing point of water), but because of the high salt content they do not freeze; 5. The dense, super-cooled brine water eventually flows down through the ice into the seawater; 6. As the dense cold brine hits the sea water, it immediately freezes it which forms these long, stalagtite-like ice tubes hanging from the botom of the sea ice. Note the one above was approximately 15 feet ( 4 m) in length.|
Once we drill an ice hole for diving, it becomes a handy place for seals to use for breathing.
Rob is shown at the end of a dive leaving the water through the dive hole.
|Ice Diving '96|
|Cinder Cones AUG '97|
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