12/21/01
65 00 S
64 30 W
-2 C, 40 knot winds, wind chill -20 C
Cloudy and snowing, rolling seas
Multiple bottom samples were collected during the early evening and overnight. Grab samples, Kasten cores and a Jumbo Piston Core or JPC were all collected.
Grab sampling is designed to sample the sediment water interface and only penetrates the seafloor 8-10 inches. The Kasten core is designed to sample the top 3 meters of the seafloor, and the JPC can collect over 30 meters of sediment under the right conditions.
Obviously we cannot see what we are sampling and have to make educated guesses based on the bottom maps created. Echo sounding profiles that penetrate the sediments allow us to estimate sediment thickness. As we have seen in the videos the seafloor here is far from regular and is scattered with boulders and outcrops along with the deep sediments. These boulders and outcrops are far smaller than we can resolve with our ship mounted equipment so each sampling station has the potential to produce a surprise.
The photo shows the Smith MacIntyre Grab sampler being brought on board with such a surprise. This large (40 lbs) boulder was sticking out of the mud right where the grab touched down. Although not designed to take this kind of sample the grab did a great job holding onto the rock as it was brought up through 600 meters of water. The rock was covered with encrusting life forms and a line is clearly visible showing exactly how much of the rock was buried in the sediment. The image also shows how this particular device works. When rigged for descent, the two long handles with the cables attached are in a vertical position and the jaws are wide open. Two large springs in the center column are fully compressed and the pad feet, just below the peoples hands, are extended somewhat. When the grab touches the seafloor, pressure on the pads releases the springs which snap the jaws shut. Flaps on the top surface of each half protect the sediment from water as the grab is brought back to the surface.
Currently we are headed back towards Anvers Island from the Palmer Deep area. Just past Anvers Island the ship will turn up the Neumayer Channel and pass Port Lockroy. Port Lockroy is a former British Research Station that is now a favorite stop for the tour ships that now come to Antarctica. At the north end of the Neumayer Channel is our next sampling station.
Today is the shortest day of the year for you northern hemisphere folks and the longest for us in the southern hemisphere.
I know that this site is being followed in the US, Canada, Spain, Ecuador, Iceland, Scotland and Norway. I'd love to hear from others to see just how world wide this web is becoming.
Cheers,
Dave
photo caption: A 40 lb. rock brought up in the Smith McIntyre grab sampler provides evidence of modern encrusting life forms living in Antarctic waters.
