Physically not us, but something is needed to retrieve our sediment cores! Read below for the process of taking a lake sediment core.Today Kristen, Al, Megan, and Antoine were up at the glacier downloading weather data, and measuring stream discharge and glacial ablation. Steve, Leo and Jesse were up valley closer to the glacier taking altimeter readings, and searching for ice core moraines. Mike, Dave, Maya, Emily and I were up at Lake Kongress taking sediment cores. At this point of our expedition most students have collected their data or samples or are in the midst of doing so. Our luggage is going to be so heavy!!!

    Up at Lake Kongress Maya recovered 2 of the 3 cores she needs from the lake, and Dave and Emily each recovered 1 core for their projects. The process of recovering cores from Lake Linne and Lake Kongress is the same although the boat at Lake Kongress is much smaller and therefore less stable. BathymetryBathymetry is the study of the depth of water in the ocean. maps, providing the depth of the lakes, have been created for both lakes making it a little easier to select locations to take cores. The objectives of the study project also assist in selecting coring sites. For instance, Maya wants a sediment core near the location where the white sediment fan empties into the lake and where the black sediment fan empties into the lake, and she will correlate the core sediment to the fan sediment.

    Emily with her core
    A Universal Coring Device is used to remove lake cores. Emily's right hand is on the weight that is used to "hammer" the corer into the lake floor.

    Transporting field samples
    A challenge in gathering field samples is getting the samples back to the lab without harm to the sample. Here the cores had to be hiked out of Lake Kongress, go for a boat ride from the south end of Lake Linne to the north end, and then hiked back to the station. And then they still need to safely make their way to Arizona after leaving Svalbard!

    An echo sounder is used to help pinpoint an exact location, and a GPSA Global Positioning System (GPS) is a satellite-based navigation system used to track the location or position of objects on the Earth’s surface. waypoint is taken for that spot. The "universal coring device" is lowered into the water while being tethered to a safety line. A tethered weight on top of the coring device is dropped onto the coring device in order to "hammer" the core tube into the soft sediment. At the point that the person coring senses that the core will not go any further into the sediments, and coring device is brought back to the surface. Before it breaks the surface another person places a cap on the bottom of the tube to prevent the sediment from falling out the bottom. At this point, the bottom half of the tube is filled with sediment and the top half is filled with lake water.

    Dewatering a core
    A hole is drilled into the core tube to release the lake water on top of the sediment

    Draining water
    The lake water is carefully drained down to a few centimeters above the sediments, and then a syringe is used to remove the balance of the water with disturbing the sediments below.

    Cutting the core tube
    The core tube is carefully cut down to a few centimeters above the sediments, and then the sediments are allowed to dry within the tube.

    Back at the shore the sediment core is taped up on both ends so it can be very carefully carried back to the station where they are "dewatered." The dewatering process removes the top half of the core and most of the lake water. The core tops are left open to allow the cores to dry some before they are carried back home to the labs of the students. Emily will be taking her cores back to the University of Arizona and another lab where she will measure "magnetic properties" within the cores. Scientists have analyzed rocks from the ocean floor to discover that over time the Earth's magnetic field has changed which changed the magnetic orientation of the geomagnetic North Pole. This study of paleomagnetism was a strong piece of evidence to support the theory of plate tectonics. This process takes thousands and thousands of years, and we now have evidence that shorter term (hundreds of years) skirmishes have occurred in the past. This magnetism is recorded in the sediments that contain elements that can become magnetized. Emily will be using special equipment that can sense the presence and magnetic strength of these special sediments. She will use this procedure to date the sediments and correlate the sediments to glacial events that occurred in Lake Linne and Lake Kongress.

    FYI: A short core can go back about 300-400 years, whereas a long core can go back about 13,000 yrs!

    Task of the day: Use a straw and a glass of water to figure out how the universal coring device works!

    Join the Svalbard REU team for the Live From IPY Event on Wednesday August 6, 2008. Click on the Live From IPY link on the left side of this page for easy instructions on how to participate and to register. Can't wait to hear you on Wednesday!

    Author
    Date
    Location
    Kapp Linne, Svalbard
    Weather Summary
    Cool with gentle breeze, foggy, then sun, then fog
    Temperature
    41
    Wind Speed
    5

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