Wednesday, 27 March 2013

My first sight of South Georgia by Melanie Leng

After 6 days of sailing on the Polarstern we saw our first glimpse of the island of South Georgia today rising through the fog. The 170 km long, narrow island has a mountainous spine rising to 3000m.

South Georgia (c) NERC
Half of the island is permanently covered with ice and snow. Glaciers have incised valleys and some still run into the sea, but where the glaciers have retreated they have left valleys and in some areas marginal hummocky ground with glacial moraines and hollows where peat bogs and lakes now occur.

Before we can disembark the ship we have to clear customs, and are currently waiting for staff from the British Antarctic Surveys King Edward Point base (which is situated in the old whaling base at Grytviken) to board the ship. We will then sail the raft (which is about 3 meters square), and two small inflatable boats, the remaining mile or so to shore.

Above: Little Jason Lagoon
(c) Mark Kenney South Georgia Journal 2012

Below: Satellite image of Cumberland Bay (E&W)
(c) BAS, NERC
 
 
We have already chosen our landing point, a small lagoon (Little Jason Lagoon) within Cumberland West Bay, on the northeastern coast. We have camping gear but a small hut there will act as our emergency shelter in case of severe weather. As soon as we have made a base camp we plan to take a core from the lagoon. We expect a 10m thick blanket of sediments on the bottom of the lagoon which will have accumulated since the ice retreated from the coast about 10,000 years ago.

Through various chemical and biological analysis of the sediments we expect to be able to reconstruct sea level. Currently the lagoon is freshwater but we assume that at times in the past, especially during warmer periods, sea level would have been higher causing the lagoon to contain more sea water. By looking at the various biological remains we will also reconstruct variations in the amounts of plants and animals in the area through the last 10,000 years and see how these differences are associated (or not) with sea level and climate.

After taking the core from the lagoon we plan to move inland to collect samples from the various glacial moraines which can be dated using cosmogenic isotope techniques. The combination of the information we can derive from the sediments and the dating of the glacial deposits will allow us to reconstruct a detailed history of glacial retreat and minor readvancements which we then link to variations in climate.  
   
Mel onboard the Polarstern

As a side note we have heard that there are many teenager fur seals still on the island although it is late in the season for them. We are hoping our first issue is not moving a pack of teenagers on from our intended camp ground! 

On ship we have seen numerous albatrosses (some of which stop on the ship’s deck to rest) and some killer whales but in general the sea is too rough (for us at least) to spend too much time on deck! The swell is around 3m but the ship is sailing at a brisk rate (10 knots) and there is the ever present chilly (around zero degrees) westerly wind. 

  Melanie Leng is on an expedition to South Georgia, see her previous blogs, and follow her on twitter @MelJLeng. To learn more about South Georgia visit their website and webcams

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