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13 Apr - All quiet on the Southern Front

Noon Position :  49011"5'S, 49009"1'W

Distance Travelled since Grimsby : 31917.5 Nautical Miles

Air temperature @ Noon today : 7.60C

Sea temperature @ Noon today : 6.70C

Weather : Good, South, 3, 1006.5
 


All quiet on the Southern Front

The James Clark Ross has been having a very quiet week.  We left FIPASS on Tuesday morning after testing the life boats in Stanley harbour but since then we have seen no land, no ships, not much ice, no whales, seals or penguins.  We have seen a lot of waves, fog, rain, snow and a little sun.  The good ship JCR is performing a swath bathymetry cruise to the north east of the Falkland Islands (see below).  The weather is slowly getting more wintry outside and the sea is rough most of the time.  We've had a few days when the sea is so rough that the swath will not work due to air bubbles under the ship disrupting the swath beam.  When the sea is very rough then we 'hove to'.  This is when the ship faces into direction of the wind and waves and so rides into the waves.  This makes it more pleasant for everyone onboard as the pitching motion is much less disruptive than the rolling one would get if the waves were coming from the side.  It has been a good chance to get down to some paper work (when the papers aren't on the floor - Ed).  Most people have been squirrelled away this week recovering from the excesses of Stanley and so there is not much else to report!


Born to Swath

by the Principal Scientific Officer, Lindsay Parson.

We are currently surveying the seafloor between the Falkland Islands and South Georgia, creating highly accurate bathymetry maps of the seafloor and its amazing terraces. State-of-the-art echo-sounding equipment fitted into the hull of the RRS James Clark Ross angles acoustic pulses far away from the ships track, and collects data from a swathe of seafloor more than thirty kilometres across. With a survey speed of about twenty kilometres an hour, we are covering an area the size of Wales every three days.  The scale of features uncovered is all on the large side - towering escarpments, hundreds of miles long, plunge to some of the deepest parts of the Atlantic Ocean more than three miles below the waves. Giant channels meander across the seafloor carrying deep water flows from the shelves of South America far to the north. The strength of the beams of sound as they return from their journey to the sea bottom varies according to the type of seafloor and these variations we see as sonographs, or “sound photographs”. These reveal the subtle network of sediment pathways across shelf, down gullies and into the basins, which over the hundred or so million years since they formed, have filled with muds, sands and silts, now several kilometres thick. While not part of the Ross’s survey programme this time, surveys in the future could reveal more about the potential resources lying on or beneath the seafloor. Besides the search for oil and gas, still active since the 1996 drilling found hydrocarbon traces just to the north of the Falklands, a possible wealth of minerals could lie in these deeper waters. One possible source is in the curious deposits known as polymetallic, or manganese nodules. These potato-sized lumps contain mixtures of iron, manganese, nickel, copper and cobalt, and can be found in such numbers they can virtually carpet the seafloor. Equally odd is the occurrence of clathrate or ‘gas hydrate”, layers within the sediment carrying frozen ice/natural gas solids, and which themselves can form a cap to untapped methane accumulations. Little is known of the distribution of these ‘alternative’ resources in the South Atlantic, but surveys like the present one will without doubt provide the “road maps” for future expeditions to navigate.

A layer of clathrate in the sea floor sediment Gas hydrate, ice that has so much gas in it, that it burns! Manganese nodules on the sea floor Click here to download a clip (800KB)
of black smoker


Thankyou this week to Lindsay for his insight into the seafloor

Coming up next week......More of the same