Broken plates on our ‘special’ day
Wednesday 23rd January 2008
We are crossing the mid-ocean South-east Indian Ridge. An email from Rob bobbed up yesterday inviting me to check out his maps which show how the great plates dividing the planet affect the ocean floor.
At around -54 South and 143 East you can see the suture line that separates the great Australia plate from the Antarctic plate. I can see on the echo sounder where we have been traveling. It’s a very flat and deep area to around 5000m. This is Old Earth. Suddenly bumpy hills several hundred metres high start to appear. The ground continues to be rough and then the clear line of the axis shows where the earth has literally torn apart. This is where we cross into New Earth, a landscape of undersea volcanoes, basalt and larva, which has bubbled up and joined onto both sides of the plates. The seabed smoothes out again and further north Old Earth returns on the Australian plate. Rob tells me that this crack in the crust is the basis of where all life on earth began.
We zoom in on the Google Earth map and look at the huge torn trenches in the sea floor radiating out from the main axis. Zoom out, and it is another wonder to see the world as a patchwork of broken plates sliding across each other around the globe. The Australian plate is heading north at 9 cm a year ploughing beneath the Indonesian one.
But what can you do?
Today is our third and last ‘special occasion’ where we each have a modest ration of beer or cheap cask wine. Appropriately the Bing Bong just before the soiree announced another reason to celebrate. We will arrive in Hobart a day earlier than planned and be back on land on Sunday at 0800.
Our soiree begins and ends in high spirits. Several music ensembles present an eclectic repertoire combining Celtic, folk, indigenous, punk, cabaret, swing and traditional jazz influences. It’s a unique combination of skills on keyboard, mandolin, didgeridoo, trumpet, percussion, saxophone, guitar, fiddle and mouth organ.
Roger’s surprise appearance and marvelous comic performance of the Tom Lehrer song ‘The Vatican Rag’ completed the cultural festival
Margot Foster is a journalist currently on board the Australian Aurora Australis, an Australian research vessel currently participating in the Census of Antarctic Marine Life (CAML, IPY project 53). She works with the Australian Broadcasting Corporation (ABC).