Monday, November 19, 2007
Back in time and almost where we would like to be: 1000 meters below the sea floor!
This is an interesting phase of our project. The drill bit is more than 940 meters below the seafloor. The rock is getting really hard and the sediment is impregnated with hard, sometimes black, cement. So deep below the surface the pressure and the temperature are much higher than at the surface and that turns sediment (like beach sand) into rock. We are drilling such a deep hole because we would like to take a journey back in time and observe what Antarctica looked like in the past. We are also trying to find out when and how Antarctica got so cold and whether it is likely to stay that way in times of future global warming. Today, Antarctica is a frigid place, as you may have seen on this blog , but we know from previous drilling that it was not always like that. The arrow points to where I am on the image made by NASA. More than 90% of the continent is covered in ice, with only some mountain ranges sticking out above the ice surface. The photo to the right is of a biodiversity study here close to the station, but as you can see there are no plants growing here now. Previous drillholes have indicated that plants were once present in Antarctica. We are finding coaly plant debris in the core for some time now. We have been sending samples to scientists off the ice in New Zealand and the U.S. who are trying to find out what type of plant the material represents. Today we found some more coaly bits in the dark grey rock to the right. The question now is whether this material represents the vegetation on the Antarctic coast at the time of the deposition of the sediments or some older coal material. We will find out later! We know that aprox. 35 million years ago Antarctica looked very much like the coast of New Zealand (see image by I. Woodward), but when did it change? That is what we are trying to find out.
Posted by Sandra Passchier at 10:35 AM