Sunshine and little wind

The good weather continues and we have had days of sunshine and little wind. We are pleased at our progress on the science and got an extra boost from a visit by a Twin Otter which delivered 685 litres of petrol mainly for skidoo travel. But wonders of wonders it brought a crate of beer, fresh vegetables and fruit, probably from Punta Arenas, and cakes! We are enormously grateful to those at Rothera who have thought of us and taken the trouble to put together such goodies. So morale is high.

People ask what we actually do on our days of science. Well, let’s start with the most exciting task. I think it must go to John’s radar survey. Imagine a chaotic mass of boulders forming ridges and basins extending several hundred metres from the ice edge to the mountain front. Well John selects a line and then gets either Scott or Malcolm to drag a sledge with the radar across the rocks. So far so good, but each measurement takes place every 10 cm! The radar beeps when it has taken a reading and then there are three seconds to move it 10 cm for another. And so on until the transect is complete! No breaks allowed for coffee! Then there is Stuart’s laser scanner. Early days involved setting up reflectors in various locations on the mountain front. Then the survey starts. A typical day starts with warming up the instrument in a thermal blanket so it can operate in the cold. Then there is some sophisticated programming to tell it what to do and in how much detail. You switch it on and leave it to map the mountain front in detail. Apparently you are allowed to sleep while the machine does the work, so you can imagine it is a popular assignment! Then the cosmogenic dating. The trick here is to know which of the multitude of stones on the mountain front to choose and why. So Andy and I have a detailed seminar discussion on every stone and we are on number 142 so far! Since we want to date the last time the ice dropped a stone we must exclude such things as human disturbance (yes even here there are cairns!), movement downslope or frost shattering since deposition, whether it has enough quartz in it, etc. Once selected we label and photograph it and its location in detail, use an angle grinder, hammer and chisel to take the surface layer of rock, and bag the sample. Many details are needed, such as altitude and possible shielding by nearby mountains, snow patches etc. You can imagine fetching out the various instruments and notebooks to do this without losing them in the wind. We have settled for big anorak front pockets containing everything in one place, for example, GPS, notebook, compass, clinometer, sample bags, marker pen, camera, sunscreen, bar of chocolate and gloves.

One huge change with the past is our ability to see films. On special occasions, such as a Saturday, Sunday or the arrival of beer all six of us cluster round a laptop and watch a film, such as The Guard and the Chalet Girl. When the sun is out the tent remains warm till late.

Our strategy on the science has been to study the Patriots in detail and probably do this till Christmas. Then we will move on to the Independent and Marble Hills. What have we discovered – provisionally at least? Well, the mountains have been submerged beneath a larger Antarctic Ice sheet flowing eastwards across the range. We have found ancient blue-ice moraines associated with this and should be able to date the episode. It could be part of an Ice Age cycle or an early stage of Antarctic glaciation millions of years ago. We have found three stages of blue-ice formation at the present ice margin and, again should be able to date these. We have a detailed laser map of the surface and structures of the moraines, almost certainly the best yet achieved in Antarctica or anywhere in the world. We have radar profiles through the moraines showing the depth of ice beneath them and the structures linked to the surface patterns. There is 180 m of ice beneath the biggest moraine! So we are better able to understand how blue-ice moraines form and their wider significance. Clearly there is lots more to do in the field and later in the lab, but so far so good.


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s