Digging ourselves a big hole

Flying back to Rothera from our day out, the pilot leaned over and shouted to me above the roar of the engines. "Rod's on the radio - he wants to know if you'll be ready to head out to Gomez tomorrow to get started on your coffee cans?"

Blimey. It was already late in the evening, and by the time we got back and unloaded the plane it would be nearly midnight. It didn't leave a lot of time to get everything ready if we were to head out again first thing in the morning. And there was a heck of a lot of stuff to get together - not so much the science kit, which I could bung back into its boxes easily enough, but camping with BAS is very far from lightweight, and there would be an inordinate number of boxes to be gathered from the field store and lugged down to the hangar.

Somehow, with plenty of help from Alistair the doctor, who was coming out to be my assistant for a few days, we got the lot shoved in the back of the plane and strapped down by the time the pilot had fuelled up and done all his checks. At Gomez we would be camping along with another field party, Liz and Pete, who were heading out to drill an ice core.

They left half an hour before us, and they had already got their tent up by the time we arrived. Liz greeted us, looking mildly concerned. 'Can't see anything of your automatic weather station' she said. Although most of the instruments I had come to dig up were expected to be fairly well buried by snow, it being two years since they were installed, the weather station mast is a 5 metre galvanised steel pole and we certainly hoped that at least part of it would be sticking above the surface.

It soon transpired that the positions I had given the pilots had been interpreted as degrees, minutes and decimal minutes, whereas in fact they were in degrees, minutes and seconds. Don't ask me why minutes should have been decimalised, but not degrees (which would surely be more logical). Anyway, it meant our camp was about 700 metres from the true position of the AWS. After pitching our own tent, we wandered over to see what we could see. Absolutely nothing; acres and acres of white snow, barely perceptibly rising away to the south and east and falling to the west. But not a single bit of meteorological hardware showing even an inch above the surface.

This was a bit more worrying. We planted a flag at the last known position of the AWS and the four of us carefully searched a two hundred metre radius. Still nothing.

Three survey poles had been planted in a triangle at a distance of a kilometre from the main site, so we sped off to hunt for those. Still just broad white expanses, flat and endless.

In the evening I checked all my figures. We did expect the instruments to have moved a little - after all, we were on a glacier which was gently flowing downhill, and measuring the rate of movement was the whole point of the survey poles. When the poles had been surveyed previously, just over a day's worth of data had been collected. By plotting out the movement during that day, I calculated that the glacier was moving about 25 cm per day, slightly north of west. So it should have moved about 150 metres from the original position.

As well as drilling her ice core, Liz happened to have a Ground Penetrating Radar with her. Although you would think that snow is pretty homogenous, in fact layers in the snow give a nice relection on a radar, and by towing the radar behind a skidoo for 20 or 30km you can see how the depth of the layers change, giving you an indication of how the accumulation of snow has changed. I reckoned the radar might also be worth trying to find my buried weather station, so the following day we went out, flagged my new best guess of where the AWS ought to have drifted to, sat Liz on a sledge behind a skidoo, peering at a laptop attached to the radar, and set off on the hunt once more.

My plan was to slowly quarter the ground around the new estimated postion, and see if anything showed up on the screen. I didn't, I have to admit, have a great deal of hope - it seemed incredible that any technology could find something buried in such a huge expanse of snow. But jigger me and call me Thomas, for I had barely driven 10 yards from the flag when there was an excited squeal from the sledge behind. 'I've found something!'. Sure enough, a strange inverted parabola had appeared on the laptop screen, superimposed on the layers of snow that the radar was probing. We did a few more passes to try and pinpoint the spot more exactly, and then I started marking out a square with my shovel to start digging in.

As I plunged the shovel into the snow for the fifth or sixth time, I felt something go crunch. A few seconds later, we had excavated enough to find that the spade had gone clean through the tail of the wind vane on the top of the AWS mast.

But that turned out to be the easy part, for now we had to dig to the very bottom of the mast to retrieve the instruments. We knew that Gomez was a reasonably snowy place, but we really hadn't expected more than 5m of accumulation in two years.

It turned out that I had brought the right assistant along, for Alistair was a dab hand with the shovel. For the next two days we slugged away with our shovels and spade. I had brought the spade along specially, and I believe it is the only one in existence in the Antarctic. But seeing as spades are designed for digging, and shovels merely for shovelling, I had had a hunch it might come in useful, and once we were down a few feet into firmer snow it did indeed prove to be a better implement than the shovels.

Initially we made grand progress, for the snow was soft and easily thrown from the hole. By 2 meters though, it was noticibly firmer and harder to break up, and it wasn't long before we couldn't throw it to the surface anyway. From there on we had to fill bags with the rubble we produced and lug them to the surface, and progress became ever slower the deeper we got. Late on the second day of digging we came across a little package taped to the mast, with a miniature bottle of whisky and a note saying there was just a metre to go! Seeing as the hole already seemed hideously deep, and every second we had been expecting to feel our spades hit the instrument boxes we were digging for, this message was perhaps not quite as encouraging as its writers had hoped. The last metre was particularly hard work in fact, and we were mightily relieved when at last we saw the gleam of an aluminium box appear as we chipped ever-smaller chunks of ice away.

We weren't finished with the digging there though. There were a total of eight boxes spread around the base of the mast, and we had to tunnel a fair bit around the sides to clear them all, and then dig enough round them to loosen them, for they were pretty firmly frozen in. But at least as we cleared each box we could have a break while we opened it to check its contents, take some pictures, and, for the three logger boxes, to connect a laptop and download the collected data. We were mightily relieved when finally we had lugged all the boxes to the surface and the hole was clear.

We still had the GPS survey to do. The survey poles were considerably shorter than the AWS mast, and so were buried even deeper, but it was easy enough to find the central stake, which was only a couple of metres from the AWS. We made an attempt to find one of the outlying poles with the GPR, but the thin aluminium stakes weren't likely to have the same reflection as the big AWS and the eight boxes at the central site, and although we quartered the area where we expected it to be, we found nothing.

For another pole we tried to calculate exactly where it would have drifted to, and flagged the spot. Then we dug around in the hope of striking it. The stake at the AWS site had been 1.5m beneath the surface, but even with a hole 2m deep and 3m wide, we found nothing. So we gave up, and spent our last day at Gomwez helping Liz and Pete set up their ice core drill. The enormous hole we had dug (we measured it at 5.42m) gave some fun ice-climbing in the evening.