Over the last two days we have been mapping and taking sediment samples of the moraines and river sediments (meltwater outwash) in the Zackenberg valley. This involved walking around an area of hummocky moraine and stream cuttings to map the landforms and make detailed observations of the sediments. Unlike ‘classic’ moraine, which usually forms in a linear or arc shape, hummocky moraine is more like an area of patchy, moraine mounds. In the Zackenberg valley these mounds are around 15 m high and extend across the valley. They are covered in large boulders and meltwater streams have now eroded into them. This means that the sediments within the moraines are nicely exposed for us to sample. The meltwater deposits were also exposed by the stream cuttings. We were able to climb down the banks and access the sediments by standing on the edge of the river.
On Saturday, while we were walking to the site we spotted a group of 4 musk ox (3 adults and a young musk ox) walking up the valley. There are lots of musk ox in the Zackenberg area, and while they are peaceful herbivores they can feel threatened if you get too close and have been known to charge at humans on rare occasions (especially if they have baby musk ox). It is therefore important to keep your distance when out in the field and keep an eye on their whereabouts. They particularly like the safety of hilly and bouldery areas (just the like the hummocky moraine!) so we have to be extra vigilant. Fortunately, it was a very hot day and the musk ox had been lying in the snow patches and bathing in the river to keep cool.
After we had mapped the area of moraine, we then looked around for suitable exposures into the landforms so that we could take samples of the sediments and describe them in detail. The best cuttings were located next to the present-day channel, where the strong meltwater currents had dissected (or ‘incised) the moraine and the gravelly sediments were clearly visible and accessible. Glacial deposits are made up of a sandy/silty ‘matrix’ and larger pebble/cobble-sized ‘clasts’. It is a bit like a fruit cake – the sponge is the matrix, and the raisins are the clasts – suspended in the spongy matrix. Go and buy a fruit cake to check (it’s a good excuse to eat cake!). We took several samples of the matrix, and measured the roundness of the clasts. Roundness can be used as a good indicator of the transport history of the clasts. Normally, rocks carried by rivers are more rounded and smoother than glacially-transported rocks because they have been eroded and rolled along by the water.
Saturday daytime entertainment was provided by ‘Zackenberg Logistics Radio’ hosted by DJ Kenny. This comprised the logistics manager playing us snippets of songs over our field radios – we are tuned in to the same channel so that we can communicate with eachother. We enjoyed a good variety from Gorillaz, Bob Marley, and the Beastie Boys. It was a hot, sunny day and the musical interludes kept us all dancing in the field!
While we were taking our samples, we watched the musk ox family have a Saturday morning swimming lesson. The three adults waded into the river to cross the channel, but the baby musk ox was not so sure! The river was very strong and the bank was very steep and covered in snow. Baby musk ox stayed on the bank waiting for the adults to come back and help him. One of the adults directed him into a smaller channel, but he still didn’t enjoy swimming. In the end, they decided not to cross the river, and continued walking up-valley. The moral of the story, whether you are a musk ox or a scientist, is: don’t bite off more than you can chew. Or failing that….just keep swimming!
On Saturday night we all had another tasty meal cooked by Dina and shared some champagne and Siberian vodka with Jannik and Mikhal who were celebrating their 10th field season here at Zackenberg. Whisky and beer was also brought out by those celebrating the weekend, and the party went on until around 3 am. We shared language lessons of English, German, Danish, and ‘loud Danish’, and listened to another wide variety of music courtesy of Kenny.