Moraines and spaghetti in the Transantarctic Mountains
The first day of geologic work at our Mt Howe field camp. We start walking on the moraines (piles of debris left by a glacier, just like around NY, Indiana, Wisconsin, where we are from) and we have to put on crampons. These are spikes that go on the bottom of our boots. This is because the moraines are really hummocky to walk on and right under just a few inches of dirt is ice, making us slip and slide and do more leg splits than we can remember!
But, we quickly identify roughly where we think the ice was during the last ice age. We can do this because the deposits are ‘grey’ in color as they do not have time to oxidize (like rust on a car). The stuff left behind by older ice ages is red in color – because it has had time to oxidize. We start collecting our first samples. Kathy and Nicole collect material to figure out the type and chemistry of the glacier deposits left behind, which will help tell them which way the ice must have been moving in the past and what kind of rocks it brought up from below. Mike K and Mike R start measuring the elevations of all the glacial deposits and more important start collecting samples from the tops of large boulders. These samples will help us figure out the time at which they were left behind. Once back home, we will use a method called cosmogenic surface exposure dating. We will use our lab facilities at Lamont-Doherty Earth Obsservatory to date the rocks, using the cosmogenic nuclides Beryllium-10 as well as Helium-3.
Over the next 6 days or so, both teams just systematically collect samples from each set of ridges or moraines that the ice sheet left behind in the past. The idea is that each distinct moraine ridge represents a different time period or glacial period when the ice sheet was bigger. The weather holds up well, an important fact when you are only a couple hundred miles from the South Pole. The temperature remains about -10 to 0 during the day. Anytime the wind picks up thought, the wind chills causes it to get colder fast. Often exposed skin has to be covered quickly. Only a few days are cloudy, otherwise the sun adds a little bit more warmth. Fortunately, the tents are warmer, especially when we run the coleman stoves. So, eating dinner is way more comfortable than being outside.
Mike K., Mike R., Kathy and Nicole