More soils work in Vulgaris today. Our arrival is greeted by an Arctic hare hopping its way through the valley and completing our list of the 4 terrestrial mammals in Greenland. Man they are big critters. Elmer Fudd would be pretty afraid, and I’m not sure what my beagle, Tracks, would think.
We are trying to date how long ago the loess deposits were eroded from the large patches on the south facing slope. Its clearly been quite awhile, as there are lichens growing on all the cobbles in the middle of the eroded areas. The erosion probably happened too recently, however for using the surface exposure dating we did yesterday. Another method for dating, this one is based on the lichens themselves, is in order. One of the lichen species, which seems to colonize most places shortly after they are exposed (as in 5-30yrs after) grows very slowly (like 0.4mm/yr). Measuring the size of this lichen enables us to calculate how long the area was exposed. Of course trusting just one lichen isn’t a good idea, so we measured a few hundred, along with their distance from the edge of the eroded areas to see if the areas were growing larger over time, or if the erosion occurred more or less all at once in the past. Whatever circumstances caused the massive loss of soil from the south facing slopes throughout the area are of interest to us. Is it possible that we will re-create these same circumstances with climate change? Triggering a similar erosion episode would not only have impacts on the local flora and fauna, but also would impact the amount of carbon stored in the soils, potentially releasing large amounts into the atmosphere.
By 4pm we’d finished this season’s work in Vulgaris Valley, with few immediate answers about the deglaciation and soil formation of the valley, but plenty of good samples to hopefully piece it together over the next year. To celebrate we decided to hike over the hill to the terminous of one arm of the massive Greenland ice sheet called Russell Glacier. Russell Glacier’s terminous is carved away by a river flowing into its face, which disappears briefly under the glacier before re-emerging to carve ice out from under it. This arrangement makes for some wonderful calving, the phenomenon when large chunks break off and come crashing down. The glacier did not disappoint, half a dozen dump-truck sized pieces of ice cascaded off the 120 foot high face as we sat and watched the ever-unpredictable show. For fun, each of us selected pieces of ice we deemed most unstable as we sat down and rooted for them to go next. We were almost always wrong as seemingly solid pieces cascaded down around the unstable ones.
While watching the glacier, distances and heights become a bit hard to comprehend. Naturally there was some disagreement on just what the glaciers height might be. A poll was taken and Matt Ayres was marked down at an estimate of 100 meters, while the Laura, Gifford, and I took estimates from 30 to 45 meters. How to settle the bet without climbing into harms way? Using the focus on my telephoto lens we were able to determine the horizontal distance to the base of the glacier from our vantage point (45m), and using Laura’s clinometer we were able to get the angle from us to the top of the glacier (30 degrees). Combining the two pieces of information with some trigonometry clearly put us in the nerd category, but got a height estimate of 26m, mark one for the students! Actually, the ice was not quite vertical, and some further highly scientific haggling put the estimate of total height at 35-40meters. Height estimates complete, and bodies beginning to be chilled by the cold wind off the ice, we headed for our last night at camp.