Monday, July 14, 2014

27th of June

This blog was originally posted on the Environment and Society in a Changing Arctic Blog on July 3, 2014.

by Lauren Krone and Samantha Morrow

Today was our first full day at Tarfala! After a restful morning and a leisurely breakfast, we hiked along the river and then up onto a lateral moraine. Moraines are piles of rock and debris that were once carried or moved by a glacier, and end up in piles, which reveal the glaciers shape and path at one point in time. We learned that lateral moraines are formed along the sides of a glacier, as compared to terminal moraines that form at the end of a glacier.

The first thing we did on the moraine was to measure the lichen that had grown on the rocks. Lichen are a symbiosis of algae and fungus. The alga does the photosynthesis, while the fungus collects nutrients from the rocks. Since photosynthesis requires sunlight, lichen can only start to grow once the glacier retreats. This allows us to date the age of the moraine by looking at the size in diameter of the lichen. Such a process is called lichen dating. Lichen growth curves are created by looking at how big lichen are on surfaces where the age is known, such as abandoned mines or old forests. These curves are then applied to the lichen on the moraines, at an average rate of 0.4mm per year.

We split up into groups, and measured different areas of the moraine. This included the inside, top, and
outside of the moraine. We found that the top of the moraine was roughly 200 years old, while the inside of the moraine was only exposed about 100 years ago.

In addition to dating the moraine, we discussed possible problems with using lichen to find the age of the moraine. First, there is difficulty in finding perfectly circular lichen, making the diameter a difficult thing to measure correctly. The uneven growth patterns are due to uneven mineral distribution in the rocks along with micro-topography of the rocks. Moreover, there is a possibility that new landslides or rock falls may cover a moraine, or cause rocks to flip or expose new surfaces. This may make a moraine look younger than it really is, because younger lichen will have colonized the newly exposed rock.

After we were finished working with the lichen on the moraine, a group went on an optional hike up the opposite side of the valley. This gave us a view of the glacier Storglaciaren which we will get to go out on tomorrow! Can’t wait!

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