Life on the Edge, Of the Greenland Ice Sheet Options

[John_Sode]

July 25, 2005

Our goal this morning is to observe and sample along the western edge of the ice sheet. We are walking along the ice-rock interface, the place where ice meets barren ground (rock).



As we are walking we encounter many interesting features. I suspect that today we will ask far more questions that we will answer. Already the ground has sorted into vegetative stripes beginning to fill with soil and plants. How old is this soil? Where did it come from? Did it form here? Did it blow in from somewhere else? Here we go—all these questions but no real answers yet.



Curious about our findings and observations so far this morning, we reverse direction and walk north along the ice sheet’s western edge. All morning a brisk wind blows damp wet air, whipping off the ice sheet to bring a cold chill to the air. This wind reminds me of a winter wind whipping off the mid-Atlantic Ocean, chilling everyone and everything to the bone.



There is more activity here. We discover sorting of rocks (separation by size) under the ice and in areas that may have just become ice-free this season. There is a remarkable degree of sorting in many areas that have probably only become ice-free in recent years, certainly in the last few hundred years since the end of the little ice age. How old are these patterns? Did they occur under the ice, before the ice age, during the ice age, or after the ice age? Which ice age? The little ice age? The last major ice age, which ended about 10,000 years ago? We don’t know the answer.



Even more interesting, we find plant material at the edge of the ice. Although apparently dead, how old is this material? Are there seeds or spores present? Is this genetic material that is thousands of years old? Is this a source from which to construct mutation rates? Are these plants blown in from other areas and only a few years old? Or, are these plants hundreds, perhaps even thousands, of years old? Have we found plants recently released from ancient ice coffins? Again, we don’t know the answers, or even all the questions to ask. We decide to harvest a few samples and seek some answers.



As we turn around to head back, we notice that the moraine being created by the ice sheet, at least in one spot, is actually a small rock covering resting on top of the ice. The ice is moving through and underneath the rock, lifting it up and carrying it along.