23 July, 2001
New Arrivals and Scouting a Site
Life on ice ... almost
It was a relatively quiet day in camp today. The REU students were finishing developing ideas for their projects, the CRREL folks were in and out working on their projects, and this morning, Greg and I finished writing abstracts for presentation at this fall's Geological Society of America national conference.
Writing an abstract is a time-intensive process, requiring many revisions: adding words, taking out sentences, reordering ideas and repeating the process with several readers.
This afternoon, Ed Evenson (from Lehigh University) and Staci Ensminger (from Northwest Missouri State) arrived in camp today. Ed was Jeff and Staci's mentor and active in the field glacial geology. He has been studying the Matanuska for many years and brings incredible insight and a wealth of practical knowledge to bear on the research being done here. Staci helps Jeff run the REU program. She wrote her PhD dissertation on the debris bands (hopefully visible in the picture below) on the Matanuska Glacier.
Science at work
This afternoon, Kendra and I crossed the Matanuska River in an inflatable raft to scout a possibility of collecting some near-surface geophysical data on the outwash plain there as a quick side project for later analysis. Last October, Kendra started a project at the same location. When she was collecting her data then, her group walked across the frozen river. Today, we pulled each other across in a somewhat precarious ferry. If we leaned too far back, the stern (back end) of the boat would dip into the standing waves on the raging river; if we leaned too far forward, the bow (front end) would slip beneath the waves. To make the adventure even more exciting, "too far forward" or "too far back" changed as one traveled across the river! By the time we both got across, the boat was nearly filled with the silt-heavy and freezing cold water. The waterproof hiking boots turned out to be a very good investment. We bailed (removed the water from) the boat with the waders we had brought along in case we encountered mud on the other side. No mud, but the boots were extremely handy nonetheless!
From the boat, we wandered over to the old site. The site we ended up scouting out on the outwash plain may not be especially well-suited for seismic data after all, even though it is the same spot Kendra used last October. The difference is ice: over the summer, the ice that covered the area last fall has melted. The ground beneath is very silty and crumbles easily. Ice holds a geophone very well; loose silt does not. To measure the "echoes" traveling in the earth, a tight fit between the geophone's spike and the ground is critical. When we returned to camp, we discussed the possibility of using ground-penetrating radar instead.
Interesting side note:
On the way back to the boat, we stopped and admired the rocks: green rocks (serpentinite?), purple rocks, orange rocks (felsic?), white rocks (mineral, really... quartz), black rocks, grey rocks (shale), speckled rocks, gold rocks (mineral, really... pyrite), rocks filled with veins of quartz, a rock made of alternating bands of black and white (gneiss), etc. Each of the rocks here were likely transported by the glacier from somewhere in the valleys to the southeast of where we were standing. This is amazing because the process to form these rocks varies from one to the next. This means that the valleys in the areas where the rocks formed went through some very different processes from each other sometime in the past.
My bed calls; I must answer.
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