12 October 2011
I’m on the plane home from the annual meeting of the Geological Society of America, held this year in Minneapolis, Minnesota. This annual event features a robust smorgasbord of science, with talks and posters detailing the research efforts of thousands of geoscientists from the US and other countries. It’s an amazing experience on many, many levels, and as I fly home now after a week in Minnesota, my feelings are mostly emotions of accomplishment, excitement, and exhaustion.
My week began 7 days ago, when I flew out to Minneapolis after a full day of teaching at NOVA. I arrived on a balmy Tuesday night, and my college friend Clare picked me up at the airport. Clare and her roommates (both opera singers) put me up for the night, and we stayed up for several hours drinking wine, eating local cheese on homemade bread, and catching up on things.
The next morning, Clare’s boyfriend Rodolfo made me breakfast and dropped me off downtown, where I met up with the other folks attending the pre-meeting structural geology field trip. Our destination was the sub-province boundaries of the Superior Province, the Archean “nucleus” of North America – it’s the largest continuous exposure of Archean-aged crust anywhere on the planet Earth, and we were interested to see how it got put together. The trip was focused at looking at the interior architecture of the Superior Province, at the ancient tectonic sutures that assembled the craton from smaller sub-units. These subprovince boundaries would be highly deformed, and therefore were of interest to the structural geologists who signed up for the trip. Our leaders were Bob Bauer, Dyanna Czeck, Peter Hudleston, and Basil Tikoff. The four of them were a structural tour de force: full of interesting ideas and the perspective that comes with years of experience.
That first day, we basically just drove north, stopping only to pee and eat. We reached International Falls, Minnesota (on the border), at dusk, and ate dinner there. I shared a pint of beer with Hugh Rance, the well spoken, fascinating individual who maintains the GSA History of Geology division’s webpage. We talked extensively about the history of geology, and I learned a lot from him. Hugh has written an epic online textbook for Historical Geology which takes the novel approach of starting in the present and working backwards through time over the course of the course.
Fed and moderately inebriated (though not the drivers, of course), we crossed the border into Canada. There was some trouble at Canadian customs when some of our more voluble participants cracked a couple of jokes about being a suspicious lot. But it all got sorted out, and they let us into Canada. We drove a short distance into Fort Frances, Ontario, and checked into a hotel for the night. My roommate, also named Hugh, was an amateur geologist, but a trained medical doctor nearing retirement, who had picked up geology as a hobby. He was full of thoughtful reflection and made a remarkable effort to document the trip in his notes.
In the morning, we all gathered by the vans and set out to explore the field area. Our first stop was a profound experience – it was a gorgeous polymictic conglomerate, interpreted as a “Timiskaming-type” syn-tectonic conglomerate, deposited in a wrench basin as the Wabigoon and Quetico sub-provinces collided in the Archean. The individual pebbles and cobbles in the conglomerate were moderately to severely strained, and not only showed flattening strain ellipsoids, but also asymmetric “wings” due to dextral shearing.
We then checked out some sheared out metavolcanics, and the margin of a granite intrusion, the Ottertail Pluton. The day wrapped up with a look at pseudoboudins and small shear zones cutting across a gabbroic sill. You’ll love the photos – but you’ll have to wait for them.
That evening, I had a couple of beers on the dock of the hotel, poking out into Rainy Lake, and the weather was lovely, and the sun set, and all was right in the world, except that I missed my wife. A dozen of the geologists on the trip gathered around a large table in the hotel restaurant, and we ate very well and talked of many things – life, job, structure, politics, and the sorts of stuff you talk about after a few drinks and over good food.
Day 3 of the field trip dawned, and we checked out of the Fort Frances hotel and visited a few more Canadian outcrops. Two of these were superb examples of the way that granitoid dikes (or ‘veins,’ as the field trip leaders called them) strained differently in the same strain field. Depending on their initial orientation, they either folded up, or boudinaged, or didn’t exhibit any stain at all.
We also saw some deformed pillow basalts that may be representative of Archean oceanic crust that was then flattened and sheared and lineated in a vertical direction due to these ancient tectonic collisions. It was profound. Wait til I show you the photos!
Then we had some lunch and re-crossed the border back into the US. We lost about an hour and a half with that process, as one of our four vans was detained at the border since one of the folks in it had recently returned from Iran. We gassed up and drove south, stopping to see some beautiful outcrops of the Vermillion Granitic Complex, and then a lens-shaped intrusion called the Wakemup Bay Pluton. Peter Davis of Pacific Lutheran University and I took turns photographing each other against the backdrop of a 10-meter-long boudin train. Another hour of driving brought us to Ely, where we stayed for the night and ate a lovely meal at Rock Wood. I ate with Warren Hamilton of the Colorado School of Mines, Monte Marshall of the University of California at San Diego, and Stefan Banzhaf of the University of Berlin, and it was great fun to talk to such a diverse group.
The morning had us up and moving at an early hour, and we began with a pavement outcrop of a shear zone where I had a major “aha” moment – though the shear zone was dextral transpressional in its kinematics, I spotted an “S” fold, which is an indicator of sinistral shear. Peter Hudleston listened politely when I pointed this out, but then replied that asymmetric folds are not a reliable shear sense indicator in highly strained rocks. He said that with progressive deformation, an initial Z fold could turn into an S fold. I wrinkled up my brow at this statement, trying to imagine how such a thing could be true. I sat down with my field notebook and drew some pictures, and sure enough, I figured out how to make it work. It made me realize how I had too simple a paradigm in mind in my interpretation of shear zones, and this felt like a major realization for me. I’ll sketch it all for you some day as the Friday fold…
We also checked out some TTG’s, which don’t really light my fire all that much – but they are extremely common components of Archean greenstone belts. TTG stands for “tonalite, trondjhemite, and granodiorite,” the three varieties of granitoids which are frequent injections into the Archean crust. One thing that was interesting about these though they don’t show visible strain petrographically, they do show distortion in their magnetic fabrics, a subtle character called Anisotropy of Magnetic Susceptibility, or AMS. Structural geologists can use AMS to detect invisible fabric elements in lightly strained plutonic rocks, including foliation and lineation.
Next, we moved on to the Vermilion District, an Archean basin fill. We had coffee that morning (for the second day in a row) at some strained pillow basalts (now greenstone) at the base of this sequence – again, the photos will convey what we saw there better than I can write, but let me say this: these pillows were much more obvious than the ones we saw in Canada. And they were weathering out in three dimensions, showing them to be slim and vertical, like a mola mola.
Upsequence from the pillows are the celebrated layers of the Soudan banded iron formation. These chemical sediments precipitated from the Archean ocean in alternating layers of red jasper and silver to black ferromagnesian minerals (magnetite, hematite, stuff like that). Unlike the BIF of the Iron Ranges to the south (which are Proterozoic BIFs), these Soudan-area B Ifs were Archean and very cool. The outcrop we visited was located near the Soudan Iron Mine, the first iron mine in Minnesota and a new state park. The BIFs were exposed in a pavement outcrop (bearing glacial striations) and had at least two generations of folding that they were subjected to. The fold interference patterns were gorgeous, as photos in the days to come will reveal.
Our final field stop was in the clastic sediments which overlay the BIF. These graywacke and black shale layers were almost certainly deposited as turbidites, bearing classic examples of graded bedding and flame structures. Then, overprinting these primary structures were gorgeous examples of en echelon Riedel shears and tension gashes, as well as conjugate joint sets impregnated with extra silica (due to fluid flow along the joints). As a result, there were now weathering out in positive relief. And of course there were glacial striations galore, too. A very cool outcrop in total, and a great one to end with. We then drove back to Minneapolis.
I had dinner Saturday night with my Rockies course co-instructor Pete Berquist, his fiancée, and another William and Mary geologist, Chris Koteas, currently at the University of Massachusetts at Amherst. At the Rock Bottom Brewery, Chris regaled us with stories about his field work in the Canadian Arctic. Pete and I were pleased to learn that he has 3 community college students working on his project, as well as the expected cadre of U-Mass students.
Sunday morning, the conference began. I managed to make it to some intriguing structural talks that first morning, and then had a lunch meeting with an editor from a major publishing firm. He had recruited me, based in part on the stuff he saw me writing on this blog, to participate in a special project related to a new edition of an introductory textbook. I’m deliberately going to be a little vague about this project, since it’s a proprietary idea, and we haven’t signed a contract yet, and also because I just enjoy keeping you all in suspense. But he and I met, and discussed, and he made me realize that the scope of the project was actually rather bigger than I had initially anticipated… intriguing!
Back to the meeting for a few more talks, starting with a terrific presentation by Cherry Lewis (the author of The Dating Game) about the scientific legacy of Arthur Holmes. It was superb, and fascinating.
I also attended a talk by a former student who spent the summer acting as an interpretive ranger in Isle Royale National Park, and then visited some other former students at their poster in the main exhibit hall. I met up with old friends in the poster aisles, talking about this and that, life and death, projects and travels, marriage, creationism, and poster design. Peter Selkin was there, as was Simon Kattenhorn. I chatted for a while with my George Mason University colleague Julia Nord at her poster, and visited a poster by two GMU students, Kristy and Stephanie.
They served afternoon beers, and I strolled through the exhibit hall, seeing fun, dynamic displays like Steve Gough’s Emriver array, and less exciting displays with lonely-looking staffers manning them. At 5:30, I met up with the other newly-elected officers of the new Geo2YC division of the National Association of Geoscience Teachers, and we went to Brit’s Pub for beers to celeb rate and strategize.
I went back to the hotel and rested a while, checked in with my wife, and then went out again to have a few more beers with friends and colleagues. back at the Rock Bottom Brewery, I caught up with the Isle Royale student, Justin, at the same table as Bob Lillie, doyen of national park geo-interpretation and recently retired professor at Oregon State University. Bob, it turns out, knows Lockwood DeWitt, author of Outside the Interzone. Small Corvallis!
Justin and I stayed up for a couple hours debriefing his master’s degree path, career options, and life in general. I went to bed and slept well, but for too short a time.
Monday morning, it was back to the talks for a while. I spent the majority of the morning in the Archean session, which included a great talk from Shoufa Lin of the University of Waterloo, a longtime collaborator with my former University of Maryland advisor Dazhi Jiang (now at the University of Western Ontario). Shoufa revealed an intriguing story of vertical tectonism (diapirism and its opposite counterpart, which he called ‘sagduction’) to explain the L-tectonite fabrics of several Manitoban greenstone belts.
Getting lunch, I ran into Dan Doctor from the USGS, and went outside to eat my gyro with him and his friend Marcus Gary, a cave explorer and hydrologist from Texas. I returned to my hotel for a brief nap, then returned to the conference for a few afternoon talks, including one from my Montana State University advisor, the structural geologist Dave Lageson.
Mid-way through the afternoon, I had a meeting with my editor again, this time in the company of the authors of the textbook they want me to help with. We met, of course, at Brit’s Pub. This was a productive, illuminating meeting, and it was revealed that these authors had an amenable vision for me being a long-term collaborator on their book. This was more than I had dared to hope, and I was very pleased. They seemed like good people, and I felt reassured that I had chanced into something very good with them.
It began to rain during that meeting, and so when we broke it up and headed outside, I jogged back to the Hilton, getting fairly wet in the process. Back in my hotel room, I realized I didn’t have my phone, so I donned a rain jacket to run back and get it. This was fortuitous, because as I was getting off the elevator, I ran into another former student, Tiffany, who was rushing off to an event of her own. We traded numbers and agreed that we needed to catch up.
I went back to Brit’s and rescued my phone, then got an hour of rest before the next event: the College of William & Mary alumni event. There, I ran into Graeme Lederer, a talented young man who graduated more recently from W&M, and is now in a PhD program at the University of California, Santa Barbara. Graeme was an early follower of my blog, and I’ve been pleased to run into him many times at conferences like these.
I had a glass of wine and talked to Heather MacDonald, professor of geology at my alma mater, and Lynsey LeMay, geology instructor at Thomas Nelson Community College and the newly-elected vice president of Geo2YC. I touched based briefly with the companionable Chuck Bailey, and then scooted out the door, bound for The Local, a neighborhood pub where the geobloggers and geotweeters at the meeting were gathering for camaraderie. On my way in, I ran into John Jamieson, a classmate from grad school at the University of Maryland, currently finishing up his PhD at the University of Ottawa. Inside, I found Alton Dooley, Brian Romans, Cole Kingsbury, Anne Jefferson, Jennifer Wade, Matt Kutchta, John Van Hoesen, Andrew Alden, Tony Martin, and Steve Gough with his lovely wife Kate. Here’s a photo of the geo-social-media types that Kate took with Cole’s camera:
Andrew had actually already left when we took this, but I photoshopped him into the back row for completeness.
Beers were had, and we closed out the tab, and then Steve and Brian and Anne and I stuck around a while longer, and more beers were had, and chatted deep into the night. For the second night in a row, I sloshed back to the Hilton and fell hard asleep. Dawn came way too early, but I got up and went downstairs to meet up with Tiffany over breakfast.
We discussed her PhD, Idaho, and the potential of collaboration on a project of mutual interest – a virtual Virginia for geology. This struck me as the epitome of why we go to conferences – a chance encounter at the elevator door leads to a breakfast meeting, which leads potentially to a big deal collaboration on a chewy project of Great Importance! Nice.
I then returned to my hotel room and began to pack up. I had an issue with my late afternoon plans: my talk was scheduled for 5pm, but my plane was scheduled to leave at 7. I was concerned that this temporal juxtaposition was cutting it a bit too close. To save some time, I figured that if I could check into my flight in advance, print a boarding pass at the hotel, and then avoid checking a bag, I would stand a better chance of making my flight. The issue, however, was the suite of Superior Province rocks I had collected on the field trip several days earlier. These would not be allowed in my carry-on luggage, and I didn’t want to take the extra time to check in my bag at the airport. So: I decided to mail them to myself. I packed them up and walked to the post office, nestled them all in a flat rate box (cushioned by dirty t-shirts and half a roll of Hilton toilet paper), and sent them back to NOVA for $15.
After checking out of the hotel, I went down to the conference center and caught two talks, reuniting along the way with Alan Smith of Cambridge (who I field-tripped with a year ago in Turkey). Then another meeting with the benevolent editor, a focus group for another textbook publisher, and then back to the meeting for a few more Archean talks. One of these was an excellent exposition by Marcia Bjornerud of Lawrence University, who cautioned listeners not to be too wedded to uniformitarianism in interpreting Archean rocks. She painted a compelling case that the tectonics back then may not necessarily have been plate driven, and indeed things may have been very weird indeed. She spoke articulately and evocatively, much like she writes.
I went over to the education session next, since that was where I would be talking. Laura Lukes, an Einstein Fellow at NSF, gave an inspiring run-down on a Greenland field experience that she runs in the summers. When my turn came, I delivered my talk quickly and with no time for questions, since I had to run and catch my flight. The talk went pretty well, I think, though I’d be curious to hear with my friends and colleagues in the audience thought. I was bummed to see low attendance – only fifteen or twenty people were in the room. It’s a shame that the talk was timed so poorly, but them’s the breaks, I reckon.
I scooted out the door, jumped in a cab, and said “to the airport!” My Somali driver and I talked about East Africa, colonialism, piracy, and corruption. Into the airport with my pre-printed boarding pass, through security in 10 minutes (although I had to give up the small Swiss Army knife in my first aid kit – Aargh!) and I got to my gate with almost 20 minutes to spare! Enough time to grab a final #GSAMinn beer (Summit EPA, if you must know) and call my wife.
I’ve spent the flight writing all this down, and we’ve begun our descent into DC – so tomorrow I’ll post this on the blog, and you’ll know how I spent the past week! It’s been an intense, fruitful experience, as I suspect you can gather from this lengthy narrative. Thanks, GSA, for a great, full meeting. I got a lot done, and it was 100% worth my time.