A blast from the past at the Lake City Caldera with Ben Kennedy

Excuse the pun, I know am not the first researcher to write about a prehistoric eruption or to reminisce about how much fun it was to do epic fieldwork, and I did have a Blast! I am now lucky enough to have a faculty position and lovely family in New Zealand at the University of Canterbury, but I don’t get to spend nearly enough time running around in the mountains or roadtripping across a continent.

On the road at Bryce canyon with Jonathan Hanson, Jonny Davidson, Ben Kennedy and Dwain the love doll.

In 2004 and 2005, I spent two amazing summers with 6 great friends and researchers driving from Montreal to Colorado and back and spending 3 months in the high San Juan mountains. We collected rock samples and tried to build on a map of a 10km wide caldera with more than a km of vertical relief. We chose Lake City caldera because it showed us a rare window into the guts of a caldera, and my PhD was all about what happens in a magma chamber during a caldera forming eruption. My amazing supervisor John Stix had been recommended Lake City by the legendary volcanologists Pete Lipman, and Ken Hon who had spent years mapping this incredible volcano.

Eoghan Holohan, Jonathan Hanson, Jonny Davidson on the northern rim of the caldera.

As a British PhD student at McGill University, it was a dream to drive across Canada and the U.S. to my field location of Lake City, in Colorado. Our mini-van was soon christened Sue after the Jonny Cash song “A boy named Sue” and was pushed to her limits on 4WD tracks, and general abuse fromher inexperienced drivers. Sue had as transformative journey as we did, and soon gained a set of bull horns (attached with duct tape), several hitch hiking mice, and a love doll named Dwain, and even functioned as a mobile hospital as I removed my own stiches in the wing mirror using my swiss army knife. Our cross continent journeys were far from boring, we visited many of the countries spectacular national parks, and during which I was misidentified as an escaped criminal from Canada, held at gun point by local police and we even accidently bribed a police man forgetting there was my 100 dollars emergency cash in my passport when asked for ID. But these are all parts of another story- this is a story about science……

The view from Sunshine Peak

When we arrived we realised the caldera was massive, rugged, and high and we loved it. After several weeks in the high mountains we became very fit and very feral, scampering up and down scree slopes at 14,000ft, scaring tourists and marmots alike. This amazing terrain enabled us to simultaneously observe and sample the erupted rock and the plutonic source. We soon accumulated more than 500kg of rocks and a love for the striking bare red mountain tops of Redcloud and Sunshine peaks. We ran from lightning storms, and spent our evenings drawing cross sections, photographing our rocks, eating bacon and mingling with the colourful locals of Lake City. We slowly pieced together a story of a caldera forming eruption involving multiple magma bodies and a feedback between the surface process and the magmatic processes beneath.

Ben Kennedy mapping resurgent intrusions in the interior of Lake City caldera.

Our data took years to properly model and prepare for publication, but eventually we could show that two magma batches evolved separately but interacted in response to the eruption and the process of resurgence. The modelling of Chad Deering and Sarah Gelman, allowed us to prove our hypothesis that crystals accumulated and remelted, and that mush barriers formed and disrupted during the evolving eruptions and the article has just been published in GSA Bulletin.

Sue the mini van off road again with driver Jonathan Hanson.

I think these summers cemented a love of igneous rocks and the earth in all of us, my then 5 inexperienced field assistants Mattheui Richer, Marc Antoine Longpre, Jonathan Hansen, Jonathan Davidson and Eoghan Holohan all now have graduate degrees and have successful volcanology careers. Matheui then went in adifferent direction and found his love of the earth by becoming spiritual leader and yoga guru. I continue to work on Lake City through my own graduate student Tom Garden who I co supervise the Darren Gravely and Chad Deering.

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