Just so you don't think I've fallen off the face of the Earth ... I have been at the 2011 Keck Geology Symposium for Undergraduate Research at Union College for the last 4 days. It was a busy, busy symposium with lots of talks and posters - all of undergraduate geology research of all flavors - along with a day long field trip to the Adirondacks (and I have the two bags full of fabulous garnet-bearing rocks to prove it - with one garnet the size of a tennis ball).
There was a lot of geology, but thought I'd mentioned two things that might interest the Eruptions crowd:
- Crater Lake: One of the Keck projects lead by Dr. Kelly McGregor (Macalester College) and Dr. Catherine Riihimaki (Drew Univ.) focussed on looking at lake sediment in the lakes of Glacier National Park in Montana. In Swiftcurrent Lake, the team found 50 cm of 7700 year old Mazama ash - yes, 50 cm! Now, both you get too excited, that 50 cm is a thickness amplified by all the ash in the drainage basin getting moved into the lake. Most estimates of ash fall in the Glacier region, which is almost 900 km from Crater Lake in Oregon, is somewhere around 5-10 cm. One cool finding is that the ash fall from Mazama might have dramatically changed the activity of diatoms in the lake thanks to the elements leached from the ash into the water - a type of volcano-life interaction at the microscopic scale that was new to me! The team also found a few other, older tephra layers in the sediment core. They haven't matched them yet, but likely they belong to eruptions from Glacier Peak and possibly St. Helens or Newberry.
- Heart Mountain: Another project looked at strange things in Wyoming. Those of you familiar with Heart Mountain in Wyoming might be thinking "what is he talking about, Heart Mt. has nothing to do with volcanoes." Heart Mountain is a big block of marble and other sediment that is sitting in a wide basin in northern Wyoming - it is what we call "highly allochthonous" - that is, it isn't where it is supposed to be (about 100-200 km away to be specific). There is a lot of speculation about why Heart Mountain and other blocks of limestone and other sediment (from such famous units as the Madison, Sundance and Morrisson) got in the middle of the valley, from processes taking 10 million years to a matter of minutes. How would you move it in a matter of minutes? Volcanically, in a giant (and I mean giant) debris avalanche, possibly related to the Eocene Absaroka Volcanics, specifically volcano dubbed "Sunlight volcano" that is thought to be a giant andesite volcano. These volcanics are long since extinct, with the potential avalanche being ~49-50 million years old, but the debris avalanche itself looks to be 40 km by 10 km. There are also lahar deposits 100 km away from the location of the volcano that seem to be from the same time, so this might have been a very active and dramatic volcanic system.
All exciting research being done by undergraduates, mostly at small colleges like Denison. Fun times, that is for sure.
I'll be back on our regular schedule sometime tomorrow!
Top left: Heart Mountain, Wyoming. Click here to see the original.