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2 June 2013
Sidewalk geologic timescales
Saw this educational graffiti on the campus of Carleton College a few weeks ago: Seems like a great way to get students to grasp the relative spans of geologic time.
24 May 2013
Friday folds: three lovely specimens from the Carleton College rock garden
I was up in Carleton College (Northfield, Minnesota) for most of the week, working on a new teaching module for the InTeGrate project. On the way between our work area and the cafeteria where we ate lunch, we passed the geology department’s rock garden. They have some great specimens there, some big, some small. Here are three that featured folds: Closer in, you can note an exquisite example of differential …
9 May 2013
Boudinage in northern Minnesota
This is my final post on the pre-GSA-Minneapolis structural geology field trip to the Superior Province. The photo above shows a roadcut exposure of boudinage in xenolith-bearing Vermillion Granitic Complex. Here’s another, smaller, more brittle example of boudinage, from another site, the following morning: Gee, it only took me 1.5 years to blog that trip in its entirety… Sheesh!
25 April 2013
Deformation in the Lake Vermillion Formation
Today, let’s go back to the Pike Dam, where we spent some lovely moments last week, agog at the lovely graded beds and flame structures visible there. In contrast, today we want to examine the deformational structures seen elsewhere at this same outcrop. There are folds and faults and joints and more exotic fare: tension gashes and Riedel shears. The deformation here is the youngest to affect the Vermillion District …
16 April 2013
Squashed pillows
Join Callan for a look at submarine volcanism and later deformation near Ely, Minnesota. Archean tectonics fluffed these pillows up and squashed them down again.
10 April 2013
Primary structures in the Lake Vermilion Formation
Callan showcases some extraordinary depositional structures (graded bedding and flame structures) seen in Archean turbidites in the Superior province of northern Minnesota.
7 June 2012
Plane views: Flatlands edition
More photos from the flight from Reno to Minneapolis in March. The photos in today’s post come from the air above the Dakotas and Minnesota. First up: a series showing the intersection of natural patterns (presumably related to ground moraine) and the palimpsest geometric regularity of anthropogenic designs: Are these kettles? A close up look at one frozen lake, gleaming like a jewel in this dun landscape: Next, consider this …
6 February 2012
Folded BIFs of Soudan, Minnesota
Why are these people smiling? photo by Yvette Kuiper Because they are structural geologists, and they are psyched to be at an extraordinary outcrop: This is a famous pavement outcrop of polyphase-folded banded iron formation (BIF) near Soudan, Minnesota. I went there last fall before the annual meeting of the Geological Society of America, on the Structural Geology of the Superior Craton’s sub-province boundaries field trip. “Oh YEAH!” What you’re …
13 October 2011
Superior Craton trip, stop 1
The first stop on our pre-GSA field trip to the subprovince boundaries of the Superior Craton was a place just north of Virginia, Minnesota, where the Mesabi Iron Ranges are mined (same Proterozoic banded iron formations that were portrayed as the backdrop of the mining activity depicted in the film North Country). The pull-off is locally known (to geologists) as “Confusion Hill,” but marked on the roadside sign as the …
12 October 2011
The GSA meeting experience, 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 …
Callan Bentley is Associate Professor of Geology at Piedmont Virginia Community College in Charlottesville, Virginia. He is a Fellow of the Geological Society of America. For his work on this blog, the National Association of Geoscience Teachers recognized him with the James Shea Award. He has also won the Outstanding Faculty Award from the State Council on Higher Education in Virginia, and the Biggs Award for Excellence in Geoscience Teaching from the Geoscience Education Division of the Geological Society of America. In previous years, Callan served as a contributing editor at EARTH magazine, President of the Geological Society of Washington and President the Geo2YC division of NAGT.