You are browsing the archive for June 2013 - Mountain Beltway.
28 June 2013
Friday fold: Summer sample #1
First sample of the summer – a new “pocket fold” showing Paleoproterozoic deformation in the northern Laramie Range, Wyoming.
27 June 2013
Paleoproterozoic dikes in Archean granite, Laramie Range, Wyoming
At Morton Pass, where highway 34 crosses the crest of the Laramie Range, you can see a nice set of (younger) mafic dikes cutting (older) granite/gneiss basement complex. The pink stuff is Archean; the black stuff is Paleoproterozoic; around 2 billion years old. Click to enlarge I got to check out this outcrop on Tuesday with colleagues from the University of Missouri and the University of Wyoming. Deformation in the …
24 June 2013
Monday macrobug: Jumping spiders that “Attack the Block”
A few weeks ago, I started seeing a new kind of jumping spider around our house. It was distinctive primarily because of its iridescent green chelicerae (think of them as “jaws”). I took a couple of blurry shots, but nothing I considered good enough for “Monday macrobug” treatment… These spiders reminded me of the unique design for the alien invaders in the fun movie Attack the Block: Clearly, they all …
21 June 2013
Friday fold: a lovely three-dimensional exposure
The Friday fold series returns to Kootenay National Park in Canada for a look at some folded Cambrian limestones.
20 June 2013
Headin’ west
Well, it’s that time of the year again. Tomorrow morning, I pack up the car and head west. I’m giving myself five days to drive out to Bozeman, Montana, with three stops along the way to see people I like and talk about interesting stuff. Next week, my family flies out to join me. It’ll be Baxter’s first plane ride! We’ve rented a condo in Bozeman for a month, and …
19 June 2013
Dwyka Tillite in South Africa
My wonderfully named e-buddy Martin Bentley recently took a field trip to a quarry in South Africa (between Grahamstown and Fort Beaufort) where the Dwyka Formation is exposed: This poorly sorted sedimentary rock (a ‘diamictite’) is usually interpreted as glacial deposits (lithified till, or ’tillite’). Alfred Wegener cited these rocks and accompanying glacial striations (and similar ones in South Africa, India, Australia, and Antarctica) as evidence for the existence of …
17 June 2013
Monday macrobug: Cranefly
Craneflies look like giant mosquitoes. They’re harmless to people – kind of like the giraffes of the insect world… In flagrante delicto…. Side-view portrait…
13 June 2013
Another example of the perplexing mystery “fossil”
In April, I posted some images of an odd structure from some of the fossiliferous siltstones of the Fort Valley. Some of the commenters suggested it was no fossil, but simply a very small scale version of soft-sediment deformation. Now, another “Fortian” has shown me another example, and this one is better preserved. Its lobes are (apparently) arranged radially, and the individual lobes have a striated appearance. The lobes vary …
11 June 2013
Weathering rinds
Some cobbles from Wyoming, showing lovely weathering rinds: …And here’s another, with a “slice” off the front. It reminds me of a slice through a sushi roll!
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.