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24 April 2013
Native copper from the Catoctin Formation
Another new insight from last week’s visit to the Outdoor Lab was that they have several fine examples of native copper found in float of the Catoctin Formation on their property. Here are a few examples: Classic examples – a bit of malachite in there too, it looks like. I wasn’t totally shocked when I saw these items, since just a month or two ago, I was shown a similar …
22 February 2013
Friday fold: Martin’s metamorphics
A guest “Friday fold” from South Africa: folded gneisses, flavored with other treats of a geological nature.
28 January 2013
Asbestiform ice
I’ve mentioned this phenomenon before, but I thought this was a particularly impressive example, found in my back yard over the weekend. Pipkrakes (ice “fibers”) with iron oxides and oak leaves, Fort Valley, Virginia, January 2013. Dana saw some in Seattle, too.
9 January 2013
Hoerikwaggo Trail 3: Joints, veins, and Liesegang banding
Callan continues his week-long recounting of his five-day backpacking trip from the Cape of Good Hope to Cape Town, South Africa, along the Hoerikwaggo Trail. Today, we examine the jointing, oxidizing and reducing fluid flow, and the emplacement of ore veins.
13 November 2012
Neoacadian Inner Piedmont trip, part II: more Walker Top
Today, I’ve got a batch of additional photos of the Walker Top Granite to share, variably mylonitized (sheared out under ductile conditions)… Nice garnets in some spots: Delta porphyroclast: Lovely sheared-out rocks…
10 November 2012
New GigaPans from the M.A.G.I.C. project
My students Chris Johnson and Robin Rohrback have been busy adding to the Mid-Atlantic Geo-Image Collection. Check out a few of these new GigaPan images: link link link link link
9 November 2012
Friday fold: Boomer Falls
The Friday fold is seen at one of the stops on Callan’s pre-GSA-Charlotte field trip: a small waterfall in North Carolina’s Inner Piedmont.
27 October 2012
Salt crystals in a tidal pool, Hermanus
Last winter, around 10 months ago, Lily and I were walking along the shore of Hermanus, South Africa, when I saw a little closed-drainage pool in the sandstone, harboring a briny distillation of the South Atlantic Ocean. Neat salt “rim” on the edge of the pool… Also note the ~cubic crystals at the bottom of the pool. Super, eh? Supersaturated….
26 June 2012
Leopard rock of the Yaak
After our “pre-honeymoon” sojourn to the Canadian Rockies last summer, Lily and I returned to the U.S. via Porthill, and then drove over to a place I’ve been wanting to visit for a long time: Yaak, Montana. Yaak (or “the Yaak“) is way up in the Kootenai National Forest, in way-way-way-northwesternmost Montana. We camped out nearby, and then in the morning, we rolled into “town,” and had breakfast (“make your …
25 June 2012
Leopard rock
Callan shares some photos of “leopard rock” (porphyritic mafic dikes) seen along the Beartooth Highway, northeast of Yellowstone National Park.
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.