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1 April 2013

“Outcrops” on the barn at Peirce Mill, DC

The Friday before last, I was in DC for a fun geology/botany field trip, and I got the opportunity to stroll around the barn at historic Peirce Mill, a historical grain mill along Rock Creek in Rock Creek Park, Washington, DC. The barn is immediately south of Tilden Street NW. It appears to have been constructed from local stone: metamorphic rocks of the Rock Creek Shear Zone, a ductile fault …

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26 March 2013

Spheroidal weathering in Laurel Formation

Another thing I saw last Friday on my DC field trip was this fine boulder exhibiting spheroidal weathering: Annotated: It’s a boulder of the Laurel Formation, a clast-poor metamorphic unit found east of the Rock Creek Shear Zone in DC. This is the first time I’ve seen it exhibit this sort of mechanical weathering. Compare it to this example from Montana or this example from the Causeway basalts of Northern …

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23 March 2013

Skunk Cabbage

On Friday, I took a field trip to DC with Geologic Map of the Washington West Quadrangle author Tony Fleming, City of Alexandria Natural Resource Specialist/Plant Ecologist Rod Simmons, and a host of interested folks from many different professions and localities. We were interested in looking at ecological relationships between rocks and plants, and had a pleasant afternoon hiking through Rock Creek Park. We also got in a little archaeology! …

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20 December 2011

Video book review: “Smithsonian Institution Secretary, Charles Doolittle Walcott”

Here’s where to get yourself a copy: Smithsonian Institution Secretary, Charles Doolittle Walcott My visit to Walcott’s grave (alluded to in the video) is here.

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28 August 2011

Damage to the Ecuadorian Embassy

My wife Lily is an Ecuadorian citizen. She was born in Quito, and we have traveled there together. (She’s also a U.S. citizen.) After the big earthquake on Tuesday, significant structural damage was reported at several Washington landmarks including the Washington Monument and the Smithsonian Castle. Another one, less recognizable to most folks, but key in our personal geography, is the Embassy of Ecuador. Not only is it an outpost …

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27 August 2011

Why those curves, Rock Creek?

On Tuesday morning, before the earthquake hit, I answered an e-mail about DC faults. I get unsolicited e-mails all the time (and occasionally phone calls, too). The contact comes from people who have a geological question, find my blog, and figure that I might be willing to answer it for them, or to direct them to someone more knowledgeable. Sometimes they ask me to identify a rock. I see answering …

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24 August 2011

Cracking up

Callan shares a geological analogue that developed in his house yesterday: en echelon tension fractures, common in sheared rocks, appeared on his ceiling due to the Mineral, Virginia earthquake.

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9 June 2011

The annual summer routine of Mr. Callan X. Bentley

Callan gets ready for a summer of travels out in the Rocky Mountains, including teaching a field geology course, participating in a workshop about teaching energy, visiting the Burgess Shale, and… getting married!

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7 June 2011

The grave of John Wesley Powell

Callan visits the grave of John Wesley Powell, second director of the USGS and explorer of the Grand Canyon, on an afternoon in Arlington National Cemetery.

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6 June 2011

DCSWA tour

Yesterday, I took about fifteen members of the DC Science Writer’s Association on a walking tour of DC’s geology. I was honored to present the capital city’s epic geologic story to an esteemed crowd of professional science writers from Nature, Science, the National Academies, the National Institutes of Health, the Washington Post, and other institutions. Here are a few photos that Harvey Leifert took on the trip: …Evidently I gesticulate …

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