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You are browsing the archive for 2010 April.

29 April 2010

Sistine Delta

Today’s imagery put me in mind of two hands reaching for one another: What do you think? Shocking coincidence? Or a bit of a stretch?

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Mineral phantasms?

Ice… serpentine… halite… What do they all have in common? I’ve discussed mineral “ghosts” here before — really, those are only pseudomorphs, where one mineral’s chemistry becomes unstable due to a change in conditions, and then a new mineral forms in the same space. I’ve also brought up the issue of clasts of minerals which are unstable over the long term (ice). Last night, at the final meeting of the …

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28 April 2010

Flames and pillows, Route 55

I took a look at some interesting blobby structures in the Swift Run Formation last week, and walked readers through my logic in tentatively concluding that they were ball & pillow structures (soft sediment deformation), though overprinted by a pervasive (Alleghanian) cleavage. As we move west in the Appalachian mountain belt, the rocks are less cleaved: the strain is instead taken up in large anticlines and synclines with a few …

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27 April 2010

A small gift

I have a student this semester, Diane, who is a flight attendant. Every weekend, she’s off to some cool European city with her husband, a pilot. Up until now, she’s been bringing me little gifts of beer from each trip. She drops 60 cents in Germany, and then that week I get to taste a new variety of ale or lager. Very, very cool! This weekend, it was off to …

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Macrobeetle

A macro shot of a beetle (length ~11 mm) I saw on the wildlife-rich George Mason University structure trip two weekends ago… Neat iridescence, eh? I love macro photography, especially of bugs.

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26 April 2010

3,2,1, Contact!

On my structure field trip just over a week ago, we found the contact between the Mesoproterozoic-aged Blue Ridge basement complex and the overlying Neoproterozoic Catoctin flood basalts (now metamorphosed to greenstone). This nonconformity can be found just west of the Appalachian Trail at the Little Stony Man parking area in Shenandoah National Park. Here’s four photos, with my left index finger for scale, in raw and annotated versions: It’s …

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25 April 2010

Heroes

For the twenty-fourth edition of the Accretionary Wedge, I selected “heroes” as the theme. For those of you new to the geoblogosphere, the Accretionary Wedge is a ~monthly geoblog “carnival,” wherein various and sundry geobloggers write posts on a common theme. Broadly speaking, submissions to this edition fell into three categories: (1) professional heroes, (2) personal heroes, and (3) individuals who were both professional and personal heroes. The ‘pros’: Neil …

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Larry Wiseman is my hero

I have many heroes, but the one I would like to pay tribute to today is Larry Wiseman, my mentor through my undergraduate years at William & Mary and beyond. Now, Larry is a biologist, not a geologist — but he probably did more to frame my life’s work than any other individual. At William & Mary, Larry was chair of the biology department, and taught the first semester intro …

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23 April 2010

Ball & pillow in cleaved Swift Run Formation?

On my structural geology field trip this past weekend, I made one major modification compared to last year’s iteration. I added a fifth detailed “field study area” at an outcrop of the Swift Run Formation, a Neoproterozoic sedimentary unit that is discontinuous in extent between the underlying Blue Ridge basement complex and overlying Catoctin Formation meta-basalts. A month ago, I didn’t know about this location, but I was introduced to …

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22 April 2010

Earth Day

… So, today is: … and not only that, it’s the 40th anniversary of the first “Earth Day.” Shall we reflect? Yes, let’s shall. My career as a geoscientist was largely inspired by desire to spend time outside, and that in turn was inspired by a lot of positive outdoor experiences as a child and young man. I feel at peace and satisfied when I am spending time in natural …

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