You are browsing the archive for May 2012 - Page 3 of 3 - Mountain Beltway.
9 May 2012
Overturned bedding in the Weverton (?) Formation
On Monday, I was out in the field at the Blue Ridge / Valley & Ridge transition (“boundary”?) in the Elkton East quadrangle, where Chuck Bailey and students (from the College of William & Mary) were leading a field review of their new geologic map. A field review is a form of field-based peer review, wherein the authors of a new geologic map take peers and interested others out into …
7 May 2012
Clark’s nutcracker on Sulphur Mountain
Friday it was geese. Today, it’s a Clark’s nutcracker: The Clark’s nutcracker is a beefy alpine corvid (perching birds related to crows) of the American west. It’s a great bird in my mind, because if you’re looking at one, it means you’re up in the high country. It means you’re out where the good stuff happens. The bird is named for William Clark, of the Lewis & Clark Expedition. There …
4 May 2012
Friday fold: ball & pillow in volcanic ash
Another guest Friday fold – this one supplied by Ander Sundell of the College of Western Idaho, and his student Katie Ursenbach, who took the shot and gave permission for me to re-post it here. You’re looking at cuspate-lobate folds due to primary sedimentary settling. the Snake River Canyon in southwestern Idaho. A pile of volcanic ash erupted into water in the Paleogene, and soon after covered by a series …
Geese at NOVA
A couple of visitors above the entrance to my building on campus today: They’re honking greetings to all the students showing up for 8am exams…
3 May 2012
Big old vesicles!
Today, for your viewing pleasure, I offer you: A series of big honkin’ gas pockets in a 615 ka basaltic lava flow in the Owens Valley of California. This same lava flow has been featured here before, since it imparted a lovely contact metamorphism to the alluvial fan over which it erupted. These things are weird – they’re all about the same size and the same shape (and the same …
2 May 2012
Veins perpendicular to foliation
To recap the week so far here on Mountain Beltway: On Monday we looked at some sweet vertical boudinage along the plane of tectonic cleavage (not to mention those folds in a (formerly) horizontal granite dike, now bearing vertical axial planes), and then on Tuesday we looked at a horizontal cut through that same outcrop, and it showed moderately distorted lava pillows, And now today, let’s look at one more …
1 May 2012
Deformed pillow basalts from southern Ontario
Have you ever seen Archean pillow basalts? How about Archean pillow basalts that have grown much taller through vertical extrusion along a ductile shear zone? Come to the southern Superior Craton to see more!