Here’s an outcrop of Miette Group slate, seen at the intersection of the Icefields Parkway with the Trans-Canada Highway, just north of Lake Louise, Alberta: There’s a lovely anticline just to the right of Zack, who obligingly provided a sense of scale. Also note how cleavage which is subparallel to bedding on the far left … Read more
Old Rag Mountain is a distinctive mountain in the eastern Blue Ridge of Virginia, contained in a little lobe of Shenandoah National Park. It’s a great hike on several levels: (1) it’s got no trees on the summit, so you can actually get a decent view from on top, (2) it’s got a great section … Read more
Lily and I took our son to the Virginia Scottish Games on Sunday. This is an annual competition of events in traditionally Scottish feats – throwing heavy things, mainly. There is also fried food, whisky, and some terrific music. The event is held at the Great Meadow, south of The Plains, Virginia. I had never … Read more
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 … Read more
More folds from the charismatic Noonday Dolostone in Mosaic Canyon, Death Valley National Park, California: Annotated: Happy Friday!
Callan and his colleague Jay Kaufman (University of Maryland) go to extraordinary lengths to document an intriguing block of rock in northern Virginia’s Blue Ridge province. Great images and a lot of fun result – but what do these rocks tell us?
I took a trip down to Charlottesville this week for a couple of meetings, and I made time along the way to capture two new GigaPans of the lovely exposures of Catoctin Formation greenstone at Rockfish Gap, where Interstate 64 traverses the Blue Ridge. This is very close to the southernmost tip of Shenandoah National … Read more
Callan attends the Geological Society of Washington’s fall field trip, examining the relationship between grape-growing and the underlying geology of two provinces in northern Virginia: the Blue Ridge and the Valley & Ridge. With GSW compatriots, Callan visits Hume Vineyards in the Blue Ridge basement complex and North Mountain Winery in the Shenandoah Valley. This is part I.
Here’s a cool outcrop of the Neoproterozoic Miette Group. Most of the Miette is classified as “slate” and “gritstone,” through these particular exposures, on the Icefields Parkway south of Jasper, are fine-grained and lacking in slaty cleavage. They don’t seem to have been too metamorphosed at all right here, as Sebastian shows in this photo: … Read more
Callan presents a collection of well-exposed amygdules, seen along the Dark Hollow Falls trail in Shenandoah National Park, Virginia. These white dots on a green background are the signatures of (1) Iapetan rifting, and (2) Alleghanian metamorphism.
I’m playing around with Microsoft Expression screen capture for the book project I’m working on, and here is a video I worked up yesterday as a demonstration of this new way of telling a geologic story: The Grenville Orogeny and the rifting of Rodinia (opening of the Iapetus Ocean): [youtube=”www.youtube.com/watch?v=g6itZWD8bQc”] I’m frustrated by the way … Read more
The Friday fold is a contribution from the Massachusetts Geological Survey. It shows a migmatite with lovely structure. An upcoming (free) field trip to this location will be part of the 2012 Structural Geology and Tectonics Forum: an event readers may be interested in attending
I took my structural geology students to that fine outcrop of the Swift Run Formation in eastern Shenandoah National Park on Friday. There, we saw lovely primary structures with tectonic fabric overprinting (as I have showcased here previously). Consider this graded bed with subsequent (vertical) cleavage: And here’s the hinge of a nice passive fold, … Read more
Last Saturday, before the rains moved in…
Some tafoni (pattern of little weathering pits) expressed on Malmesbury Group (~700 Ma) turbidite sandstones at a little outcrop on the eastern shore of False Bay, South Africa: That last one seems to have some concentric layering to the tafoni pits – exfoliation? Spheroidal weathering? Hmm…
In December, Callan found an outcrop of Neoproterozoic-aged turbidites in South Africa, on the eastern shore of False Bay.
Callan visits the Sea Point migmatite, a contact between intrusive granite and older metasedimentary rocks, along the west coast of South Africa near Cape Town. His guide? None other than AGU Blogosphere blogger Evelyn Mervine of Georneys!
More pillow-like structures, seen in the Catoctin Formation, on the west side of the Blue Ridge Parkway about ten miles south of Interstate 64. Mini Sharpie for scale – what do you think? They don’t seem to be as strongly fracture-controlled as the Stony Man area “pillows.” But dang, they sure are small… Read the … Read more
Callan and three students visit a world-class outcrop of columnar jointing in Shenandoah National Park.
I saw this boulder lining a garden this past weekend down in Nellysford, Virginia, in the scenic valley of the Rockfish River draining the eastern slope of the Blue Ridge. It’s a piece of the Neoproterozoic-aged Catoctin Formation, a series of lava flows and associated rocks that erupted on the breakup of the early supercontinent … Read more