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You are browsing the archive for neoproterozoic Archives - Page 2 of 6 - Mountain Beltway.

6 June 2016

Cleavage refraction in Konnarock Fm. rhythmites – a virtual sample

Here’s a visualization combination that leverages the advantages of the GIGAmacro system with the 3D ‘virtual sample’ perspective of the Sketchfab-hosted model: the same sample presented in both formats. In this case, it’s a lovely example of cleavage refraction going from meta-clay-shale (now ‘slate’) through a graded bed of fine sand and silt. Link GIGAmacro by Callan Bentley Photoscan model by Marissa Dudek The sample is of the Neoproterozoic Konnarock …

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24 May 2016

Nine new GigaPans from Team M.A.G.I.C.

Alethopteris fern fossil: Link GIGAmacro by Robin Rohrback Rapid River Canyon, Idaho: Link GigaPan by Callan Bentley River cobble of brecciated Columbia River Basalt, Hammer Creek (Salmon River), Idaho: Link GIGAmacro by Callan Bentley Petersburg Granite exposed at Belle Isle, Richmond, Virginia: Link GigaPan by Jeffrey Rollins Ammonite: Link GIGAmacro by Callan Bentley Slickensides in ultramafic rocks of the Wallowa Terrane, just outboard of the paleo-Laurentian tectonic margin, Salmon River, …

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20 April 2016

Cooling columns of the Catoctin Formation, Indian Run Overlook, Shenandoah National Park

An inaugural visit to an outcrop in Shenandoah National Park reveals the signature of lava flows ~600 million years old.

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12 August 2015

Student guest post: the Belt Supergroup in Glacier National Park

As longtime readers know, late summer is when my Rockies students submit their final projects – web-based explanations of key geologic sites they examined during the trip. Today, I offer you a guest blog post by student John Leaming. You’ll notice that I’m not *completely* absent from the post, however – I make a couple of cameos as “sense of scale.” Enjoy, -CB ______________________________________________________________ Glacier National Park, Belt Supergroup I …

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18 July 2015

Purcell Sill → Dike, Grinnell Glacier Cirque, Montana

The Neoproterozoic Purcell Sill is a stark, obvious black stripe in the strata of Glacier National Park. Here it is emerging from behind “The Salamander” glacier, above Grinnell Glacier Cirque: Zooming in, you can see the “baked” (bleached) zones above and below this concordant intrusion. But this time, during my visit to this special place, I noticed a discordant offshoot from the main sill: See it? Up there at the …

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16 March 2015

Mechum River Formation, near Batesville, VA

A quick virtual field trip to the Neoproterozoic glaciogenic sedimentary rocks from the central Virginia Blue Ridge province: Can you feel the chill of Snowball Earth?

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27 January 2015

Miette Group gritstone showing scours, mudchip rip-ups, cross-bedding, and dropstones

The coarser strata of the Neoproterozoic Miette Group in the Canadian Rockies of Alberta record changing water current strength over time, and maybe an iceberg or two.

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12 December 2014

Friday fold: Miette slate, Alberta

The Friday fold returns to Canada, looking at Neoproterozoic slate and quartzite at the southern terminus of the Icefields Parkway. Bonus features include ripple marks, graded beds, cross-bedding, cleavage, and boudinage.

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19 September 2014

Friday fold: Miette Group anticline in Banff National Park, Alberta

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 side of the outcrop, becomes perpendicular to bedding along the crest of the anticline… Happy …

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16 June 2014

Weathering on Old Rag Mountain 1: feeder dikes

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 of full-body rock scrambling on the Ridge Trail, and (3)  it’s long (9.2 miles round …

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