shale

Miette outcrop

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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

Guest post: Red Rock Canyon

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A guest post by Callan’s student Jacob Douma Traveling with Callan Bentley and Pete Berquist through the Canadian Rockies on their Regional Geology Field Course in July 2012, we were exposed to a variety of physiographic features. Among them, was Red Rock Canyon located 16 km from Waterton Townsite within Waterton Lakes National Park, Alberta. … Read more

Visiting the Swift Run

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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

Friday folds: Cape Liptrap

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I got this note via email last week. Hi Callan, First of all, congratulations to your blog. It is just great. I would like to contribute to your “Friday fold” section. A few words about myself. I am born in Austria and did my BSc and MSc at the Montanuniversitaet Leoben. In September 2011 I started … Read more

Slip-shine

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When are sedimentary layers also faults? …When the slab-like layers slip over and under one another during the act of folding. Structures traditionally confined to faults show up on the bedding plane in these circumstances. Callan shares a shiny example from West Virginia in the form of an animated GIF.

Contact of the Campus Andesite with host rocks

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First thing we saw on the post-InTeGrate field trip to the rocks of El Paso, Texas, was this contact between the aforementioned Campus Andesite, and the Cretaceous sedimentary rocks into which it intruded (contact metamorphosed in the area of this photo): I decided to try switching up my annotation fonts. Whaddya think?

Beautiful rust

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Rust swirls on shale fragment, new New Route 55, Valley & Ridge province of West Virginia. I’m not sure if I can call this “Liesegang banding,” since it’s just on the joint surface (two-dimensional) rather than permeating the rock in a three-dimensional blob. Anyhow… It’s pretty.

Sed or meta? Yes.

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Today, two examples of outcrops that reveal an overprinting relationship between metamorphic cleavage and sedimentary bedding. Both are Devonian in depositional age, from the new stretch of New Route 55 in West Virginia, west of Moorefield. The first is from limestones of the Helderberg Group, and the second is from shale of the Brallier Formation. … Read more

Brallier cross-beds

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More evidence of currents in the Devonian deep… Primary structures that give us clues, preserved in a place where preservation over 360 million years isn’t necessarily guaranteed. As you might expect, this turbidity currents roared in from the east, where the mountains were rising, and generating a fair bit of sand and mud, during the … Read more

Friday fold: one from Romney (West Virginia)

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Last weekend, my wife and I joined friends for a weekend of cross-country skiing in the wonderful Canaan Valley of West Virginia. On the way back, between the towns of Burlington and Romney, West Virginia, I saw this folded shale on the north side of Route 50: You can click on that panorama to make … Read more

Two new macro GigaPans

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With my new “macrogigapan” rig from Four Chambers Studio, I produced these images last week as part of my Mid-Atlantic Geo-Image Collection project (M.A.G.I.C.). … Dive in! Porphyritic andesite from the Beartooth Plateau, Montana: Foliated limestone slate, location unknown: Clicking on the word “GigaPan” in the lower right corner will take you to a fuller-screen … Read more

Currents in the Devonian deep

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This blog has been noticeably photo deficient lately! Time to remedy that. Today, I offer you a couple of shots of the Brallier Formation (shale / fine-grained sandstone) in West Virginia’s Valley & Ridge province, a few miles northwest of Moorefield, on the newly-opened section of New Route 55. The Brallier was deposited in a … Read more

Friday fold: cleaved slate in Kootenay National Park

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This summer, a week or two after our wedding, my wife and I found ourselves in the Canadian Rockies for a pre-honeymoon. Part of our time was spent on a backpacking trip to Floe Lake in Kootenay National Park, British Columbia. On our hike in, we passed this outcrop of Chancellor Slate, a Cambrian aged … Read more

A Burgess plume

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At the Burgess Shale this summer, it wasn’t all fun and fossils. I also saw a lovely, distinctly feather-shaped plume: This is an example of plumose structure – the subtle branching micro-topography that forms on the surface of a joint as the fracture propagates out from its origin. The more obvious “rib” that is perpendicular … Read more