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You are browsing the archive for May 2016 - Mountain Beltway.

31 May 2016

A baked horizon in the Columbia River flood basalts

How did this bold orange layer develop? It’s seen in an outcrop near Wilson Creek, Washington, in the Columbia River basalts.

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30 May 2016

Scenes from a cut bank

My family and I went canoeing this weekend, and one of the more photogenic things we saw on the river was this fine cut bank: The bank is being actively undercut by the river, as evidenced by the overhanging soil + grass carpet, the slump scarps at the bottom (showing fresh, wet soil), and the bare tree roots that hang out like orange cables: I also shot a little video …

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27 May 2016

Friday fold: Castile Formation GIGAmacro

I’ve posted here before about the extraordinary intra-layer folds in the varved evaporite deposits of West Texas’ Permian Basin, but today I can go one better and offer a GIGAmacro look at these lovely folds: Link GIGAmacro by Callan Bentley Enjoy checking these amazing small-scale folds out. They will boggle your mind.

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26 May 2016

Glaciotectonic thrust at Waubonsee Community College

Glaciers can cause thrust faults! Explore an example from a trench south of Chicago.

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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 May 2016

Friday fold: core

At the Rocky Mountain Section meeting of the Geological Society of America this week, there were several displays of interesting cores. I’m not sure where this one came from, but it had a fold in it, and since no one else had volunteered a Friday fold for this week, I took a photo: It’s standard core diameter; I’d guess that’s about 2 inches. Given that I’m headed out on an …

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18 May 2016

Pillow basalt exposures in the Columbia River basalts

Pillow basalts form when mafic lava erupts underwater. Here are several examples from the Miocene Columbia River flood basalts, a large igneous province in eastern Washington state.

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17 May 2016

Spheroidal weathering in Columbia River basalt

I’m in Idaho for the Rocky Mountain section meeting of the Geological Society of America. Yesterday, I was delighted to tour around in eastern Washington’s Channeled Scablands with my colleague Bill Richards (North Idaho College). I took a lot of photos, but here are two to start – lovely examples of “onion skin” style weathering in fractured basalt, producing “kernstones” of increasingly spherical shape: This is a particularly well expressed …

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16 May 2016

Trace fossils in the Massanutten Sandstone

Over the weekend, my wife and I took a walk with our son at the Storybrook Trail, an accessible trail with a fine overlook to the east over the Page Valley. There, the Massanutten Sandstone shows a bunch of big beefy trace fossils at this site: both bedding-parallel (Arthophycus-like) and bedding-perpendicular (Skolithos-like) traces. Here’s Bax on a photogenic slab of the quartz arenite, showing the inch-wide bioturbation: A short distance …

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13 May 2016

Friday fold: 3D syncline in Macigno Formation

Alan Pitts is the source of today’s fold, a beautiful 3D model of a differentially-weathered sycline in the Late Oligocene to Early Miocene deep water Macigno Formation from western Tuscany, Italy. Here’s a photo: Now for the 3D model, hosted by Sketchfab; After it loads, use your mouse to grab this thing and finesse it around. What an outcrop! What a great 3D model! Thanks for sharing this, Alan!

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