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7 February 2017

Basaltic strata, faulting, and glaciation in western Iceland

Today, let’s journey to Iceland, to a bit northwest of Reykjavík. This is a view from the top of the Grábrók cinder cone, across the valley to the east. With very few exceptions, Iceland is a big pile of basalt, and that shows through in the walls of this valley, which display a stack of basaltic lava flows, intercalated in places with pyroclastic debris or volcaniclastic sediment. One portion of …

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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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18 February 2016

Sand shadow

A couple of weeks ago, before a series of snowfalsl altered my daily work routine in a destabilizing way, I took a walk through the braided floodplain / gravel fan of Passage Creek, where it exits the Massanutten Mountain system near the state fish hatchery. There, no longer restrained by the steep walls of quartzite, the creek’s water can expand during flood times over a broad forested plain of channel …

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22 September 2015

New LiDAR of the Fort Valley & surrounding area

New LiDAR imagery for the Fort Valley reveals bedrock structures and subtle aspects of fluvial geomorphology.

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12 September 2015

New GigaPans from Team M.A.G.I.C.

Hampshire Formation outcrops on Corridor H, West Virginia: link (Marissa Dudek) link (Callan Bentley) Faults in the Tonoloway Formation, Corridor H, West Virginia: link (Marissa Dudek) Conococheague Formation, showing stromatolites and cross-bedding: link (Callan Bentley) link (Jeffrey Rollins) Tiny folds and faults, from a sample I collected somewhere, sometime… oh well, it’s cool regardless: link (Robin Rohrback-Schiavone) Fern fossil in Llewellyn Formation, St. Clair, Pennsylvania: link (Robin Rohrback-Schiavone) Cross-bedding in …

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8 December 2014

Fluvial geomorphology of Mather Gorge

What hath the Potomac River wrought on the rocks of Mather Gorge? Some interesting shapes to the land surface reveal a fascinating history.

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6 November 2013

Natural Bridge, Yoho National Park: Bedding/cleavage relationships

Check out the scene at Natural Bridge in Yoho National Park, British Columbia, Canada: Don’t confuse this “Natural Bridge” with the one in Virginia. Here, in the western Canadian Rockies, the structural geology is much better. You may recall that I’ve previously featured outcrops from nearby this site as a Friday fold. It’s a great place for examining bedding / cleavage relationships in the rocks. Here’s the previous picture, annotated: …

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1 November 2013

Massanutten trip double-feature

As soon as I got back from GSA, I had to run two field trips, back to back. Both are the same trip: my Historical Geology field trip to the Massanutten Synclinorium. Here’s yesterday’s crew perched on a moderately-dipping slab of Massanutten Sandstone along Passage Creek: Today, it’s the same routine all over again, though the weather ain’t as purty… Here’s Friday’s group at one of the four Veach Gap …

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22 August 2013

Natural Bridge, Virginia

Our three-day karst theme wraps up today with a visit to Natural Bridge, Virginia, an impressive sight: I went to Natural Bridge early last week to give a talk to a group of Road Scholars (an Elderhostel-like program) about the Snowball Earth. Part of my compensation for the talk was a night’s lodging at the Natural Bridge hotel, meals, and tickets to the Natural Bridge’s suite of six tourist attractions, …

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12 March 2013

Five new GigaPans from Thoroughfare Gap

Yesterday, I took five new GigaPans at Thoroughfare Gap, a water gap where Broad Run cuts through Bull Run Mountain, the eastern limb of the Blue Ridge Anticlinorium at my latitude. The rocks here are the Cambrian-aged Chilhowee Group, with bedding tilted moderately to the east during Alleghanian mountain-building in the late Paleozoic. To the west is the crystalline core of this massive regional fold, and to the east is …

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