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9 February 2017

Gabion

Gabion

Do you remember the blog post four years ago about documenting the doomed outcrops at Scientists’ Cliffs, Maryland? It was the site of gorgeous Miocene fossil exposures in the Calvert Formation. Here’s what the site looks like now: Photo by Peter Vogt   That ugly thing at the base of the cliff is a gabion, protecting the houses on the clifftop and making fossil access impossible. I’m glad we got …

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7 February 2017

Basaltic strata, faulting, and glaciation in western Iceland

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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16 January 2017

Shear zones in Scottish gabbros

Shear zones in Scottish gabbros

A quest to visit the “first shear zones” described in the scientific literature leads to an alternate location, and some GIGAmacro images of samples from the real, original spot.

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13 January 2017

Friday fold: Smaull Graywacke at Saligo Bay, Islay

Friday fold: Smaull Graywacke at Saligo Bay, Islay

On the western coast of Islay, Saligo Bay showcases turbidites of the Neoproterozoic Colonsay Group. The Smaull Graywacke shows Caledonian (late Ordovician) folding and cleavage superimposed on world-class graded bedding. There’s also a nice dolerite dike to examine.

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30 December 2016

Friday fold: one from the archive

Friday fold: one from the archive

As noted previously, my colleague Declan De Paor recently retired from Old Dominion University, and I was lucky enough to inherit some of his rock samples. I’ve been making super-high resolution images of the samples ever since. Here’s a particularly striking fold, weathered out differentially. Enjoy exploring it – and have a happy final Friday of 2016! Link 2.04 Gpx GIGAmacro by Callan Bentley (If the embedded GigaPan doesn’t work …

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8 December 2016

Silent samples, holey samples

Silent samples, holey samples

Two very different samples tell stories that are full of holes. What’s going on with this weathered sandstone? What’s going on with this fossil scallop shell?

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29 November 2016

Islay’s Port Askaig tillite

Islay's Port Askaig tillite

The Port Askaig Tillite is a Neoproterozoic diamictite on the eastern shore of Islay (Scotland) that may record a “Snowball Earth” glaciation.

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25 November 2016

Friday fold: intrafolial folds in Eriboll mylonite

Friday fold: intrafolial folds in Eriboll mylonite

At the birthplace of the term “mylonite,” we can find Friday folds hidden in the foliation.

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21 November 2016

GIGAmacro sample preparation: 3 techniques

Here are three pairs of GIGAmacro images to illustrate a few techniques I’ve used in preparing the samples and the images. The image pairs here illustrate the effects of transparent acrylic coatings, pressure-washing, and post-imaging clean-up in Photoshop. Let’s begin with a meta-ignimbrite of the Catoctin Formation, cut with a rock saw and polished using a handheld grinding wheel with diamond grit pads, and then with one of the two …

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16 November 2016

Cobble diversity of Fetlar’s beaches

Now that we’ve examined the geology of the outcrops at Funzie Bay on the island of Fetlar in northeast Shetland, let’s stroll along two beaches. Here we have cobbles from Funzie Beach and a small beach eroded from serpentenite and metaharzburgite of the island’s ophiolite complex. Compare. Contrast. Rejoice. Link GigaPan by Callan Bentley Link GigaPan by Callan Bentley Both of these were handheld panoramas of ~60 photos apiece. It’s …

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