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22 September 2017

Friday fold: bend in a vesicular lava flow, Etna

It’s the First Friday of Fall! Here’s a sort of fold to help you celebrate: a section through a ∧ shaped bend in a vesicular basalt flow from the eastern flanks of Mount Etna in Sicily. It’s due to volcanic lava flowing rather than ductile deformation of a pre-existing solid rock (our usual habit with this feature), but I think we can appreciate it regardless:


15 July 2017

Flow-banded rhyolite from Vulcano, Italy

I collected only a single rock on my summer travels in France and Italy. (Those of you who know me will realize how extraordinary this low number is!) It’s a flow-banded rhyolite from Vulcano, in the Aeolian Islands north of Sicily a few weeks ago. It contains porphyritic vesicular basalt xenoliths. I featured a similar sample on Twitter yesterday on the occasion (supposedly) of “International Rock Day”: For #InternationalRockDay , …


15 May 2017

Monday Geology Picture: Pahoehoe Lava Flow

For this week’s “Monday Geology Picture” here’s a stunning example of a pahoehoe lava flow. I took this picture back in March when I visited Piton de la Fournaise volcano on Réunion Island. I’ll be sharing more pictures from Réunion soon – stay tuned!


1 May 2017

Accretionary lapilli from Archean volcanic eruptions

Volcanic “hailstones” called accretionary lapilli rained down on South Africa 3 billion years ago, and have survived to be seen in the present day, along the R40 road through Barberton Mountain Land, near the Bulembu border crossing into Swaziland.


26 April 2017

Pseudocraters at Lake Mývatn, Iceland

Near the southern end of Lake Mývatn, astride the Mid-Atlantic Rift in northern Iceland, lies a field of “pseudocraters” that result from steam explosions beneath a fresh lava flow. Put on your head-net and join us to check it out!


2 March 2017

A virtual field trip to the Grind of the Navir

On the northwestern coast of the Northmavine Peninsula of Shetland, there is an unusual coastal landform: a gate-like entrance to an elevated amphitheater, like something out of Tolkien, and a storm beach of slab-like boulders inland of that.


1 February 2017

An oddball at Eshaness

In eastern Shetland, the sea chews away at the innards of a Devonian stratovolcano. But there’s an odd visitor there too – and we’re not talking about the blogger.


11 January 2017

More Messengers from the Mantle

Since I showed off the 3D kimberlite intrusion breccias yesterday, I feel as if I owe you some other photos from that lovely exhibit at the IGC. I apologize for the poor quality of these photos – the gorgeous samples were behind glass and brightly lit, which made photography difficult. But the rocks are sooooooooo pretty, I think you’ll enjoy viewing them just the same. Let’s start with a gargantuan …


5 December 2016

Cinder cones in Iceland (with lichen)

What makes an Icelandic cinder cone even better? A coating of fuzzy lichens, perhaps…


24 October 2016

GIGAmacro views of komatiite

Erik Klemetti posted today at Eruptions about komatiite, which is apropos, considering I just finished imaging some samples of that ultramafic volcanic rock. Have a look at three samples from Barberton Greenstone Belt here, each from the 3.27 Ga Weltevreden Formation: [gigapan src=”,hidetitle/iframe/flash.html” height=”250″ scrolling=”no” width=”100%”] Link GigaPan by Callan Bentley [gigapan src=”,hidetitle/iframe/flash.html” height=”250″ scrolling=”no” width=”100%”] Link GigaPan by Callan Bentley [gigapan src=”,hidetitle/iframe/flash.html” height=”250″ scrolling=”no” width=”100%”] Link GigaPan by Callan …


6 October 2016

Oddball Icelandic rocks, part I: A green ignimbrite

Iceland does basalt really, really well. But there are a few non-basaltic igneous rocks to be found there, too. One of them is a green ignimbrite (pyroclastic conglomerate) that crops out in coastal Berufjörður, eastern Iceland. Check it out!


21 September 2016


Based on this photo, what do you think Stađarbjargavík might have to offer? If you guessed columnar jointing in basalt, you’d be right! Looking down the fjord, south of Hofsós (in Iceland): The place is basically a series of miniature Giant’s Causeways, full of unpopulated exemplars of cooling columns! Little coves separate the small peninsulas, each filled with rounded column bits: Here’s a spot where one more is about to …


15 September 2016

Pillow basalts from eastern Washington: a 3D model

Since I showed off some Icelandic pillow basalts yesterday, today I thought I would showcase a new 3D model of big pillows in Columbia River basalt of eastern Washington, taken from a photo set I made when I was out there in May:


14 September 2016

Pillows in Icelandic basalts

Time is short these days, but I know you hanker for amazing geology. How about some pillow basalts from the Snæfellsnes* Peninsula, far western Iceland? Note the cm-demarcated pencil for scale. See if you can find it in the GigaPan version below: [gigapan src=”,hidetitle/iframe/flash.html” height=”250″ scrolling=”no” width=”100%”] Link Handheld GigaPan by Callan Bentley, stitched with Microsoft ICE _________________________ * “Snay full snooze”


4 July 2016

Virtual field trip to Kinkell Braes, Scotland

Walking along the shore east from St. Andrews, Scotland, along the seaside sandstones of Kinkell Braes, you encounter several extraordinary examples of geology. It’s a great place for the next stop on our Grand Tour of the geology of the British Isles. Here’s the scene: The first stop is a giant eurypterid trackway, potentially the largest invertebrate trackway in the world (Whyte, 2005), on the underside of an overhanging sandstone …


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.


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.


15 April 2016

Friday fold: Shiny pahoehoe

James Farrell is our newest Friday fold source. Today he shares a primary (not tectonic)  fold – the fold is in the ropy texture of a pahoehoe flow: Those colors! What a gorgeous rock. Thanks for sharing, James! You, too, can share your folds here. Send me your images. I look forward to featuring them on the Friday fold!


17 March 2016

3D virtual sample of a deep sea pillow basalt

Our local NSF geoscience education guru, Jill Karsten, is retiring. She and her husband, Rodey Batiza, are packing up their lives and moving back home, vacating the Beltway for good. This might be viewed as a shame as far as geoscience education funding is concerned: Jill has made her mark acting as an advocate of diversifying the geoscience workforce. I hope they get someone similarly awesome to replace her at …


30 September 2013

Monday Geology Picture(s): Stunning Shots of Santorini

Last week I shared a lovely view of Santorini taken by my friends Patrick and Nia during their vacation back in June. This week I thought I’d share several more of their Santorini shots. Some of them are quite stunning. Enjoy! When Patrick and Nia sent through these pictures to me, my husband commented: Ah, a geologist’s nightmare. Photographs without scale! Except for the one with the boat… and the …