Cinder cones in Iceland (with lichen)
What makes an Icelandic cinder cone even better? A coating of fuzzy lichens, perhaps…
volcano
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: Link GigaPan by Callan Bentley Link GigaPan by Callan Bentley Link GigaPan by Callan … Read more
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!
Stađarbjargavík
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, … Read more
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:
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: Link Handheld GigaPan by Callan Bentley, stitched with Microsoft ICE _________________________ * “Snay … Read more
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 … Read more
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.
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.
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 … Read more
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 … Read more
Friday fold: Flow banding in obsidian, Newberry Volcano National Monument, Oregon
Lockwood Dewitt is the purveyor of this week’s Friday fold ensemble: All these folds are primary (not tectonic) in nature: they are flow banding of the viscous lava that oozed out to make the Big Obsidian Flow at Newberry. And closer in: One more: Awesome stuff! Thanks for sharing, Lockwood! Happy Friday, everyone!
Epidotized tuff, Tucson Mountains, Arizona
I was in Tucson this past weekend for a book project meeting, and my editor and coauthor and I took a hike on Sunday morning in the Tucson Mountains to Wasson Peak. Not far from the summit, we saw an epidotized tuff, where the fiamme and pumice blobs had undergone reactions to produce pods of … Read more
The lip of the caldera
One last post from my September trip to Greece. Here’s a look north along the inside wall of the central caldera of Santorini, taken from the deck of the Santos Winery. It’s not hard to imagine the volcanic edifice that filled the space to the left (west) prior to The Big One.
Santorini panorama
Here is the view north across the central caldera of Santorini, Greece: Click to enlarge to 9000 pixels wide This caldera formed during the Bronze Age, maybe as early as 1628 BCE or so, maybe as late as 1500 BCE. There are new volcanic islands rising in the center.
Santorini ashfall and Akrotiri
Santorini is an island with nice exposures of the Tethyan subduction complex, yes. But did you know there’s also a volcano there? 🙂 Here’s a shot of some snorkelers, with a lovely stack of pyroclastics rising up behind them. Ash, lapilli, more ash — Santorini’s volcano has been very active over the years. This is … Read more
In search of Santorini’s blueschist, part 1: into the Valley of the Shadow of Ash
While in Santorini, Greece, your humble geoblogger braves a warm afternoon to search the hillsides for evidence of subduction.
Sea arch in pyroclastic deposits, Santorini, Greece
A series of blog posts on the geology of Santorini and Athens, Greece begins with a look at a sea arch on the south shore of Thera.
The wonder of cracking open a xenobomb
On “Border to Beltway”‘s visit to Kilbourne Hole, after we whet our appetite with Hunt’s Hole, Michael finds a xenobomb. Ernie and Boris look on with envy: A “xenobomb” is a xenolith (in this case, of mantle peridotite), slathered in a coating of lava and tossed out of a volcano in the middle of a … Read more
Hunt’s Hole: Climbing ripples in volcanic surge deposits
Check out the immense climbing ripples preserved in surge deposits at Hunt’s Hole (a maar volcanic crater in southern New Mexico) and imagine the strong currents couples with an extraordinary amount of entrained pyroclastic material.