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22 September 2017
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 September 2017
The Friday fold comes from highly foliated rocks in a shear zone near Tyrol, Italy. It was contributed by reader Samuele Papeschi.
25 August 2017
Okay, I’ll admit this is a bit of a stretch, but here’s your Friday fold: The mosaic-covered floor of this long hallway in the Villa Romana di Casale in central Sicily shows profound warping. The middle shadowed area sags downward by at least a meter, maybe more. It’s not a geological material that’s been deformed, but an architectural element instead. Still: the principle of original horizontality applies to floors as …
18 August 2017
When in Rome, do Friday folds as the Romans do? Here are some images from my brief, sweltering visit to the Roman Forum(s) this past summer. The whole region is a jumblepile of ancient ruins in a thousand styles. Almost nothing is labeled. It looks like this: This particular building held up a bit better, and its lovely columns sported some folded marbles: Close-up shots to show the folding internal …
21 July 2017
My friend Ander Sundell at the College of Western Idaho is the source of today’s Friday fold. It’s from somewhere in Sardinia, and I think you’ll find it visually striking: Ander says: The rocks here are Silurian phyllites generated from mudstones that were deposited on the floor of the rheic ocean basin. The color and grain size variation do an excellent job highlighting compositional layering. They were deformed during the …
18 July 2017
I’ve just finished three weeks of travel in Italy, and I was absolutely delighted to read this terrific book by Walter Alvarez while I was there. Alvarez is famous the world over for being the nucleus of the team that proposed an extraterrestrial meteorite impact as the cause of the end-Cretaceous extinction, prompted to that bold hypothesis by the discovery that the clay seam marking the boundary between the Mesozoic …
15 July 2017
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 , …
14 July 2017
The Friday fold visits the Apennine Range of central Italy.
7 July 2017
It’s Friday. Let’s find a historic sort of Friday fold in the ruins of Herculaneum, Naples, Italy.
23 June 2017
I was in southern France last week, exploring an awesome suite of caves cut into the Causses limestone plateau. My family and I took an afternoon to paddle a canoe down 5 kilometers of the Célé River. While floating along, we spied a gentle, open fold in the limestone layers that crop out along the banks. This low-amplitude fold is highlighted with the “horizontal” reference line of the river’s edge. …
26 May 2017
It’s Friday. We return to Italy’s Macigno Formation for a fold, courtesy of blog reader Samuele Papeschi.
11 May 2017
The Seven Hills of Rome: A Geological Tour of the Eternal City, by Grant Heiken, Renato Funiciello, and Donatella de Rita
I’m preparing for some time in Italy this summer, and picked up a couple of books to bring me up to speed geologically. The first is a geological guide for Rome. It’s structured around the archetypal “seven hills” of Rome, but the story is simpler in many regards than some other seven-hilled European capitals I could name. Rome’s geology appears to consist of four major units: older sedimentary rocks (which …
4 May 2017
Seventy-five percent of EU inhabitants depend on groundwater for their water supply, which makes groundwater management extremely important. To manage groundwater effectively during drought periods like 2015, data about groundwater levels are needed in (near-) real time.
20 June 2016
Want a geological irony? Here’s one! You’re looking at a rounded boulder of Cushendun Conglomerate, a Devonian “Old Red Sandstone” unit (Cross Slieve Group) exposed at Cushendun Caves, Northern Ireland, U.K. The irony lies in the repetition of history – a tumbling environment of high water energy, rounding cobbles and boulders and depositing them, in order to make the conglomerate. And now, ~400 million years later, history repeats itself, with …
13 May 2016
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. [sketchfab id=”3f0259ea2c6b4807a32fe3c950d13324″ start=”0″ spin=”” controls=”0″] What an outcrop! What a great 3D model! Thanks …
2 April 2016
Here are a few new images I’ve been working on with my home-based Magnify2 imaging system from GIGAmacro. Strophomenid brachiopods from Mississippian Mauch Chunk Formation, West Virginia: [gigapan src=”http://gigapan.org/gigapans/185738/options/nosnapshots,hidetitle/iframe/flash.html” height=”250″ scrolling=”no” width=”100%”] Link Boninite from New Caledonia: [gigapan src=”http://gigapan.org/gigapans/185707/options/nosnapshots,hidetitle/iframe/flash.html” height=”250″ scrolling=”no” width=”100%”] Link Lepidodendron scale-tree bark from Poland: [gigapan src=”http://gigapan.org/gigapans/185689/options/nosnapshots,hidetitle/iframe/flash.html” height=”250″ scrolling=”no” width=”100%”] Link Potassium feldspar crystal, from a pegmatite: [gigapan src=”http://gigapan.org/gigapans/185688/options/nosnapshots,hidetitle/iframe/flash.html” height=”250″ scrolling=”no” width=”100%”] Link Catoctin Formation greenstone from …
4 December 2015
Samuele Jæger Papeschi shares one more fold with us: some deformation here… type III (Ramsay…) interference pattern in Cretaceous calcschists… Cavo, Elba Island Awesome! I hope everyone has a great Friday.
20 November 2015
Samuele Jæger Papeschi not only provided this week’s Friday fold, but he also serves as its sense of scale: According to Samuele, these are: folded metalimestones in Punta delle Rocchette, Grosseto. This are pretty interesting transected folds, showing about 10 degrees of foliation dip in respect to their axis Thanks for sharing, Samuele, and happy Friday, all!
13 November 2015
Samuele Jæger Papeschi is the source for today’s fold: Those are: chevron-folds in radiolarian cherts – Jurassic radiolariti fm. – Quercianella – Leghorn, Italy Cool. They look a lot like the chevron-folded cherts near San Francisco. Same age, too.