Reader Christian Gronau returns with another “guest Friday fold” submission. Christian writes, Greetings from a cold and wet west coast. A good time to root through old rock samples – and let the imagination run free … The little compilation below strikes me as visually compelling (both photographs are mine) – but how … Read more
It’s Friday! Adam Forte, a geology professor at LSU, posted this image yesterday on Twitter: It’s a box of sheets of newsprint, stored vertically and ignored for a while, now rotated 90° so we’re looking at a cross-sectional view. To me, this is an excellent example of a physical analogue modelling experiment (albeit inadvertent) that … Read more
The Friday fold is a lovely little sandbox analogue model by Prof. Marco Martins-Ferreira, who posted it on Twitter this week: As deformation proceeds, you can see the layers develop folds that then morph into faults, shoving deeper layers atop more shallow strata. As a bonus, you can hear Marco’s baby cooing in the … Read more
Check this out: Maybe I’ve got low blood sugar, but I think I see a magma chamber in that jar of honey. There is clearly some crystal settling going on there, and it appears that the more crystals there are, the easier it is to trap bubbles. When the clots of crystals get too dense, … Read more
So we ended up getting 13 or 14 inches of snow yesterday. It was wet, and the temperature was right around freezing. As soon as it stopped falling, it started melting. One interesting aspect of this is that big wads of slushy snow were plopping off the trees every time a gust of wind came … Read more
Saw this in a greasy / soapy baking pan in my kitchen sink the other day: Do you see those lobe-shaped light areas, separated by dark septae? I think that’s the semi-gelled signature of gravitational instability, perhaps thermally driven. I’m speaking of convection: upwelling in the round light areas, and sinking of denser material in … Read more
Evelyn put up a cat photo on Geokittehs earlier today, and it reminded me of anatexis, the process of partial melting. Anatexis is my favorite way to produce a migmatite. In this model, the light-colored (felsic) ginger cat is derived from the partial melting of another cat, partly dark (mafic) and partly felsic (ginger). Where … Read more
A few shots from Fossil Falls, in the southern Owens Valley, California… This is the now-dry river bed of the Owens River. There’s abundant evidence of water-induced erosion (potholes, polishing, etc.), but nary a drop of water to be seen – Though this particular portion of the Owens River drainage dried up in the Pleistocene, … Read more
On the campus of the University of Texas at El Paso, there is a sign for the Kidd Seismic Observatory. The sign has seen some brittle deformation of its reflective letters. I infer this due be due to differential shrinkage of the letters (relative to the sign they are attached to) in the intense Texas … Read more
We were making dinner last week and took out a block of “silken” tofu* with less care than we should have, and it broke. But what a break! The fracture showed a gorgeous elliptical joint face that broken up into a twisted series of hackles along its fringe: That’s something nice homogeneous fine-grained rocks do, … Read more
Last fall, when I was out backpacking in Dolly Sods, we left one of Lily’s water bottles on the dashboard of the locked (and windows-rolled-up) Subaru. When we got back to the car, we found it had experienced heterogeneous solid-state deformation. I took a few photos, so that those of you who are interested in … Read more
Straight-limbed open synform in an organic-rich formation of limited areal extent, featuring some brittle extensional features at the hinge. Kootenay National Park, British Columbia, summer 2011. (The bridge was broken before we got there.)
Northern Colorado’s route 287 connects Fort Collins, Colorado with Laramie, Wyoming. Along its length, it displays roadcuts into Archean-aged basement complex. Two of these outcrops are featured in this post: one metamorphic (mostly), and a second igneous (mostly), with some intriguing polka-dotted plutons.
The current edition of the Accretionary Wedge geology blog carnival (hosted by Evelyn Mervine of Georneys) is built around the theme of favorite geology words. My favorite geology word is derived from the French boudin, for sausage. It’s “boudinage,” and it’s best said with a heavy French accent and a leering, dirty expression. “Boo-din-ahhdj” I … Read more
This morning, my cat Lola (a.k.a. “LOLa”) had squirmed herself in between the sheets, and it reminded me of something: If this pose inspires you to another LOLcat caption, you can click through for the original image file, unadorned. Modify it as you like, and give us a link to your creation in the comments … Read more
Dana posted early this morning with an invitation to “LOLcat” with a geological flavor. Here’s the best I could come up with: If you’re not familiar with the LOLcat genre, you might want to take a look at a random sampling of LOLcat images for context. Yes: I have the day off today, and can … Read more
My friend JT, who got her MS in geology at the University of Maryland when I did, is now at the Colorado School of Mines working on her PhD in Environmental Science and Engineering. A water main broke outside her house this morning, and I’m pleased that her first thought was to photo-document the resulting … Read more
Here’s a joint extracted from gelatin during this year’s GMU structural geology “Make a Joint” exercise: A soda bottle full of congealed gelatin serves a “rock.” We then use construction clamps to impart a stress field to the gelatin bottle. Into it, we inject fluid plaster of Paris. The extra pore fluid pressure causes a … Read more