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