Friday fold: Dextral asymmetry in a shear zone, Italy
The Friday fold comes from highly foliated rocks in a shear zone near Tyrol, Italy. It was contributed by reader Samuele Papeschi.
The Friday fold comes from highly foliated rocks in a shear zone near Tyrol, Italy. It was contributed by reader Samuele Papeschi.
Happy Friday! Here are two more folds in gneisses of the Lewisian, in the North West Highlands of Scotland, near Tarbet. Enjoy!
The Friday fold is a sheet of paper. Yes, really!
Explore a dozen photos highlighting the structural geology of an outcrop of limestone and shale near Lexington, Virginia. Cleavage refraction, overturned beds, boudinage, folds, and even a small fossil – we’ve got something for everyone. Bring the whole family!
Garnetiferous beds from the aureole of the Leinster Granite east of Baltinglass, County Wicklow, Ireland (Declan De Paor’s senior thesis mapping area, 1973). Manganese-rich metasediments. The prominent ‘elasticas’ or fan folds (folds with a negative inter-limb angle) are superimposed on isoclinal folds: so the brownish layer at top and bottom are the same, though that … Read more
The scenic arch of Dore Holm (“Door Island”) in Shetland shows off the most efficient way of breaking a slab of rock. The island’s shape is a reflection of the parsimonious nature of natural deformation.
A quest to visit the “first shear zones” described in the scientific literature leads to an alternate location, and some GIGAmacro images of samples from the real, original spot.
As noted previously, my colleague Declan De Paor recently retired from Old Dominion University, and I was lucky enough to inherit some of his rock samples. I’ve been making super-high resolution images of the samples ever since. Here’s a particularly striking fold, weathered out differentially. Enjoy exploring it – and have a happy final Friday … Read more
Don’t you hate it when plate tectonics ruins a perfectly good fossil? This is a sketch of a belemnite from the Swiss Alps: The thing has been broken into segments, with calcite filling the gaps between the segments. What a bummer! Now we’re going to have a much harder time reconstructing the life habits of … Read more
At the birthplace of the term “mylonite,” we can find Friday folds hidden in the foliation.