structure

Friday fold: the importance of younging direction

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Today’s edition of the Friday fold is a cross-section: Doesn’t look too spectacular, does it? — “Why, it’s just a bunch of strata folded into anticlines and synclines,” I’ll bet you’re thinking. But no… it’s actually more complicated than that. We know it’s more complicated by examining geopetal primary structures in the strata. Geopetal structures … Read more

Let’s coin a name for this phenomenon

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I didn’t mention it yesterday, but there was one other structure that I saw at my newest outcrop on New 55. This is it: That’s a bunch of fractures. The broken rock is being altered by preferential fluid flow through the fractures. The fluid is not inert; it’s chemically active, and reacting with the rock. … Read more

Snowy detachment

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I think snow can act as a nice analogue for larger-scale rock deformation. I explored this a bit last February, and I was reminded of it again last week, when I walked to my car one morning and saw this: Notice how the slab of snow on the hood (“bonnet” for British readers) of my … Read more

Friday fold(s): a few from Fossen

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Norwegian structural geologist Haaken Fossen contributes two incredible images for this week’s Friday fold: a pavement of drastically-shortened banded iron formation from Minnesota, and a trio of three white granitoid dikes, buckled within a gneiss from the Jotun Nappe, in the Norwegian Caledonides. Gorgeous images of gorgeous folds, with links to the rest of Fossen’s collection.