Today’s featured Friday fold comes to us from “Effjot” – an environmental engineer with a focus on groundwater. In reply to my plea for fold imagery several weeks ago, he shared this example from Germany:
I note the well developed gently-inclined cleavage in the muddier layers, as well as the layer-perpendicular jointing in the blockier layers. Both limbs dip to the left, one steeply and one subhorizontally. The cleavage also dips that same direction, meaning that all else being equal, this steep limb (main focus of the photograph) is tectonically overturned.
Zoom in & see what I mean:
…Which is to say:
More detail in this blog post by the source author. (but it’s in German)
Also, he told me that, “This is the first fold I’ve come across as a child and realised rock could be bent. The first foundation for my interest in geology.”
What a great moment to have anchored in one’s memory – Realizing rock can bend – that’s huge! I remember a particular boulder of pinkish vein quartz that I learned as a child was called “rose quartz,” a term for a discrete phenomenon I could observe. Other phenomena, other terms would follow. For me, that boulder was my “geo-anchor,” the beginning of my Earth science awareness. This fold was Effjot’s.
Readers: Do you have a similar memory of the moment that geoscience became a subject of interest for you? If so, please share.
I was 11, and had planned to be a vet, when a friend took me to visit an acquaintance in Cullinan, North of Pretoria in the old Transvaal Province of South Africa. This gentleman had a typical South African farm house with verandas all the way round (stoeps to a South African) and he had the most amazing collection of rocks – not minerals, rocks – all around it. I was completely enchanted. From then on I only ever wanted to be a geologist. It took me a while to get there!
Thanks for linking to this age-old post of mine! There’s an English version, with a little less detail, and the stylesheet (esp. for the stratigraphic table) is broken for unknown reasons. In case the automatic language switcher doesn’t work, use this link:
http://blog.effjot.net/en/2009/01/falte-an-der-riedbergpasstrase-im-allgau/
seeing fern fossils in shale in Pennsylvania at age 6!
geologist from then on and still am 60 years later!!
ps love your blogs – keeps mr fresh on structural geo 🙂
Picking up a piece of phyllite in my back yard, looking at the subtle iridescent ripples on its surface, and thinking it was a fragment of a man-made object, then realizing it wasn’t.
Seeing a big outcrop of fractured, folded rock, stacks of it sticking up near each other but leaning in crazy different directions like a group of drunken sailors on shore leave, and thinking, “What the heck happened here?”
Realizing that geology explained how both those things came to be that way.
The moment I knew geoscience was of interest to me was sitting in a geology class in learning how the Massanutten Synclinorium was created. I’ve never been more interested in learning geomorphology. Also being able to see a transgression right in front of my face on corridor H in WV was totally unbelievable.
Mitch!!
Thanks – glad to know this was own class!
🙂