6 September 2019

Friday fold: Gonzen, Switzerland

Posted by Callan Bentley

Science writer Gabe Popkin shared two fold photos with me this week – both from near Sargans, Switzerland, adjacent to the Rhine River Valley and the border with Lichtenstein. The photos shows the mountain called Gonzen. There, Jurassic limestones crop out in a very wavy pattern:

I don’t know the geology of this area in any kind of detail, but I decided to trace out a distinctive upper surface of these limestone beds to get a better sense of what’s going on.

…The big central antiform appears to be overturned!

It occurred to me that this potentially implies some faulting, like this:

These are merely armchair speculations as I try to make sense of the pixels in the photo – but it makes me eager to go and visit the Alps to see these rocks in person! In the interest of “doing my homework” on the site in the limited amount of time I have this week, I found this paper, which seems to show at least one thrust fault on the mountain in one figure, and suggests these Jurassic limestones are part of Glarus Nappe Complex just to the southwest, which would be awesome.

If anyone reading the blog knows more about this area, please chime in below…

Thanks for sharing the images, Gabe!

Happy Friday, all.